Hearing Aid Apparatus Powered by Capacitor

The present invention relates generally to a self-contained hearing aid and, more particularly, to an improved power source and recharging arrangement for a self-contained hearing aid.

For those who have a hearing impairment, conventional battery-powered hearing aids have been a blessing, because they permit the person to hear accurately while moving freely about. This is particularly true of the miniature hearing aids commonly referred to as in-the-ear models. Nevertheless, although these conventional hearing aids have been generally adequate for their intended purposes, they have not been satisfactory in all respects.

In particular, because they are usually operated continuously during the waking hours of the user, the batteries in them must be either recharged or replaced on a frequent basis. In the case of replaceable batteries, this involves the expense and hassle of purchasing and maintaining a supply of replacement batteries, the need to remember to make the necessary replacement on a regular basis, and the ecological implications associated with disposal of the used batteries. With respect to rechargeable batteries, there is the occasional expense of replacing the rechargeable battery, as well as the more frequent need to remember to recharge the battery currently in the unit.

One known hearing aid with a rechargeable battery also has an internal coil and a rectifier coupling the coil to the battery, and a physically separate recharging unit is provided to generate an AC magnetic field that causes the coil in the hearing aid to produce an AC signal which the rectifier converts to a DC signal to recharge the battery. The user usually places the hearing aid on the recharging unit when the user goes to bed so that the hearing aid is recharged while the user sleeps, and the user replaces the hearing aid in his or her ear upon arising.

One object of the present invention is to provide an improved hearing aid which does not use any form of replaceable or rechargeable battery, and in particular which has a power source that can be recharged and never needs replacing.

A further object of the invention is to provide such a hearing aid in which the power source can be charged more rapidly than in known hearing aids, and preferably can be recharged almost instantaneously.

Yet a further object is to provide such a hearing aid which can be recharged easily and conveniently from conventional batteries of the type commonly used in flashlights or radios, in a manner providing a lower effective cost than the conventional approach of using the relatively expensive replaceable batteries designed and sold specifically for hearing aids.

Still another object of the invention is to provide a recharging unit which holds the battery and is separate from the hearing aid, and which facilitates recharging of the power source in the hearing aid from the battery.

The objects and purposes of the invention, including those set forth above, are met according to one form of the present invention by providing a hearing aid which includes: a sound pickup arrangement responsive to sounds external to the hearing aid for generating an electrical signal representative of the sounds; a circuit arrangement for amplifying the electrical signal; a sound emitting arrangement responsive to the amplified electrical signal from the circuit arrangement for emitting audible sound to the exterior of the hearing aid which corresponds to the electrical signal; and a capacitor coupled to the circuit arrangement and serving as a primary source of power for the circuit arrangement during normal operation of the hearing aid.

A different form of the present invention involves the provision of: a hearing aid which includes a sound pickup arrangement responsive to sounds external to the hearing aid for generating an electrical signal representative of the sounds, a circuit arrangement for amplifying the electrical signal, a sound emitting arrangement responsive to the electrical signal amplified by the circuit arrangement for emitting externally of the hearing aid audible sound which corresponds to the electrical signal, and a capacitor coupled to the circuit arrangement and serving as a primary source of power for the circuit arrangement during normal operation of the hearing aid; and a recharging arrangement for facilitating periodic recharging of the capacitor, the recharging arrangement including a recharging unit physically separate from the hearing aid.

Preferred embodiments of the present invention are described in detail hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of a hearing aid embodying the present invention;

FIG. 2 is a diagrammatic exterior view of the hearing aid of FIG. 1;

FIG. 3 is a view similar to FIG. 2 of an alternative embodiment of the hearing aid of FIG. 1;

FIG. 4 is a sectional side view of a recharging unit for the hearing aids of FIGS. 1-3;

FIG. 5 is a sectional view taken along the line 5--5 in FIG. 4;

FIG. 6 is a sectional side view of an alternative embodiment of the recharging unit of FIG. 4; and

FIG. 7 is a block diagram of a further embodiment of a hearing aid and a recharging unit.

FIG. 1 is a block diagram of a hearing aid 10, which in the preferred embodiment is a self-contained unit of the in-the-ear type. The hearing aid 10 includes a plastic housing 12, a miniature microphone 13 which is supported on the housing 12 and generates an output signal representative of sounds external to the housing 12, a miniature speaker supported on the housing, and an amplifier circuit 16 which is disposed within the housing, which amplifies the electrical output signal from the microphone 13, and which uses the amplified signal to drive the miniature speaker 17. The circuit 16, in addition to amplifying the electrical signal from the microphone 13, may also perform functions such as filtering of the signal in order to eliminate signal components outside the normal audible frequency range, or attenuation of signal components in one audible frequency range relative to signal components in another audible frequency range. A manually operable volume control 18 is also provided on the housing 12, and can be used to vary the gain of the amplifier circuit 16.

