DE2030845C - Acoustically effective element in front of a microphone membrane - Google Patents

Description

with a covering surface (2.3; 6.1), for example an annular surface, which runs close to the membrane surface, delimits a flat volume (2.31; 6.11) whose coupling cross-section (2.32; 2.33; 6.2) to the associated coupling path (2.1; 2.2; 2.21; 2.22 ) is smaller than the ao area (1.11) of the central area (1.1) and / or the edge area (1.22) of the membrane that is not covered by the active element (2; 5).

2. Acoustically effective element according to claim 1, characterized in that the height (2.31; 6.11) of the throat volume between the membrane surface and the cover surface is constant or almost constant.

3. Acoustically effective element according to claim 1, characterized in that the height of the flat volume between the membrane (1) and the cover surface (2.3) from the coupling point of the flat volume on the associated coupling path (2.1; 2.2) beginning, itself to the actual electroacoustic transducer element, for example the voice coil (S), at least narrows on part of this path.

4. Acoustically effective element according to one or more of the preceding claims, characterized in that the separate coupling paths (2. Γ 2.2) acoustic coupling elements (2.11; 2.21; 2.22) between their associated areas of the membrane (1.1; 1.2) and the free Form a sound field, for example in the form of funnels (2.11; 2.22), open arrows (2.21), chain ladders or the like.

5. Acoustically effective element according to claim 4, characterized in that at least one of the separate coupling elements has a certain frequency range, for example the top frequency range, preferred.

6. Acoustically effective element according to one or more of the preceding claims, characterized in that the flat volume covers only part of the central area (1.11).

7. Acoustically effective element according to one or more of the preceding claims, characterized in that the flat volume covers only part of the edge area (1.22).

8. Acoustically effective element according to one or more of the preceding claims, characterized in that the flat volume covers both part of the central area (1.1) and part of the edge area (1.22).

9. Acoustically effective element after one

• (of the several preceding claims, in which the adaptation element for the central area of the membrane is cm funnel (2.11) , characterized in that the diameter of the funnel opening (2.110) directed towards the sound source is greater than the outer diameter of the flat volume.

10. Acoustically effective element according to one or more of the preceding claims, characterized in that the predominantly ring-shaped sound inlet on the outer edge of the membrane is limited by a jacket part (4), the jacket surface of which runs approximately parallel to the perpendicular perpendicular to the membrane surface.

11. Acoustically effective element according to claim 10, characterized in that the volume enclosed by Act Mantplflärhe forms an open pipe (2.21).

12. Acoustically effective element according to claim 11, characterized in that the Length of the open pipe is less than half the diameter of the diaphragm.

13. Acoustically effective element according to one or more of the preceding claims, characterized characterized in that the predominantly ring-shaped sound inlet has an annular cylinder cross-section owns.

14. Acoustically effective element according to one or more of the preceding claims, characterized in that the casing part (4), which encloses a predominantly annular sound inlet (2.21) , has at least two openings or opening areas, for. B. perforated wreaths, which serve for coupling to the surrounding sound field and which have different distances from the membrane and are covered with acoustic resistances, the acoustic resistances of the openings or opening areas are smaller with increasing distance from the membrane.

15. Acoustically effective element according to one or more of the preceding claims, characterized characterized in that the predominantly ring-shaped sound inlet in the area of the outer edge the membrane is bounded by a funnel-shaped casing part (6), the central axis of this Funnel runs approximately parallel to the perpendicular perpendicular to the membrane surface.

16. Acoustically effective element according to claim 15, characterized in that the smallest diameter of the funnel-shaped shell part is smaller than the outer diameter of the Bead part of the membrane.

17. Acoustically effective element according to one or more of the preceding claims, characterized characterized in that the membrane in the middle part (1.1), for example in the Kaloüteil, is reinforced.

The invention relates to an acoustically effective element in front of the membrane of a microphone.

