United States Patent
`US 6,658,124 B1
`(10) Patent No.:
`(12)
`Meadows
`(45) Date of Patent:
`Dec. 2, 2003
`
`
`US006658124B1
`
`(54) RECHARGEABLE HEARING AID
`
`(75)
`
`Inventor: Paul M. Meadows, Sylmar, CA (US)
`
`3/1997 Grosfilley occ 321/4
`5,610,494 A
`
`» 429/163
`7/2001 Saaskiet al.
`6,265,100 Bl *
`... 381/323
`6,310,960 B1 * 10/2001 Saaskietal.
`5/2002 Leysieffer .........0..00. 600/25
`6,394,947 B1 *
`
`(73) Assignee: Advanced Bionics Corporation,
`Sylmar, CA (US)
`
`* cited by examiner
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 328 days.
`
`(21) Appl. No.: 09/811,065
`(22)
`Filed:
`Mar. 16, 2001
`
`(60)
`
`an
`; Related. US. Application Data
`Provisional application No. 60/195,578, filed on Apr. 6,
`2000.
`(SV) Unt. C17 eee eeeeeeceeeeeees eee eeteeeenenees HO4AR 25/00
`
`52) US. Ch.
`coccccccccccccccececcsscscesesssesseeees 381/323; 381/328
`(52)
`/323;
`381/
`(58) Field of Search oo... eee 381/323, 322,
`381/328, 331, FOR 127, FOR 133, FOR 135,
`FOR 137, 23.1, 312, 324, 327, 330; 429/94,
`161, 163, 164, 175, 176, 189, 209
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`.
`.
`.
`Prumary Examiner—Curtis Kuntz
`Assistant Examiner—Brian Ensey
`(74) Attorney, Agent, or Firm—Kenneth L. Green; Bryant
`R. Gold
`°
`
`ABSTRACT
`67)
`A rechargeable hearing aid eliminates the requirement for
`frequent replacement of a disposable hearing aid battery.
`The rechargeable hearing aid features inductive recharging
`using a charging reservoir. In a preferred embodiment, a
`lithium-ion battery 1s used with a Completely-In-the-Canal
`CIC) hearing
`aid. The CIC hearing
`aid is inserted into a
`gs
`g
`reservoir throat of the charging reservoir. In a preferred
`embodiment a primary coil of the inductive recharger is
`wound around the reservoir throat, and a secondary coil of
`the hearing aid is wound around the diameter of the body of
`the CIC hearing aid, thus providing coupling of the primary
`and secondarycoils that is independentofthe rotation of the
`hearing aid in the charger throat.
`
`4,379,988 A
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`4/1983 Mattatall oo... eee 320/4
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`13 Claims, 4 Drawing Sheets
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`12
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` Fo IS
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`APPLE 1073
`Apple v. GUI
`IPR2021-00471
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`1
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`APPLE 1073
`Apple v. GUI
`IPR2021-00471
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`U.S. Patent
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`Dec. 2, 2003
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`Sheet 1 of 4
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`US 6,658,124 B1 x
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`FIG.
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`U.S. Patent
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`Dec. 2, 2003
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`Sheet 2 of 4
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`US 6,658,124 B1
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`U.S. Patent
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`US 6,658,124 B1
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`U.S. Patent
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`US 6,658,124 B1
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`Dec. 2, 2003
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`Sheet 4 of 4
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`US 6,658,124 B1
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`1
`RECHARGEABLE HEARING AID
`
`The present application claims the benefit of U.S. Pro-
`visional Application Serial No. 60/195,578, filed Apr. 6,
`2000, which application is incorporated herein by reference.
`BACKGROUND OF THE INVENTION
`
`The present invention relates to hearing aids, and more
`particularly to a recharging system for an in-the-ear
`rechargeable hearing aid. Such rechargeable hearing aid
`system eliminates the burden of replacing the hearing aid
`battery, and thus provides significant advantages to the
`elderly and others with impaired eyesight or reduced manual
`dexterity.
