FR3133962A1 - Headphone earpiece with internal pressure balancing system - Google Patents

Abstract

Earpiece for headphones comprising an internal pressure balancing system Earpiece (14) for headphones, comprising: a shell (22), a cushion (24), and a speaker (26). The earphone defines: - a first chamber (34) at a pressure P1, extending from the membrane (32) of the speaker towards the front, - a second chamber (36) at a pressure P2, extending from the membrane towards the rear inside the loudspeaker, - a third chamber (38) at a pressure P3, delimited by the shell and the loudspeaker, - a first orifice (40) for communication between the third chamber and the surrounding atmosphere (42), a second port (44) for communication between the third chamber and the second chamber, and a pressure balancing system (46) connecting the first chamber to the second chamber or to the third chamber, configured to be passing or non-passing depending on a pressure difference between the rooms. Figure for abstract: Figure 2

Description

Headphone earpiece with internal pressure balancing system

The present invention relates to an earpiece for audio headphones, the earpiece comprising: a shell, a pad fixed on the shell and intended to be applied against a user of the earphone, and at least one speaker comprising a chassis, a motor magnetic, and a membrane adapted to emit acoustic waves, the membrane being mounted movable in translation along an axis of the speaker relative to the magnetic motor. The diaphragm axially defines a front side of the speaker relative to the magnetic motor. The earphone defines: a first acoustic chamber extending from the membrane towards the front side and intended to be partially delimited by said ear, and at least one other acoustic chamber extending from the rear side of the membrane.

The invention also relates to an audio headset comprising at least one such earphone, and in practice two earphones.

There are headphones in which the acoustic chambers, or cavities, are connected through holes and with the surrounding atmosphere. This helps to absorb the static overpressure that is created in the first acoustic chamber when the user places the headphones on their ears and the ear cushions crush. The excess pressure naturally flows to the surrounding atmosphere via the orifices.

These headphones provide a certain passive acoustic insulation, by reducing the influence of ambient noise on the first chamber, thanks to the cushion and the orifices which limit the propagation of external excess pressure towards the first chamber.

However, this passive acoustic insulation remains quite limited, and this type of earphone does not allow a good bass level (frequencies typically below 100 Hz) to be maintained when the speaker plays in the first room.

Different solutions have been imagined, which implement active (controlled) valves between the first chamber and the surrounding atmosphere, or between an internal chamber and the surrounding atmosphere. These solutions provide good passive insulation against ambient noise and a correct bass level, but do not eliminate static overpressure. Additionally, active valves introduce complexity and cost, as well as risks of malfunction or failure.

Still other solutions, involving a flexible valve between the first chamber and the surrounding atmosphere, or between the first chamber and an internal chamber, only partially resolve the problem of overpressure in the earphone, either by only allowing a pressure balancing between the two sides of the membrane, or by only treating excess pressures coming from the first chamber.

An aim of the invention is therefore to provide an earphone ensuring sufficient evacuation of static overpressures, while preserving good passive insulation against ambient noise, and a good bass level.

For this purpose, the subject of the invention is an earpiece for an audio headset, the earpiece comprising:

- a shell,

- a pad fixed to the shell and intended to be applied against a user of the earphone,

- at least one loudspeaker comprising a chassis, a magnetic motor, and a membrane adapted to emit acoustic waves, the membrane being mounted movable in translation along an axis of the loudspeaker relative to the magnetic motor, the membrane axially defining a front side of the speaker in relation to the magnetic motor,

the listener defining:

- a first acoustic chamber extending from the membrane towards the front side and intended to be partially delimited by the user, the first chamber containing air at a pressure P1,

- a second acoustic chamber extending from the membrane towards the rear side inside the loudspeaker, the second chamber containing air at a pressure P2, and

- a third acoustic chamber delimited by the shell and the loudspeaker, the third chamber containing air at a pressure P3,

the listener further defining:

- at least one first communication orifice between the third chamber and a surrounding atmosphere, and at least one second communication orifice between the third chamber and the second chamber, and

- a pressure balancing system connecting the first chamber to the second chamber, or to the third chamber respectively, the pressure balancing system being configured to be:

- passing from the first chamber, towards the second chamber or towards the third chamber respectively, if the difference P1 - P2, or the difference P1 - P3 respectively, is greater than a threshold S1,

- passing from the second chamber or the third chamber respectively, towards the first chamber, if the difference P2 - P1, or the difference P3 - P1 respectively, is greater than a threshold S2, and

- closed otherwise.

