JP2548062Y2 - Transmitter structure - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a microphone mounting structure incorporated in a telephone or a portable video camera.

[0002]

2. Description of the Related Art It is desirable for a transmitter such as a telephone to have a capability of collecting a speaker's voice with high sensitivity and not responding to a breath or a wind of the speaker. In particular, condenser microphones have sufficiently high microphone sensitivity even in a low frequency band, and thus tend to easily respond to wind and airflow having low frequency components. For this reason, some measures have been taken to reduce wind noise.

FIG. 8 is a sectional view showing a conventional transmitter shown in, for example, Japanese Patent Publication No. 60-17191. In the figure, 11 is a transmitter, 12 is a microphone unit, 13 is a front hole, 14 is a cavity, and 15 is an opening. Next, the operation will be described. A sound wave such as a speaker's voice passes through the opening 15, propagates through the cavity 14, further passes through the front hole 13, reaches the diaphragm of the microphone unit 12, and generates a voltage proportional to the sound pressure. Wind and air currents also pass through apertures 15 and
to go into. Here, since the cross-sectional area and volume of the cavity 14 are configured to be larger than the cross-sectional volume of the opening 15, the airflow velocity is reduced due to the viscosity and compliance of the air in the cavity 14 and the like, and the wind noise is reduced. It is said to be effective in reducing the amount. In the conventional example, the cross-sectional area of the cavity 14 is 1 cm in radius,
An example in which the cavity height is 0.3 to 0.75 cm is shown.
On the other hand, recently, there is a strong demand for small and thin mobile phones and the like, and a microphone unit having a size of about φ6 × t5 mm is used. The volume of this unit is 0.14c
m3, and the volume of the cavity 14 is 6.7 times to 16 times
Equivalent to double.

[0004]

Since the conventional transmitter is configured as described above, a large space is required to reduce wind noise, and it is difficult to reduce the size and thickness of the transmitter. There was a problem.

The present invention has been made to solve the above problems, and has as its object to provide a transmitter structure which can reduce wind noise and can be reduced in size and thickness.

[0006]

The structure of the transmitter according to the present invention is such that a sound path is formed by providing a concave portion in a vibration isolating rubber surrounding the microphone unit, and a microphone front opening and a housing opening are formed. It has been shifted.

[0007]

According to the present invention, the sound path formed on the vibration isolating rubber attenuates wind and airflow due to its viscosity.

Further, since a part of the vibration isolating rubber is used as a sound path, a newly large cavity is not used.

[0009]

[Embodiment 1] FIG. 1 is a diagram showing a transmitter structure according to an embodiment of the present invention. FIG. 1 (a) is a cross-sectional view in which a microphone is mounted on a housing, and FIG. 1 (b) is a silicon rubber used as a vibration-proof rubber. It is a perspective view of. In the figure, 1 is a microphone, 2 is silicon rubber used as a vibration-proof rubber, 3 is breathable,
A drip-proof sheet that allows sound waves to pass through but does not allow water droplets to pass through. Is a housing hole into which the sound wave enters the housing 4.

Next, the operation will be described. The voice of the speaker enters through the housing hole 7 and reaches the recess 6 through the breathable drip-proof sheet 3. The upper surface of the concave portion 6 is closed by the drip-proof sheet 3 and the housing 4, and an elongated sound path is formed from the housing hole 7 to the front hole 5. Therefore, the sound wave of the sound propagates along the elongated sound path, reaches the front hole 5, and vibrates the diaphragm of the microphone 1 to generate a voltage proportional to the sound pressure.

[0011] Wind and airflow enter through the housing hole 7 and pass through the elongated sound path of the concave portion. Since the height of the sound path is equal to the thickness of the silicone rubber 2, the thickness of the anti-vibration silicone rubber 2 is about 1 mm.

It is known that wind and airflow passing through such a gap are attenuated by viscous resistance. According to the knowledge of hydrodynamics, the flow velocity u is given by u∝d2 / μ (1) where d is the height of the sound path and μ is the viscosity coefficient. The higher the viscosity coefficient, the lower the speed. Since the velocity of the flow is proportional to the square of the height of the sound path, a sound path having a height of about 1 mm is sufficiently effective in reducing wind and airflow. Also, gaps,
It is known that wind noise is reduced when the length of the thin tube is long. In the embodiment, since the positions of the housing hole 7 and the front hole 5 are shifted, the length of the sound path is long. For example, as compared with the case where the housing hole 7 is opened right above the front hole 5, the length can be increased by about the radius of the microphone 1. Therefore, wind noise is further reduced.

On the other hand, the width of the sound path can be made large in the circumferential direction of the silicone rubber 2, so that the cross-sectional area necessary for the propagation of sound waves can be secured. The radius of the front hole 5 is about 1 mm, and the required area of the housing hole 7 is about 2 × 1 mm.
mm, the cross-sectional area of the sound path is about twice that of the housing hole 7,
Sound wave attenuation can be reduced. Further, the recess 6
When the open-cell urethane material is filled in the housing hole 7, the wind noise is further attenuated.

FIG. 2 shows an example in which the shape of the concave portion 6 of the silicone rubber 2 is changed. The recess 6a has a narrow end near the housing hole 7 and a wide end near the front hole 5. The cross-sectional area of the sound path is small at the end of the housing hole 7 close to the entrance and gradually increases toward the front hole 5. Therefore, the wind or the air current entering from the housing hole 7 is diffused in the sound path, and has an effect of reducing the speed.