`Knownhearing aids utilize very small non-rechargeable
`batteries for their power source. Various in-the-ear hearing
`aids have been developed that provide both good perfor-
`mance and are less visible than traditional behind-the-ear
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`patent therefore requires that the hearing aid be carefully
`positioned in the recharging device. Such positioning
`requirement duplicates one of the problems the *494 patent
`is intended to solve because the hearing aid must be placed
`precisely in the correct position to line up the contacts. Due
`to the soft structure of a hearing aid, such positioning may
`be difficult for those with vision problems or reduced manual
`dexterity. There is also a requirement to keep the contacts
`clean. Dueto the low voltage nature of the charging circuit,
`even small resistance may impact charging performance.
`Such inefficiencies in charging are especially costly when
`the recharger is itself a portable battery powered recharger.
`The °494 patent also teaches that recharging could be
`accomplished using an inductive charger, but that a large
`coil would be required in the hearing aid that would unac-
`ceptably increase the bulk of the hearing aid. The ’494 patent
`is incorporated herein by reference.
`Whatis therefore needed is a rechargeable hearing aid that
`can be recharged without removing the battery, and which
`recharging may be performed without precise placement of
`the hearing aid within a charging device.
`
`SUMMARYOF THE INVENTION
`
`It is a further feature of the invention to recharge the
`hearing aid battery inductively. The present invention pro-
`vides power required for recharging using inductive cou-
`pling between a primary coil in a charging reservoir, and a
`secondary coil in a hearing aid. Inductive charging advan-
`tageously eliminates the need for contacts on the exterior of
`the hearing aid, which contacts are required for non-
`inductive charging of the battery, and which contacts may
`
`hearing aids. Versions of in-the-ear hearing aids are known
`that are entirely in the ear canal, mostly within the ear canal,
`and only partially within the ear canal. In spite of their
`differences, all of these in-the-ear hearing aids share the
`requirement for a very small battery.
`invention addresses the above and other
`The present
`The need for a small battery for hearing aids has been met
`needs by providing a rechargeable hearing aid that
`is
`using known zinc air batteries. The zinc air batteries are
`recharged by placing the hearing aid in an inductive charg-
`inexpensive and have a useful
`life up to several days.
`ing reservoir. Power for recharging the hearing aid battery is
`However, the very small size that makesthe zinc air batteries
`provided through inductive coupling of a primary coil in a
`practical for a small hearing aid also make the batteries
`charging reservoir and a secondary coil in the hearing aid.
`difficult to handle. Hearing aid users with poor eyesight or
`The inductive power transmission requires only a general
`reduced manual dexterity have difficulty replacing the zinc
`air batteries. Both of these infirmities are associated with
`alignment of the hearing aid with the charging reservoir. In
`a preferred embodiment, a lithium ion battery is used in the
`advancedage, andare likely to be found in hearingairusers.
`rechargeable hearing aid becauseof the energy density of the
`Additionally, there is a risk of dropping and damaging the
`lithium ion battery and capacity for a very large numberof
`hearing aid when changingthe batteries.
`recharges.
`The disposable batteries are considered dangerous if
`swallowed, and therefore the ingestion of such batteries
`In accordance with one aspect of the invention, there is
`presents a health risk. There is therefore a risk of small
`provided a rechargeable hearing aid that permits recharging
`children or
`infants swallowing the small hearing aid
`the hearing aid battery without removing the battery from
`40
`batteries, thereby requiring careful storage of new batteries,
`the hearing aid. Many hearing aid users are advanced in
`and immediate disposal of used batteries. Additionally, due
`years and suffer fromaloss of sight and/or manual dexterity.
`to their size and shape, the batteries can be mistaken for
`Such individuals often find it difficult
`to perform the
`pills, which pills are also common place with those of
`manipulation required to replace a very small battery in a
`advanced age who frequently have diminished vision.
`small device. The cumbersome task of removing a very
`small battery from a small device is replaced by simply
`The chemicals used in replaceable batteries are often
`placing the entire hearing aid in a charging reservoir.
`classified as being a toxic material. As society becomes
`increasingly more protective of the environment,the cost of
`It is also a feature of the present invention to eliminate the
`disposing or recycling batteries will rise, and be a further
`hazards resulting from the use of disposable batteries. For
`deterrent to the use of disposable batteries.