According to particular embodiments, the earphone comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- the pressure balancing system is passive;

- threshold S1 is equal to threshold S2 to plus or minus 5%;

- threshold S1 and threshold S2 are between 100 Pa and 700 Pa;

- threshold S1 and threshold S2 are between 200 and 600 Pa;

- the pressure balancing system comprises: a first subsystem allowing passage of air from the first chamber to the second chamber, or to the third chamber respectively, if the difference P1 - P2, or the difference P1 - P3 respectively, is greater than the threshold S1, and closed otherwise; and a second subsystem distinct from the first subsystem and ensuring a passage of air from the second chamber, or from the third chamber respectively, towards the first chamber, if the difference P2 - P1, or the difference P3 - P1 respectively, is greater than the threshold S2, and closed otherwise;

- the pressure balancing system comprises at least a first flexible valve ensuring a passage of air from the first chamber, towards the second chamber or the third chamber, the first flexible valve having a threshold for triggering said passage of the air equal to threshold S1;

- the first flexible valve comprises a conduit, a movable part relative to the conduit, and a return spring fixed on the movable part and on the conduit, the movable part and the return spring respectively having a mass and a stiffness together defining a resonance frequency less than 20 Hz or greater than 20,000 Hz; And

- a second flexible valve ensuring a passage of air from the second chamber or the third chamber, towards the first chamber, the second flexible valve having a triggering threshold for said passage of air equal to the threshold S2.

For this purpose, the invention also relates to an audio headset comprising at least one such earpiece.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawing, in which:

there is a schematic front view of an audio headset according to the invention,

there is a schematic view, in section, of one of the headphones of the audio headset shown on the ,

there is a schematic view of an earphone constituting a variant of the earphone shown in Figures 1 and 2, the pressure difference seen by the pressure balancing system being sufficient to allow air to pass in one direction,

there is a view analogous to that of the , the pressure difference seen by the pressure balancing system being sufficient to allow air to pass in a direction opposite to that of the , And

there is a view similar to those of Figures 3 and 4, the pressure difference seen by the pressure balancing system being insufficient to allow air to pass through.

In reference to the , we describe an audio headset 10 according to the invention.

The audio headset 10 is intended to be worn by a user 12, and comprises two headphones 14, 16 adapted to be applied respectively to the ears 18, 20 of the user 12.

In the example, the two earphones 14, 16 are similar to each other so only the earphone 14 will be described below with reference to the .

The earphone 14 comprises a shell 22, a pad 24 fixed on the shell and intended to be applied against one of the ears 18, 20 of the user 12. The earphone 14 comprises at least one speaker 26 comprising a chassis 28 , a magnetic motor 30, and a membrane 32 adapted to emit acoustic waves, the membrane being mounted movable in translation along an axis to the magnetic motor.

The earphone 14 defines a first acoustic chamber 34 extending from the membrane 32 towards the front side and partially delimited by the user 12, the first chamber 34 containing air at a pressure P1. The earpiece 14 defines a second acoustic chamber 36 extending from the membrane 32 towards the rear side inside the loudspeaker 26, the second chamber containing air at a pressure P2. The earpiece 14 defines a third acoustic chamber 38 delimited by the shell 22 and the loudspeaker 26, the third chamber containing air at a pressure P3.

In addition, the earpiece 14 defines at least a first orifice 40 for communication between the third chamber and a surrounding atmosphere 42 at a pressure P0. The earpiece 14 also defines at least one second communication port 44 between the third chamber 38 and the second chamber 36.

The earphone 14 includes a pressure balancing system 46 connecting, in the example shown, the first chamber 34 and the third chamber 38.

The shell 22 comprises for example a front part 48, on which the pad 24 is fixed, and a rear part 50 forming a back of the earphone 14 and fixed on the front part.

The front part 48 is located on the ear 18 side with respect to the rear part 50. The front part 48 comprises a side wall 52 defining a front opening 54, around the periphery of which the pad 24 extends, and a bottom 56 defining in the example an orifice 58 across which the loudspeaker 26 extends.

The rear part 50 comprises a side wall 60 extending in the extension of the side wall 52 of the front part 48, and a bottom 62 for example parallel to the bottom 56 of the front part 48.

In the example, the first chamber 34 is delimited by the front part 48 of the shell 22, the membrane 32 of the speaker 26, the cushion 24 and the user 12, in particular his ear 18. The first chamber 34 does not does not extend inside the speaker 26.

The cushion 24 is adapted to collapse when the user 12 wears the audio headset 10, and to limit the exchange of air between the first chamber 34 and the surrounding atmosphere 42.

In the example, the second chamber 36 is delimited by the membrane 32, the magnetic motor 30 and the chassis 28. The second chamber 36 does not extend outside the loudspeaker 26.

