Buzzer and method of manufacturing the buzzer

Abstract

To provide a method of manufacturing a buzzer that can reduce sound pressure variance of a sound that the buzzer generates.SOLUTION: In a process of manufacturing a buzzer, an enclosure cover 16 is pressed in and coupled to an enclosure base 15 to form a resonance chamber 14a between the enclosure base 15 and enclosure cover 16. The capacity of the resonance chamber 14a is therefore so adjusted that the sound pressure of the buzzer 10 is within a predetermined allowable range. Therefore, even if a piezoelectric diaphragm varies in resonance frequency, the enclosure resonance frequency determined by the size of the resonance chamber 14a can be adjusted according to the resonance frequency of the piezoelectric diaphragm. Then the sound pressure of the buzzer 10 increases and decreases according to the frequency difference between the resonance frequency of the piezoelectric diaphragm and the resonance frequency of the enclosure, so that variance in sound pressure of the buzzer 10 can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a buzzer and a method for manufacturing the buzzer. [Background technology]

[0002] Patent Document 1 describes a piezoelectric buzzer. The piezoelectric buzzer in Patent Document 1 includes an outer case in which a sound emission hole and an opening are formed, and a buzzer unit having circuit components including a piezoelectric diaphragm. The buzzer unit is assembled to the outer case in a press-fit state. A resonance chamber for increasing the sound pressure of the sound emitted from the sound emission hole is formed within the outer case as a result of the buzzer unit being press-fitted into the outer case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-237473 Summary of the Invention [Problem to be solved by the invention]

[0004] In a buzzer, sound pressure at the drive frequency is ensured by the resonance of the piezoelectric diaphragm and the housing. However, in the piezoelectric buzzer of Patent Document 1, the manufacturing process cannot adjust either the resonance frequency of the piezoelectric diaphragm or the resonance frequency determined by the size of the resonance chamber in the housing, so there is no means for adjusting the relationship between the voltage applied to the piezoelectric diaphragm and the sound pressure.

[0005] Furthermore, in recent years, regulations, for example, have made it necessary to narrow the tolerance range of the sound pressure of buzzers. As a result, it may be difficult for the piezoelectric buzzer of Patent Document 1 to achieve the required sound pressure tolerance. The inventors have found the above as a result of detailed investigations.

[0006] In view of the above, an object of the present disclosure is to provide a buzzer that can reduce the variation in sound pressure of the sound emitted by the buzzer, and a method for manufacturing the buzzer. [Means for solving the problem]

[0007] In order to achieve the above object, a method for manufacturing a buzzer according to one aspect of the present disclosure includes: A method for manufacturing a buzzer including a piezoelectric diaphragm (12), a housing (14) that houses the piezoelectric diaphragm, and that has formed therein a sound emission hole (16b) that emits sound generated by the piezoelectric diaphragm to the outside and a resonance chamber (14a) that is connected to the sound emission hole and transmits sound from the piezoelectric diaphragm to the sound emission hole, Preparing a first housing member (15) and a second housing member (16) included in a housing (S101); The method includes connecting the second housing member to the first housing member by press-fitting to form a resonance chamber between the first housing member and the second housing member, and adjusting the volume (Vr) of the resonance chamber, which changes depending on the amount of press-fitting (Zi) in the press-fitting, so that the sound pressure of the sound emitted from the sound emission hole falls within a predetermined allowable range (S102 to S104, S201 to S207).

[0008] In this way, even if the resonant frequency of the piezoelectric diaphragm varies, the resonant frequency determined by the size of the resonant chamber in the housing, i.e., the resonant frequency of the housing, can be adjusted according to the resonant frequency of the piezoelectric diaphragm. Furthermore, since the sound pressure of the buzzer increases or decreases according to the difference between the resonant frequency of the piezoelectric diaphragm and the resonant frequency of the housing, it is possible to reduce the variation in the sound pressure of the buzzer.

[0009] Furthermore, a buzzer according to another aspect of the present disclosure includes: A buzzer that emits a sound, A piezoelectric diaphragm (12), a housing (14) that houses the piezoelectric diaphragm, and that has formed therein a sound emission hole (16b) that emits sound generated by the piezoelectric diaphragm to the outside and a resonance chamber (14a) that is connected to the sound emission hole and that propagates sound from the piezoelectric diaphragm to the sound emission hole; The housing has a first housing member (15) and a second housing member (16) that form a resonance chamber therebetween, The first housing member and the second housing member are connected by pressing the second housing member into the first housing member, and the volume (Vr) of the resonance chamber is configured to change according to the amount (Zi) of pressing the second housing member into the first housing member.