`example, batteries are known to contain toxic substances,
`and are dangerous if swallowed. A typical hearing aid
`Onereason for the development of miniature hearing aids
`battery is similar in size and shape to commonpills. A
`is to reduce the unsightly appearance of the device in the
`hearing aid user with poor eyesight may easily mistake a
`patient’s ear. However, the flap covering the replaceable
`used battery for a pill, and swallow the battery. The dispos-
`battery in knownhearingaids is on the surface of the hearing
`able batteries are also a hazard to children who may place
`aid that is visible when the hearing aid is inserted into the ear
`the batteries in their mouths. Additionally, there are also
`canal, and drawsthe attention that the miniature hearing aid
`environmental costs surrounding the disposal of used bat-
`was developed to avoid.
`teries due to the toxic content of the batteries.
`A rechargeable hearing aid is described in U.S. Pat. No.
`Advantageously, rechargeable hearing aids avoid all of these
`5,610,494 for “Device for Recharging the Storage Battery of
`hazards.
`an Intra-auricular Prosthesis and Method for Manufacturing
`Same,” issued Mar. 11, 1997. While the °494 patent
`addresses the issues raised here, it does not provide the best
`solution. The ’494 patent teaches a recharging system requir-
`ing contacts on the exterior of the intra-auricular prosthesis
`(ie., hearing aid), and a charger comprising a box with
`recesses matching the shape of the hearing aid, which
`recesses contain electrical contact which cooperate with the
`contacts on the hearing aid. A device according to the *494
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`US 6,658,124 B1
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`becomesoiled, thus impairing their conductivity. Inductive
`charging further eliminates the requirement
`to precisely
`align hearing aid contacts with recharger contacts, which
`alignmentis difficult for a hearing aid user with poor sight
`or poor manual dexterity.
`It is an additional feature of the invention to eliminate the
`
`need to provide access for replacement of a disposable
`battery. The requirementto regularly replace the disposable
`battery creates a requirement
`that
`the battery be easily
`accessible. In known Completely-In-the-Canal (CIC) hear-
`ing aids, the disposable battery is removable through a door
`in the end of the hearing aid facing away from the ear drum,
`and the battery is located just inside the door. The placement
`of the battery in this location interferers with placement of
`the hearing aid’s microphone. The placementof a recharge-
`able battery within the hearing aid allows the hearing aid
`designer to optimally select and locate the microphone.
`Additionally, the battery door in known CIC hearing aids is
`visible when the hearing aid is in the user’s ear canal, thus
`reducing the cosmetic value of a CIC hearing aid. The use
`of a rechargeable battery eliminates the requirementfor the
`unsightly door.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other aspects, features and advantages of
`the present invention will be more apparent from the fol-
`lowing more particular description thereof, presented in
`conjunction with the following drawings wherein:
`FIG. 1A depicts a Completely-In-the-Canal (CIC) hearing
`aid and a corresponding human ear;
`FIG. 1B shows the CIC hearing aid and its charging
`reservoir;
`FIG. 2A provides a side view of a charging reservoir;
`FIG. 2B shows a cross-sectional view of the charging
`reservoir, taken along line 2B—2B of FIG. 2A;
`FIG. 3A provides a side view of a CIC hearing aid;
`FIG. 3B shows a cross-sectional view of a CIC hearing
`aid taken along line 3B—3Bof FIG. 3A;
`FIG. 4 illustrates the cooperation of primary and second-
`ary coils when the CIC hearing aid in placed in its charging
`reservoir; and
`FIG. 5 provides a diagram of a charging circuit suitable
`for a rechargeable lithium battery.
`Corresponding reference characters indicate correspond-
`ing components throughout the several views of the draw-
`ings.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`The following description is of the best mode presently
`contemplated for carrying out the invention. This descrip-
`tion is not to be taken in a limiting sense, but is made merely
`for the purpose of describing the general principles of the
`invention. The scope of the invention should be determined
`with reference to the claims.
`
`The rechargeable hearing aid of the present invention
`provides a simple to use system relieving the hearing aid
`user from the cumbersome task of regularly removing and
`replacing the hearing aid small disposable hearing aid bat-
`teries. In a preferred embodiment, the invention is exercised
`in a rechargeable Completely-In-the-Canal (CIC) hearing
`aid 12 as shownin FIG. 1A. The CIC hearing aid 12 has the
`advantageof fitting entirely within an ear canal 10 of a user,
`and is nearly invisible when in use.
