Technical Field

The specification relates to a microphone device according to the preamble of claim 1. Such a microphone device can be a part of another device, such as a headset, a headphone, a mobile phone. It could also be an individual microphone apparatus, which can connected by wire or wirelessly to other devices. Thus, the microphone device can be a part of Bluetooth headset, which can be wirelessly connected to a mobile phone. It could also be provided at the end of a microphone arm on a headset primarily designed to be used in offices or contact centres. It could also be a small Lavalier microphone or a head worn microphone which is typically worn in television studios and on theatre stages.

Background Art

Microphone devices should be designed to reduce negative impacts from the environment in which they are used. A god microphone device should pick up the audio it is desired to pick up and not noise of different kinds. The noise to be avoided, could be wind noise, puffs from a mouth and handling noise, which occurs when the microphone device is touched by f. ex. a user's hand or rubbed against clothes. Wind noise can be very problematic, especially when the microphone device is used out door.

US 9,143,850 (GN Netcom A/S) shows a microphone device comprising a housing, a cavity enclosed by the housing, at least one microphone unit acoustically coupled to the cavity, the housing comprising an outer side and a first wall section with a number of sound holes extending in a first direction from the outer side of the housing to the cavity, whereby sound can enter the cavity from the surroundings via the sound holes. A problem with this device is that turbulence can occur in the relatively long holes, whereby noise is created.

US 2015/0271587 (Red Tail Hawk Corporation) shows a microphone device comprising a housing, a cavity enclosed by the housing, at least one microphone unit acoustically coupled to the cavity, the housing comprising an outer side and a first wall section with a number of sound holes extending in a first direction from the outer side of the housing to the cavity, whereby sound can enter the cavity from the surroundings via the sound holes. The sound holes are rounded to the outer side of the housing wall in order to reduce wind turbulence.

A disadvantage with this way of reducing turbulence is, that it affects the outer design, and that the enlarged openings on the outer side may capture dirt.

US 2,787,675 discloses a microphone device according to the preamble of claim 1.

It is possible to use a strong material such as metal, whereby the sound holes can be short and a sufficient strength and rigidity be obtained. However, this requires the use of strong and expensive materials. Thus, at sheet of metal of 0.2-0.4 millimetre may be strong enough to withstand physical stresses during use but thin enough to prevent the through going holes to act as tunnels causing turbulence noise. When a plastic sheet is used instead of metal sheet a higher thickness, maybe 0.6-1 mm is needed to obtain a sufficient stiffness and strength.

Disclosure of Invention

A microphone device according to the invention comprises a microphone housing, a cavity enclosed by the housing, at least one microphone unit acoustically coupled to the cavity, the housing comprising an outer side and a first wall section with a number of sound holes extending in a first direction from the outer side of the housing to the cavity, whereby sound can enter the cavity from the surroundings via the sound holes, wherein the cross-sectional area of the sound holes expands when moving along the first direction, characterized in that the sidewalls of the sound holes are shaped as arched vaults. With such a solution, a sufficiently strong wall section can be obtained while the same time reducing the problems with wind turbulence created in long holes. Furthermore, by the increased cross-sections of the sound holes, the increased volume of the sound holes compared to sound holes with constant cross-sections from the outer side to the inner side adds to the volume in front of the microphone unit, which is desirable, as it dampens the effect of strong pressure rises due to air gusts.

According to an embodiment, the first wall section is made of moulded plastics. Typically, it will be made of moulded plastics.

The sound holes may have a circular cross-section seen in the first direction.

According to an embodiment, the sound holes are arranged in a at least two parallel rows of equally distanced sound holes, where two neighbouring rows are displaced a half hole distance measured between hole centres.

According to an embodiment, the first wall section has a wall thickness of at least 0,6 mm, 0.8 or 1 millimetre.

The invention also relates to a headset comprising a microphone device according to any of the preceding claims and at least one speaker.

Brief Description of the Drawings

The invention is explained in detail below with reference to the drawing illustrating embodiments of the invention and in which

Fig. 1 is a perspective view of a headset incorporating a microphone device according to the invention,

Fig. 2 a cross-sectional view through the microphone device,

Fig. 3 discloses an upper wall part and a lower wall part, Fig. 4 a perspective view of a wall section of the microphone device,

Fig. 5 the same view as in fig. 4 seen from directly below,

Fig. 6 a cross-sectional view of the wall section shown in figures 4 and 5,

Fig. 7 a perspective cross-sectional view of the wall section shown in figures 4-6,

Fig. 8 a schematic cross-sectional view through the wall section of a second embodiment,

Fig. 9 a schematic top view of the wall section according to the second embodiment,

Fig. 10 a schematic cross-sectional view through the wall section of a third embodiment,

Fig. 11 a schematic top view of the wall section according to the third embodiment,

Fig. 12 a schematic cross-sectional view through the wall section of a fourth embodiment,

Fig. 13 a schematic top view of the wall section according to the fourth embodiment,

Fig. 14 a schematic cross-sectional view through the wall section of a fifth embodiment,

Fig. 15 a schematic top view of the wall section according to the fifth embodiment,

Fig. 16 a schematic cross-sectional view of a prior art microphone mesh of sheet metal,

Fig. 17 a schematic cross-sectional view of a prior art microphone mesh of moulded plastic, and Fig. 18 a schematic cross-sectional view of the second embodiment.