[0010] In this way, the resonant frequency of the housing can be adjusted according to the resonant frequency of the piezoelectric diaphragm during the manufacturing process of the buzzer, and the sound pressure of the buzzer increases or decreases according to the difference between the resonant frequency of the piezoelectric diaphragm and the resonant frequency of the housing, thereby reducing the variation in sound pressure of the buzzer.

[0011] In addition, in each section of the application documents, each element may be assigned a reference number in parentheses. In this case, the reference number merely indicates an example of the correspondence between the element and the specific configuration described in the embodiment described below. Therefore, the present disclosure is not limited in any way by the description of the reference number. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a buzzer in a first embodiment. [Figure 2] 2 is a view taken in the direction of an arrow II in FIG. 1 and is a top view of the buzzer. [Figure 3] 1A and 1B are diagrams showing the relationship between the resonance of the piezoelectric diaphragm and the resonance of the housing in the buzzer of the first embodiment, in which FIG. 1A is a diagram showing a schematic representation of the frequency characteristics of sound pressure in the piezoelectric diaphragm, and FIG. 1B is a diagram showing a schematic representation of the frequency characteristics of sound pressure in the housing. [Figure 4] 3 is a flowchart showing a manufacturing process of a buzzer in the first embodiment. [Figure 5] FIG. 5 is a diagram schematically showing how the resonance frequency of the piezoelectric diaphragm is measured in step S102 of FIG. 4 in the first embodiment. [Figure 6]FIG. 5 is a diagram schematically showing a press-fit target map used in step S103 of FIG. 4. [Figure 7] FIG. 6 is a diagram illustrating a state in which the sound pressure of the buzzer is measured in step S105 of FIG. 4 in the first embodiment, and corresponds to FIG. 5. [Figure 8] 10 is a flowchart showing a manufacturing process of a buzzer according to the second embodiment. [Figure 9] 8 is a diagram illustrating a state in which the sound pressure of a buzzer is measured in the second embodiment, and corresponds to FIG. 7. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

[0014] (First embodiment) 1 and 2, buzzer 10 of this embodiment is a piezoelectric buzzer that emits sound using piezoelectric diaphragm 12. Buzzer 10 includes piezoelectric diaphragm 12, a housing 14, and electrical components (not shown) for driving piezoelectric diaphragm 12.

[0015] In the description of this embodiment, the first direction D1, second direction D2, and third direction D3 shown in Figures 1 and 2 may be used to indicate the orientation of the buzzer 10, etc. The first direction D1, second direction D2, and third direction D3 intersect with each other, or more precisely, are perpendicular to each other.

[0016] Piezoelectric diaphragm 12 includes a piezoelectric element and is formed, for example, in a disk shape. When an AC voltage is applied to piezoelectric diaphragm 12, it emits sound at a frequency corresponding to the frequency of the AC voltage. Piezoelectric diaphragm 12 is disposed so that its thickness direction is in a first direction D1 and it extends in a second direction D2 and a third direction D3.

[0017] Housing 14 forms the outer shell of buzzer 10 and houses piezoelectric diaphragm 12 and electrical components (not shown). Housing 14 is formed, for example, in a substantially rectangular parallelepiped shape. Housing 14 also has sound emission holes 16b that emit sound generated by piezoelectric diaphragm 12 to the outside, and sound emission holes 16b are open facing one side in first direction D1.

[0018] The housing 14 has a housing base 15 as a first housing member and a housing cover 16 as a second housing member. The housing base 15 and the housing cover 16 are parts made of, for example, resin.

[0019] Piezoelectric diaphragm 12 is attached to housing base 15. Specifically, housing base 15 has diaphragm mounting wall 151, which is a wall on one side of housing base 15 in first direction D1, and sound-generating opening 151a, which is an opening penetrating diaphragm mounting wall 151 in first direction D1, is formed in diaphragm mounting wall 151. Piezoelectric diaphragm 12 is disposed so as to close sound-generating opening 151a, and is fixed to diaphragm mounting wall 151 at the periphery of sound-generating opening 151a.

[0020] Additionally, a wiring chamber 15a, which is a space for accommodating electrical components and wiring (not shown) for driving the piezoelectric diaphragm 12, is formed within the housing base 15. The wiring chamber 15a is disposed on the other side of the diaphragm mounting wall 151 and the piezoelectric diaphragm 12 in the first direction D1.

