Patent Description:
In the art, various earphones are known, which employ passive noise reduction (PNR) to reduce the amount of acoustic noise reaching the wearer's ears. PNR is typically achieved by acoustic dampening in structural components, such as earphone shells and ear cushions. It is further known to combine PNR with active noise cancelling (ANC) that actively counteracts acoustic noise approaching the wearer's ears, thereby attempting to cancel out and thus remove the noise from the sound reaching the ears. ANC is typically achieved by controlling the output of a driver in the earphone such that it counteracts the residual noise that escapes the PNR.

PNR is generally effective at frequencies above about <NUM>, while the effect decreases towards lower frequencies and is practically non-existing at frequencies below about <NUM>. Conversely, ANC is generally effective in the frequency range below about <NUM>, while it is difficult to achieve good results for higher frequencies. Noise reduction using a combination of PNR and ANC can thus in principle be made effective within the entire audio frequency range.

For some earphones passive attenuation of ambient noise is desired while at the same time obtaining a proper low frequency audio reproduction.

Typically, earphones providing passive noise reduction and audio are two-chamber earphones, having a front cavity and a rear cavity, and comprising a speaker, i.e. an actively driven diaphragm suspended in a wall between the two cavities.

To obtain a good reproduction of low frequency audio, flow restrictions on the side of the diaphragm facing away from the ear should be avoided or limited. This may for example be obtained by having a rear cavity which is sufficiently large or by having an opening in rear cavity.

On the other hand, to provide good passive noise attenuation the rear cavity should be closed and relatively small which however restricts flow on the side of the diaphragm facing away from the ear.

There is thus a trade-off between passive noise attenuation and good audio reproduction at low frequencies.

It has been suggested to solve this trade-off by providing a so-called vent in the rear cavity, i.e. a hole in the rear cavity covered with an acoustic resistive material. By providing a low vent resistance, a fair low frequency reproduction may be obtained, while a high vent resistance provides for a higher passive attenuation, but a poorer low frequency reproduction.

<CIT> discloses an earphone comprising a rear chamber which is connected to the ambient space by a port and a resistive opening in parallel with the port. The acoustic mass of the port and the compliance of the rear chamber are tuned to a resonance frequency of about <NUM>. This causes the rear chamber to be acoustically closed above <NUM> and acoustically open below <NUM>.

<CIT> discloses an earphone where the rear chamber is connected to the ambient space by a port structure with a port wall comprising acoustically permeable sections. Explanation of how acoustic tuning of earphones are provided by openings, tubes and resistive meshes are explained in detail in <CIT>, which is incorporated herein by reference.

It can be problematic to fit the vent and port structures of the prior art into earphones of restricted size, inter alia because the ports often need to be of a certain length. As these earphone housing often a manufactured by injection moulding, the port and venting structures needs complex molds with movable core parts and cost increasing tooling and/or assembling steps after the injection molding process.

The object of the invention is to provide a new and improved earphone and a method of manufacturing such an earphone.

<CIT> discloses intra-concha earphones including a housing having a rear space divided into a back volume, a bass duct, and a vent chamber between a driver and a rear wall. <CIT> discloses an earphone comprising a loudspeaker unit, an audio signal wire electrically connected to the loudspeaker unit, and an auxiliary structure comprising a front cover and a housing. <CIT> discloses an earphone apparatus comprising an electro-acoustic driver, a housing for receiving the electro-acoustic driver, and a sensor plate mounted on the housing.

Embodiments are given by the dependent claims.

The invention provides a simple and compact structure, that is easy and cheap to manufacture and fit into a compact earphone construction.

According to an embodiment, an ear cushion is arranged and configured to attenuate acoustic signals entering the front chamber from ambient space, when the earphone is in the operating position.

According to an embodiment, the recess cavity has a length of <NUM>-<NUM>.

According to an embodiment, the recess cavity has a width of <NUM>-<NUM>.

According to an embodiment, the recess cavity has a depth of <NUM>-<NUM>.

According to an embodiment, the recess cavity has a cross-section of <NUM>-<NUM><NUM>.

According to an embodiment, the recess is curved.

According to an embodiment, the recess cavity is tuned to provide a resonance frequency in one of the ranges: <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>.

According to an embodiment, the earphone comprises a unitary earphone element comprising an end wall and a circumferential side wall, and wherein the recess is provided in the end wall, and wherein the earphone element is shaped, such it can be manufactured in an injection mould without overhangs.

The invention also relates to a method of manufacturing an earphone, wherein the earphone element is manufactured in an injection molding process, where after the mesh device is attached to the earphone element.

