Waterproof electromagnetic transducer

Abstract

A pressure-resistant electromagnetic sound transducer (20) with the following features is disclosed: - a sound transducer module (22); - a watertight housing (24) which has a receptacle (26) for the sound transducer module (22); - a pressure plate (28) that covers the sound transducer module (22) in such a way that a cavity (32) is formed between a vibration element (30) of the sound transducer module and the pressure plate (28), which enables sound propagation; - wherein the pressure plate (28) has a plurality of openings (34) through which the sound can pass through the pressure plate (28); - a grid (36) covering the openings (34) and having openings (38) that have a smaller diameter than the openings (34) of the plurality of openings (34); - a flexible membrane (40) stretched over the grid (36) in such a way that under normal pressure a space (42) is formed between the membrane (40) and the grid (36) and under water pressure the membrane (40) rests on the grid (36); - a lid (44) designed to protect the membrane (40) against rough, external mechanical impact and to allow the flexible membrane (40) to vibrate in order to emit sound through holes in the lid (44).

Description

[0001] The invention relates to a pressure-water-resistant electromagnetic sound transducer, for example for mounting on an underwater vehicle.

[0002] Water-resistant electromagnetic transducers must solve the problem of requiring a vibrating membrane to radiate sound into air (loudspeaker operation) or to convert alternating sound pressures into an electrical signal (microphone operation). At the same time, the electromagnetic transducer must also withstand high water pressures, for example, 50 bar, without damaging the membrane or allowing water to penetrate the electromagnetic transducer, so that the electromagnetic transducer continues to function after resurfacing. A well-known loudspeaker as an electromagnetic transducer is in Fig. 1. To date, a mechanical, spring-loaded pressure seal was used to achieve compressive strength, which was closed by the membrane 10 under the influence of water pressure. The pressure seal comprises a pressure plate 12 with a plug 14 and a further plate 17 located between the pressure plate and the membrane and mounted by a spring 16. To allow sound from the sound transducer module arranged beneath the pressure plate to pass through the pressure seal, the pressure plate and the further plate have offset openings 18, 19. The openings 18 of the pressure plate are closed by the further plate. The openings 19 of the further plate correspond to the position of the plugs 14, so that the plugs 14 engage in the openings 19 to close the pressure seal.

[0003] The problem here, however, is that the mechanical closure often becomes jammed, for example, due to corrosion or resinous grease, and can no longer be opened by the spring action. The electromagnetic transducer is therefore no longer functional.

[0004] The object of the present invention is therefore to create an improved concept for a pressurized water-resistant electromagnetic sound transducer.

[0005] This problem is solved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent patent claims.

[0006] Embodiments show a pressurized water-resistant electromagnetic sound transducer. The electromagnetic sound transducer comprises a sound transducer module for sound conversion, ie, for sound generation (loudspeaker) or for sound recording (microphone). In particular, the electromagnetic sound transducer module for sound conversion has a vibration element, e.g., a (sound transducer) membrane. The sound conversion should preferably take place between an electrical signal and (airborne) sound.

[0007] Electromagnetic sound transducers are understood to be loudspeakers or microphones, for example, although it should be noted that electromagnetic sound transducers can in principle be used both as loudspeakers and as microphones, depending on their electrical wiring.

[0008] Furthermore, the pressure-water-resistant electromagnetic sound transducer comprises a pressure-water-resistant housing that has a receptacle for the sound transducer module. The sound transducer module is arranged in the receptacle of the housing. The side of the sound transducer module facing away from the main sound transmission direction advantageously faces the direction of the housing receptacle. Advantageously, the housing has an opening in the main sound transmission direction for the sound to exit or enter. The sound transducer module is preferably an electromagnetic sound transducer module.