[0021] Further, a press-fit groove 15b is formed in the housing base 15. This press-fit groove 15b is formed to open on one side in the first direction D1 and have a groove bottom on the other side in the first direction D1. When viewed in the first direction D1, the press-fit groove 15b extends in a ring shape, for example, surrounding the entire periphery of the piezoelectric diaphragm 12 and the wiring chamber 15a.

[0022] The housing cover 16 is provided on one side of the housing base 15 in the first direction D1, and is fixed to the housing base 15 in a state in which it is press-fitted into the housing base 15. More specifically, the housing cover 16 has a press-fit portion 161 press-fitted into the press-fit groove 15b. When viewed in the direction along the first direction D1, the press-fit portion 161 extends so as to surround the piezoelectric diaphragm 12, similar to the press-fit groove 15b. Note that the housing cover 16 is press-fitted into the housing base 15, but in addition to this press-fitting, it is also joined and fixed to the housing base 15 by welding or adhesive, as will be described later.

[0023] By connecting the housing cover 16 to the housing base 15, a resonance chamber 14a is formed between the housing base 15 and the housing cover 16. The sound emission hole 16b is formed in the housing cover 16 of the housing 14. The resonance chamber 14a is a space formed within the housing 14, connected to the sound emission hole 16b, and through which sound propagates from the piezoelectric diaphragm 12 to the sound emission hole 16b. In other words, the resonance chamber 14a constitutes at least a part of the sound propagation path through which sound generated by the piezoelectric diaphragm 12 propagates from the piezoelectric diaphragm 12 to the sound emission hole 16b. Therefore, for example, the wiring chamber 15a does not qualify as the resonance chamber 14a.

[0024] In this embodiment, the sound-emitting opening 151a is provided on one side of the piezoelectric diaphragm 12 in the first direction D1, i.e., on the sound output hole 16b side, and therefore the sound-emitting opening 151a is included in the resonance chamber 14a. Therefore, the piezoelectric diaphragm 12 faces the resonance chamber 14a and is in contact with the resonance chamber 14a from the other side in the first direction D1.

[0025] The sound emission hole 16b is provided, for example, in a wall 162 of the housing cover 16 that faces the resonance chamber 14a from one side in the first direction D1, and is formed as a through-hole that penetrates the wall 162 in the first direction D1.

[0026] Here, the sound pressure of the sound emitted from sound emission hole 16b by buzzer 10, i.e., the sound pressure of buzzer 10, will be described. In buzzer 10, when a voltage signal of a predetermined drive frequency is input to piezoelectric diaphragm 12, the sound pressure of the sound emitted from sound emission hole 16b becomes greater than the sound pressure of the sound emitted by piezoelectric diaphragm 12 alone due to the resonance of piezoelectric diaphragm 12 and the resonance of housing 14. In this embodiment, this phenomenon is utilized to ensure the sound pressure of buzzer 10. Diagrams for explaining this phenomenon are shown in Figures 3(a) and 3(b).

[0027] For example, FIG. 3A shows the frequency characteristic Cfa of the sound pressure in the piezoelectric diaphragm 12, and the frequency characteristic Cfa of the sound pressure represents the resonant frequency f0 of the piezoelectric diaphragm 12. Meanwhile, FIG. 3B shows the frequency characteristic Cfb of the sound pressure in the housing 14, and the frequency characteristic Cfb of the sound pressure represents the resonant frequency fc determined according to the size of the resonant chamber 14a in the housing 14, i.e., the resonant frequency fc of the housing 14. In the buzzer 10, the smaller the frequency difference Δf between the resonant frequency f0 of the piezoelectric diaphragm 12 and the resonant frequency fc of the housing 14, the greater the sound pressure of the sound emitted from the sound emission hole 16b. This becomes more pronounced, for example, at frequencies between the resonant frequency f0 of the piezoelectric diaphragm 12 and the resonant frequency fc of the housing 14. In the description of this embodiment, the resonant frequency f0 of the piezoelectric diaphragm 12 may be referred to as the diaphragm resonant frequency f0, and the resonant frequency fc of the housing 14 may be referred to as the housing resonant frequency fc.

[0028] Next, a manufacturing process of the buzzer 10 of this embodiment will be described. As shown in Fig. 4, first, in step S101, the semi-finished buzzer 20 and the housing cover 16 shown in Fig. 5 are prepared.

