GB2364463A

GB2364463A - Protective casing for a microphone.

Info

Publication number: GB2364463A
Application number: GB0103617A
Authority: GB
Inventors: Volker Riedel
Original assignee: Sennheiser Electronic GmbH and Co KG
Current assignee: Sennheiser Electronic GmbH and Co KG
Priority date: 2000-03-01
Filing date: 2001-02-14
Publication date: 2002-01-23
Anticipated expiration: 2021-02-14
Also published as: DE10009847A1; FI20010377A0; NO20011041L; FI20010377A; NO20011041D0; GB0103617D0; GB2364463B; DE10009847C2

Abstract

The invention provides weather protection for a microphone, which also permits use of the microphone under extreme ambient conditions without in that respect the directional characteristic and the recording quality being adversely affected even in long-term use. That object is attained by weather protection for a microphone, which is of a rotationally symmetrical configuration, which at an end 12 is flattened substantially perpendicularly to the axis of rotation 8 and which at its opposite end has a spherical portion 11, comprises a sound-permeable but not rain-permiable material and has a bore 3 for receiving a sound pick-up.

Description

2364463 Sennheiser electronic GmbH & Co. KG Am Labor 1, 30900 Wedemark

Protective casing for microphones The present invention concerns weather protection for microphones and in particular protection from rain and weather.

If microphones are to be used outside closed rooms or spaces or in 5 closed rooms or spaces with an extreme atmosphere, the microphone has to be protected against the environmental influences which can result in the microphone or its properties and qualities being adversely affected.

A known problem is the effect of interference noises and in particular wind noises on the recording quality of a microphone. Foam 10 enclosures for microphones are generally known, for the purpose s of avoiding low-frequency wind noises and for attenuating high-frequency rustling and crackling noises and hissing noises. In the rest of the spectral range however those foam-enclosed microphones have a really low level of damping attenuation so that they attain a high level of quality in terms 15 of the sounds to be recorded and the spoken voice. The directional action of the foam-enclosed microphones is influenced only slightly by virtue of being enclosed with foam on all sides. Foam enclosures of that kind for microphones admittedly afford adequate protection from wind noises, but they are not suitable in terms of affording protection from rain or spray 20 water. In addition, because the rapid rate of material ageing, thefoanT- enclosure is not suitable for long-term use outside closed rooms or spaces.

Laid-open application DE 24 04 943 discloses an electroacoustic transducer, in the sound path of which is arranged a plate which protects 5 the transducer element from spray water and which comprises two rigid grids, between which is disposed a plastic mesh. In order to achieve a low frequency-dependent attenuation effect in the frequency range to be transmitted, the grids and the plastic mesh must be dimensioned in a particular manner so that the sound is practically not reflected at them.

10 As the spray water protection only comprises two grids and a plastic mesh, it can only serve to a limited extent as protection from spray water.

In addition, laid-open application DE 26 52 039 discloses a hand microphone which protects an acoustic transducer from large amounts of water and wind noises. For that purpose, a water-impermeable 15 membrane is provided between the transducer and the outside parts of the casing and an open-pore foamed plastic enclosure on the microphone. Water which drips onto the microphone is repelled by the waterimpermeable membrane whereby the water accumulates in the open-cell enclosure of the microphone. The water which is in the open-cell 20 enclosure can be easily removed by turning the microphone casing over and lightly tapping against it. A disadvantage of that invention is that the operator is required to repeatedly remove the water which has accumulated in the enclosure, by turning the microphone over and lightly tapping it. That means that this hand microphone is not suitable for long- 25 term use without constant checking by an operator. In addition, an openpore foamed plastic is not suitable for permanently withstanding extreme ambient conditions.

DE 199 34 260 discloses a wind weather protection arrangement for a microphone, which is of a rotationally symmetrical configuration and 30 which at one end is flattened substantially perpendicularly to the axis of rotation. The wind protection comprises fine-pore foam material and is thus capable of transmitting sound. EP-A-0 543 087 discloses a protection arrangement for an electroacoustic transducer, In that case the protection body comprises a sintered material, more specifically fine-grain sintered plastic. US-A 5 4 363 937 discloses a microphone protection arrangement with which a given sound nuisance, in particular sound-like noise pulses, can be suppressed.