It is known that membranes are used for pressure gradient receivers must be sufficiently stiff to pass the high frequencies to the actual transducer element, for example to the voice coil of a dynamic electroacoustic transducer. It is also known that in membranes of this type the lower limit frictionality is then approximately in the Area is between 150 and 200 Hz. To the frequency range through acoustic means to deeper ones

3 4

To expand the frequency, it is also known. Another embodiment of the invention is to couple the Mt nbran air plug as an additional mass, characterized by the fact that the level of the flat load can be coupled. It is also known to reduce the volume between the diaphragm (1) and the Vu diaphragm drive at low frequencies due to the special cover surface (2.3) from the coupling point of the rag, large detours in the rear entrance several separate systems, beginning at (2.1; 2.2), towards one for the low frequencies and an actual electroacoustic transducer element, furthermore for the high frequencies, to be used. for example the voice coil (5), at least on It is also known to narrow the back pressure effect in part of this path. Area of the high and highest frequencies at the io Another embodiment of the invention is to use a relatively large membrane, characterized in that the separate coupling in this frequency range provides useful directional paths (2.1; 2.2) coupling elements (2.11; 2.21; kung. (2.22) between the areas assigned to them uicbc icLMiiiK iiai uf: n rsacnien, uais sie nei aen egg iviemoran ^ ii; i. ^; Unu ucm ncn-u ov-ii-uf - »- * transducers with a small membrane Form 15, for example in the form of funnels (2.11; diameter not towards the desired quality 2.22), open pipes (2.21), Ka: ^ ladders or the like. Visible frequency band, constant frequency r frets- Another embodiment of the invention is there and signal-to-noise ratio, characterized in that at least one of the objects of the invention is to avoid these coupling elements, which are difficult to separate, and to ensure that the high ao quenz ^ eb iet, for example the uppermost frequency band, and highest frequencies preferred by the compliant.

Edge part of the membrane, for example the beading Another embodiment of the invention is there-

part, poorly transferred, essentially only characterized by that the flat volume only

the naturally stiff middle part of the membrane, covers part of the middle area (1.1),

for example the dome, mean special acu 25 Another embodiment of the invention is there-

Stical adaptation elements to the sound field are characterized in that the flat volume only

are preferentially fed. This results in a part of the edge area (1.22) covering,

high and highest frequencies at the middle part Another embodiment of the invention is there-

the diaphragm has a slightly increased sound pressure and is characterized by the fact that the flat volume

thus a large diaphragm drive. With a suitable 30 probably part of the central area (1.1) as well

Dimensioning of the acoustic adaptation element covers part of the edge area (1.22),

ments, e.g. B. by means of a funnel arrangement, an embodiment of the invention in which the

very good bundling in the upper frequency band adaptation element for the central area of the mem-

achieved unc this is a funnel in its shape to the pressure branch, is characterized by

gradient characteristic in the remaining frequency band 35 that the diameter of the

of the microphone. The invention directed funnel opening (2.110) is larger than that

also provides for the rest of the frequency band and the outer diameter of the flat volume,

the entire mem- Another embodiment of the invention is there-

bran, d. H. so the middle part and the yielding part are characterized by the fact that the predominantly nng-

Edge part to be coupled to the sound field. Because the 40-shaped sound inlet on the outer edge of the membrane

compliant part no frequencies in the uppermost fre- is limited by a shell part (4) whose man-

frequency band approximately above 7 to 8 kHz to transmit telfläche approximately parallel to the perpendicular perpendicular to the

needs, it can be made very soft. Runs on the membrane surface.

this way the resonance frequency of the mem-

bran in a very simple way further to depth 45 characterized in that the from the lateral surface

Frequencies shifted towards. enclosed volume an open pipe (2.21)

The object of the invention is achieved by bilüei.

that the acoustically effective element (2; 4; 6) in front of A further embodiment of the invention is there-

the membrane (1) of a microphone for the central part, characterized in that the length of the open

(1.1) the membrane, for example the dome, and 50 pipe is smaller than half the diameter of the

for the edge area (1.2) of the membrane, for example membrane. .

wise the bead part, separate coupling paths Another embodiment of the invention is there-

(2.1; 2.2) to the sound field in direction (3) to be characterized by that the predominantly rmg-

Sound source forms and that this element (2; 4; 6) -shaped sound inlet has an annular cylinder cross-section

to separate these coupling paths close to the 55 has. .

Membrane with a close in front of the membrane surface A further embodiment of the invention is there-

extending cover surface (2.3; 6.1), for example characterized in that the jacket part (4.), wel-

a ring surface, a flat volume (2.31; 6.11) and a predominantly ring-shaped tube

limited, whose coupling cross-section (2.32; 2.33; (2.21) encloses, on its lateral surface at least

6.2) to the associated coupling path (2.1; 2.2; 60 at least two openings or opening areas, e.g. II .

