Patent Application
20210306777
The present invention is related to hearing systems, devices and methods. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in many applications in which a signal is used to stimulate the ear.
People like to hear. Hearing allows people to listen to and understand others. Natural hearing can include spatial cues that allow a user to hear a speaker, even when background noise is present.
Hearing devices can be used with communication systems to help the hearing impaired. Hearing impaired subjects need hearing aids to verbally communicate with those around them. Open canal hearing aids have proven to be successful in the marketplace because of increased comfort and an improved cosmetic appearance. Another reason why open canal hearing aids can be popular is reduced occlusion of the ear canal. Occlusion can result in an unnatural, tunnel-like hearing effect which can be caused by large hearing aids which block the ear canal. In at least some instances, occlusion be noticed by the user when he or she speaks and the occlusion results in an unnatural sound during speech. However, a problem that may occur with open canal hearing aids is feedback. The feedback may result from placement of the microphone in too close proximity with the speaker or the amplified sound being too great. Thus, feedback can limit the degree of sound amplification that a hearing aid can provide. Although feedback can be decreased by placing the microphone outside the ear canal, this placement can result in the device providing an unnatural sound that is devoice of the spatial location information cues present with natural hearing.
In some instances, feedback may be decreased by using non-acoustic means of stimulating the natural hearing transduction pathway, for example stimulating the tympanic membrane, bones of the ossicular chain and/or the cochlea. An output transducer may be placed on the eardrum, the ossicles in the middle ear, or the cochlea to stimulate the hearing pathway. Such an output transducer may be electro magnetically based. For example, the transducer may comprise a magnet and coil placed on the ossicles to stimulate the hearing pathway. Surgery is often needed to place a hearing device on the ossicles or cochlea, and such surgery can be somewhat invasive in at least some instances. At least some of the known methods of placing an electromagnetic transducer on the eardrum may result in occlusion in some instances.
One promising approach has been to place a magnet on the eardrum and drive the magnet with a coil positioned away from the eardrum. The magnets can be electromagnetically driven with a coil to cause motion in the hearing transduction pathway thereby causing neural impulses leading to the sensation of hearing. A permanent magnet may be coupled to the ear drum through the use of a fluid and surface tension, for example as described in U.S. Pat. Nos. 5,259,032 and 6,084,975.
However, there is still room for improvement. For example, with a magnet positioned on the eardrum and coil positioned away from the magnet, the strength of the magnetic field generated to drive the magnet may decrease rapidly with the distance from the driver coil to the permanent magnet. Because of this rapid decrease in strength over distance, efficiency of the energy to drive the magnet may be less than ideal. Also, placement of the driver coil near the magnet may cause discomfort for the user in some instances. There can also be a need to align the driver coil with the permanent magnet that may, in some instances, cause the performance to be less than ideal.
For the above reasons, it would be desirable to provide hearing systems which at least decrease, or even avoid, at least some of the above mentioned limitations of the current hearing devices. For example, there is a need to provide a comfortable hearing device which provides hearing with natural qualities, for example with spatial information cues, and which allow the user to hear with less occlusion, distortion and feedback than current devices.
Patents and publications that may be relevant to the present application include: U.S. Pat. Nos. 3,585,416; 3,764,748; 3,882,285; 5,142,186; 5,554,096; 5,624,376; 5,795,287; 5,800,336; 5,825,122; 5,857,958; 5,859,916; 5,888,187; 5,897,486; 5,913,815; 5,949,895; 6,005,955; 6,068,590; 6,093,144; 6,139,488; 6,174,278; 6,190,305; 6,208,445; 6,217,508; 6,222,302; 6,241,767; 6,422,991; 6,475,134; 6,519,376; 6,620,110; 6,626,822; 6,676,592; 6,728,024; 6,735,318; 6,900,926; 6,920,340; 7,072,475; 7,095,981; 7,239,069; 7,289,639; D512,979; 2002/0086715; 2003/0142841; 2004/0234092; 2005/0020873; 2006/0107744; 2006/0233398; 2006/075175; 2007/0083078; 2007/0191673; 2008/0021518; 2008/0107292; commonly owned U.S. Pat. No. 5,259,032 (Attorney Docket No. 026166-000500US); U.S. Pat. No. 5,276,910 (Attorney Docket No. 026166-000600US); U.S. Pat. No. 5,425,104 (Attorney Docket No. 026166-000700US); U.S. Pat. No. 5,804,109 (Attorney Docket No. 026166-000200US); U.S. Pat. No. 6,084,975 (Attorney Docket No. 026166-000300US); U.S. Pat. No. 6,554,761 (Attorney Docket No. 026166-0017000S); U.S. Pat. No. 6,629,922 (Attorney Docket No. 026166-0016000S); U.S. Publication Nos. 2006/0023908 (Attorney Docket No. 026166-000100US); 2006/0189841 (Attorney Docket No. 026166-000820US); 2006/0251278 (Attorney Docket No. 026166-000900US); and 2007/0100197 (Attorney Docket No. 026166-0011000S). Non-U.S. patents and publications that may be relevant include EP1 845919 PCT Publication Nos. WO 03/063542; WO 2006/075175; U.S. Publication Nos. Journal publications that may be relevant include: Ayatollahi et al., “Design and Modeling of Micromachines Condenser MEMS Loudspeaker using Permanent Magnet Neodymium-Iron-Boron (Nd—Fe—B)”, ISCE, Kuala Lampur, 2006; Birch et al, “Microengineered Systems for the Hearing Impaired”, IEE, London, 1996; Cheng et al., “A silicon microspeaker for hearing instruments”, J. Micromech. Microeng., 14(2004) 859-866; Yi et al., “Piezoelectric microspeaker with compressive nitride diaphragm”, IEEE, 2006, and Zhigang Wang et al., “Preliminary Assessment of Remote Photoelectric Excitation of an Actuator for a Hearing Implant”, IEEE Engineering in Medicine and Biology 27th Annual Conference, Shanghai, China, Sep. 1-4, 2005. Other publications of interest include: Gennum GA3280 Preliminary Data Sheet, “Voyager TDTM.Open Platform DSP System for Ultra Low Power Audio Processing” and National Semiconductor LM4673 Data Sheet, “LM4673 Filterless, 2.65 W, Mono, Class D audio Power Amplifier”; Puria, S. et al., Middle ear morphometry from cadaveric temporal bone microCT imaging, Invited Talk. MEMRO 2006, Zurich; Puria, S. et al, A gear in the middle ear ARO 2007, Baltimore, Md.
