JPH0725692U - Anti-vibration structure of line microphone - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an anti-vibration structure for a line microphone that is easy to assemble and can be manufactured at low cost. [Structure] In a line microphone 1, a unit holding portion 5 holding a microphone unit 3 and a resonator portion 6 which is an opening communicating with the unit holding portion 5 along the same axis to introduce a sound wave into the microphone unit 3.
And a holding member 4 made of an elastic body having a plurality of protrusions 7, 8 and 9 which are provided on the outer peripheral surface and both ends in the axial direction and contact the inner surface of the acoustic tube. With the microphone unit 3 held on the projections 7, 8, 9
To elastically contact the inner surface of the acoustic tube 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a line microphone that is a narrow directivity microphone, and more particularly, to a vibration isolation structure of a line microphone that has a narrow directivity by fitting an acoustic tube into a microphone unit.

[0002]

[Prior art]

 Among condenser microphones, unidirectional and sharp directivity microphones are often used as microphones mounted on video cameras and the like. In the case of a video camera for general household use, a unidirectional condenser microphone is usually used because of problems such as miniaturization of the external appearance, and in the case of a commercial video camera for creating broadcast programs, a sharp directivity is used. Condenser microphones are often used.

There is a narrow directivity microphone called a line microphone as a microphone that is required to have such directivity. In this line microphone, one end of a leaky acoustic tube is fitted to the front acoustic terminal of the microphone unit, and sound waves from angles other than the main sound collection axis are emitted from the front end surface and side openings of the acoustic tube. Sharp resistance is obtained by passing through the resistance material and entering the acoustic tube, and attenuating the sound wave on the main sound collection axis by the phase difference.

Such a conventional line microphone is composed of a microphone unit having a front acoustic terminal and a rear acoustic terminal, and an acoustic tube having slit openings formed on its peripheral surface. One end of the acoustic tube is fitted to the front acoustic terminal side of the microphone unit, and the rear acoustic terminal side of the microphone unit is located in the free sound field. An acoustic resistance material made of non-woven fabric such as felt or nylon mesh is provided on the outer or inner surface of the acoustic tube.

By the way, the video camera has a large number of rotating parts, and the rotation thereof may reach the microphone as sound waves or vibrations and be picked up. So with this kind of microphone. The front acoustic terminal of the microphone unit is firmly connected to the rear portion of the acoustic tube, and the acoustic tube and the entire microphone unit are covered with an elastic body such as rubber to prevent vibration.

[0006]

[Problems to be solved by the device]

 However, in order to prevent the vibration as described above, not only the number of parts is increased, but also the assembly is troublesome and the cost is increased.

Therefore, an object of the present invention is to provide an anti-vibration structure for a line microphone that can be easily assembled and manufactured at low cost.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention fixes a microphone unit of a line microphone, which has a microphone unit and an acoustic tube whose rear end is fitted to the front end of the microphone unit, inside the acoustic tube in an anti-vibration state. In the anti-vibration structure of the line microphone, the unit holding part that holds the microphone unit, the opening that communicates with the unit holding part along the same axis and introduces sound waves into the microphone unit, and the outer peripheral surface and both axial ends A holding member having a substantially cylindrical shape, which is made of an elastic body and has a plurality of projections that project from the inner surface of the acoustic tube and contact the inner surface of the acoustic tube. , Is elastically brought into contact with the inner surface of the acoustic tube by the projection.

[0009]

[Action]

 With the configuration described above, the microphone unit is inserted into the unit holding portion of the holding member and held, and the holding member is simply mounted inside the acoustic tube to hold it against the inner surface of the acoustic tube or the member arranged in the axial direction. The protrusions of the members come into contact with each other, and the microphone unit can be elastically fixed to the acoustic tube, which enables vibration-proof support of the microphone unit. Further, since the microphone unit is held at a certain distance from the inner wall of the acoustic tube, the front acoustic terminal and the rear acoustic terminal of the microphone unit are coupled in the acoustic tube with acoustic impedance and function as a high-frequency resonator. The opening that becomes can also be integrally formed.

[0010]

【Example】

 An embodiment of the present invention shown in the drawings will be described below. FIG. 1 shows the main part of the whole line microphone. The line microphone 1 is fitted with an acoustic tube 2 made of a metal such as aluminum and a holding member 4 in the rear end of the acoustic tube 2. It is composed of a microphone unit 3 to be touched.

As shown in the sectional view of FIG. 2 and the right side view of FIG. 3, the holding member 4 has a substantially cylindrical shape, and is integrally formed of neoprene rubber having a hardness of 30 degrees, for example. The holding member 4 is provided with cylindrical openings having different diameters along the axis, and the large-diameter opening on the right side in FIG. 2 is the unit holding part 5 for holding the microphone unit, and the small-diameter opening on the left side. The part is a resonator part 6 which communicates with the unit holding part 5 and functions as a high frequency resonator. On the outer circumference of the holding member 4, projections 7 are integrally formed at two locations in the axial direction at three locations every 120 degrees in the circumferential direction, and at both locations, three locations offset by 60 degrees from the projection 7. The projections 8 and 9 are respectively provided on the. The holding member 4 may be made of any elastic material having the same properties as neoprene rubber, and the material is not particularly limited.

