JPH0440648B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a calibration sound source in which a plurality of sound sources are connected in a straight line by a joint sleeve, a sound absorbing material for preventing the generation of standing waves is installed inside, and an adjustment hole is installed. By connecting one end of a waveguide with a hole in it and supplying sound waves to the microphone from the other end of the waveguide, a calibration test of the microphone can be performed without removing the microphone. , relates to a microphone calibration sound source device.

[Conventional technology]

Traditionally, microphones have been used as acoustic detection sensors in normal temperature atmospheres or in ^hot air (approx.
℃) is used as an acoustic detection sensor.
Microphones are periodically subjected to sensitivity calibration tests.

[Problem that the invention seeks to solve]

This sensitivity calibration test is performed with the microphone removed from the installation location. When a microphone is installed in the reactor containment vessel, there is a problem in that the reactor must be shut down in order to remove it, which requires a large amount of time and expense for inspection. Furthermore, since the removal work is performed under high radiation conditions, there are problems in handling such as being extremely dangerous. moreover,
Even if the microphone is installed in a room-temperature atmosphere, if it is installed in a narrow space, the microphone cannot be removed from the installation location, and a sensitivity calibration test cannot be performed.

The present invention was made to solve the problems of the prior art.

[Means for solving problems]

Means for solving the above problems will be explained below using FIG. 1 corresponding to the embodiment. In the present invention, the calibration sound source 10 includes a plurality of 20A, 20B, 2
0C is linearly connected by a joint sleeve 21, a sound absorbing material 22 for preventing standing wave generation is installed inside, and one end of a waveguide 30 having an adjustment hole 25 is connected to the waveguide. This is a microphone calibration sound source device that supplies sound waves to the microphone from the other end of the microphone.

[Effect]

With this configuration, a sound wave is supplied from the calibration sound source 10 to the microphone via the waveguide 20, and a sensitivity calibration test can be performed without removing the microphone.

[Embodiment] FIG. 1 is a diagram showing an embodiment of the present invention.
In FIG. 1, 10 is a calibration sound source, and 20 is a waveguide. The calibration sound source 10 includes a speaker 11 serving as a sound source, a speaker duct 12 that is fixed behind the speaker 11 and emits sound pressure from the back of the speaker 11 to the outside, and a speaker throat 13 that emits sound waves from the speaker 11. is fixed to speaker 11 via
1, a speaker cover 15 fixed to the speaker holder 14, a shortphone 16 fixed to the speaker holder 14 and propagating sound waves, and a waveguide fixed to the shortphone 16. 2
0 and a sleeve 17 to which one end of the sleeve 17 is connected. The speaker 11 is a dome-shaped speaker, and 11A is its diaphragm. Vibration membrane 11A
When the calibration sound source 10 is used in a high-temperature atmosphere, it is made of a heat-resistant material such as titanium to block heat from hot air passing through the waveguide 20. A driving wire (not shown) of the speaker 11 is drawn out from an outlet of the speaker cover 15, and the outlet is sealed with silicone adhesive. The speaker duct 12 is provided with a plurality of holes 12A, and the sound pressure on the back surface of the speaker 11 is emitted to the outside through the holes 12A. This emission improves the particularly low frequency characteristics of the speaker 11. speaker throat 1
3 is placed in front of the vibrating membrane 11A, and squeezes and releases the sound waves of the vibrating membrane 11A from a hole 13A provided in the center thereof. The speaker throat 13 is screwed to a speaker holder 14, and the speaker holder 14 is screwed to a speaker cover 15. The short phone 16 is screwed onto the speaker holder 14, and the sleeve 17 is screwed onto the short phone 16. When the calibration sound source 10 is used in a high-temperature atmosphere, the sleeve 17 is made of silicone rubber and blocks heat and vibration transmitted from the waveguide 20.