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`The recharging system of the invention is shown in FIG.
`1B. The recharging system comprises a simple charging
`reservoir 14 that the CIC hearing aid 12 is dropped into for
`charging. The CIC hearing aid 12 has a substantially cylin-
`drical shape. The only alignment requirementfor charging is
`that the longitudinal axis of the CIC hearing aid 12 be
`aligned with the opening in the charging reservoir 14. A
`reservoir body 20 is shown in FIG. 1B as having a conical
`shape. This shape is merely used as an example, and those
`skilled in the art will recognize that many other shapes may
`be used and do not depart from the scope of the present
`invention.
`
`Aside view of the charging reservoir 14 is shown in FIG.
`2A. A cross-sectional view of the charging reservoir 14
`taken along line 2B—2B of FIG. 2A is shown in FIG. 2B.
`Areservoir throat 22 provides for the removable insertion of
`the CIC hearing aid 12 into the charging reservoir 14. The
`reservoir throat 22 is designed to allow easy insertion of the
`CIC hearing aid 12 with the only requirementbeing that the
`CIC hearing aid is longitudinally aligned with the axis of the
`reservoir throat. A primary coil 26 is oriented coaxial with
`the reservoir throat 22, and near the top of the reservoir
`throat. Advantageously, this positioning of the primary coil
`provides a maximum degree of freedom in placementof the
`CIC hearing aid 12 within the charging reservoir, as will be
`discussed in the description of FIG. 4 below. A reservoir
`circuit 28 provides power to the primary coil 26. The
`reservoir circuit 28 comprises a known class E, or similar
`power amplifier, operating at a carrier frequency from 20
`KHz to 100 KHz. Poweris provided to the charging reser-
`voir 14 through a power cord 29 which provides for con-
`nection to a typical wall outlet. Though this embodiment
`teaches a charger powered by household power, a battery or
`otherwise powered unit may also be utilized, thus allowing
`recharging in a car or anywhere that household poweris not
`available. The use of other alternative power sources will be
`apparent to those skilled in the art and are intended to come
`within the scope of the present invention.
`Movingto FIG. 3A,a side view of the CIC hearing aid 12
`is shown. A cross-sectional view of the CIC hearing aid 12
`taken along line 3B—3B of FIG. 3A is shown in FIG. 3B.
`While a hearing aid body 30 is substantially cylindrical,
`known CIC hearing aids bodies are molded to fit the user’s
`ear canal. The molded CIC bodies may have a slight turn,
`and be somewhat out of round. These and other shapes are
`intended to come within the scope of the present invention.
`The basic hearing aid functions are carried out by a
`microphone 32 that converts sound waves to electrical
`signals. The electrical signals are processed by the Signal
`Processor (SP) circuit 33. The processed signal is provided
`to a speaker 34 that provides an amplified acoustic signal to
`the hearing aid user. Asecondary coil 36 is tuned to the same
`carrier frequency as the primary coil 26 of FIG. 2B, and
`receives, rectifies, and filters the power transmitted by the
`primary coil 26. The processed poweris then provided to a
`charging circuit 37. The output of the charging circuit 37 is
`used to charge a rechargeable battery 38. The rechargeable
`battery 38 provides powerfor the SP circuit 33. The details
`of the charging circuit 37 are provided in FIG. 5, described
`below. In a preferred embodiment, the rechargeable battery
`38 is a lithium-ion battery.
`In a second preferred
`embodiment, the rechargeable battery 38 is a zinc-air bat-
`tery. The best battery for a specific application of the present
`invention depends on the space available in the hearing aid,
`the power requirements of the signal processing circuit, and
`the individual requirements of the user.
`The cooperation of the CIC hearing aid 12 with the
`charging reservoir 14 is illustrated in FIG. 4. The CIC
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`US 6,658,124 B1
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`5
`hearing aid 12 is shown inserted into reservoir throat 22.
`Importantly, the primary coil 26 is shown surrounding the
`secondary coil 36. This relationship of the primary to
`secondary coils maximizes the inductive transmission of
`power from the primary coil 26 to the secondary coil 36.