[0009] The sound transducer module is covered by a pressure plate in such a way that a cavity is formed between the vibration element of the sound transducer module and the pressure plate, which enables sound propagation from the vibration element (loudspeaker) or to the vibration element (microphone). This means that the pressure plate is arranged in the main sound transmission direction of the sound transducer module. The main sound transmission direction (for loudspeaker operation) runs in the opposite direction to a main sound reception direction (for microphone operation). If only one operating mode (loudspeaker operation or microphone operation) is referred to within the scope of this disclosure, the use in the other operating mode is also disclosed analogously.

[0010] The pressure plate has a plurality of openings through which sound can pass. In one example, the openings can have a diameter of a few millimeters, for example, between 1 mm and 5 mm, preferably between 2 mm and 4 mm. The pressure plate can also be referred to as a pressure bulkhead.

[0011] The pressure-water-resistant electromagnetic sound transducer further comprises a grid that covers the apertures and itself has openings that have a smaller diameter than the apertures of the plurality of apertures. The grid can also be referred to as a sieve. In one example, the openings of the grid can have a diameter between 0.3 mm and 1.5 mm, preferably between 0.5 mm and 1 mm.

[0012] Instead of the specified diameters of the apertures or openings of the grid, corresponding surface areas are also disclosed if their area is not a circle.

[0013] A flexible membrane is stretched over the grid in such a way that, under normal pressure, a gap forms between the membrane and the grid, and under water pressure, the membrane rests on the grid. The grid is therefore positioned between the membrane and the pressure plate (particularly in the main sound transmission direction). The membrane has a thickness of between 0.5 mm and 3 mm, particularly between 0.7 mm and 1.5 mm.

[0014] A cover protects the diaphragm against rough, external mechanical influences. The cover is also designed to allow the diaphragm to vibrate in order to emit sound through holes in the cover. The cover is therefore arranged behind the diaphragm in the main sound emission direction. Optionally, the cover and housing can completely enclose the pressure plate, the grille and the diaphragm. However, it is also possible to form a stack in the edge region comprising the housing, the cover and any selection of the pressure plate, the grille and the diaphragm. To protect the diaphragm against external mechanical influences, the holes in the cover can have such a small diameter that common means of damaging the diaphragm, such as screwdrivers or fish hooks, cannot penetrate the holes.

[0015] The idea is to replace the mechanical, spring-loaded, error-prone closure of the electromagnetic sound transducer with a simplified, less error-prone and more cost-effective design. This design has no moving parts other than the vibrating element of the sound transducer module and the membrane that transmits the sound waves from the vibrating element to the environment. Instead, a grid is placed over the relatively large openings in the pressure plate, onto which the membrane rests under water pressure. The openings in the grid are chosen to be large enough that the membrane cannot be pushed through and thus destroyed. The thicker the membrane, the larger the openings in the grid can be. However, a thin membrane is preferred, as this transmits sound better. However, the holes in the grid cannot be made arbitrarily small, as the sound still has to pass through them.A trade-off must be made here. Furthermore, a smaller hole size in the grille requires a smaller grille wire gauge. A smaller grille wire gauge also carries the risk of the grille, along with the membrane, being pulled into the openings in the pressure plate, which would also damage the membrane. A trade-off must therefore also be made here.

[0016] In exemplary embodiments, the cover has a labyrinth of holes in the main sound transmission direction to allow sound to pass through but to make it difficult for solid objects to penetrate the membrane. In particular, the accidental penetration of sharp objects such as screwdrivers or fishhooks is to be prevented. To form the labyrinth, the cover can comprise two plates spaced apart in the sound transmission direction, each of which has holes arranged offset from one another.

[0017] Further embodiments show that the housing is shaped such that the electromagnetic sound transducer fits precisely in the receptacle in order to reduce cavities behind the vibration element. Additionally or alternatively, the pressure plate has a curvature that projects into the cavity between the pressure plate and the vibration element in order to reduce the cavity. Cavities that are not required for sound propagation should preferably be kept very small overall in the pressure-water-resistant electromagnetic sound transducer. The cavity for the propagation of the sound from the sound transducer module should also preferably be dimensioned only as large as necessary. Technically, this offers the advantage that less air is trapped in the pressure-water-resistant electromagnetic sound transducer. The trapped air can expand and, in the worst case, press the membrane against the cover of the pressure-water-resistant electromagnetic sound transducer or, for example,When the enclosed air volume cools down, the membrane is pulled against the grille, causing the electromagnetic sound transducer to lose its functionality.