In the example, the third chamber 38 is delimited by the rear part 50 of the shell 22, the bottom 56 of the front part 48, and the chassis 28 and the magnetic motor 30 of the speaker 26. The third chamber 38 does not does not extend inside the speaker 26.

The first orifice 40 and the second orifice 44 are adapted to put the surrounding atmosphere 42, the third chamber 38 and the second chamber 36 into fluid communication respectively, and advantageously to limit this fluid communication so as to maintain acoustic independence (for the passive insulation) between the surrounding atmosphere 42 and the third chamber 38, and between the third chamber 38 and the second chamber 36.

The first orifice 40 and the second orifice 44 are for example simple orifices.

According to variants not shown, a fabric or a porous material is arranged across the first orifice 40 and/or the second orifice 44 to limit air exchange between the surrounding atmosphere 42 and the third chamber 38 and/or between the third bedroom 38 and the second bedroom 36.

According to other variants not shown, the first orifice 40 and/or the second orifice 44 are defined by a calibrated tube.

The first orifice 40 and the second orifice 44, via their respective diameters and lengths, and the possible presence of an acoustically resistive fabric in these orifices, are advantageously adapted to reduce the similar stiffness of the air In the second chamber 36 and the third chamber 38, in order to maintain a pressure level at low frequencies, for example between 20 Hz and 100 Hz.

As an indication, the lengths of the first orifice 40 and the second orifice 44 are for example of the order of 1.0 to 10 mm, their diameters are of the order of 0.5 to 5 mm, and the possible resistive fabrics are of the order of 10 to 150 rayls (1 rayl = 1 kg∙s ⁻¹ ∙m ⁻² ). This combination makes it possible to obtain an acoustic resistivity of the order of ten rayls at low frequencies, and a hundred rayls at high frequencies, for example between 100 Hz and 20 kHz.

According to other variants not shown, there may be several communication orifices between the surrounding atmosphere 42 and the third chamber 38 and/or several orifices between the third chamber 38 and the second chamber 36.

The pressure balancing system 46 shown on the is configured to pass from the first chamber 34 to the third chamber 38 if the difference P1 - P3 is greater than a threshold S1 (P1 - P3 > S1), passing in the opposite direction if the difference P3 - P1 is greater than a threshold S2 (P3 - P1 > S2), and closed otherwise. In other words, the pressure balancing system 46 is closed if P1 - P3 ≤ S1 and P3 - P1 ≤ S2.

The pressure balancing system 46 is advantageously passive, that is to say it does not contain an electrically or electronically controlled member. The pressure balancing system 46 is only driven by the pressure difference between the first chamber 34 and the third chamber 38.

In the example, the pressure balancing system 46 comprises a first subsystem 46A allowing passage of air from the first chamber 34 to the third chamber 38 if P1 - P3 > S1, and closed otherwise. Still in the example, the pressure balancing system 46 comprises a second subsystem 46B, distinct from the first subsystem 46A, and ensuring passage of air from the third chamber 38 to the first chamber 34 if P3 - P1 > S2, and closed otherwise.

Advantageously, the threshold S1 is equal to the threshold S2 to plus or minus 5%, and preferably to plus or minus 1%. In other words, the pressure balancing system 46 has a symmetry of plus or minus 5%, and preferably of plus or minus 1%.

Ideally, S1 is equal to S2, which is achieved in particular if the pressure balancing system 46 behaves like a spring mass system.

The threshold S1 and the threshold S2 are for example between 100 Pa and 700 Pa. Below 100 Pa, there is a risk that the bass level is affected in the first chamber 34. Above 700 Pa, there is a risk that the membrane 32 is damaged.

For example, the threshold S1 and the threshold S2 are between 200 Pa and 600 Pa, preferably between 300 Pa and 500 Pa.

The first subsystem 46A is for example constituted by a first flexible valve 64 ensuring a passage of air from the first chamber 34 to the third chamber 38, the first flexible valve having a trigger threshold for said passage of air equal to at the S1 threshold.

Likewise, the second subsystem 46B is for example constituted by a second flexible valve 66 ensuring a passage of air from the third chamber 38 towards the first chamber 34, the second flexible valve having a threshold for triggering said passage of the air equal to threshold S2.

The first flexible valve 64 and the second flexible valve 66 are for example structurally similar to each other and only differ in their direction of assembly between the first chamber 34 and the third chamber 38. Also, only the first flexible valve 64 will be described below. After.

The first flexible valve 64 comprises a conduit 68, a part 70 movable relative to the conduit, and a return spring 72 fixed on the movable part and on the conduit.