According to an embodiment, the dividing wall is attached to the circumferential side wall after the injection molding of the earphone element
The invention can be utilised with circumaural earphones, which encompass the ears, and supra-aural earphones, which press against the ears and in-ear earphones.

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

<FIG> is a front view of a headset <NUM> comprising a headband <NUM>, an earphone <NUM> and a second earphone <NUM>', a microphone arm <NUM> with a microphone <NUM> and a cable <NUM> connecting the headset with a not-shown telecommunication device such as a smart phone or laptop. Each of the earphones <NUM>, <NUM>' comprises an ear cushion <NUM>. The invention relates to the earphone <NUM> and will described further in the following.

<FIG> a schematic cross-sectional view through the earphone <NUM> according to a first embodiment of the invention. The headband <NUM> other parts, which are not relevant for the invention, are left out. The figure shows the earphone <NUM> in a state of use, where the ear cushion <NUM> encompasses a user's ear <NUM> and engages the head <NUM> of the user. The earphone <NUM> comprises a housing wall <NUM>, which includes an end wall <NUM>, an opposite dividing wall <NUM> and a side wall <NUM> connecting the end wall <NUM> and the dividing wall <NUM>. A speaker <NUM> with a diaphragm <NUM> is arranged inside the earphone housing <NUM> close to the dividing wall <NUM>. Sound holes <NUM> are provided in the dividing wall <NUM> to let audio from the speaker <NUM> pass to a front chamber <NUM>, which is encompassed by the dividing wall <NUM>, the ear cushion <NUM> and the user's head <NUM>. The housing wall <NUM> is made up by an earphone element <NUM> and the dividing wall <NUM>. The earphone element <NUM>, which comprises the end wall <NUM> and the side wall <NUM>, is a molded plastic part which is welded together with the dividing wall <NUM> with a welding seam <NUM>. In the end wall <NUM> a vent structure <NUM> is provided, which will be explained further in the following.

<FIG> is an end view of the earphone <NUM> according to the first embodiment. The end wall <NUM> comprises the vent structure <NUM>, which includes a recess opening <NUM> and a mesh device <NUM>. The mesh device comprises three layered mesh parts 18A, 18B and 18C.

<FIG> is a perspective view of the earphone element <NUM> for manufacturing and earphone <NUM> according to the invention. The earphone element <NUM> is somewhat cup shaped comprising the end wall ("cup bottom") <NUM> and side wall <NUM>. In the end wall <NUM> a recess <NUM> is provided. The recess <NUM> is defined by a bottom wall <NUM> and recess walls <NUM> connecting the bottom wall <NUM> and the end wall <NUM>. A recess cavity <NUM> provided by the recess <NUM> is oblong with a length Lr that is larger than the a Wr. At a first end <NUM> of the recess <NUM> there is a recess opening <NUM> providing a fluid connection between the rear chamber and the ambient space <NUM>. The side wall <NUM> extends all the way around the end wall <NUM>. The end opposite the end wall <NUM> is open. The side wall <NUM> and the recess walls <NUM> are designed with no "overhangs" and slightly angled, so that the earphone element <NUM> can be injection molded and ejected from a relatively simple and inexpensive mold. No slides, that move into the molding cavity perpendicular to the draw direction, to form overhanging part features is needed. At the periphery of the recess <NUM>, a shoulder <NUM> is provided for attachment of the mesh device <NUM>, which will be explained in the following.

<FIG> discloses three different mesh parts 18A, 18B, 18C for manufacturing a mesh device <NUM> for an earphone <NUM> according to the invention. The mesh parts 18A, 18B, 18C can have different lengths and acoustic permeability and be combined in different ways to provide the desired acoustic characteristics of the vent structure <NUM>. Here is shown a first mesh part 18A, a second mesh part 18B and a third mesh part 18C. In the first embodiment shown in <FIG> the mesh structure <NUM> comprises all three mesh parts 18A, 18B, 18C.

<FIG> is a schematic cross-sectional view through an injection mold <NUM> for manufacturing the earphone element <NUM>. The injection mold <NUM> comprises a core part <NUM> and a cavity part <NUM>. In <FIG> the mold is in a closed position, and the mold cavity is filled with plastics to form the earphone element <NUM>.

<FIG> is a schematic cross-sectional view through the injection mold <NUM> in open position, where the core part <NUM> and the cavity part <NUM> are moved away from each other in the draw direction <NUM>. The finished earphone element <NUM> is removed.