[0018] In other embodiments, the membrane is predominantly made of polysiloxane, i.e., silicone. Silicone has the advantage that it experiences little permanent plastic stretching, for example, during a long dive. Conversely, a silicone membrane returns to almost its original shape after the excess pressure is removed. The tension of the membrane thus drops, if only slightly, but its functionality is not impaired.

[0019] Preferred embodiments of the present invention are explained below with reference to the accompanying drawings. They show: Fig. 1: a schematic perspective sectional view of a known pressure-water-resistant loudspeaker, to which reference has already been made in the introduction to the description; Fig. 2a: a schematic perspective sectional view of a pressurized water-resistant electromagnetic sound transducer according to an embodiment; Fig. 2b: a technical drawing of a pressurized water-resistant electromagnetic sound transducer according to an embodiment.

[0020] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0021] On Fig. 1 has already been discussed in the introduction to the description.

[0022] Fig. Figure 2a discloses a schematic sectional view of a pressure-water-resistant electromagnetic sound transducer 20, here primarily configured as a loudspeaker. The pressure-water-resistant electromagnetic sound transducer comprises a sound transducer module 22 and a pressure-water-resistant housing 24. The pressure-water-resistant housing 24 includes a receptacle 26 for the sound transducer module 22.

[0023] Furthermore, a pressure plate 28 is shown. The pressure plate covers the electromagnetic sound transducer module 22 such that a cavity 32 is formed between a vibration element 30 of the sound transducer module 22 and the pressure plate 28, which cavity allows sound to propagate from the vibration element 30. The pressure plate has a plurality of openings 34 through which the sound can pass through the pressure plate 28.

[0024] A grid 36 covers the openings 34 and has openings 38 of its own, which have a smaller diameter than the openings 34. A flexible membrane 40 is stretched over the grid. Under normal pressure, the membrane 40 has a gap 42 between it and the grid, and under water pressure, the membrane rests on the grid. By resting on the grid 36, the membrane 40 is not destroyed by the water pressure. Through the gap 42 under normal pressure, the membrane can transmit the sound generated by the vibration element 30 to the environment.

[0025] A cover 44 protects the diaphragm against harsh external mechanical influences. Furthermore, the cover 44 allows the flexible diaphragm 40 to vibrate. To allow the sound to penetrate to the outside, the cover has holes 46 through which the sound transmitted by the diaphragm 40 can exit the pressure-water-resistant electromagnetic sound transducer 20.

[0026] In one embodiment, the cover is constructed from two plates 44a, 44b, each having holes arranged offset from one another. In a Fig. 2b, the thin gap 44c between the plates allows sound to propagate between the plates 44a, 44b. Alternatively, the holes 46 can be connected to each other by means of individual grooves in the plates 44a, 44b. Such an arrangement of interconnected holes in the plates can be referred to as a hole labyrinth. Other measures, such as providing a sufficiently small hole diameter, can also prevent objects from penetrating the membrane.

[0027] Furthermore, Fig. 2a optional elevations 48 in the area of ​​the receptacle 26. These elevations serve to adapt the shape of the housing 24 to the contour of the sound transducer module 22. By means of the elevations, the housing can be shaped such that the sound transducer module 22 fits precisely in the receptacle in order to reduce cavities behind the vibration element 30.

[0028] Also revealed Fig. 2a optionally a curvature 50 of the pressure plate 28, which protrudes into the cavity 32 between the pressure plate 28 and the vibration element 30. The curvature 50 also reduces the air volume enclosed in the pressure-water-resistant electromagnetic sound transducer.