The present invention is related to hearing systems, devices and methods. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in many applications in which a signal is used to stimulate the ear.
Embodiments of the present invention can provide improved hearing which overcomes at least some of the aforementioned limitations of current systems. In many embodiments, a device to transmit an audio signal to a user may comprise a transducer assembly comprising a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer can be configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force. This driving of the ear drum and support with a force opposite the mass can result in more direct driving of the eardrum, and can improve coupling of the vibration of transducer to the eardrum. The transducer assembly device may comprise circuitry configured to receive wireless power and wireless transmission of an audio signal, and the circuitry can be supported with the eardrum to drive the transducer in response to the audio signal, such that vibration between the circuitry and the transducer can be decreased. The wireless signal may comprise an electromagnetic signal produced with a coil, or an electromagnetic signal comprising light energy produce with a light source. In at least some embodiments, at least one of the transducer or the mass can be positioned on the support away from the umbo of the ear when the support is coupled to the eardrum to drive the eardrum, so as to decrease motion of the transducer and decrease user perceived occlusion, for example when the user speaks. This positioning of the transducer and/or the mass away from the umbo, for example on the short process of the malleus, may allow a transducer with a greater mass to be used and may even amplify the motion of the transducer with the malleus. In at least some embodiments, the transducer may comprise a plurality of transducers to drive the malleus with both a hinging rotational motion and a twisting motion, which can result in more natural motion of the malleus and can improve transmission of the audio signal to the user.
In a first aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an ear drum. The device comprises a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer is configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force.
In many embodiments, the piezoelectric transducer is disposed between the mass and the support.
In many embodiments, the device further comprises at least one flexible structure disposed between the piezoelectric transducer and the mass.
In many embodiments, the piezoelectric transducer is magnetically coupled to the support.
In many embodiments, the piezoelectric transducer comprises a first portion connected to the mass and a second portion connected to the support to drive the mass opposite the support.
In many embodiments, the support comprises a first side shaped to conform with the eardrum. A protrusion can be disposed opposite the first side and affixed to the piezoelectric transducer.
In many embodiments, the device further comprises a fluid disposed between the first side and the eardrum to couple the support to the eardrum. The fluid may comprise a liquid composed of at least one of an oil, a mineral oil, a silicone oil or a hydrophobic liquid. In some embodiments, the support comprises a second side disposed opposite the first side and the protrusion extends from the second side to the piezoelectric transducer.
In many embodiments, the support comprises a first component and a second component. The first component may comprise a flexible material shaped to conform to the eardrum and flex with motion of the eardrum. The second component may comprise a rigid material extending from the transducer to the flexible material to transmit the first force to the flexible material and the eardrum. In at least some embodiments, the rigid material comprises at least one of a metal, titanium, a stainless steel or a rigid plastic, and the flexible material comprises at least one of a silicone, a flexible plastic or a gel.
In many embodiments, the device further comprises a housing, the housing rigidly affixed to the mass to move the housing and the mass opposite the support. In some embodiments, the support comprises a rigid material that extends through the housing to the transducer to move the mass and the housing opposite the support.
In many embodiments, the mass comprises circuitry coupled to the transducer and supported with the support and the transducer. The circuitry is configured to receive wireless power and wireless transmission of the audio signal to drive the transducer in response to the audio signal.
In many embodiments, the piezoelectric transducer comprises at least one of a piezoelectric unimorph transducer, a bimorph-bender piezoelectric transducer, a piezoelectric multimorph transducer, a stacked piezoelectric transducer with a mechanical multiplier or a ring piezoelectric transducer with a mechanical multiplier.
In some embodiments, the piezoelectric transducer comprises the bimorph-bender piezoelectric transducer and the mass comprises a first mass and a second mass. The bimorph bender comprises a cantilever extending from a first end supporting the first mass to a second end supporting the second mass. The support is coupled to the cantilever between the first end and the second end to drive the ear drum with the first force and drive the first mass and the second mass with the second force.
In some embodiments, the piezoelectric transducer comprises the stacked piezoelectric transducer with the mechanical multiplier. The mechanical multiplier comprises a first side coupled to the support to drive the eardrum with the first force and a second side coupled to the mass to drive the mass with the second force.
In some embodiments, the piezoelectric transducer comprises the ring piezoelectric transducer with the mechanical multiplier. The mechanical multiplier comprises a first side and a second side. The first side extends inwardly from the ring piezoelectric transducer to the mass. The second side extends inwardly toward a protrusion of the support. The mass moves away from the protrusion of the support when the ring contracts and toward the protrusion of the support when the ring expands. The ring piezoelectric multiplier may define a center having central axis extending there through. The central protrusion and the mass may be disposed along the central axis.
In some embodiments, the piezoelectric transducer comprises the bimorph bender. The mass comprises a ring having a central aperture formed thereon. The bimorph bender extends across the ring with a first end and a second end coupled to the ring. The support extends through the aperture and connects to the piezoelectric transducer between the first end and the second end to move the support opposite the ring when the bimorph bender bends. The bimorph bender can be connected to the ring with an adhesive on the first end and the second end such that the first end and the second end are configured to move relative to the ring with shear motion when the bimorph bender bends to drive the support opposite the ring.
In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum. The device comprises a transducer, circuitry coupled to the transducer, and a support configured to couple to the eardrum and support the circuitry and the transducer with the eardrum. The circuitry is configured to receive at least one of wireless power or wireless transmission of the audio signal to drive the transducer in response to the audio signal.