Also disposed within the housing 12 is a power source 21, which includes two capacitors 22 and 23 connected in parallel with each other and having respective ends connected to respective input terminals of the amplifier circuit 16. The hearing aid 10 of FIG. 1 contains no batteries. During normal operation, the amplifier circuit 16 has as its sole and primary power source the capacitors 22 and 23, and in particular operates from an electrical charge stored on the capacitors 22 and 23. Although FIG. 2 shows two capacitors, it will be recognized that there could be only one capacitor or that there could be two or more capacitors, the number of capacitors and their capacitance determining how long the amplifier circuit 16 can be operated from the power source 21 before the power source 21 becomes discharged.

Also supported on the housing 12, preferably within a recess 28, are a pair of charging terminals 26 and 27, which are each connected to a respective end of capacitor 23. When operation of the amplifier circuit 16 has effectively discharged the capacitors 22 and 23, the capacitors 22 and 23 can be recharged by bringing respective terminals of a conventional battery into contact with the respective charging terminals 26 and 27. A feature of the present invention is that the capacitors 22 and 23 become recharged by the battery almost instantaneously, and thus the hearing aid 10 is almost immediately ready for further use by the user, without any need for the user to wait several hours while a rechargeable internal battery is recharged.

FIG. 2 is a diagrammatic view of the exterior of the hearing aid 10, showing that the housing 12 has a back plate 31 with a rectangular opening 32 that can be closed by a small door or hatch 33 hingedly coupled at 34 to the back plate 31. The opening 32 provides access to the recess 28 and the charging terminals 26 and 27 therein when the hatch 33 is open. Conventional hearing aids sometimes have an opening and door similar to those shown at 32 and 33, but for the purpose of removing and replacing batteries. Since, as mentioned above, the hearing aid 10 does not have internal batteries, the opening 32 in FIGS. 1 and 2 is provided for purposes of obtaining access to the charging terminals 26 and 27 in order to effect recharging of the capacitors 22 and 23.

FIG. 3 is a view which is similar to FIG. 2 and which shows a hearing aid 41 that is a variation of the hearing aid 10 of FIGS. 1 and 2. The hearing aid 41 is identical to the hearing aid 10 except that, instead of the opening and door shown at 32 and 33 in FIG. 2, the back plate 42 of the hearing aid 41 has two spaced holes 43 and 44 through it. The terminals 26 and 27 are not visible in FIG. 3, but are each disposed immediately adjacent the inner end of a respective one of the holes 43 and 44.

FIGS. 4 and 5 are sectional views showing a recharging unit that can be used to recharge the capacitors in the hearing aid 10 of FIGS. 1 and 2, or the capacitors in the hearing aid 41 of FIG. 3. The recharging unit 51 includes a plastic case 52 of approximately rectangular shape, the case having therein two conventional cylindrical 1.5 volt batteries 53 and 54, such as batteries of the type commonly identified as size AA, size AAA, size C or size D. The case 52 has four sidewalls 56-59, and a lid 61 that serves as a bottom wall is pivotally coupled to the sidewall 57 at the lower end thereof by a hinge arrangement 62. A detent arrangement 63 and 64 provided at the outer end of lid 61 and the lower end of sidewall 59 is capable of releasably holding the lid 61 in a closed position. The lid 61 has secured to its inner side a metal strip 67, one end of which can engage a positive terminal 68 of battery 53 when the lid 61 is in its closed position. The other end of the strip 67 has a projection 69 engageable with the negative end of battery 54.

The case 52 has a top wall 72 integral with and extending between the upper ends of sidewalls 56-59. The top wall 72 has an upward projection 73 in the center thereof, and has two circular holes 76 and 77 extending vertically therethrough adjacent the projection 73 on opposite sides thereof. Another metal strip 81 is fixedly secured to the inner side of top wall 72, has a downward projection 82 engageable with the negative end of battery 53, and has an upperwardly extending wire-like charging probe 83, the probe 83 extending upwardly through the hole 76 to a location which is a small distance above the upper end of projection 73. A further metal strip 86 is fixedly secured to the inner side of wall 72 so as to be engaged by the positive terminal 87 of battery 54, and has a wire-like charging probe 88 that extends upwardly through the hole 77 to a location spaced a small distance above the upper end of projection 73.