[0029] The semi-finished buzzer 20 prepared in step S101 is equivalent to the finished buzzer 10 of Fig. 1 with the housing cover 16 removed. That is, the semi-finished buzzer 20 becomes the buzzer 10 of Fig. 1 when the housing cover 16 is press-fitted and fixed into the housing base 15. Therefore, the semi-finished buzzer 20 includes the housing base 15 to which the piezoelectric diaphragm 12 is attached, and the electrical wiring for the piezoelectric diaphragm 12 is also completed in the semi-finished buzzer 20. In short, when a buzzer input signal Vin for driving the piezoelectric diaphragm 12 is input to the semi-finished buzzer 20, the piezoelectric diaphragm 12 will produce a sound in accordance with the buzzer input signal Vin.

[0030] In step S102 following step S101 in Fig. 4, the diaphragm resonance frequency f0 is measured. Specifically, as shown in Fig. 5, the semi-finished buzzer 20 is placed in a predetermined posture in a soundproof box 30 and electrically connected to a measuring device 31, which is an electronic control device.

[0031] The measuring device 31 then inputs the buzzer input signal Vin to the semi-finished buzzer product 20, causing the piezoelectric diaphragm 12 to emit a predetermined sound for measurement. At the same time, the measuring device 31 acquires an audio signal Vs output from a microphone 32 provided inside the soundproof box 30 in association with the sound emitted by the piezoelectric diaphragm 12. The audio signal Vs is an electrical signal that indicates the sound received by the microphone 32.

[0032] When the measuring device 31 acquires the audio signal Vs, it obtains the frequency characteristic Cfa of the sound pressure in the piezoelectric diaphragm 12 (see FIG. 3(a)) based on the audio signal Vs. Then, the measuring device 31 obtains the diaphragm resonance frequency f0 from the frequency characteristic Cfa of the sound pressure in the piezoelectric diaphragm 12. In this way, the measuring device 31 measures the diaphragm resonance frequency f0 indicated by the frequency characteristic Cfa of the sound pressure.

[0033] The measuring device 31 is configured as a microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, etc. (not shown). That is, the measuring device 31 reads and executes a computer program stored in a ROM or non-volatile rewritable memory, which is a non-transitory tangible recording medium. Execution of this computer program results in the execution of a method corresponding to the computer program. After step S102 in FIG. 4, the process proceeds to step S103.

[0034] In step S103 of FIG. 4, the target value Zit of the press-fit amount Zi of the housing cover 16 relative to the housing base 15, i.e., the target value Zit of the press-fit amount of the housing cover 16, is determined from the press-fit target map MP of FIG. 6 based on the diaphragm resonance frequency f0 measured in step S102.

[0035] This press-fit target map MP is an experimentally determined relationship between the press-fit amount target value Zit of the housing cover 16 and the diaphragm resonance frequency f0. For example, the press-fit target map MP is experimentally set so that the sound pressure of the completed buzzer 10 falls within a predetermined allowable range, and is stored in advance in the measuring device 31. The allowable range of the sound pressure of the buzzer 10 is determined, for example, from the product specifications of the buzzer 10. For example, in this embodiment, the measuring device 31 determines the press-fit amount target value Zit of the housing cover 16 from the press-fit target map MP based on the diaphragm resonance frequency f0.

[0036] As shown in Figure 1, the press-fit amount Zi of the housing cover 16 into the housing base 15 is, more specifically, the press-fit depth to which the press-fit portion 161 of the housing cover 16 is press-fit into the press-fit groove 15b of the housing base 15 in the first direction D1.

[0037] Furthermore, the volume Vr of the resonance chamber 14a changes depending on the press-fit amount Zi of the housing cover 16 into the housing base 15, and there is a one-to-one relationship between the press-fit amount Zi of the housing cover 16 and the volume Vr of the resonance chamber 14a. Therefore, determining the target press-fit amount Zit of the housing cover 16 also means determining the target value Vrt of the volume Vr of the resonance chamber 14a, i.e., the resonance chamber volume target value Vrt.

[0038] That is, the target press-in amount Zit of the housing cover 16, which constitutes the vertical axis of the press-in target map MP in Fig. 6, can be replaced with the target resonance chamber volume Vrt. However, in this case, as can be seen from Fig. 1, the magnitude relationship between the target press-in amount Zit of the housing cover 16 and the target resonance chamber volume Vrt will be reversed, so that the larger target press-in amount Zit of the housing cover 16 corresponds to the smaller target resonance chamber volume Vrt, as shown in Fig. 6.