In many embodiments, the transducer is configured to drive the support and the eardrum with a first force and drive the circuitry with a second force opposite the first force.
In many embodiments, the circuitry is rigidly attached to a mass and coupled to the transducer to drive the circuitry and the mass with the first force. In some embodiments, the circuitry is rigidly attached to the mass and coupled to the transducer to drive the circuitry and the mass with the second force.
In many embodiments, the circuitry is flexibly attached to a mass and coupled to the transducer to drive the circuitry and the mass with the first force. In some embodiments, the circuitry is flexibly attached to the mass and coupled to the transducer to drive the circuitry and the mass with the second force.
In many embodiments, the circuitry comprises at least one of a photodetector or a coil supported with the support and coupled to the transducer to drive the transducer with the at least one of the wireless power or wireless transmission of the audio signal.
In many embodiments, the transducer comprises at least one of a piezoelectric transducer, a magnetostrictive transducer, a magnet or a coil.
In another aspect, embodiments of the invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum having a mechanical impedance. The device comprises a transducer and a support to support the transducer with the eardrum. A combined mass of the support and the transducer supported thereon is configured to match the mechanical impedance of the eardrum for at least one audible frequency between about 0.8 kHz and about 10 kHz.
In many embodiments, the combined mass comprises no more than about 50 mg. In some embodiments, the combined mass is within a range from about 10 mg to about 40 mg.
In many embodiments, the combined mass comprises at least one of a mass from circuitry to drive the transducer, a mass from a housing disposed over the transducer or a metallic mass coupled to the transducer opposite the support. In some embodiments, the transducer, the circuitry to drive the transducer, the housing disposed over the transducer and the metallic mass are supported with the eardrum when the support is coupled to the eardrum.
In many embodiments, at least one audible frequency is between about 1 kHz and about 6 KHz.
In many embodiments, the transducer and the mass are positioned on the support to place at least one of the transducer or the mass away from an umbo of the eardrum when the support is placed on the eardrum. This positioning can decrease a mechanical impedance of the support to sound transmitted with the eardrum when the support is positioned on the eardrum.
In many embodiments, the piezoelectric transducer comprises a stiffness. The stiffness of the piezoelectric transducer is matched to the mechanical impedance of the eardrum for the at least one audible frequency.
In many embodiments, the eardrum comprises an umbo and the acoustic input impedance comprises an acoustic impedance of the umbo. The stiffness of the piezoelectric transducer is matched to the acoustic input impedance of the umbo.
In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the ear drum at an umbo. The device comprises a transducer and a support to support the transducer with the eardrum. The transducer is configured to drive the eardrum. The transducer is positioned on the support to extend away from the umbo when the support is placed on the eardrum.
In many embodiments, a mass is positioned on the support for placement away from the umbo when the support is placed against the eardrum, and the transducer extends between the mass and a position on the support that corresponds to the umbo so as to couple vibration of the transducer to the umbo. The mass can be positioned on the support to align the mass with the malleus away from the umbo when the support is placed against the eardrum.
In many embodiments, the transducer is positioned on the support so as to decrease a first movement of the transducer relative to a second movement of the umbo when the eardrum vibrates and to amplify the second movement of the umbo relative to the first movement of the transducer when the transducer vibrates. In some embodiments, the first movement of the transducer is no more than about 75% of the second movement of the umbo and the second movement of the umbo is at least about 25% more than the first movement of the transducer. The first movement of the transducer may be no more than about 67% of the second movement of the umbo and the second movement of the umbo may be at least about 50% more than the first movement of the transducer.
In many embodiments, the device further comprises a mass, and the transducer is disposed between the mass and the support.
In many embodiments, the support is shaped to the eardrum of the user to position the support on the eardrum in a pre-determined orientation. The transducer is positioned on the support to align the transducer with a malleus of the user with the eardrum disposed between the malleus and the support when the support is placed on the eardrum. In some embodiments, the support comprises a shape from a mold of the eardrum of the user.
In many embodiments, the transducer is positioned on the support to place the transducer away from a tip of the malleus when the support is placed on the eardrum.
In many embodiments, the transducer is positioned on the support to place the transducer away from the tip when the support is positioned on the eardrum. The malleus comprises a head and a handle. The handle extends from the head to a tip near the umbo of the eardrum.
In many embodiments, the transducer is positioned on the support to align the transducer with the lateral process of the malleus with the eardrum disposed between the lateral process and the support when the support is placed on the eardrum. In some embodiments, the support comprises a rigid material that extends from the transducer toward the lateral process to move the lateral process opposite the mass.
In many embodiments, the transducer comprises at least one of a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, a coil or a magnet.
In many embodiments, the transducer comprises the piezoelectric transducer. The piezoelectric transducer may comprise a cantilevered bimorph bender, which has a first end anchored to the support and a second end attached to a mass to drive the mass opposite the lateral process when the support is placed on the eardrum.
In many embodiments, the device further comprises a mass coupled to the transducer and circuitry coupled to the transducer to drive the transducer. The mass and the circuitry is supported with the eardrum when the support is placed on the ear. The support, the transducer, the mass and the circuitry comprise a combined mass of no more than about 60 mg, for example, a combined mass of no more than about 40 mg or even a combined mass of no more than 30 mg.
In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an ear drum. The device comprises a first transducer, a second transducer, and a support to support the first transducer and the second transducer with the eardrum when the support is placed against the eardrum. The first transducer is positioned on the support to couple to a first side of the malleus. The second transducer positioned on the support to couple to a second side of the malleus.
In many embodiments, the first transducer is positioned on the support to couple to the first side of the malleus and the second transducer is positioned on the support to coupled to the second side of the malleus which is opposite the first side of the malleus.
In many embodiments, the support comprises a first protrusion extending to the first transducer to couple the first side of the malleus to the first transducer and a second protrusion extending to the second transducer to couple the second side of the malleus to the second transducer.
