Electrical audio signal processing systems and devices – Hearing aids – electrical – Specified casing or housing
Reexamination Certificate
1999-06-07
2001-11-27
Tran, Sinh (Department: 2743)
Electrical audio signal processing systems and devices
Hearing aids, electrical
Specified casing or housing
C381S312000, C381S324000, C381S330000, C181S129000
Reexamination Certificate
active
06324291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a hearing aid of the type to be worn at the head, having a housing composed of two mating shells that accepts components of the device such as at least one signal receiver, an amplifier and transmission stage, an earphone and a battery.
2. Description of the Prior Art
German OS 11 39 549 discloses a hearing aid to be worn behind the ear that has a housing composed of two cover shells and a plate-shaped middle part in which a microphone, an amplifier, an earphone, a battery, etc. are arranged. In order to be able to utilize the full amplification of the device and in order to shield the microphone from the sound which emanates from the earphone and is conducted via the air ad via the hearing aid structure, the housing chamber which contains the earphone is sealed from the housing chamber which contains the microphone. To that end, sealing ribs projecting from the cover shells lie directly on the surfaces of the plate-shaped middle part and are intended to keep the acoustic waves of the earphone away from the microphone. Instead of ribs, sound-damping material can also be used, this being placed between the plate-shaped middle part and the cover shells. A combination of sealing ribs and sound-damping material is also possible. All of these measures are intended to serve for the suppression of feedback between the acoustic transducers.
Hearing aids with housing shells as in the case of hearing aids to be worn at the head and, in particular, to be worn behind the ear or to be worn at hearing aid glasses usually have thin plastic housing shells containing at least one microphone and/or an induction coil, an earphone, a battery as well as an amplifier and transmission part. In such hearing aids it has been found that oscillations of the housing parts and/or of the hearing aid components can occur due to self-resonance and/or outside excitation. In particular, a printed circuit board component of the amplifier and transmission stage can be effected by these oscillations. This leads to feedback problems which are different from the aforementioned feedback addressed in German AS 11 39 549. These different feedback problems associated with the amplifiers and transmission stage can cause malfunctions in the transmission behavior of the hearing aid.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hearing aid of the type initially described, wherein feedback problems which can produce a disturbing influence on the amplifier and transmission stage are avoided.
In a hearing aid of the type initially described, this object is achieved by introducing formed parts of elastic material into the housing shells, these formed parts pressing against the amplifier and transmission part at both sides when the housing, equipped with the device components, is closed and filling the interspace between the amplifier and transmission part and the insides of the housing shells, and arresting the amplifier and transmission part in the housing. Inventively, the oscillations at the housing parts and at the amplifier and transmission stage that cause the aforementioned transmission behavior disturbances in the hearing aid are avoided by the formed parts and their arrangement in the housing. Differing from built-in hearing aid parts that are cast integrally to form modules that, given a malfunction or given a change of the transmission characteristic, must be completely replaced, the formed parts in the invention can be removed from the amplifier and transmission stage, or from the further built-in hearing aid components after opening the housing, and changes at the build-in hearing aid parts can be carried out.
In an embodiment of the inventive hearing aid, the amplifier and transmission part is composed of a folded, multi-layer printed circuit board unit, and formed parts are also arranged between the printed circuit board layers.
In another embodiment of the invention those sides of the formed parts in contact on the amplifier and transmission stage respectively form a negative impression of the surface of the amplifier and transmission stage facing toward them. According to this embodiment, an especially effective support is achieved between the printed circuit board layers and the electrical and electronic component parts of the amplifier and transmission stage arranged thereon, as well as support by the inside walls of the housing shells.
In order to avoid vibration at the housing shell edges along the seam of the housing, a seal, for example a silicone or rubber seal, is provided in the seam between the housing shells.
The formed parts are manufactured of an elastically yielding material such as, for example, an elastic impression compound, of silicone, foamed plastic or soft rubber. The formed parts can be placed into the housing shells, or foamed, injected or glued into the housing shells.
REFERENCES:
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patent: 4617429 (1986-10-01), Bellafiore
patent: 4729451 (1988-03-01), Brander et al.
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patent: 4962537 (1990-10-01), Basel et al.
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Dabney P.
Schiff & Hardin & Waite
Siemens Audiologische Technik GmbH
Tran Sinh
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