[0039] Regarding the press-fit target map MP in FIG. 6, the press-fit target map MP is set so that the resonance chamber volume target value Vrt decreases as the diaphragm resonance frequency f0 increases. In other words, as shown in FIG. 1, the volume Vr of the resonance chamber 14a decreases as the press-fit amount Zi of the housing cover 16 increases. Therefore, in the press-fit target map MP, the press-fit amount target value Zit of the housing cover 16 increases as the diaphragm resonance frequency f0 increases. The press-fit target map MP is set in this manner because, as can be seen from FIG. 3, in order to suppress variations in the sound pressure of the buzzer 10, the housing resonance frequency fc must also increase as the diaphragm resonance frequency f0 increases. After step S103 in FIG. 4, the process proceeds to step S104.

[0040] 4, the semi-finished buzzer 20 is removed from the soundproof box 30. Then, the housing cover 16 is connected to the housing base 15 of the semi-finished buzzer 20 by press-fitting so that the press-fit amount Zi of the housing cover 16 becomes the target press-fit amount Zit of the housing cover 16. As described above, there is a one-to-one relationship between the press-fit amount Zi of the housing cover 16 and the volume Vr of the resonance chamber 14a. In other words, the housing cover 16 is connected to the housing base 15 of the semi-finished buzzer 20 by press-fitting so that the volume Vr of the resonance chamber 14a becomes the target resonance chamber volume Vrt.

[0041] Once the press-fitting of the housing cover 16 is complete, the housing base 15 and the housing cover 16 are fixed to each other by welding, bonding, or the like so that they do not move relative to each other. In other words, the housing base 15 and the housing cover 16 are finally fixed to each other by welding, bonding, or the like. This completes the buzzer 10 in which the resonance chamber 14a is formed. In the buzzer 10, the housing base 15 and the housing cover 16 are fixed to each other by welding, bonding, or the like, so the volume Vr of the resonance chamber 14a does not change even if an external force is applied to the housing base 15 or the housing cover 16.

[0042] 4, housing cover 16 is connected to housing base 15 by press-fitting, thereby forming resonance chamber 14a between housing base 15 and housing cover 16. At the same time, volume Vr of resonance chamber 14a is adjusted so that the sound pressure of buzzer 10 falls within a predetermined allowable range.

[0043] As can be seen from the content of step S104, if buzzer 10 of this embodiment does not have the final fixation between housing base 15 and housing cover 16 by welding or adhesive bonding, then housing base 15 and housing cover 16 are configured as follows: In other words, if there is no final fixation, housing base 15 and housing cover 16 are configured so that volume Vr of resonance chamber 14a changes depending on the amount Zi of press-fit of housing cover 16 into housing base 15. After step S104 in FIG. 4, the process proceeds to step S105.

[0044] 4, the sound pressure of buzzer 10 is measured and it is checked whether the sound pressure of buzzer 10 is within a predetermined tolerance range. Specifically, as shown in FIG. 7, buzzer 10 is placed in a predetermined position in soundproof box 30 and electrically connected to measuring device 31.

[0045] Then, the measuring device 31 inputs the buzzer input signal Vin to the buzzer 10, causing the piezoelectric diaphragm 12 to emit a predetermined sound for inspection. At the same time, the measuring device 31 acquires an audio signal Vs output from a microphone 32 provided inside the soundproof box 30 in association with the sound emitted by the piezoelectric diaphragm 12. Upon acquiring the audio signal Vs, the measuring device 31 determines whether the sound pressure of the buzzer 10 is within a predetermined tolerance range, based on the audio signal Vs. If the sound pressure of the buzzer 10 being measured is within the tolerance range, the buzzer 10 is determined to be a non-defective product. If the sound pressure of the buzzer 10 is outside the tolerance range, the buzzer 10 is determined to be a defective product. The buzzer input signal Vin used for inspecting the buzzer 10 in step S105 may be the same as or different from the buzzer input signal Vin used for measuring the semi-finished buzzer 20 in step S102.

[0046] In this manner, the buzzer 10 of this embodiment is manufactured.

[0047] 4, the housing cover 16 is press-fitted into the housing base 15 to form the resonance chamber 14a between the housing base 15 and the housing cover 16. At the same time, the volume Vr of the resonance chamber 14a is adjusted so that the sound pressure of the buzzer 10 falls within a predetermined allowable range.