The waveguide 20 supplies the sound waves from the calibration sound source 10 to the microphone at a level that provides a sufficient S/N against external noise.
It is constructed by linearly connecting 0B and 20C with a joint sleeve 21. Waveguide 20A
has a substantially U-shape, one end of which is disposed on the front surface of the sound receiving section 3, and one end of which is connected to the joint sleeve 21. The waveguide 20B has a straight shape,
Both ends thereof are connected to a joint sleeve 21. The waveguide 20C is linear and has one end connected to the joint sleeve 21 and the other end connected to the sleeve 17. 1 waveguide 20
Not real waveguides, but waveguides 20A, 20B, 2
The reason for using 0C is to control the frequency characteristics in front of the sound receiving section 3 in accordance with the characteristics of the speaker 11 by changing its length and thickness. Further, in order to prevent standing waves from occurring in the waveguide 20, the sound absorbing material 22 inserted into the waveguide 20 is fixed at a predetermined position. A horn cap 23 is screwed onto one end of the waveguide 20A, and a grid 24 having many small holes is inserted between one end of the waveguide 20A and the horn cap 23. Also, between the other end of the waveguide 20A and one end of the waveguide 20B, between the other end of the waveguide 20B and one end of the waveguide 20C, and between the other end of the waveguide 20B and one end of the waveguide 20C.
A grid 2 is connected between the other end and the short phone 16.
4 is inserted. A sound absorbing material 22 is mounted and fixed within the waveguides 20A and 20B by means of a grid 24. When the calibration sound source 10 is used in a high temperature atmosphere, glass wool or the like is used as the sound absorbing material 22.
In addition to preventing the generation of standing waves in the waveguide 2
To protect a calibration sound source 10 by preventing hot air from entering through 0. To explain the effect of the sound absorbing material 22, as shown in FIG. 2A, there are many peaks and valleys in the characteristics due to the number of stations in the waveguide 20, but when the sound absorbing material 22 is added, as shown in FIG. 2B. As shown, the characteristic peaks and valleys due to standing waves within the waveguide 20 have disappeared. The waveguide 20B is configured to have a larger diameter than the waveguides 20A and 20C. This is a one-step expanded react-tape silencer structure, and the frequency characteristics change between the entrance and exit of the sound. Further, the frequency characteristics can be changed by changing the diameter, length, etc. of the waveguides 20A, 20B, and 20C. FIG. 3 is a diagram showing the frequency characteristics when the diameter and length of the waveguides 20A, 20B, 20C are changed without changing the total extension length of the waveguides 20A, 20B, 20C. Waveguide 20A inner diameter φ6, length 45mm Waveguide 20B inner diameter φ8, length 125mm, waveguide 20C
When the inner diameter of the waveguide is φ6 and the length is 15 mm, B is the waveguide 20
Inner diameter of A is φ6, length is 95mm, inner diameter of waveguide 20B is φ8,
When the length is 75 mm, the inner diameter of the waveguide 20C is φ6, and the length is 15 mm, C is the inner diameter of the waveguide 20A, φ6, the length is 85 mm,
Waveguide 20B inner diameter φ6, length 85mm, waveguide 20
This is when the inner diameter of C is φ8 and the length is 15 mm. Therefore, in accordance with the frequency characteristics from the calibration sound source 10,
By optimally selecting the diameter, length, etc. of the waveguides 20A, 20B, and 20C, the frequency characteristics at the exit of the waveguide 20A can be flattened.

By changing the inner diameter of the shotphone 16 and the inner diameter of the waveguide 20C, as shown in FIG.
The frequency characteristics at the exit of the waveguide 20A can be adjusted. In FIG. 4, A is when the inner diameter of the shot phone 16 is φ5 and the inner diameter of the waveguide 20C is φ5, and B is when the inner diameter of the shot phone 16 is φ6 and the inner diameter of the waveguide 20C is φ8.

An adjustment hole 25 is bored in the waveguide 20C, and this adjustment hole 25 becomes a mass element, corresponds to a coil of an equivalent circuit, and constitutes a high-pass filter. By adjusting the size and number of holes, the cutoff frequency can be changed. When the adjustment hole 25 with a diameter of 1 mm is provided, as shown in FIG. 5B, the level below the midrange is lowered compared to FIG. 5A without the adjustment hole 25, and the frequency characteristics at the exit of the waveguide 20A are flattened. can be converted into Furthermore, waveguide 2
If abnormally high sound pressure enters from the 0A exit,
The pressure is distributed by the adjustment hole 25, and the vibration membrane 1
1A can be prevented from being damaged.