The object of the present invention is to provide weather protection for a microphone, which also permits use of the microphone under extreme ambient conditions without in that respect the directional characteristic and the recording 10 quality being adversely affected even in long-term use.

That object is attained by weather protection for a microphone, which is of a rotationally symmetrical configuration, which at an end is flattened substantially perpendicularly to the axis of rotation and which at its opposite end has a spherical portion, comprising a sound-permeable material and has a bore for 15 receiving a sound pick-up.

The advantages which the invention entails are in particular that it provides extremely robust protection in relation to rain and wind for microphones, without the omnidirectional characteristic of the microphone being impaired. It will be noted that the terms spherical, sphere and its variants as used herein refer to a 20 part having an at least partially spherical surface and not necessarily or usually a complete sphere.

An advantageous embodiment -of the invention provides that the weather protection comprises two separate portions. The first portion is flattened off at one end and has a funnel-shaped opening at the opposite end and the second 25 portion is funnel-shaped at one end and at the opposite end has a spherical portion with a bore along the axis of rotation. In that arrangement the funnel shaped end of the second portion fits substantially into the funnel- shaped opening of the first portion. By virtue of the two-part arrangement of the weather protection and due to the spherical portion, the microphone has an omnidirectional characteristic even in the higher-frequency range.

In a particularly preferred embodiment of the invention the first and second portions of the weather protection are held together by at least 5 one holding element. In that arrangement, an annular foam inlay or insert is disposed between the first and second portions. In addition, there is a bore through the second portion along the axis of rotation, for accommodating the sound pick-up. Positioning the sound pick-up in the through bore permits an improvement in the microphone pick-up quality 10 as the sound can pass essentially undamped through the intermediate space between the first and second portions to the sound pick-up. For the purposes of reducing wind noises and interference noises, an annular foam inlay or insert is fitted into the intermediate space between the two portions.

15 A particularly preferred embodiment of the invention provides that the second portion is so dimensioned that the centre point of the sphere on which the spherical portion is based is disposed on the axis of rotation in the region of the through bore. This exact dimensioning of the second portion results in a further improvement in the omnidirectional 20 characteristic of the microphone, even for high-frequency noises.

A further advantageous embodiment of the invention provides that the weather protection comprises Delrin. The selection of this material also ensures long-term use of the weather protection outside closed rooms or spaces.

25 A further preferred embodiment of the invention provides that there is a bore along the axis of rotation at the flattened end of the weather protection. By means of the bore, it is possible to fit the weather protection to a fixing device, in which case, the first portion faces upwardly and the second portion faces downwardly. That prevents for 30 example rainwater from passing into the part between the first and second portions.

Further advantageous embodiments of the invention are set forth in the appendant claims.

An embodiment by way of example of the invention is described hereinafter with reference to the drawing in which:

5 Figure 1 is a view in section through the weather protection, Figure 2 shows a frequency characteristic of the weather protection inclusive of a sound pick-up capsule element in a situation involving lateral sound incidence and without a foam insert, Figure 3 shows the directional characteristic of the weather 10 protection with the sound pick-up capsule element without the foam insert, and Figure 4 shows a photo of a prototype of the weather protection.

The weather protection which comprises two portions 1 and 2 is mounted by means of a bore 7 in the first portion 1 to a fixing device such 15 as for example a rod or pole. In that case the first portion 1 forms the upper part of the weather protection and the second portion 2 forms the lower part of the weather protection. The upper and lower portions 1 and 2 are held together by three screwthreaded rods 5 in such a way that an intermediate space is formed between the first portion 1 and the second 20 portion 2. An annular foam insert is fitted into that annular,space. A sound pick-up capsule element is mounted in the bore 6 and the bore 3 can accommodate for example the electronic processing system or a part thereof.

An annular foam insert is used in order to protect the sound pick-up 25 capsule element which is disposed in the bore 6 from interference noises such as for example wind noises.