[0048] Therefore, even if the diaphragm resonance frequency f0 varies, the housing resonance frequency fc, which is determined according to the size of the resonance chamber 14a, can be adjusted according to the diaphragm resonance frequency f0. Furthermore, since the sound pressure of the buzzer 10 increases or decreases according to the frequency difference Δf between the diaphragm resonance frequency f0 and the housing resonance frequency fc, it is possible to reduce the variation in the sound pressure of the buzzer 10.

[0049] Furthermore, because the variation in sound pressure of the buzzer 10 is reduced as described above, the specifications of the piezoelectric diaphragm 12, such as the tolerance of the diaphragm resonance frequency f0, can be set more loosely. This allows for greater freedom in selecting the piezoelectric diaphragm 12.

[0050] Furthermore, according to this embodiment, as shown in FIG. 1, the housing base 15 and the housing cover 16 in the buzzer 10 are configured so that the volume Vr of the resonance chamber 14a changes depending on the amount of press-fit Zi of the housing cover 16 into the housing base 15.

[0051] 4, the housing resonant frequency fc can be adjusted in accordance with the diaphragm resonant frequency f0 as described above. The sound pressure of buzzer 10 increases or decreases in accordance with the frequency difference Δf between the diaphragm resonant frequency f0 and the housing resonant frequency fc, so it is possible to reduce the variation in the sound pressure of buzzer 10.

[0052] 4, the final fixing of housing base 15 and housing cover 16 is performed by welding or adhesive bonding, etc. Therefore, the press-fit amount Zi of housing cover 16 cannot be changed in buzzer 10 as a finished product.

[0053] (1) According to this embodiment, in step S102 of Fig. 4, the diaphragm resonance frequency f0 is measured, and in step S103, the target press-fit amount Zit of the housing cover 16 is determined from the press-fit target map MP of Fig. 6 based on the measured diaphragm resonance frequency f0. Then, in step S104, the housing cover 16 is connected to the housing base 15 of the semi-finished buzzer 20 by press-fitting so that the press-fit amount Zi of the housing cover 16 becomes the target press-fit amount Zit of the housing cover 16. Note that there is a one-to-one relationship between the press-fit amount Zi of the housing cover 16 and the volume Vr of the resonance chamber 14a, and therefore, determining the target press-fit amount Zit of the housing cover 16 also means determining the target resonance chamber volume Vrt.

[0054] Therefore, there is no need to adjust the press-fit amount Zi of the housing cover 16 by trial and error so that the sound pressure of the buzzer 10 falls within a predetermined allowable range, and the housing cover 16 can be press-fit into the housing base 15 through efficient work.

[0055] (Second embodiment) Next, a second embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described. Furthermore, parts that are the same as or equivalent to the first embodiment will be omitted or simplified.

[0056] Buzzer 10 of this embodiment is as shown in Fig. 1 and is similar to that of the first embodiment. In the manufacturing process of this embodiment, as in the first embodiment, housing cover 16 is connected to housing base 15 by press-fitting, thereby forming resonance chamber 14a between housing base 15 and housing cover 16. At the same time, volume Vr of resonance chamber 14a is adjusted so that the sound pressure of buzzer 10 falls within a predetermined allowable range.

[0057] However, as shown in FIG. 8, this embodiment differs from the first embodiment in the method of adjusting the volume Vr of the resonance chamber 14a in the manufacturing process of the buzzer 10 so that the sound pressure of the buzzer 10 falls within a predetermined allowable range.

[0058] Specifically, as shown in Fig. 8, first, in step S101, the semi-finished buzzer 20 and the housing cover 16 shown in Fig. 5 are prepared. This step S101 is the same as in the first embodiment.

[0059] 8, in step S201, the housing cover 16 is assembled to the housing base 15 of the semi-finished buzzer 20. At this time, the press-fit portion 161 of the housing cover 16 is press-fit into the press-fit groove 15b of the housing base 15, thereby connecting the housing cover 16 to the housing base 15. However, in this step S201, the press-fit amount Zi of the housing cover 16 into the housing base 15 is set to the minimum press-fit amount on the condition that the press-fitting can proceed in step S203, which will be described later.

[0060] Then, when the housing cover 16 is assembled to the housing base 15 of the semi-finished buzzer 20, the buzzer 10 including the housing base 15 and the housing cover 16 is installed in a predetermined posture in the soundproof box 30 as shown in Fig. 9, and is electrically connected to the measuring device 31. After step S201 in Fig. 8, the process proceeds to step S202.