The mobile part 70 and the return spring 72 respectively have a mass and a stiffness configured so that the first flexible valve 64 becomes conducting when the pressure difference P1-P3 exceeds the threshold S1. In addition, the mass and the stiffness together define a resonance frequency of the first flexible valve 64 advantageously less than 20 Hz or greater than 20,000 Hz.

With reference to Figures 3 to 5, we describe an earphone 100 constituting a variant of the earphone. The earpiece is similar to the earpiece shown in Figures 1 and 2. Similar elements bear the same reference numerals and will not be described again. Only the differences will be described in detail below.

The earphone 100 includes a pressure balancing system 146 which is not mounted between the first chamber 34 and the third chamber 38, located at the rear of the speaker 26, but between the first chamber 34 and the second chamber 36, located in speaker 26.

The pressure balancing system 146 does not include a first flexible valve 64 and a second flexible valve 66 mounted in opposite directions, but a two-way flexible valve 164, which performs the functions of the first flexible valve 64 and the second flexible valve 66. One-way valves have the advantage of being more common than reversible (two-way) valves. Two one-way valves advantageously replace a reversible valve.

Thus, the pressure balancing system 146 shown in Figures 3 to 5 is configured to pass from the first chamber 34 to the second chamber 36 ( ) if the difference P1 - P2, is greater than a threshold S1 (P1 - P2 > S1), passing in the opposite direction ( ) if the difference P2 - P1 is greater than a threshold S2 (P2 - P1 > S2), and closed otherwise. In other words, the pressure balancing system is closed if P1 - P2 ≤ S1 and P2 - P1 ≤ S2.

Generally speaking, everything that has been said for the balancing system 46 shown on the is transposed to the balancing system 146 shown in Figures 3 to 5 by replacing “third chamber 38” by “second chamber 36”, and “P3” by “P2”.

The operation of the earphone 100 will now be described.

When the membrane 32 of the loudspeaker 26 emits acoustic waves in the first chamber 34, the pressure variations involved in the first chamber 34 and the second chamber 36 are low, generally of the order of 20 Pa maximum . Thus P1 - P2 ≤ S1 and P2 - P1 ≤ S2. The pressure balancing system 146 remains closed ( ). The third chamber 38, in particular the shell 22, provides passive acoustic insulation against ambient noise. The first chamber 34 is isolated from the second chamber 36 and the third chamber 38 by the pressure balancing system 146, which allows a good level of bass in the first chamber 34, therefore for the user 12. user is isolated from ambient noise whose intensity is insufficient to obtain P1 - P2 > S1 or P2 - P1 > S2.

Violent environmental noise, such as shock waves, can generate strong static pressures, and correspond to pressure variations generally greater than the S1 and S2 thresholds. If such a noise arrives on the earphone 100, the pressure P3 and the pressure P2 rise. Indeed, the first orifice 40 and the second orifice 44 ensure fluid communication between the third chamber 38 and the surrounding atmosphere 42 on the one hand, and the second chamber 36 and the third chamber 38 on the other hand.

When P2 - P1 > S1 ( ), the thresholds S1 and S2 being equal in the example, air from the second chamber 36 passes into the first chamber 34. The pressures P1 and P2 equalize, in the sense that P2 - P1 returns below the threshold S1, advantageously in less than 10 milliseconds. Then, when P2 - P1 ≤ S1, the first chamber 34 is again isolated from the second chamber 36 and the third chamber 38. This makes it possible to protect the membrane 32.

In the event of overpressure in the first chamber 34, for example due to the fact that the user 12 puts on the audio headset 100, air passes from the first chamber 34 to the second chamber 36 as soon as P1 - P2 > S1 ( ). The pressures P1 and P2 equalize, in the sense that P1 - P2 returns below the threshold S1, advantageously in less than 10 milliseconds. This allows any excess pressure to be evacuated from the first chamber 34 to the second chamber 36 and the third chamber 38, then to the surrounding atmosphere 42 via the second orifice 44 and the first orifice 40. Then, when P1 - P2 ≤ S1, the first chamber 34 is again isolated from the second chamber 36 and the third chamber 38.

The pressure balancing system 146 prevents damage to the loudspeaker 26, in particular to its membrane 32, which could be caused by too great a pressure difference on either side of the membrane.

We understand that the value of the thresholds S1 and S2 can be adjusted by the designer of the loudspeaker 26 so as to favor either the good bass level in the first chamber 34, or the protection of the membrane 32 against overpressure, the values mentioned above are therefore only preferred values.