The adjustment hole 25 is provided in the waveguide 20C farthest from the sound outlet for the purpose of preventing sound leakage to the sound receiving section 3.

When calibrating the microphone, use the waveguide 20A
may be placed in front of the sound receiving section 3, and the calibration sound source 10 may be driven. Sound waves generated by driving the calibration sound source 10 are applied to the sound receiving section 3 through the waveguide 20 . There is no need to remove the microphone for calibration.

A case where the calibration sound source 10 and the waveguide 20 are integrated with a microphone will be described below with reference to FIGS. 6, 7, and 8. 6, 7, and 8, 1 is an impedance converter, 2 is a converter case, 3 is a sound receiver, 4 is a vibration isolation case, 5 is a flange base, 6 is a case holder,
7 is a connector base. The calibration sound source 10 is placed inside the converter case 2, and the waveguide 20 is supported by the vibration-proof case 4 via a pipe holder 26.

The speaker holder 14 is attached to the connector base 7
The speaker 11 is fixed to the connector base 7. The speaker cover 15 is
It is fixed to the speaker holder 14 and the converter case 2, and the speaker 11 is fixed to the converter case 2. The sealing gasket 18 is disposed between the speaker duct 12 and the speaker cover 15 and seals the inside of the converter case 2. Further, the converter case 2 is screwed to the connector base 7. Anti-vibration case 4
A spring receiver 8 is screwed into one end, and a case holder 6 is screwed into the other end. A seal pipe 9 passes through this interior, and a seal pipe joint 30 is inserted from one end surface, and a seal pipe joint 30 is inserted from the other end surface. 9 stands out. Anti-vibration springs 31A, 31
B is attached to the sound receiving section 3 and the seal pipe joint 30 with the spring receiver 8 in between. Metal springs are used as the vibration isolation springs 31A and 31B, and are arranged symmetrically. One end of a moisture-proof cover 34 is attached to the other end of the seal pipe 9 with a spring holder 32 and a cap 33, and the other end of the moisture-proof cover 34 is inserted into the connector base 7 with a board holder 35. Heat-resistant rubber with a small spring constant is used as the moisture-proof cover 34 so as not to affect the vibration-proofing effect. The board holder 35 is screwed to the connector base 7. The converter case 2 is screwed to the connector base 7, and includes an impedance converter 1 and a calibration sound source 10.
is stored inside. Impedance converter 1
is fixed to the connector base 7 by the support column 7A and a nut, and is sealed inside the converter case 2. Outer stay 3 is attached to flange base 5
One end of the connector 6 is screwed, and the other end is elastically fixed to the connector base 7 by a set screw 36A, a nut 36B, and a vibration isolating rubber 36C.
The outer stays 36 are arranged at 90° intervals. One end of the inner stay 37 is screwed to the case holder 6, and the other end is secured with a set screw 37A, a nut 37B, and a vibration isolating rubber 37C.
It is elastically fixed to the connector base 7 by. The inner stays 37 are arranged at intervals of 12 degrees. Stainless steel with low thermal conductivity is used for the inner stay 37, and its cross-sectional area is made as small as possible and its length is made as long as possible. Although the case holder 6 and the flange base 5 are arranged concentrically, they are not connected. Connector 38 is screwed to converter case 2. The signal line 39 is for introducing the output signal from the sound receiving section 3 into the impedance converter 1, and is connected to the input of the impedance converter 1 through the seal pipe joint 30, the seal pipe 9, the moisture-proof cover 34, and the board holder 35. connected to the side. The output side of the impedance converter 1 is connected to the input side of the connector 38. The calibration sound source 10 is sealed inside the converter case 2 and isolated from the impedance converter 1. Therefore, even if abnormal wind pressure from the high temperature side atmosphere passes through the waveguide 20 and damages the diaphragm 11A,
Impedance converter 1 is not affected and operates normally as an acoustic wave detection sensor. Although the calibration sound source 10 is placed inside the converter case 2 in order to make the device compact, it goes without saying that the calibration sound source 10 may be placed outside the converter case 2.