[0061] In step S202, the measurement device 31 inputs the buzzer input signal Vin to the buzzer 10, causing the piezoelectric diaphragm 12 to start emitting a predetermined sound for measurement. At the same time, the measurement device 31 also starts acquiring an audio signal Vs output from the microphone 32 provided in the soundproof box 30 in association with the sound emitted by the piezoelectric diaphragm 12. This sound emission by the piezoelectric diaphragm 12 and acquisition of the audio signal Vs continue until stopped in step S206, which will be described later. After step S202 in FIG. 8, the process proceeds to step S203.

[0062] In step S203, as shown by arrow A1 in Fig. 9, the press-fitting of the housing cover 16 into the housing base 15 begins. That is, the press-fitting amount Zi of the housing cover 16 into the housing base 15 starts to be gradually increased. This press-fitting of the housing cover 16 continues until it is stopped in step S207, which will be described later. Furthermore, the rate at which the press-fitting of the housing cover 16 progresses, i.e., the rate at which the press-fitting amount Zi increases, is set to be small enough to allow immediate stopping, for example.

[0063] For example, the press-fitting of the housing cover 16 is performed by a press-fitting device (not shown) that is controlled by the measuring device 31 and presses the housing cover 16 against the housing base 15 as indicated by arrow A1 in Fig. 9. Steps S202 and S203 are performed simultaneously or approximately simultaneously. After step S203 in Fig. 8, the process proceeds to step S204.

[0064] In step S204, the measuring device 31 measures the sound pressure of the buzzer 10 based on the audio signal Vs acquired from the microphone 32. After step S204 in FIG. 8, the process proceeds to step S205.

[0065] In step S205, the measuring device 31 determines whether the sound pressure of the buzzer 10 measured in step S204 is within a predetermined allowable range.

[0066] If it is determined in step S205 that the sound pressure of the buzzer 10 is within the allowable range, the process proceeds to step S206. On the other hand, if it is determined that the sound pressure of the buzzer 10 is outside the allowable range, the process returns to step S204, and measurement of the sound pressure of the buzzer 10 continues.

[0067] In step S206, the measuring device 31 stops outputting the buzzer input signal Vin and stops sound generation from the piezoelectric diaphragm 12. After step S206 in FIG.

[0068] In step S207, the press-fitting of the housing cover 16 into the housing base 15 is stopped. In this case, when the press-fitting of the housing cover 16 is stopped, the press-fitting amount Zi at the time when the press-fitting was stopped is maintained. Steps S207 and S206 are performed simultaneously or approximately simultaneously.

[0069] In step S207, for example, the press-fitting of housing cover 16 is stopped immediately when the sound pressure of buzzer 10 falls within the allowable range, but the press-fitting of housing cover 16 may be stopped after proceeding by a predetermined amount from the press-fit amount Zi at the time when the sound pressure falls within the allowable range. This is to bring the sound pressure of buzzer 10 closer to the median value of the allowable range, and the predetermined amount is experimentally set in advance so that the sound pressure of buzzer 10 approaches the median value within the allowable range. After step S207 in FIG. 8, the process proceeds to step S208.

[0070] 8, the press-fit amount Zi of housing cover 16 into housing base 15 is changed while measuring the sound pressure of the sound emitted from sound emission hole 16b, i.e., the sound pressure of buzzer 10. If the sound pressure of buzzer 10 falls within a predetermined allowable range while the press-fit amount Zi is being changed, the press-fitting of housing cover 16 into housing base 15 is stopped.

[0071] In step S208, housing base 15 and housing cover 16 are fixed to each other by welding, adhesive, or the like so that they do not move relative to each other. In other words, housing base 15 and housing cover 16 are finally fixed together. This completes buzzer 10.

[0072] In this manner, the buzzer 10 of this embodiment is manufactured.

[0073] (1) As described above, according to this embodiment, the press-fit amount Zi of the housing cover 16 into the housing base 15 is changed while the sound pressure of the buzzer 10 is measured, as shown in Fig. 8. If the sound pressure of the buzzer 10 falls within a predetermined allowable range while the press-fit amount Zi is being changed, the press-fitting of the housing cover 16 into the housing base 15 is stopped.

[0074] Therefore, since the volume Vr of the resonance chamber 14a is determined while the sound pressure of the buzzer 10 is measured, it is possible to keep the sound pressure of the buzzer 10 within a predetermined allowable range with greater accuracy than, for example, the first embodiment.