Modes for Carrying out the Invention

Fig. 1 discloses a perspective view of a headset 10 incorporating a microphone device according to the invention. The headset 10 is a monaural headset comprising an earphone housing 11, a microphone arm 15 extending from the earphone housing 11 and a

microphone device 1 at the free end of the microphone arm 15. An ear hook 14 extends from the earphone housing 11. A multifunction button 16 is arranged on the outer side 17 of the earphone housing 11 and an eargel 12 is arranged on the inner side 18 of the earphone housing 11. When the headset 10 is arranged with the ear hook 14 around the right ear of a user, the eargel 12 extends into the outer ear and the microphone arm 15 is pointing in the direction of the user's mouth. The eargel 12 is a soft funnel like structure leading the sound from a speaker inside the earphone housing 11 into the ear of the user. The headset 10 is a wireless headset comprising a not shown DECT transceiver and a rechargeable battery. However, this is not so relevant for the invention, and further details about this are left out.

Fig. 2 is a cross-sectional view through the outer end of the microphone arm 15 and the microphone device 1, which are integrated and comprise an upper wall part 21 and a lower wall part 22. These wall parts 21, 22 define together with a microphone boot 20 a microphone housing 2. In the microphone housing 2, a microphone unit 5 is arranged.

Microphone wiring 19 extends from the microphone unit 5 through the microphone housing 2 and the microphone arm 15 to the earphone housing 11. The microphone unit 5 is resting in a recess in the microphone boot 5. A first side of the microphone unit 5 is facing a cavity 6 of the microphone housing 2. This cavity 6 is facing a wall section 3 of the upper wall part 21 comprising a number of sound holes 4, which will be explained in more detail later. A second side of the microphone unit 5 is in acoustic connection with the surroundings via a secondary sound hole 13 in the microphone boot 20. As both sides of microphone membrane of the microphone unit 4 are in acoustical connection with the surroundings a directivity is obtained. Fig. 3 discloses the upper wall part 21 and lower wall part 22 in disassembled state. As shown, the wall section 3 comprises a number of sound holes 4 providing an acoustic connection from the surroundings to one side of the microphone unit.

Figs. 4 and 5 discloses the upper wall part 22 from two different angles. The wall section 3 comprises 28 sound holes in total distributed in three parallel rows 23, 24 and 25. Each of the first row 23 and the third row 25 comprise4 sound holes, while the middle second row 24 comprise 10 sound holes. In each row all the sound holes 4 are arranged with equal hole distances XI. The second row 24 is displaced a half hole distance XI in the longitudinal direction, whereby a kind of honeycomb like structure is obtained. The sound holes 4 are shaped as domes 26 or vaults or arched vaults on the inner side of the upper wall part 40 with through going openings 28 in the uppermost area. The domes intersect each other, such that arches 27 defines boundaries between the domes 26. The arches 27 are rounded. This geometry provides a relative rigid and sturdy structure without corresponding to a thick plate and without the "tunnel effect", which can occur with cylindrical holes in a relatively thick plate. The combined space provided by the domes on the inner side also provides a compartment of air reducing wind speed and thereby noise.

Figs. 6 and 7 are cross-sectional views of the wall section shown in figures 4 and 5. The wall thickness WT immediately outside the wall section 6 with the sound holes 4 is about 1-1.2 mm. The diameter X2 of the through-going openings 28 is about 0.4-0.6 mm. The distance X3 between the outer surface and the closest part of the arches 27 is about 0.4-0.8 mm.

The outer edge 30 of the through going opening is rounded. As seen in Fig. 7 the side walls 9 of the sound holes 4 are vaulted.

Fig. 8 is a schematic cross-sectional view through the wall section according to a second embodiment. The sound holes 4 are shaped as truncated cones.

Fig. 9 is a schematic top view of the wall section according to the second embodiment. Fig. 10 is a schematic cross-sectional view through the wall section according to a third embodiment. The sound holes 4 are shapes as truncated ellipsoids.

Fig. 11 is a schematic top view of the wall section according to the third embodiment.

Fig. 12 is a schematic cross-sectional view through the wall section according to a fourth embodiment. The sound holes 4 are "trumpet" shaped.

Fig. 13 is a schematic top view of the wall section according to the fourth embodiment.

Fig. 14 is a schematic cross-sectional view through the wall section according to a fifth embodiment. The sound holes 4 are overlapping truncated cones.

Fig. 15 is a schematic top view of the wall section according to the fifth embodiment.

The second, third, fourth and fifth embodiments may have rounded outer edges 30 like the first embodiment shown in Figs. 1-7.

Fig. 16 is a schematic cross-sectional view of a prior art microphone mesh of sheet metal. Due to the thin sheet of only 0.2-0.4 mm thickness, no turbulence will occur in the sound holes 4.

Fig. 17 is a schematic cross-sectional view of a prior art microphone mesh of moulded plastic. This prior art "sheet" is made by moulded plastic, which is a cheaper solution than the metal solution shown in Fig. 16. However, as plastic is weaker than metal a greater wall thickness WT is needed to obtain sufficient rigidity and strength. This cause longer tubular sound holes 4, in which turbulence can occur causing noise. Fig. 18 is a schematic cross-sectional view of the second embodiment. Plastic is used like the embodiment shown in Fig. 17. However, due the shape of the sound holes 4, turbulence and thereby noise will not occur.

Reference signs:

D1 first direction

XI hole distance

X2 diameter of sound opening

X3 distance between the outer surface and the closest part of the arches WT wall thickness

1 microphone device

2 microphone housing

3 wall section

4 sound hole

5 microphone unit

6 cavity

7 surroundings

8 outer side of housing wall

9 side wall of sound hole

10 headset

11 earphone housing

12 ear gel

13 secondary sound hole

14 earhook

15 microphone arm

16 multi-function button

17 outer side of earphone housing

18 inner side of earphone housing

19 microphone wiring

20 microphone boot

21 upper wall part

22 lower wall part

23 first row of sound holes

24 second row of sound holes 25 third row of sound holes

26 dome

27 arch

28 through going openings

29 microphone boot insert

30 outer edge of through going opening