[0029] An electrical interface 54 enables the contacting of the pressurized water-resistant electromagnetic sound transducer, particularly in a watertight manner. Furthermore, connecting elements 52 are disclosed, with which the elements are mechanically connected in the edge region. It should be noted that in the examples in Fig. 2a and Fig. 2b, the pressure plate rests on an edge of the housing in the edge area. The cover also rests on the pressure plate 28. This allows for better (water) pressure absorption by the pressure plate.

[0030] Fig. Figure 2b shows a technical drawing of the pressurized water-resistant electromagnetic sound transducer 20 in another embodiment. The description of the individual elements from Fig. 2a applies to Fig. 2b. The explanation of the individual reference symbols can therefore be found in the description Fig. 2a.

[0031] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0032] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein. List of reference symbols: 10 Membran 12 printing plate 14 plugs 16 spring 17 more records 18 openings in the pressure plate 19 openings in the further plate 20 pressure-water-resistant electromagnetic sound transducers 22 transducer module 24 pressure-water-resistant housing 26 recording 28 printing plate 30 Vibration element 32 cavity 34 openings in the printing plate 36 grids 38 openings of the grille 40 flexible membrane 42 Space between membrane and grid 44 lids 46 holes of the lid 48 surveys 50 Thickening of the printing plate 52 fasteners 54 electrical interface

Claims

[1] Pressure-water-resistant electromagnetic sound transducer (20) with the following features: - a sound transducer module (22); - a pressure-water-resistant housing (24) having a receptacle (26) for the sound transducer module (22); - a pressure plate (28) which covers the sound transducer module (22) in such a way that a cavity (32) is formed between a vibration element (30) of the sound transducer module and the pressure plate (28), which cavity enables the sound to propagate; - wherein the pressure plate (28) has a plurality of openings (34) through which the sound can pass through the pressure plate (28); - a grid (36) covering the apertures (34) and having openings (38) having a smaller diameter than the apertures (34) of the plurality of apertures (34); - a flexible membrane (40) which is stretched over the grid (36) in such a way that under normal pressure a gap (42) is formed between the membrane (40) and the grid (36) and under water pressure the membrane (40) rests on the grid (36); - a cover (44) designed to protect the membrane (40) against rough, external mechanical influences and to allow the flexible membrane (40) to vibrate in order to emit the sound through holes in the cover (44). [2] A pressure-water-resistant electromagnetic sound transducer (20) according to claim 1, wherein the cover (44) has a labyrinth of holes in the sound transmission direction to allow the sound to pass through but to make it difficult for solid objects to penetrate to the diaphragm (40). [3] A pressure-water-resistant electromagnetic sound transducer (20) according to any one of the preceding claims, wherein the housing (24) is shaped such that the electromagnetic sound transducer module (22) fits snugly in the receptacle (26) to reduce cavities behind the vibration element (30). [4] Pressure-water-resistant electromagnetic sound transducer (20) according to one of the preceding claims, wherein the pressure plate (28) has a curvature which projects into the cavity (32) between the pressure plate (28) and the vibration element (30) in order to reduce the cavity (32). [5] Pressure-water-resistant electromagnetic sound transducer (20) according to one of the preceding claims, wherein the membrane (40) consists predominantly of a polysiloxane. [6] Pressure-water-resistant electromagnetic sound transducer (20) according to one of the preceding claims, wherein the openings (34) of the pressure plate (28) have a diameter between 1 mm and 5 mm or a corresponding surface area. [7] Pressure-water-resistant electromagnetic sound transducer (20) according to one of the preceding claims, wherein the openings (38) of the grid (36) have a diameter between 0.3 mm and 1.5 mm or a corresponding area. [8] Pressure-water-resistant electromagnetic sound transducer (20) according to one of the preceding claims, wherein the membrane (40) has a thickness between 0.5 mm and 3 mm.

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