In many embodiments, the first transducer and second transducer are positioned on the support and configured to twist the malleus with a first rotation about a longitudinal axis of the malleus when the first transducer and second transducer move in opposite directions. The first transducer and second transducer can be positioned on the support and configured to rotate the malleus with a second hinged rotation when the first transducer and second transducer move in similar directions.
In many embodiments, the device further comprises circuitry coupled to the first transducer and the second transducer. The circuitry is configured to generate a first signal to drive the transducer and a second signal to drive the second transducer. In some embodiments, the circuitry is configured to generate the first signal at least partially out of phase with the second signal and drive the malleus with a twisting motion. The circuitry can be configured to drive the first transducer substantially in phase with the second transducer at a first frequency below about 1 kHz, and the circuitry can be configured to drive the first transducer at least about ten degrees out of phase with the second transducer at a second frequency above at least about 2 kHz.
In many embodiments, the first transducer comprises at least one of a first piezoelectric transducer, a first coil and magnet transducer, a first magnetostrictive transducer or a first photostrictive transducer, and the second transducer comprises at least one of a second piezoelectric transducer, a second coil and magnet transducer, a second magnetostrictive transducer or a second photostrictive transducer.
In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum. The method comprises supporting a mass and a piezoelectric transducer with a support on the eardrum of the user and driving the support and the eardrum with a first force and the mass with a second force, the second force opposite the first force.
In many embodiments, the ear comprises a mechanical impedance. The mass, the piezoelectric transducer and the support comprise a combined mechanical impedance. The combined mechanical impedance matches the mechanical impedance of the eardrum for at least one audible frequency within a range from about 1 kHz to about 6 KHz.
In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum. The method comprises supporting circuitry and a transducer coupled to the circuitry with the eardrum and transmitting the audio signal with a wireless signal to the circuitry to drive the transducer in response to the audio signal.
In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum having a mechanical impedance. The method comprises supporting a transducer and a support coupled to the eardrum with the eardrum. A combined mass of the support and the transducer supported thereon matches the mechanical impedance of the eardrum for at least one audible frequency between about 0.8 kHz and about 10 kHz.
In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the ear drum at an umbo. The method comprises supporting a transducer with a support positioned on the eardrum and vibrating the support and the eardrum with the transducer positioned away from the umbo. In many embodiments, a first movement of the transducer is decreased relative to a second movement of the umbo when the eardrum is vibrated and the second movement of the umbo is amplified relative to the first movement of the transducer.
In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the eardrum at an umbo. The method comprises supporting a first transducer and a second transducer with a support positioned on the eardrum. The first transducer and the second transducer are driven in response to the audio signal to the twist the malleus such that the malleus rotates about an elongate longitudinal axis of the malleus.
A hearing aid system using wireless signal transduction is shown in
FIGS. 8B1 and 8B2 shows a perspective view of ring mass with a bimorph piezo with flexible structures to couple the bimorph piezo to the ring mass, in accordance with the system of
Embodiments of the present invention can provide optically coupled hearing devices with improved audio signal transmission. The systems, devices, and methods described herein may find application for hearing devices, for example open ear canal hearing aides. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in any application in which a signal is wirelessly received and converted into a mechanical output.
As used herein, the umbo of the eardrum encompasses a portion of the eardrum that extends most medially along the ear canal, so as to include a tip, or vertex of the ear canal. As used herein, a twisting motion and/or twisting encompass a rotation of an elongate body about an elongate axis extending along the elongate body, for example rotation of a rigid elongate bone about an elongate axis of the bone. Twisting as used herein encompasses rotation of the elongate body both with torsion of the elongate body about the elongate axis and also without torsion of the elongate body about the elongate axis. As used herein torsion encompasses a strain, or deformation, that can occur with twisting, such that one part of the elongate body twists, or rotates, more than another part of the elongate body.
Input transducer assembly 20 includes a signal output source 12 which may comprise an electromagnetic source such as a light source such as an LED or a laser diode, an electromagnet, an RF source, or the like. Alternatively, an amplifier of the input assembly may be coupled to the output transducer assembly with a conductor such as a flexible wire, conductive trace on a flex printed circuitry board, or the like. The signal output source can produce an output signal based on the sound input. Output transducer assembly 30 can receive the output source signal and can produce mechanical vibrations in response. Output transducer assembly 30 may comprise a transducer responsive to the electromagnetic signal, for example at least one photodetector, a coil responsive to the electromagnet, a magenetostrictve element, a photostrictive element, a piezoelectric element, or the like. When properly coupled to the subject's hearing transduction pathway, the mechanical vibrations caused by output transducer assembly 30 can induce neural impulses in the subject which can be interpreted by the subject as the original sound input.
The output transducer assembly 30 can be configured to couple to a point along the hearing transduction pathway of the subject in order to induce neural impulses which can be interpreted as sound by the subject. As shown in
The axes of the malleus ML, incus IN and stapes ST can be defined based on moments of inertia. The first axis may comprise a minimum moment of inertia for each bone. The second axis comprises a maximum moment of inertia for each bone. The first axis can be orthogonal to the second axis. The third axis extends between the first and second axes, for example such that the first, second and third axes comprise a right handed triple. For example first axis 110 of malleus ML may comprise the minimum moment of inertia of the malleus. Second axis 113 of malleus ML may comprise the maximum moment of inertia of malleus ML. Third axis 115 of malleus ML can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis 110 and second axis 113. Further first axis 120 of incus IN may comprise the minimum moment of inertia of the incus. Second axis 123 of incus IN may comprise the maximum moment of inertia of incus IN. Third axis 125 of incus IN can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis 120 and second axis 123. First axis 130 of stapes ST may comprise the minimum moment of inertia of the stapes. Second axis 133 of stapes ST may comprise the maximum moment of inertia of stapes ST. Third axis 135 of stapes ST can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis 130 and second axis 133.