A grill 10 is formed at the tip of the acoustic tube 2, and behind the grill 10 is a front damper 11 made of an acoustic resistance material that transmits sound waves that have penetrated through the openings of the grill 10. ing. Behind the front damper 11, a wire mesh 12 and a tube damper 13 made of an acoustic resistance material are provided along the inner circumference of the acoustic tube 2 while being held on the inner surface of the acoustic tube 2 by its shape restoring force. To be These are adhered and fixed to the inner surface of the acoustic tube 2 at the ends by an adhesive.

The holding member 4 is mounted in the acoustic tube 2 in a state where the microphone unit 3 is inserted into the unit holding portion 5 and is held in the holding portion 5. The rear end of the holding member 4 which holds the microphone unit 3 is located in front of the opening 14 for the rear acoustic terminal formed in the rear portion of the acoustic tube 2, and has the breathability fitted in the acoustic tube 2. Is in contact with the front elastic ring 17 made of rubber or expandable synthetic resin. The front elastic ring 17 is fixed by the edge portion of the wire mesh 15 inserted into the acoustic tube 2 so as to cover the opening 14. The other end of the wire net 15 is fixed by a bottom pad 16 inserted into the acoustic tube 2.

The front end of the resonator portion 6 of the holding member 4 is made of the same material as that of the front elastic ring 17, and the front fastener 20 via a front buffer ring 19 having an outer diameter at least equal to the inner diameter of the acoustic tube 2. The movement is regulated by. Although not shown in detail, the front fastener 20 has a ring portion having a diameter smaller than the inner diameter of the acoustic tube 2 and a plurality of leg portions projecting outward from the ring portion. It is fixed in the acoustic tube 2 with air permeability. Reference numeral 21 is an opening for introducing a sound wave from the side surface of the acoustic tube 2 to the front acoustic terminal.

With this configuration, the microphone unit 3 is inserted into and held by the unit holding portion 5 of the holding member 4, and is simply inserted into the rear side of the tube damper 13 of the acoustic tube 2 together with the above-mentioned members in order. Can be easily assembled. Moreover, since the protrusions 8 and 9 contact the other member in the axial direction and the protrusion 7 contacts the inner peripheral surface of the acoustic tube 2 in the circumferential direction, the vibration transmitted from the acoustic tube 2 side to the microphone unit 3 side. Can be effectively blocked, and good assembling and anti-vibration properties can be realized at the same time.

It should be noted that, in the frequency band above the midrange, the resonator portion 6 side of the holding member 4 serves as the front acoustic terminal, but at low frequencies, the tip of the acoustic tube 2 similarly serves as the front acoustic terminal and the rear acoustic terminal. The distance from the opening at the rear end of the acoustic tube 2, which is the acoustic terminal, becomes long, and an extremely large pressure difference occurs between the two. However, a gap is created between the holding member 4 and the inner peripheral surface of the acoustic tube 2 due to the projection 7, and an air leakage path from the front fastener 20 through the sponge ring 19 and the front elastic ring 17 to the rear acoustic terminal. Even if there is a pressure difference between the front acoustic terminal and the rear acoustic terminal, the air on the high pressure side can flow into the low pressure side, so the pressure difference becomes small and wind noise is reduced. It can also contribute to mitigation.

[0017]

[Effect of device]

 As described above, the anti-vibration structure for a line microphone according to the present invention includes a unit holding portion that holds the microphone unit, an opening that communicates with the unit holding portion along the same axis, and introduces a sound wave into the microphone unit. It has a substantially cylindrical holding member made of an elastic body with its outer peripheral surface and a plurality of protrusions protruding from both ends in the axial direction and abutting the inner surface of the acoustic tube. The unit holding portion holds the microphone unit. In this state, the protrusion is elastically brought into contact with the inner surface of the acoustic tube, so that it is possible to provide a line microphone that can be easily assembled and has excellent vibration damping properties at low cost. Further, an opening serving as a resonator functioning as a high frequency resonator can also be formed integrally with the holding member.

[Brief description of drawings]

FIG. 1 is a front view showing a cross section of a main part of a line microphone having an acoustic tube according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing only the holding member.

FIG. 3 is a side view of a holding member.

[Explanation of symbols]

 1 Line microphone 2 Acoustic tube 3 Microphone unit 4 Holding member 5 Unit holding part 6 Resonator part 7,8,9 Protrusion

Claims (1)

[Scope of utility model registration request] 1. An anti-vibration structure for a line microphone, wherein the microphone unit of a line microphone having a microphone unit and an acoustic tube having a rear end fitted to the tip of the microphone unit is fixed in the acoustic tube in an anti-vibration state. In, a unit holding portion for holding the microphone unit, an opening communicating with the unit holding portion along the same axis line to introduce a sound wave into the microphone unit, and an outer peripheral surface and projectingly provided on both axial end portions, The acoustic tube has a substantially cylindrical holding member made of an elastic body having a plurality of protrusions that come into contact with the inner surface of the acoustic tube, and the microphone is held by the unit holding portion. An anti-vibration structure for a line microphone, which is elastically brought into contact with the inner surface of the pipe.