[0075] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0076] (Other embodiments) (1) In each of the above-described embodiments, as shown in Fig. 1, the sound emission holes 16b open to the outside facing one side in the first direction D1, but there is no limitation on the direction in which the sound emission holes 16b open. For example, the sound emission holes 16b may be formed in the side surface of the housing cover 16 and may open facing the second direction D2 or the third direction D3.

[0077] (2) In the first embodiment described above, in step S102 of Fig. 4, the measuring device 31 determines the diaphragm resonance frequency f0 from the frequency characteristic Cfa of the sound pressure in the piezoelectric diaphragm 12. However, this is just one example. For example, the measuring device 31 may measure the frequency characteristic of the impedance in the piezoelectric diaphragm 12 and determine the diaphragm resonance frequency f0 from the frequency characteristic of the impedance.

[0078] (3) In each of the above-described embodiments, when the housing base 15 and the housing cover 16 are connected by press-fitting, the housing cover 16 is press-fitted into the housing base 15. However, this is just one example. Conversely, for example, the housing base 15 and the housing cover 16 may be configured so that the housing base 15 is press-fitted into the housing cover 16.

[0079] (4) In the first embodiment described above, in step S104 of Fig. 4, the housing base 15 and the housing cover 16 are finally fixed to each other by welding or bonding, but this final fixing is not essential. Similarly, in the second embodiment, step S208 of Fig. 8 is also not essential.

[0080] (5) The present disclosure is not limited to the above-described embodiments and can be implemented in various modifications. Furthermore, in each of the above-described embodiments, it goes without saying that elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0081] Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of components of the embodiments are mentioned, they are not limited to the specific numbers, except when it is particularly clearly stated that they are essential or when they are clearly limited to a specific number in principle, etc. Furthermore, in each of the above embodiments, when the material, shape, positional relationship, etc. of components are mentioned, they are not limited to the material, shape, positional relationship, etc., except when it is particularly clearly stated or when they are clearly limited to a specific material, shape, positional relationship, etc. in principle, etc. [Explanation of symbols]

[0082] 10 Buzzer 12 Piezoelectric diaphragm 14. Case 14a Resonance chamber 15 Housing base (first housing member) 16 Housing cover (second housing member) Zi Press-in amount

Claims

1. A method for manufacturing a buzzer comprising: a piezoelectric diaphragm (12); a housing (14) that houses the piezoelectric diaphragm; a sound emission hole (16b) that emits sound generated by the piezoelectric diaphragm to the outside; and a resonance chamber (14a) that is connected to the sound emission hole and transmits sound from the piezoelectric diaphragm to the sound emission hole, Preparing a first housing member (15) and a second housing member (16) included in the housing (S101); a step of connecting the second housing member to the first housing member by press-fitting to form the resonance chamber between the first housing member and the second housing member, and adjusting a volume (Vr) of the resonance chamber, which changes depending on a press-fit amount (Zi) of the press-fitting, so that the sound pressure of the sound emitted from the sound emission hole falls within a predetermined allowable range (S102 to S104, S201 to S207).

2. The adjusting (S102 to S104) Measuring the resonance frequency (f0) of the piezoelectric diaphragm (S102); Determining a target value (Vrt) of the volume of the resonance chamber from a predetermined relationship (MP) based on the measured resonance frequency (S103); 2. The method for manufacturing a buzzer according to claim 1, further comprising: connecting the second housing member to the first housing member by press-fitting so that the volume of the resonance chamber becomes the determined target value (S104).

3. 2. The method for manufacturing a buzzer according to claim 1, wherein, in the adjusting (S201 to S207), the press-fitting amount is changed while measuring the sound pressure of the sound emitted from the sound emission hole, and when the sound pressure falls within the allowable range, the press-fitting of the second housing member into the first housing member is stopped.

4. A buzzer that emits a sound, A piezoelectric diaphragm (12), a housing (14) that houses the piezoelectric diaphragm, and that has formed therein a sound emission hole (16b) that emits sound generated by the piezoelectric diaphragm to the outside and a resonance chamber (14a) that is connected to the sound emission hole and that propagates sound from the piezoelectric diaphragm to the sound emission hole; The housing has a first housing member (15) and a second housing member (16) that form the resonance chamber therebetween, The first housing member and the second housing member are connected by press-fitting the second housing member into the first housing member, and the volume (Vr) of the resonance chamber is configured to change depending on the press-fit amount (Zi) of the second housing member into the first housing member.

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