Vibration of the output transducer system induces vibration of eardrum TM and malleus ML that is transmitted to stapes ST via Incus IN, such that the user perceives sound. Low frequency vibration of eardrum TM at umbo UM can cause hinged rotational movement 125A of malleus ML and incus IN about axis 125. Translation at umbo UM and causes a hinged rotational movement 125B of the tip T of malleus ML and hinged rotational movement 125A of malleus ML and incus IN about axis 125, which causes the stapes to translate along axis 135 and transmits vibration to the cochlea. Vibration of eardrum TM, for example at higher frequencies, may also cause malleus ML to twist about elongate first malleus axis 110 in a twisting movement 110A. Such twisting may comprise twisting movement 110B on the tip T of the malleus ML. The twisting of malleus ML about first malleus axis 110 may cause the incus IN to twist about first incus axis 120. Such rotation of the incus can cause the stapes to transmit the vibration to the cochlea where the vibration is perceived as sound by the user.
With the output transducer assembly positioned over the eardrum TM on the umbo UM, the combined mass of the output transducer assembly can be from about 10 to about 60 mg, for example from about 10 to about 40 mg. In some embodiments, the combined mass comprises no more than about 50 mg. The combined mass may comprise the mass of the support, the transducer, a mass opposite the support and/or the circuitry to receive a wireless signal and drive the transducer. The support can be configured to support the transducer, a mass opposite the support and/or the circuitry to receive a wireless signal and drive the transducer with the eardrum when the support is placed against the eardrum.
The mass of transducer assembly 30 for placement away from the umbo can be similar to ranges described above for the configuration placed over the umbo, and may be scaled accordingly. For example, with the output transducer assembly positioned over the eardrum TM away from the umbo UM, for example over the lateral process, the combined mass of the output transducer assembly can be from about 20 to about 120 mg, for example from about 40 to about 80 mg. In many embodiments, the combined mass of output transducer assembly 30 over the lateral process can be from about 20 mg to about 60 mg to provide occlusion and transmission losses similar to a mass of about 10 mg to about 30 mg over the umbo.
Output transducer assembly 30 may have a number of exemplary specifications for maximum output. Output transducer assembly 30 may produce a sound pressure level of up to 106 dB. For example, a sound pressure level of up to at least about 90 dB can be sufficient to provide quality hearing for many hearing impaired users. The “center” of the eardrum, or the umbo, may move at 0.1 um/Pa at 1 kHz and 0.01 um/Pa at 10 kHz. The velocity can be 630 um/s/Pa from about 1 kHz and 10 kHz. The area of the eardrum may be about 100 mm2. The ear drum may have an impedance of about 0.2 Ns/m for frequencies greater than 1 kHz, which may be damping in nature, and an impedance of about 1000 N/m for frequencies less than 1 kHz in nature, which may be stiffening in nature. Thus, the power input into the ear at up to 106 dB SPL may be up to about 1 uW.
Output transducer assembly 30 may comprise a number of exemplary specifications for frequency response. Output transducer assembly 30 can have a frequency response of 100 Hz to 10 kHz. For an open canal system, it may be acceptable if low frequency response rolls off below 1 kHz since most hearing impaired subjects have relatively good low frequency hearing and the natural sound pathway can provide this portion of the sound spectrum. A relatively flat response may be good and it may be ideal if a resonance is generated at 2-3 kHz without affecting response at other frequencies. Variability between subjects may be +/−3 dB. This includes variability due to variable insertions and movement of the transducer with jaw movements. Variability across subjects may be +1-6 dB. Even in low responding subjects may need to have adequate output above their thresholds at all frequencies. Subject based calibrations may likely be problematic for clinicians and best avoided if possible.
Output transducer assembly 30 may further comprise a number of other exemplary specifications. For example, output transducer assembly 30 may have less than 1 percent harmonic distortion of up to 100 db SPL and less than 10 percent distortion of up to 106 db SPL. Output transducer may have less than 30 dB SPL noise equivalent pressure at the input. Output transducer may provide 15 dB of gain up to 1 kHz and 30 dB of gain above 1 kHz.
I. Power Sources:
Both power and signal may be transmitted to the output transducer assembly 30. 1 uW of power into the ear may need to be generated to meet maximum output specifications. Methods of transmitting power may include light (photovoltaic), ultrasound, radio frequency, magnetic resonant circuits.
In exemplary embodiments, a piezoelectric transducer driven by a photovoltaic (PV) cell or a number of photovoltaic (PV) in placed in series. The maximum voltage and current provided by the cells can be limited by the area and the amount of incident light upon them. 70 mW may be a good upper limit for the amount of electrical power available for the output transducer at its maximum output. This power can be limited by the amount of heat that can be dissipated as well as battery life considerations.
LEDs may be about 5% efficient in their conversion of electrical power into light power. The maximum light power coming out of the LEDs may be near 3.5 mW. The light coming out of the LED can cover a broader area than the area of the photovoltaic cell. The broader area may be set based on the movement of the ear canal and the ability to point the light directly at the photovoltaic cells. For example, a spot with a diameter that is twice a wide as a square 3.16 mm×3.16 mm photocell may be used. This spot size would have an area of 31.4 mm2 (leading to an optical efficiency of 32%). The photodetector area may comprise two parts—one part to move the transducer in a first direction and another part to move the transducer in a second direction, for example as described in U.S. Pat. App. No. 61/073,271, filed on Jun. 17, 2008, entitled “OPTICAL ELECTRO-MECHANICAL HEARING DEVICES WITH COMBINED POWER AND SIGNAL ARCHITECTURES”, (attorney docket no. 026166-001800US), the full disclosure of which is incorporated herein by reference. This two part photodetector area may further reduce the efficiency by a factor of two to 16%. This efficiency may be improved depending on the result of studies showing how much the motion of the ear canal moves the light as well as the ability to initially point the light down the ear canal. With a 16% efficiency, 560 uW of light power impinges on the surface of each of the two photovoltaics. The device may comprise at least one photo detector, for example as described in U.S. Pat. App. No. 61/073,281, filed Jun. 17, 2008, entitled “OPTICAL ELECTRO-MECHANICAL HEARING DEVICES WITH SEPARATE POWER AND SIGNAL COMPONENTS”, (attorney docket no. 026166-001900US), the full disclosure of which is incorporated by reference.