With the batteries 53 and 54 disposed within case 52 and the lid 61 in a closed position, the probes 88 and 83 can be inserted through the opening 32 (FIGS. 1 and 2) and into the recess in the hearing aid 10 so as to each electrically contact a respective one of the charging terminals 26 and 27, so that capacitors 22 and 23 are almost instantaneously charged by the batteries 53 and 54. With respect to the hearing aid 41 of FIG. 3, the probes 88 and 83 of the recharging unit 51 have the same spacing as and would be inserted through the holes 43 and 44, in order to contact the charging terminals of the hearing aid 41 for purposes of charging the capacitors in that hearing aid.

FIG. 6 is a sectional side view of a recharging unit 101 which is an alternative embodiment of the unit 51 of FIGS. 4 and 5. The unit 101 includes a plastic case 102 for a conventional 9 VDC battery 103. The case 102 has four sidewalls, two of which are visible at 106 and 107 in FIG. 6. The case 102 does not have a bottom wall, but does have a top wall 111 integral with and extending between the upper ends of the four sidewalls. The top wall 111 has an upward projection 112 in its center, and has circular holes 113 and 114 extending vertically through it on opposite sides of the projection 112. Two metal strips 116 and 117 are fixedly mounted at spaced locations on the inner side of the top wall 111, and each have a respective charging probe 118 or 119 extending upwardly through a respective hole 113 or 114 to a location spaced slightly above the upper end of projection 112. Cooperating clasp arrangements 121 and 122 of a conventional type each include a first part which is a positive or negative terminal of the battery 103, and a complementary second part which is fixedly mounted on a respective strip 116 or 117. The recharging unit 101 is used to recharge the hearing aids 10 and 41 of FIGS. 1-3 in substantially the same manner as the recharging unit 51 (FIGS. 4-5).

FIG. 7 shows a hearing aid 141 which is a further alternative embodiment of the hearing aid 10 of FIG. 1, and which includes a plastic housing 142. Components of the hearing aid 141 which are identical to corresponding components of the hearing aid 10 are identified with the same reference numerals, including a miniature microphone 13, an amplifier circuit 16, a miniature speaker 17, a manual volume control 18, and a power source 21 that includes capacitors 22 and 23. The basic difference between the hearing aid 141 of FIG. 7 and the hearing aid 10 of FIG. 1 is that the externally accessible charging terminals 26 and 27 of the hearing aid 10 are not present in the hearing aid 141. Instead, a coil 146 is coupled to input terminals of a rectifier circuit 147, which in turn has outputs coupled to respective ends of the capacitor 23.

A recharging unit 151, which is not part of the hearing aid 141 and which is not present during normal operation of the hearing aid 141, includes an AC source 152 which drives a coil 153 in order to produce an AC electromagnetic field in the region of recharging unit 151. When the hearing aid 141 is physically close to the recharging unit 151, the AC electromagnetic field induces a flow of AC current in the coil 146, which is rectified by the rectifier circuit 147 in a conventional manner in order to produce a DC signal that charges the capacitors 22 and 23. During normal operational use, the hearing aid 141 is in the ear of the user and is nowhere near the recharging unit 151, as a result of which the coil 146 and rectifier circuit 147 are effectively inactive. Thus power source 21 serves as the sole or primary circuit power for amplifier circuit 16 during normal operation, the amplifier circuit 16 operating totally from the charge stored on capacitors 22 and 23. When the capacitors 22 and 23 need recharging, the hearing aid 141 is removed from the ear of the user and is placed in close proximity to the recharging unit 151, so that the electromagnetic field from coil 153 causes the coil 146 and rectifier circuit 147 to charge capacitors 22 and 23. The recharging unit 151 preferably is a unit which sits on a bedside table of the user and has a line cord connected to a standard 120 VAC wall outlet to provide power to the AC source 152. The user places the hearing aid 141 on the recharging unit 151 when the user retires at night, so that the capacitors 22 and 23 are charged during the night, and then the user replaces the hearing aid 141 in his or her ear the following morning. In the embodiment of FIG. 7, the recharging unit 151 does not charge the capacitors 22 and 23 instantaneously, but the period of time required to charge the capacitors 22 and 23 is substantially less than the period of time required with a conventional hearing aid to recharge one or more rechargeable internal batteries.

Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of these embodiments, including the rearrangement of parts, lie within the scope of the present invention.