Embodiment 2 FIG. FIG. 3 shows another embodiment. In the figure, a housing hole 7 is provided outside the radius of the microphone 1 to lengthen the sound path. Therefore, the effect of attenuating the wind noise increases. The concave portion 6 of the silicone rubber 2 extends to the circumferential end of the silicone rubber, and the length of the sound path is increased. Reference numeral 8 denotes a depression formed in the housing 4. If a plurality of housing holes 7 and recesses 8 are provided in the shape of a circular arc of a concentric circle, it is difficult to distinguish which of the recesses is the housing hole 7 of the transmitter, so that the opening of the transmitter cannot be distinguished. There are advantages.

Embodiment 3 FIG. FIG. 4 shows a third embodiment. In the figure, 7a and 7b are housing holes a and b, respectively. In the figure, two housing holes having substantially the same size are provided. By using two housing holes 7a and 7b, the acoustic resistance of the microphone 1 to the sound wave is reduced by half, the attenuation of the sound wave by the sound path is reduced, and the sound pressure sensitivity of the microphone 1 can be increased. Further, since there are two housing holes for one recess 6, the fluctuation pressure of the wind or airflow that enters from one housing hole escapes from the other housing hole and is applied to the front hole 5. The pressure drops.
Therefore, the effect of reducing a fluctuating pressure strongly applied to one of the two housing holes is great.

Embodiment 4 FIG. FIG. 5 shows a fourth embodiment. The figure is a cross-sectional view of the mounting, and the housing holes 7a to 7a are positioned asymmetrically with respect to the microphone 1.
d is provided. FIG. 6 shows a housing hole arrangement of the fourth embodiment viewed from above the housing 4. Four housing holes 7a to 7d
Are arranged point-symmetrically in a concentric arc, but are arranged so that the distances from the front hole 5 of the microphone 1 are different from each other.

FIG. 7 is a diagram for explaining the operation of the fourth embodiment. Consider a case where a parallel wind or airflow flows along the housing 4 as shown in the figure. The flow away from the housing 4 passes without any influence, but the flow near the housing surface enters the housing holes 7a and 7b and causes a new pressure fluctuation.

Since the housing surface is flat and the sizes of the housing holes 7a and 7b are the same, the flow entry state is almost the same, and therefore, the generated fluctuating pressure is in the same phase and the same level. The generated fluctuating pressure passes through the sound path 9 and passes through the front hole 5
Reach Since the fluctuating pressure in the housing hole 7a is transmitted through the sound path by the distance La and the fluctuating pressure in the housing hole 7b is transmitted by the distance Lb, a phase difference occurs in the fluctuating pressure due to the transmission distance difference Lb-La. Therefore, near the front hole 5, the fluctuating pressures of the two cancel each other out. Since the fluctuating pressure is considered to be transmitted along the flow of the wind, the transmission speed is substantially equal to the wind speed. For example, assuming a microphone having a diameter of 6 mm in FIG. 7 and a distance difference of 6 mm and a wind speed of 4 m / sec,
The 333 Hz component is out of phase and will be canceled. Similarly, the frequency component corresponding to the distance difference from the other housing holes 7c and 7d is canceled out. On the other hand, since the propagation speed of the speaker's voice is about 340 m / sec, the cancellation of the voice band component does not occur with a distance difference of about 6 mm.

By arranging a plurality of housing holes at different distances, the wind noise component is reduced. Although an example in which the number of the housing holes is four is shown, the number of the holes may be two or three, or five or more.
It is clear that the same effect can be obtained with more than one.

[0021]

As described above, according to the present invention, a concave portion is provided in the vibration isolating rubber to form a sound path, and the microphone front hole and the housing hole are shifted and mounted. This has the effect that a transmitter capable of reducing wind noise can be configured.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a transmitter structure according to an embodiment of the present invention;

FIG. 2 is a diagram showing a structure of another modification of the present invention.

FIG. 3 is a diagram showing a structure according to another embodiment of the present invention.

FIG. 4 is a diagram showing a structure according to a third embodiment of the present invention;

FIG. 5 is a diagram showing a structure according to a fourth embodiment of the present invention;

FIG. 6 is a diagram showing a housing hole arrangement according to a fourth embodiment of the present invention.

FIG. 7 is a diagram for explaining the operation of the fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a conventional transmitter.

[Explanation of symbols]

 Reference Signs List 1 microphone 2 anti-vibration rubber 3 drip-proof sheet 4 housing 5 front hole 6 recess 7 housing hole

Claims (2)

(57) [Scope of request for utility model registration] 1. A housing having an opening, and a housing accommodated in the housing.
Microphone unit with a front hole
Microphone unit is attached and long and narrow sound path groove
One end of this sound path groove is connected to the microphone unit.
Connect to the front hole of the knit and open the housing at the other end.
Through the mouth, sound from the outside of the housing from the opening
Front hole of the microphone unit through the sound path groove
And a vibration isolating rubber held by the housing so as to reach the speaker. 2. A housing having a plurality of openings, and the housing
Microphone unit housed inside and having a front hole
And the anti-vibration rubber to which this microphone unit is attached
The microphone unit in the housing.
The vibration isolation so as to form a cavity between the
The rubber is held in the housing, and the rubber
The sound is transmitted from the plurality of openings to the microphone through the cavity.
If the distance to the front hole of the crophone unit is different
A transmitter structure characterized by having