The LED/photovoltaic system may supply approximately 224 uA of current and 0.4V. Voltage can be increased by putting cells in series but the voltage increase may be at the proportional cost of current. 90 uW of power may be available to the transducer for producing motion of the eardrum. However, the amount of power utilized can depend on the load characteristics. The optimal load may be a 1800 ohm resistor (0.4V/224 uA). In either the piezoelectric case (capacitive load) or the voice coil case (inductive load), the load impedance may change as a function of frequency. A frequency at which this optimal impedance is matched may be chosen. For the capacitive load case, the system may be current limited above this frequency and voltage limited below this frequency. For the inductive load case, the situation may reverse. In the current limited cases, one may not be able to reach the desired maximum output levels. In the voltage limited regions, driving the system too hard may highly distort the output. If 2 kHz is chosen as the optimal frequency, this impedance may correspond to a capacitance of 44 nF or an inductance of 143 mH. Even with an optimal load attached, the overall efficiency of the optical power transfer is 0.04%. Yet even with this efficiency, the amount of power produced by the PV is 90× greater than what we expect to need to input into the ear.
Table 1 below summarizes the above-mentioned exemplary power specifications.
Other power transmission potions may include ultrasonic power transmission, magnetic resonant circuits, and radiofrequency power transmission. For magnetic resonant circuits, the basic concept is to produce two circuits that resonant with each other. The “far” coil should only draw enough power from the magnetic fields to perform its task. Power transfer may be in the 30-40% efficient range.
II. Output Transducer Specifications
In exemplary embodiments, an output transducer may comprise two major characteristics; the physics used to generate motion and the type of reference method used. The choices for the physics used to generate motion can include electromagnetic (voice coils, speakers, and the like), piezoelectric, electrostatic, pryomechanical, photostrictive, magnetostrictive, and the like. Regardless of what physics are used to generate motion, the energy of the motion can be turned into useful motion of the eardrum. In order to produce motion, forces or moments that act against the impedance of the eardrum may be generated. To generate forces or moments, the reaction force or moment is resisted. To resist such forces or movements, a fixed anchor point may be introduced, a floating inertia may be used, for example, utilizing
translational and rotational inertia, or deforming an object so that the boundaries produce a net force that moves the object, i.e., using a deformation transducer.
Exemplary physical specifications may be placed on the transducer based on the size of the ear canal, the ability of an output transducer to remain in position and the perception of occlusion resulting from having a mass present on the eardrum. Table 2 below show these specifications.
Output transducer assembly 30 may use a piezoelectric element to generate motion. Material properties of exemplary piezoelectric elements are shown in the table 3 below.
III. Exemplary Output Transducers
Output transducer assembly 30 may comprise a piezoelectric based output transducer, for example, a transducer comprising a piezoelectric unimorph, piezoelectric bimorph, or a piezoelectric multimorph. Exemplary output transducers may comprise a simply supported bimorph bender 400 as shown in
Cantilevered bimorph bender 500 includes mass 510 and cantilever 520. Some embodiments may include more than one mass, cantilever, and/or support.
FIGS. 8B1 and 8B2 show perspective views of mass, for example a ring mass, with a piezoelectric transducer, for example a bimorph piezoelectric transducer 803, in which the mass is coupled to the piezoelectric transducer with a flexible intermediate structure, for example intermediate element 815, suitable for incorporation with transducer assembly 30 as described above. The flexible intermediate structure can relax a boundary condition at the edge of the piezoelectric transducer so as to improve performance of the piezoelectric transducer coupled to the mass. Although an elongate rod is shown, the flexible intermediate structure may comprise many known flexible shapes such as coils, spheres and leafs. Bimorph 810 is indirectly and flexibly connected to washer ring 820. The ends of bimorph 810 can be directly connected to intermediate elements 815. Intermediate elements 815 can in turn be directly connected to washer ring 820. Washer ring 820 can serve as a mass. The ends of bimorph 810 may be rigidly attached to intermediate elements 815, for example, via an adhesive or glue. Intermediate elements 815 may be rigidly attached to intermediate elements 815, for example, via an adhesive or glue. Intermediate elements 815 is flexible so as to provide a flexible boundary condition or a flexible connection between bimorph 810 and washer ring 820. For example, intermediate elements 815 may comprise a rod made of a flexible material such as carbon fiber or a similar composite material. Such a flexible material may be more prone to twisting than bending. By providing such a flexible boundary
condition, the force outputted by transducer 803 can be greater, for example, twice as great, as the force outputted if bimorph 810 were instead directly and rigidly connected to washer ring 820.
Bimorph 810 is coupled with a support 830. Support 830 comprises a protrusion 830P protruding from the bimorph 810 and a support member 830E adapted to conform with the eardrum TM. Protrusion 830P is coupled to support member 830E. For example, protrusion 830P can comprise a first magnetic member 831 P and support member 830E may comprise a complementary second magnetic member 831E so that protrusion 830P and support member 830E are magnetically coupled. Both first magnetic member 831 P and second magnetic member 831E may comprise magnets. Alternatively, one of first magnetic member 831P or second magnetic member 831E may comprise a magnet while the other comprises a ferromagnetic material. To position transducer 803 on the eardrum TM, support member 830E may first be placed on the eardrum TM, followed by the remainder of the transducer 803 as guided by first magnetic member 831P and second magnetic member 831E. The use of magnetism to guide the positioning of transducer 803 can reduce a hearing professional's reliance on vision to position transducer 803 on the eardrum TM.