When the flange base 5 is fixed to the low-temperature side of the location where it is used, for example, to the outer wall of the nuclear reactor insulation box, the sound receiving section 3, waveguide 20A, etc.
℃), and the moisture-proof cover 34, the calibration sound source 10, etc. are placed outside the heat-insulating box in a low-temperature atmosphere (50 degrees Celsius).
Heat conduction from the high temperature section to the low temperature section is prevented by the sleeve 17 and the inner stay 37. Further, since the signal line 39 is sealed within the seal pipe 9 and the moisture-proof cover 34, it is not affected by external moisture.
Furthermore, external vibration from the flange base 5 is transmitted through vibration isolating springs 31A, 31B, vibration isolating rubbers 36C, 37
C. Sufficient attenuation by sleeve 17.

When calibrating the microphone, it is sufficient to simply drive the calibration sound source 10. Sound waves generated by driving the calibration sound source 10 are applied to the sound receiving section 3 through the waveguide 20 . During calibration, there is no need to enter the reactor containment vessel, which has a high radiation atmosphere, and there is no need to shut down the equipment (reactor).

〔Effect of the invention〕

As explained above, the present invention provides a calibration sound source in which a plurality of calibration sound sources are linearly connected by a joint sleeve, a sound absorbing material for preventing standing wave generation is installed inside, and an adjustment hole is drilled. One end of the waveguide is connected to the other end of the waveguide, and sound waves are supplied to the microphone from the other end of the waveguide. Therefore, microphone calibration tests can be performed without removing the microphone. Therefore, according to the present invention, it is possible to safely and easily perform a sensitivity calibration test regardless of where the microphone is installed.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an embodiment of the present invention, and Fig. 2 is a diagram showing the frequency characteristics due to standing waves in the waveguide. Figures 3A, B, and C show the frequency characteristics when the diameter and length of the waveguide are changed without changing the total length of the waveguide, and Figures 4A, B is a diagram showing the frequency characteristics at the waveguide exit when the inner diameter of the shotphone and the inner diameter of the waveguide are changed.
Figure 5 shows the frequency characteristics at the exit of the waveguide depending on whether there is an adjustment hole or not.
6 and 7 are partial sectional views when the microphone calibration sound source device according to the present invention is integrated with the microphone, and FIG. 8 shows the microphone calibration sound source device according to the present invention when there is an adjustment hole. FIG. 3 is a perspective view of the microphone integrated with the microphone. 10...Calibration sound source, 20...Waveguide.

Claims (1)

[Claims] 1. One end of a waveguide in which a plurality of waveguides are linearly connected to a calibration sound source by joint sleeves, a sound absorbing material for preventing the generation of standing waves is installed inside, and an adjustment hole is bored. and a microphone calibration sound source device that connects the waveguide and supplies sound waves to the microphone from the other end of the waveguide. 2. The calibration sound source is transmitted through a speaker that serves as a sound source, a speaker duct that is fixed behind the speaker and emits sound pressure from the back of the speaker to the outside, and a speaker throat that emits sound waves from the speaker. A speaker holder fixed to the speaker and supporting the speaker, a speaker cover fixed to the speaker holder, a shortphone fixed to the speaker holder and propagating sound waves, and a shortphone fixed to the shortphone. 2. The microphone calibration sound source device according to claim 1, further comprising a sleeve to which one end of the waveguide is connected. 3. The microphone calibration sound source device according to claim 1 or 2, wherein the waveguide is constructed by linearly connecting a plurality of waveguides of the same size. 4. The microphone calibration sound source device according to claim 1 or 2, wherein the waveguide is constructed by linearly connecting a plurality of waveguides of different sizes.