The earpiece 14 operates in a similar manner to the earpiece 100, replacing above "second chamber 36" by "third chamber 38", and "P2" by "P3", when the balancing system is in question. 46.

Thanks to the characteristics described above, the headphones 14, 100 ensure sufficient evacuation of static overpressures through the first orifice 40 and the second orifice 44, while preserving good passive insulation against ambient noise thanks to the third chamber 38, and a good bass level thanks to the isolation of the first chamber 34 from the other chambers by the pressure balancing systems 46, 146.

Furthermore, thanks to the optional feature that the pressure balancing systems 46, 146 are passive, the risk of breakdown and manufacturing costs are reduced.

Claims (10)

Earpiece (14; 100) for audio headphones (10), the earpiece (14; 100) comprising:
- a shell (22),
- a pad (24) fixed on the shell (22) and intended to be applied against a user (12) of the earphone (14; 100),
- at least one loudspeaker (26) comprising a chassis (28), a magnetic motor (30), and a membrane (32) adapted to emit acoustic waves, the membrane (32) being mounted movable in translation along an axis (X) of the loudspeaker (26) relative to the magnetic motor (30), the membrane (32) axially defining a front side of the loudspeaker (26) relative to the magnetic motor (30),
the listener (14; 100) defining:
- a first acoustic chamber (34) extending from the membrane (32) towards the front side and intended to be partially delimited by the user (12), the first chamber (34) containing air at a pressure P1 ,
- a second acoustic chamber (36) extending from the membrane (32) towards the rear side inside the loudspeaker (26), the second chamber (36) containing air at a pressure P2, and
- a third acoustic chamber (38) delimited by the shell (22) and the loudspeaker (26), the third chamber (38) containing air at a pressure P3,
the earpiece (14; 100) further defining:
- at least one first orifice (40) for communication between the third chamber (38) and a surrounding atmosphere (42), and at least one second orifice (44) for communication between the third chamber (38) and the second chamber (36) ), And
- a pressure balancing system (46; 146) connecting the first chamber (34) to the second chamber (36), or to the third chamber (38) respectively, the pressure balancing system (46; 146) being configured to be:
- passing from the first chamber (34), towards the second chamber (36) or towards the third chamber (38) respectively, if the difference P1 - P2, or the difference P1 - P3 respectively, is greater than a threshold S1,
- passing from the second chamber (36) or the third chamber (38) respectively, towards the first chamber (34), if the difference P2 - P1, or the difference P3 - P1 respectively, is greater than a threshold S2, and
- closed otherwise. An earphone (14; 100) according to claim 1, wherein the pressure balancing system (46; 146) is passive. Earphone (14; 100) according to claim 1 or 2, in which the threshold S1 is equal to the threshold S2 to plus or minus 5%. Earphone (14; 100) according to any one of claims 1 to 3, in which the threshold S1 and the threshold S2 are between 100 Pa and 700 Pa. Earphone (14; 100) according to claim 4, in which the threshold S1 and the threshold S2 are between 200 and 600 Pa. Earphone (14) according to any one of claims 1 to 5, in which the pressure balancing system (46) comprises:
- a first subsystem (46A) allowing passage of air from the first chamber (34) to the second chamber (36), or to the third chamber (38) respectively, if the difference P1 - P2, or the difference P1 - P3 respectively, is greater than the threshold S1, and closed otherwise, and
- a second subsystem (46B) distinct from the first subsystem (46A) and ensuring a passage of air from the second chamber (36), or from the third chamber (38) respectively, towards the first chamber (34 ), if the difference P2 - P1, or the difference P3 - P1 respectively, is greater than the threshold S2, and closed otherwise. Earphone (14) according to any one of claims 1 to 5, in which the pressure balancing system (46) comprises at least one first flexible valve (64) ensuring passage of air from the first chamber (34). ), towards the second chamber (36) or the third chamber (38), the first flexible valve (64) having a triggering threshold for said air passage equal to the threshold S1. Earphone (14) according to claim 7, wherein the first flexible valve (64) comprises a conduit (68), a part (70) movable relative to the conduit (68), and a return spring (72) fixed on the movable part (70) and on the conduit (68), the movable part (70) and the return spring (72) respectively having a mass and a stiffness together defining a resonance frequency less than 20 Hz or greater than 20,000 Hz. Earphone (14) according to any one of claims 6 to 8, further comprising a second flexible valve (66) ensuring passage of air from the second chamber (36) or the third chamber (38), towards the first chamber (34), the second flexible valve (66) having a triggering threshold for said air passage equal to threshold S2. Audio headset (10) comprising at least one earphone (14; 100) according to any one of claims 1 to 9.