• »21 · 2 22) is smaller than that of the effective perforated rim, which is used for coupling to the surrounding

Element (2; 6) uncovered area (1.11) of the transmitting panel are used and the various output

Central area (1.1) and / or the edge area (1.22) stand from the membrane and with acoustic

The membrane see resistances are occupied, whereby the acoustic resistance of the openings or _{oilrnimgskätze 6 5} see that the height (2.31; 6.11) of the flat area with increasing distance from the Meiii-Vokimens between the membrane surface and the industry will become smaller.

Cover area is constant or nearly constant. Another embodiment of the hrliiuliiMg is ui-

characterized in that the predominantly ring proposal is ensured that the coupling

shaped sound inlet in the area of the outer edge cross section 2.33 of the flat volume 2.31 smaller

the membrane is not separated from the active element 2 by a funnel-shaped jacket

(6) is limited, the central axis of this covered area of the edge area. This area will

The funnel approximately parallel to the vertical line of FIG. 5, analogous to surface 1.11, approximately through the surface ₍

Membrane surface runs. 112 symbolizes. It is the projection of the vaulted

An embodiment of the invention is thereby th edge surface 1.2 of the membrane as a plane

characterized that the smallest diameter of the imaginary total membrane area,

funnel-shaped casing part is smaller than that of FIG. 2 shows another embodiment

Outside diameter of the bead part of the membrane. io of the invention .. The designations 1; 1.1; 1.11; 1.12;

An embodiment of the invention is thereby 1.2; 2; 2.2; 2.3; 2.31; 2.32; 2.33 correspond to the

indicates that the membrane in the middle part (1.1), representation of Fig. 1. With 1.210 is a known one

for example in the dome part, is reinforced. horizontal mounting surface referred to, the t

FIGS. 1 to 4 are intended to explain the invention. Attaching the membrane, for example on the \

The figure shows a schematic representation of the 15 magnet housing that is used. This illustrated example invention. The membrane, for example for a shows that the coupling path 2.1 of the F i g. 1 in dynamic microphone, is denoted by 1. Your Fig. 2 a coupling element to the free central sound area, in this case the dome, is formed with 1.1, 2.11 field in the form of a funnel. The edge area, here the bead part, is marked with 1.2. Shape of the funnel, for example an exponential. The jacket 1.21 is used in a known manner ao funnel, due to its length and its smallest for centering and fastening the membrane on the cross-section and the cross-section of its Ankoppdem magnet part. He can open the air at a defined frequency

The acoustically effective element is designated area 2, for example above 7 to 9 kHz. It separates the coupling paths of the entire membrane as and the shape of the directional characteristic of the microphone, to the sound field, bolstered to influence the frequency response. The arrow 3 shows in The figure also shows that the diameter 2.110 is in the direction of the sound source. The coupling path 2.1 of the opening directed towards the sound source decouples the central part of the membrane to the sound funnel 2.11 which is larger than the outer diameter field. In this example it forms a short circle of the flat volume 2.31. This outer through cylinder, which if necessary also becomes a tubular knife, can be reduced in its diameter by the diameter of the rinse, which can form the coupling cross-section 2.33. The coupling path 2.2 couples the edge area of the membrane to the sound field. He's in for the invention. The designations 1; 1.2; 1.21; 2 in this example through the outer edge 2.4 of the aku 2.11; 2.3; 2.31; 2.32; 2.4 correspond to Fig. 1 stically effective element 2 and through the outer 35 and 2. The coupling path 2.2 forms a Ankopp ren diameter of the edge area of the membrane treatment element 2.21 to the free sound field in the form; limited. It thus forms approximately a circular ring area. an open pipe with a ring cross-section. The open so that the incoming whistle via the coupling path 2.1 is limited by the cylinder jacket 4 to the outside sound essentially only on the central part 1.1 of the. Its outer surface runs roughly parallel to the diaphragm is effective, delimits the acoustically 40 mid-perpendicular to the diaphragm. Inwardly H effective element 2 with its membrane pulling the open pipe through the outer surface 2.5 dt, turned cover surface 2.3, a flat volume of part 2 bounded. With corresponding Dimensionic 2.31. The active frequency of the open pipe 2.21 can be coupled to the coupling path 2.1 via the coupling cross-section 2.32. The coupling path lived for example in the area of 5 to 8 kHz is a flat 45 in this example. Becomes the jacket 4 of the open pipe with a circular cylinder. Its circular cross-section is limited in several openings, which are essentially used for coupling those of the active element 2 not to the surrounding panel and the covered area 1.11 of the central area U. According to different distances from the membrane and the proposed invention, the coupling cross-with acoustic resistances are occupied, the sections 2.32 being smaller than the area 1.11 of the mean distance from the membrane not covered by the effective acoustic resistance of the openings with the increasing element 2, area 1.1. The size of the coupling cross section results in a relatively broadband open tes 2.32 is calculated in this case from the height of the pipe, which for example prefers the entire area of the flat volume and its circumference at around 4 to 8 kHz. Aaf in this way it flows into the associated coupling path 2.1. 55 possible, the usually above 7 to 8 kHz This coupling cross-section so the cladding effective funnel 2.1111 is below this area surface a * _a ore flat circular cylinder to supplement the amount of which still is small for influencing the frequency Very and the diameter of which very large band and the bundling of the microphone with respect to this height is in this manner has FIG. 4 Trains t another Auiführangsbeispiel the flat volume 2.31 a large acoustic Im- 60 of the invention. The designations 1; 2.1; 2, 2Jl; pedanz, and the whole through the coupling «- 2.3; 2.32; 2.33 correspond to the designations of Weg2.1 on the not acoustically effective Fig. 2. Deviating from the area 1.11 of the middle part covered in Fig. 2 dargestell-element 2 th example is the height of the flat volume 2.31