`While the availability of household power reduces the
`importance of efficient power transfer, applications where
`the charging reservoir is battery powered benefit signifi-
`cantly from such efficient power transfer. Further,
`this
`arrangementof the primary and secondarycoils is invariant
`to rotation of the CIC hearing aid 12. Thus, there is no
`alignment requirement for the insertion of the CIC hearing
`aid 12 into the reservoir throat 22. This is particularly
`advantageous for hearing aid users with poor eyesight. Still
`further, the vertical placementof the primary and secondary
`coils results in effective coupling regardless of which end of
`the CIC hearing aid 12 is inserted into the reservoir throat
`22. While this particular arrangement provides marked
`advantages to older users, other locations for the primary
`and secondarycoils, that are less effective, will be apparent
`to those skilled in the art and are within the scope of the
`present invention.
`A charging circuit for a CIC hearing aid 12 using a
`lithium-ion (Li-Ion) rechargeable battery, or any battery with
`similar charging requirements, is shownin FIG. 5. Effective
`charging of a Li-Ion battery requires a charger that operates
`in two modes. In a first mode of charging,
`the charger
`charges at a constant current determined by an input Iset.
`When the battery voltage, Vbattery,
`reaches a voltage
`threshold, Vthresh, the charger switches to a second mode.
`The voltage threshold Vthresh is a function of resisters R1
`and R2, and an input reference voltage, Vref:
`
`Vthresh=[(R1+R2)/R1]* Vref
`
`the charger charges at a constant
`In the second mode,
`voltage. When the charging current, Icharge, drops below a
`current threshold, Cthresh, the charging is terminated and
`the battery is ready for use. The current threshold, Cthresh,
`is a function of an input reference current, Iready:
`
`Cthresh=n*Iready
`
`The Ready signal is changed to indicate a fully charged
`battery.
`While this description is directed to a CIC hearing aid, the
`inductive charging system taught by the present invention
`also applies to other hearing aid types. The invention applies
`directly to an In-The-Canal (ITC) hearing aid. The ITC
`hearing aid partially enters the ear canal, and thus has a
`cylindrical part that is similar to the CIC hearing aid. The
`secondary coil may be built into the cylindrical part, and the
`cylindrical part is inserted into the reservoir throat, just as
`the CIC hearing aidis inserted into the charging reservoir for
`charging. Other hearing aids that have no cylindrical part
`may similarly be used with a charging reservoir that has a
`bowl shaped reservoir throat.
`Thus, the use of inductive charging with any hearing aid
`type eliminates the requirement for a precise alignment of
`the hearing aid with the charging reservoir, and as a result
`the casual placement of the hearing aid within the reservoir
`throat
`is sufficient for effective charging. The inductive
`charging circuit of the embodiment described herein pref-
`erably utilizes a class E power amplifier. Other known
`inductive charging circuits will be apparent to those skilled
`in the art, and are within the scope of the present invention.
`While the principal use of the secondarycoil, as described
`above,
`is to provide power to recharge the rechargeable
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`battery, the secondary coil may have other uses. U.S. Pat.
`No. 5,876,425, issued Mar. 2, 1999 for “Power Control Loop
`for Implantable Tissue Stimulator” describes the coopera-
`tion of a primary and a secondary coil to both provide
`control signals and back telemetry of data. The circuit
`described in the ’425 patent may similarly be used in a CIC
`or other hearing aids to provide a means to control the
`hearing aid remotely, and to back transmit diagnostic mes-
`sages. The *425 patent is incorporated herein by reference.
`While the invention herein disclosed has been described
`
`by meansof specific embodiments and applications thereof,
`numerous modifications and variations could be made
`
`thereto by those skilled in the art without departing from the
`scope of the invention set forth in the claims.
`Whatis claimedis:
`1. A rechargeable hearing aid system comprising:
`a hearing aid, wherein the hearing aid includes an energy
`storage device that is rechargeable, and wherein the
`hearing aid includes a secondary coil coupled to the
`energy storage device; and
`an inductive charger including a primary coil and a
`reservoir throat, wherein the primary coil completely
`encircles and is coaxial with the reservoir throat,
`wherein the energy storage device of the hearing aid is
`rechargeable by the inductive charger without removal
`of the energy storage device from the hearing aid; and
`wherein the hearing aid is adapted to be inserted into the
`reservoir throat for charging, and
`wherein whenthe hearing aid is inserted into the reservoir
`throat for charging the primary coil surrounds the
`secondary coil and is inductively coupled therewith,
`thereby allowing an efficient inductive transmission of
`power from the primary coil
`to the energy storage
`device through the secondarycoil.