Support member 830E may comprise a mold shaped to conform with the eardrum TM. Support member 830E can comprise a flexible material such as silicone, flexible plastic, a gel, or the like. The portion of support member 830E in contact with protrusion 830P may be rigid, for example, the portions may comprise a metal, titanium, a rigid plastic, or the like. Support 830 may be configured so that protrusion 830P is directly over the umbo UM. Transducer 803 may also comprise circuitry 824. Circuitry 824 may be configured to receive an signal, for example, an external, wireless signal. Circuitry 824 can cause bimorph 810 to bend or flex and thus push against washer 820. The pushing action causes a force in a direction 852 on washer 820 and also a force on the support 830 in a direction 853. The force on the support 830 causes a translational movement of the umbo UM which can rotate malleus ML to produce sensations of sound.
Ring mass with double bimorph piezoelectric transducer 804 may comprise circuitry configured to receive an external, wireless signal and cause bimorph 810a and bimorph 810b to bend and/or flex and thus push against washer 820. The wireless signal may comprise a first signal configured to drive first bimorph 810a and a second signal configured to drive second bimorph 810b. The pushing action of the first transducer in response to the first signal causes a first force in a first direction 852a on washer 820 and an opposite force on the support 830 in an opposite direction 853a. The pushing action of the second transducer in response to the second signal causes a second force in a second direction 852b on washer 820 and an opposite force on the support 830 in an opposite direction 853b. The force on the support 830 in first direction 853a and second direction 853b causes a translational movement which drives the eardrum TM to produce sensations of sound.
The dual transducer 804 allows the malleus to be driven in more than one dimension, for example with a first translational motion to rotate the malleus with hinged motion about the head of the malleus and second rotational motion to twist the malleus about an elongate axis of the malleus extending from a head of the malleus toward the umbo. When bimorphs 810a and 810b are flexed at the same time and in the same direction,′ ring-mass-double-bimorph-piezoelectric-transducer 804 may work similar to same as ring-mass-double-bimorph-piezoelectric-transducer 804. However, flexion of bimorphs 810a and 810b at different times and/or in different directions or phase may produce a rotational twisting motion along the elongate axis of the malleus with support 830 and thus induce rotation at the umbo of eardrum TM. For example, the received external, wireless signal may cause only one of bimorph 810a and bimorph 810b to bend or flex. Alternatively or in combination, the received external, wireless signal may cause bimorph 810a to bend or flex more than bimorph 810b, or vice versa, so as to cause a rotational twisting motion of the malleus to occur along with the hinged rotation motion of the malleus to translate the umbo of eardrum TM. Arrows 853TW show twisting motion of the malleus at umbo UM with a first rotation of the malleus about an elongate axis of the malleus. Arrows 853TR show translational motion of the umbo UM with hinged rotation of the malleus comprising pivoting of the malleus about the head of the malleus. The first transducer and the second transducer can be driven with a signal having a time delay, for example a phase delay of 90 degrees, such that translation movement and twisting of the malleus and umbo occur. Thus, a first portion support 830 may translate in a first direction 853 and a second portion of support 830 may translate in a second direction 853b opposite first direction 853a so as to rotate the malleus with twisting motion. Thus, the first transducer and the second transducer comprising bimorphs 810a and 810b can be driven so as to cause translational movement and a rotational movement of eardrum TM. Hinged rotational movement of the malleus to effect translational movement of the umbo UM may be made at low frequencies less than about 5 kHz, for example frequencies less than about 1 kHz. Rotational twisting movement of the malleus may be made at frequencies greater than about 2 kHz, for example high frequencies greater than 5 kHz.
Tables 4 and 5 below show characteristics of exemplary piezoelectric output transducers as described above, including simply supported bimorph bender 400, cantilevered bimorph bender 500, stacked piezo with mechanical multiplier 600, disk or narrow ring piezo with a mechanical multiplier 700, and bimorph or wide ring piezo 800.
Capacitance
Stiffness
Capacitance
1st Mechanical Resonance
Stiffness
Capacitance
The mass can be positioned away from the umbo and/or aligned with the malleus ML in many ways so as to reduce the input impedance of the transducer assembly. For example, mass 510 can be positioned on support 1060 such that mass 510 is supported with the lateral process LP when support 1060 is placed against the ear. Also cantilevered bimorph bender 500 and support 530 can be placed directly on the eardrum TM such that mass 510 is aligned with malleus ML, for example aligned with lateral process LP. As shown in
Many of the above embodiments can be evaluated on an empirical number of patients, for example 10 patients to optimize the transducers, for example transducer mass, positioning, support and circuitry. For example, experiments can be conducted on an empirical number of ten patients to determine improved coupling of sound with differential movement of the first transducer and second transducer. In addition to testing with patients, the embodiments can be tested with computer simulations and laboratory testing. The below described experiments are merely examples of experiments that can be performed, and a person of ordinary skill in the art will recognize many variations and modifications that can be used to improve and optimize the performance of the transducer devices described herein.
IV. Experimental
For exemplary piezoelectric elements, five key characteristics were looked at as a function of geometric parameters. The five parameters were: 1) minimum manufacturable layer thickness, 2) electrical capacitance, 3) 1st mechanical resonant frequency (if available), 4) low frequency stiffness, and 5) maximum displacement achievable with a photodetector power source. For each exemplary piezoelectric element, a contour plot of the maximum displacement achievable at 2 kHz was made.
On top of the contour map shown, other parameters are shown as “constraint lines”. For example, the minimum manufacturable thickness is represented as a line. Any design point falling below or to the right of this line may be achievable. Any design point falling above or to the left calls for a layer thickness that is not currently available from any of the contacted vendors. Often, only integer numbers of layers are possible. Similarly, the capacitance is shown in a line. Any design falling below or to the right of this line has less than the optimal capacitance for 2 kHz. Any design above or to the left has a higher capacitance. At this point, one must remember that the displacement contours are shown at kHz. At different frequencies, there will be a different optimal capacitance. (Optimizing for higher frequencies will require smaller capacitances.) Designs that have a 1st mechanical resonance of 10 kHz are shown as a line. Designs to the right have higher resonant frequencies; designs to the left have lower resonant frequencies. Designs that have a low frequency stiffness equal to the umbo stiffness at 10 kHz are shown with a line. Designs to the right have higher stiffnesses; designs to the left have lower stiffnesses. In exemplary embodiments, piezoelectric element parameters that are below and to the right of all the constraint lines while at the same time maximizing location on the displacement contour are chosen. Contour maps can be made for embodiments of bimorph piezoelectric transducers using the parameters set forth in Table 7.