Due to the curvature of the spherical portion and the curvatures of the side walls of the funnel-shaped opening and the funnel, the sound can reach the pick-up capsule element without a high level of attenuation 30 effect. The rotationally symmetrical configuration of the weather protection also affords an improvement in the ornnidirectional characteristic of the microphone.

Due to the specific configuration of the first and second portions 1, 2, no rainwater can penetrate into the intermediate space and thus result 5 in an impairment in the pick-up properties of the microphone.

Figure 3 plots the omnidirectional characteristics for a microphone with the weather protection for some frequencies. In this case, it is found for frequencies of greater than 16 KHz (Figures 3f, g and h) that in actual fact it is possible to achieve a good ornnidirectional characteristic.

10 In regard to acoustic monitoring of gas lines, the frequencies of greater 16 KHz are of particular interest as gas escape noises in that frequency range involve the most energy. For automatic long-term monitoring of external installations of extensive length such as for example gas lines, what is wanted is not lifelike reproduction, but 15 automatic detection of special or exceptional situations or malfunctions.

The ornnidirectional characteristic of the microphone is required in particular for monitoring over an extensive length, as fault and interference noises can come from various directions.

Long-term monitoring of external installations involving an 20 extensive length requires microphones which are not going to be adversely affected by the climatic conditions. For use on external installations, it is therefore important for the microphone to be protected from rainwater. In that respect however the pick-up properties of the microphone are not to be impaired.

25 The noises which are picked up by the microphone are converted into acoustic patterns and compared to patterns from an acoustic database. If now a recorded acoustic pattern coincides with an acoustic pattern which is stored in the database, a warning can possibly be given.

Claims

1. Weather protection for a microphone, in particular protection from rain and wind, wherein the weather protection is of a rotationally symmetrical configuration, characterised in that the weather protection is flattened at one end (12) substantially perpendicularly to the axis of rotation (8) and at the opposite end has a spherical portion (11), that the weather protection comprises a sound-permeable but not rain-permeable material, and there is provided a bore (3) for receiving a sound pick-up.

2. Weather protection according to claim 1 characterised in that the weather protection comprises a first portion (1) and a second portion (2), wherein the first portion (1) is flattened at one end and has a funnelshaped opening at the opposite end, and the second portion (2) is of a funnel-shaped configuration at one end and at the opposite end has a spherical portion with the bore (3).

3. Weather protection according to claim 2 characterised in that the bore (3) is provided along the axis of rotation (8).

4. Weather protection according to claim 2 or claim 3 characterised in that the funnel-shaped end of the second portion fits substantially into the funnel-shaped opening of the first portion.

5. Weather protection according to one of claims 2 to 4 characterised in that the side walls (9) of the funnel and of the funnelshaped opening each involve a constant curvature.

6. Weather protection according to one of claims 2 to 5 characterised in that the first and second portions (1, 2) of the weather protection are held together by at least one holding element (5).

7. Weather protection according to one of claims 2 to 6 characterised in that an annular insert (4) is disposed between the first and second portions (1, 2).

8. Weather protection according to claim 7 characterised in that the insert (4) is 5 in the form of a foam insert.

9. Weather protection according to one of claims 2 to 8 characterised in that there is provided a bore (8) through the second portion (2) along the axis of rotation (8), for receiving the sound pick-up. 10 10. Weather protection according to claim 9 characterised in that the centre point of the sphere which forms the basis for the spherical portion is disposed on the axis of rotation (8) in the region of the through bore (6).

15 11. Weather protection according to one of claims 2 to 10 characterised in that the transition between the spherical portion and the funnel-shaped end of the second portion is of a rounded-off configuration.

12. Weather protection according to one of the preceding claims characterised 20 in that the weather protection comprises Delrin.

13. Weather protection according to one of the preceding claims characterised in that a bore (7) is provided at the flattened end (12) of the weather protection.

25 14. Weather protection according to claim 13 characterised in that the bore (7) is provided along the axis of rotation (8).

15. Weather protection as herein described with reference to the accompanying figures.