`2. The rechargeable hearing aid system of claim 1 wherein
`the reservoir throat includes:
`
`a reservoir body;
`a reservoir circuit that includes said primary coil, and
`means for providing powerto the reservoir circuit and the
`primarycoil.
`3. The rechargeable hearing aid system of claim 2 wherein
`the means for providing power is a power cord connectable
`to household power.
`4. The rechargeable hearing aid system of claim 2 wherein
`the reservoir throat is substantially cylindrical, and wherein
`the primary coil is substantially coaxial with the reservoir
`throat, and
`wherein the hearing aid has at least some substantially
`cylindrical part, and wherein the cylindrical part is
`removably insertable into the reservoir throat, and
`wherein the secondary coil is substantially coaxial to
`the cylindrical part.
`5. The rechargeable hearing aid system of claim 4 wherein
`the hearing aid comprises a Completely-In-the-Canal (CIC)
`hearing aid or an In-The-Canal (ITC) hearing aid, and
`wherein the cylindrical part is removably insertable into the
`ear canal for hearing aid use.
`6. The rechargeable hearing aid system of claim 2 wherein
`the secondary coil also serves as a receiving and transmitting
`antenna for receiving control signals and transmitting back
`telemetry data, and wherein the hearing aid includes means
`to process and execute control signals received through the
`secondary coil and means for transmitting back telemetry
`data through the secondary coil; and wherein the primary
`coil also serves as a transmitting and receiving antenna for
`transmitting control signals and receiving back telemetry
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`US 6,658,124 B1
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`7
`data, and wherein the inductive charger includes means for
`generating control signals transmitted through the primary
`coil and means for processing back telemetry data received
`through the primary coil.
`7. The rechargeable hearing aid system of claim 1 wherein 5
`the energy storage device comprises a rechargeable battery.
`8. The rechargeable hearing aid system of claim 7 wherein
`the rechargeable battery is a rechargeable lithium ion bat-
`tery.
`9. The rechargeable hearing aid system of claim 7 wherein
`the rechargeable battery is a rechargeable zinc air battery.
`10. A rechargeable Completely-In-the-Canal (CIC) or
`In-The-Canal (ITC) hearing aid system comprising:
`a hearing aid having a substantially cylindrical part for
`insertion into an ear canal, and further having a
`rechargeable battery and a secondary coil coupled to
`the rechargeable battery;
`a charging reservoir having a reservoir throat and a
`primary coil, wherein the primary coil surrounds and is
`coaxial with the reservoir throat
`to permit efficient
`inductive coupling between the primary coil and the
`secondary coil of the CiC hearing aid when the CIC
`hearing aid is placed in the reservoir throat,
`wherein the hearing aid is inductively rechargeable
`through cooperation with the charging reservoir.
`11. The rechargeable hearing aid system of claim 10
`wherein
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`the charging reservoir further comprises:
`a reservoir body;
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`wherein the reservoir throat is an opening in the reservoir
`body, and wherein the reservoir throat accepts the
`cylindrical part of the hearing aid;
`a reservoir circuit;
`wherein the reservoir circuit provides powerto the pri-
`mary coil to create a magnetic field for inductive power
`transmission to the hearing aid, and wherein the pri-
`mary coil surrounds the secondary coil when the res-
`ervoir throat accepts the cylindrical part of the hearing
`aid; and
`means for providing power to the reservoir circuit; and
`wherein the hearing aid further comprises:
`a charging circuit, wherein the primary coil cooperates
`with the secondary coil as processed and controlled
`by the charging circuit to charge the rechargeable
`battery, and wherein the rechargeable battery pro-
`vides powerfor the hearing aid;
`a microphone;
`a signal processing (SP) circuit; and
`a speaker, wherein a signal from the microphone is
`processed by the SP circuit to provide a signal to the
`speaker.
`12. The rechargeable hearing aid system of claim 11
`wherein the rechargeable battery is a lithium ion battery.
`13. The rechargeable hearing aid system of claim 11
`wherein the rechargeable battery is a zinc air battery.
`*
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