<FIG> is an end view of an earphone according to a second embodiment of the invention, where the first mesh part 18A and the second mesh part 18B are combined to a mesh device.

<FIG> is an end view of an earphone according to an example not forming part of the present claimed invention, only a first mesh part 18A is used to provide a mesh device.

<FIG> is a cross-sectional view of the vent structure <NUM> according to the first embodiment. The vent structure <NUM> can be regarded as a combination of resistive opening <NUM>, a port or tube <NUM> with a permeable tube wall <NUM>. The depth of the recess cavity <NUM> provided by the recess <NUM> is Dr. The resistive opening <NUM> has an opening size S<NUM> and an acoustic resistivity as the sum of the resistivities of the first, second and third mesh parts 18A, 18B, 18C. The arrow F<NUM> represents airflow through the resistive opening <NUM>. The tube <NUM> has a length Lt and a tube opening <NUM> with the size of St. The acoustic resistance of the tube opening <NUM> is the resistance of the mesh part 18A. The arrow Ft represents airflow through the tube opening <NUM>. First and second mesh parts 18A and <NUM> provides the permeable tube wall part <NUM> with an acoustic resistance corresponding to the sum of the resistances of the first and second mesh parts 18A, 18B. The arrows FL represents airflow through the permeable tube wall part <NUM>. The dimensions of the resistive opening <NUM>, the tube <NUM> and the tube opening <NUM>, and the resistance of the mesh parts can be chosen to tune the earphone to the desired acoustic properties. Thus, the tube can be tuned to have a resonance frequency between f. <NUM> and <NUM>.

<FIG> is a cross-sectional view of the vent structure according to the second embodiment. This embodiment differs from the first embodiment by the third mesh part 18C is left out. Thus, the acoustic resistance of the resistive port <NUM> is only provided by the first and second mesh parts 18A, 18B.

<FIG> is a cross-sectional view of the vent structure according to the third embodiment.

Here, the resistance of the resistive port <NUM>, the tube port and the permeable tube wall part <NUM> is only provided by the first mesh part 18A.

<FIG> is an end view of a fourth embodiment of the claimed invention. Here the recess <NUM> is shaped as a half-circle. In this way a relative long tube can be obtained. The mesh device <NUM> is layered in the same way as the mesh device of the first embodiment.

The mesh device <NUM> can be premanufactured with by layering different mesh parts in any combination, which mesh device <NUM> in a simple step can be attached on the shoulder <NUM> along the edge of the recess <NUM> by f. gluing or welding.

The invention can be utilised with circumaural earphones, which encompass the ears supra-aural earphones, which press against the ears and in-ear earphones.

Claim 1:
An earphone (<NUM>) configured to provide an acoustic output to an ear (<NUM>) of a wearer and further configured to be arranged on the wearer's head (<NUM>) in an operating position such that a front chamber (<NUM>) between the head (<NUM>) and the earphone (<NUM>) is separated from ambient space (<NUM>), the earphone (<NUM>) comprising:
a housing (<NUM>) comprising a housing wall (<NUM>) separating a rear chamber (<NUM>) from ambient space (<NUM>), the housing wall (<NUM>) including an end wall (<NUM>), an opposite dividing wall (<NUM>) separating the rear chamber (<NUM>) from the front chamber (<NUM>) and a side wall (<NUM>) connecting the end wall (<NUM>) and the dividing wall (<NUM>),
a diaphragm (<NUM>) suspended across an opening (<NUM>) in the dividing wall (<NUM>) and configured to be actively driven to provide the acoustic output,
a vent structure (<NUM>) fluidly connecting the rear chamber (<NUM>) and ambient space (<NUM>) through the housing wall (<NUM>),
wherein the vent structure (<NUM>) comprising
- a longitudinal recess (<NUM>) in the housing wall, which recess (<NUM>) is defined by a bottom wall (<NUM>) and recess walls (<NUM>) extending from the bottom wall (<NUM>) to the end wall (<NUM>) of the housing wall (<NUM>),
- a recess opening (<NUM>) in the recess (<NUM>), which recess opening (<NUM>) connects the recess (<NUM>) and the rear chamber (<NUM>),
- a mesh device (<NUM>) arranged parallel with the bottom wall (<NUM>), whereby a longitudinal recess cavity (<NUM>) is provided between the bottom wall (<NUM>) and the mesh structure (<NUM>), the earphone (<NUM>) characterized in that
the mesh device comprises at least two different mesh parts (18A, 18B, 18C) having different acoustic permeability.