1.1 the sound power supplied to the membrane is not constant. Its height decreases sk'i from? Effective on the central part of the membrane. On the other hand, 65 is coupling cross-section 2.32 in the direction of the oscillating coil 5 via coupling path 2.2 to the edge area up to approximately the area labeled A

1.2 supplied sound power only on the edge area to the reduced height 2 321. This remains effective for the membrane if according to the invention up to the coupling cross section 2.33 constant. This

(ο

7 8

Of course, representation does not exclude that Iungswcg 2.22 should be based on the invention proposal

the HLherringcrung will also be smaller than the uncovered area of the coupling up to the coupling

Lung cross-section 2.33 over the entire flat volume edge area of the membrane.

men can drag. In this example, too, FIGS. 1 to 4 show different types of situations where the condition that the coupling device of the invention remains satisfied. They can be combined or exchanged as desired with a cross-section 2.32 which is still slightly smaller than the other. The akuvom active element 2 uncovered area sweet elements, e.g. B. the funnel or the open 1.11 of the central area 1.1. With the whistle in this way, reduced input impedance of the flat volume can be shaped and dimensioned depending on the requirements. Also combinations 2.31 from Ankopplungsweg2.11 or also 2.1 io NEN of funnels with acoustic lines or the like. Seen here one achieves that the incident as acoustic coupling elements are possible. The sound-acted area 1.1 of the membrane means invention is not limited to the part shown is enlarged. The specific surface examples of acoustic coupling elements. The load on this part of the membrane is reduced and any other acoustic impedances, undesirable membrane deformations at high 15 such as tubes, or special resonators, such as amplitudes of high frequencies, for example in radial resonators, as special coupling elements, 2,31 pop music, are avoided. These deformations or parts of them are used by them. ^x have been shown to be a source of linear and nonlinear In conclusion, it should be noted that there are / distortions. Furthermore, FIG. 4 it is very advantageous to mechanically reinforce the central part (1.1) of the membrane, another example of the design of the coupling ao for example the dome, ventilation path 2.2. It forms an acoustic coupling . In the area of the outer edge of the central part of the membrane from the outset from starch membrane, it is made by a funnel-shaped jacket as rem material. Limited by the reinforcement part 6. The inner delimitation of the ring straightening, undesired membrane deformations occur through the outer surface 2.4 of the EIe with high sound pressure, avoided. It is the gementes 2. The casing part 6 is simultaneously shaped so that the entire sound power falling on the membrane is fed with its electroacoustic transducer facing the edge part 1.2 and delimits a flat volume 6.11 in elek area 6.1. Des- 30 trischc performance implemented. Linear and non-linear coupling cross-sections 6.2 at the coupling distortions are avoided.

1 sheet of drawings

Claims (1)

Patent claims: 1. Acoustically effective element (2; 4; 6) in front of the membrane (1) of a microphone, thereby s characterized that this element for the central area (1.1) of the membrane, for example the dome, and for the edge area (1.2) the membrane, for example the beading part, separate coupling paths (2.1; 2.2) to the Forms sound field in the direction (3) to the sound source and that this element (2; 4; 6) to separate