Contour maps can be made for embodiments of simply supported bimorph piezoelectrics using the parameters set forth in Table 8 The bimorph with the greatest displacement that meets all of the constraints may be selected. Exemplary embodiments SSBM1, SSBM2, SSBM3, SSBM4, SSBM5, SSBM6, SSBM7, SSBM8, SSBM12, SSBM15, and SSBM18 give displacements greater than 0.1 um at 2 kHz.
The PZT506 material appears to be the suitable for making the bimorph. Its combination of thin layer thicknesses, high piezoelectric constants and moderate permittivity provides a suitable best output. Also, it appears that a wide range of beams all produce roughly the same output, 0.15 um. Choosing between these options can be based on tradeoffs of manufacturing. For example, layers in the bimorph can be traded-off against segmenting the photodetector.
Contour maps can be made for embodiments of back-to-back amplified stack piezoelectric elements, a TRS single crystal back-to-back stack with displacement amplifier, respectively. A displacement amplified stack piezoelectric elements may comprise a scissor jack with two stacks placed back-to-back pushing outwards. In this configuration, the centerline of the assembly does not move. Therefore, the maximum stack length to consider for displacement purposes is 2.5 mm or half of the maximum allowable dimension. However, the effective capacitance may be needed to account for both stacks. The lever ratio may be limited to be between 1 and 15. In between those limits, the stiffness of the stack can be matched to the impedance of the umbo at 10 kHz. Since the number of layers in a stack is high, the thickness of the glue/electrodes between layers may need to be considered. For example, a glue/electrode layer thickness of 16 um may be used. Like with simply supported bimorph piezoelectric elements above, amplified stack piezoelectric elements were analyzed at a variety of thicknesses and assuming various numbers of photodetectors in series. Neither the stiffness nor the 1st resonance of the stack was a limiting factor while layer thickness, capacitance and length may be limiting factors.
Table 9 below shows some exemplary ranges of parameters for embodiments of back-to-back amplified stack piezoelectric elements.
Table 10 below shows parameters for several embodiments of back-to-back amplified stack piezoelectric elements Both the single crystal material and the PZT506 material appear to have maximum outputs near 0.3 um. Several embodiments of back-to-back amplified stack piezoelectric elements produce similar amounts of displacement. Thus, there may be flexibility in manufacturing.
Embodiments of piezoelectric elements were also tested using a laser vibrometer to measure the velocity (and hence the displacement) of a target. Data was analyzed to yield displacement per volt and plotted versus frequency. Data was determined using the equations mentioned above and plotted alongside the test data.
A single Morgan stacked as shown in
A Steiner and Martins cofired Piezo series bimorph as shown in
A TRS Single Crystal Bimorph Cantilever as shown in
A TRS Single Crystal Bimorph on a washer as shown in
A stacked piezo pair with V-jack type displacement amplification as shown in
Embodiments of output transducers which were placed on a subject's eardrum were tested. The transducer was wire driven, connected directly to the audiometer to determine the acoustic threshold. In order to reduce the effect of the wires, 48 AWG wire was used between the transducer and a location just outside the ear canal. The position of the transducer was verified by a physician using a video otoscope.
Once in place, the audiometer driven transducer was energized across a 12 kΩ load and the audiometer setting adjusted to reach threshold. The threshold was recorded at each frequency tested. After the testing was complete and the transducer removed from the subject's ear, the transducer was reconnected to the audiometer and the voltage measured. Often, the audiometer setting was increased by 40 dB to make a reliable measurement.
The data collected was converted to pressure equivalent using Minimum Audible Pressure curves and plotted against the specifications, bench-top data and average electromagnetic or EM system output. In all cases, the assumption is that the input to the transducer is 0.4V peak and 75 mW. The bench-top data was determined by measuring the unloaded displacement and comparing to the known displacement of the umbo at each frequency plotted.
In addition to the threshold measurements, the feedback pressure was measured at two locations: at the umbo and at the entrance to the ear canal. Often, the transducer was driven by a laptop running SYSid, and operated at 1 V peak, with the feedback measured with an ER-7c microphone. The resulting data gives a measure of the gain margin for each transducer design/location if the microphone is located either deep in the canal or at the canal entrance.
While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.
The present application is a continuation of U.S. patent application Ser. No. 15/911,595, filed Mar. 5, 2018; which is a divisional of U.S. patent application Ser. No. 15/042,595, filed Feb. 12, 2016; which is a continuation of U.S. patent application Ser. No. 13/069,282, filed Mar. 22, 2011; which is a continuation of PCT Application No. PCT/US2009/057716, filed Sep. 21, 2009; which claims priority to U.S. Patent Application Nos.: 61/139,526 filed Dec. 19, 2008; 61/217,801 filed Jun. 3, 2009; 61/099,087 filed Sep. 22, 2008; and 61/109,785 filed Oct. 30, 2008; the full disclosures of which are incorporated herein by reference.
This invention was supported by grants from the National Institutes of Health (Grant No. R44DC008499-02A1). The Government may have certain rights in this invention.
| Number | Date | Country | |
|---|---|---|---|
| 61217801 | Jun 2009 | US | |
| 61139526 | Dec 2008 | US | |
| 61109785 | Oct 2008 | US | |
| 61099087 | Sep 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15042595 | Feb 2016 | US |
| Child | 15911595 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15911595 | Mar 2018 | US |
| Child | 17232070 | US | |
| Parent | 13069282 | Mar 2011 | US |
| Child | 15042595 | US | |
| Parent | PCT/US2009/057716 | Sep 2009 | US |
| Child | 13069282 | US |
