Surgery – Respiratory method or device – Means for transmitting – or facilitating – voice communication...
Reexamination Certificate
1999-10-04
2001-10-23
Lewis, Aaron J. (Department: 3761)
Surgery
Respiratory method or device
Means for transmitting, or facilitating, voice communication...
C128S205250
Reexamination Certificate
active
06305370
ABSTRACT:
BACKGROUND OF THE INVENTION
A voice transmitter for a breathing protective mask is disclosed in European patent publication 0,413,861. The voice transmitter disclosed in this publication includes two housing components between which a voice membrane is clamped. The pretensioning of the voice membrane is necessary for a good voice transmission and is achieved with interengaging cylindrical and inclined surfaces. The two housing components are held together by a snap mechanism. The known voice transmitter can be assembled in a simple manner but it is no longer possible to subsequently change the voice membrane tension. This causes a large range of variation of the voice transmitting characteristics.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a voice transmitter of the kind referred to above which is improved in that the pretensioning of the voice membrane can be adjusted in a simple manner.
The voice transmitter of the invention is for a breathing protective mask and includes: a housing having a base wall and an annular wall extending upwardly from the base wall; the annular wall defining a longitudinal axis and the base wall having an annular projection formed thereon and projecting upwardly from the base wall so as to be concentric with the annular wall; a clamping ring having a lower end facing toward the base wall and having an annular support surface formed on the lower end so as to be interdigitated with respect to the annular projection when the clamping ring is in the housing; the annular wall of the housing and the clamping ring conjointly defining a threaded interface permitting the clamping ring to be moved along the longitudinal axis toward and away from the base wall when the clamping ring is rotated in the threaded interface about the longitudinal axis; and, a voice transmitting membrane subdivided into an annular outer portion fixedly clamped in the threaded interface and an inner portion spanned over the support surface transversely to the longitudinal axis and in pressing contact engagement with the annular projection so as to permit adjusting the membrane in tension as the clamping ring is moved along the longitudinal axis.
The advantage of the invention is essentially that a pretensioning change can be achieved via the depth to which the clamping ring is threadably engaged in the membrane housing. This is achieved by tensioning the voice transmitting membrane on a clamping ring having an outer thread and screwing the clamping ring with the membrane into the membrane housing. The membrane housing is provided on the housing base with an annularly-shaped projection in order to provide a defined support surface for the voice transmitting membrane. The voice transmitting membrane is clamped via this annularly-shaped projection. The diameter of the projection and the clear distance of the support surface of the voice transmitting membrane on the clamping ring are so dimensioned that the voice transmitting membrane is not sheared off in the boundary region between the support surface and the projection.
With the voice transmitter according to the invention, it is also possible to first coarsely adjust the pretension of the voice membrane and then, after a tempering operation wherein the voice membrane is artificially aged, to adjust the tension to the final value. Plastic foils (for example, made of polypropylene) are suitable as voice membranes.
REFERENCES:
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patent: 2326650 (1943-08-01), Husted
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patent: 3109425 (1963-11-01), Gongoll et al.
patent: 3124130 (1964-03-01), Klinger
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patent: 3602219 (1971-08-01), Warncke
patent: 4402316 (1983-09-01), Gadberry
patent: 4756308 (1988-07-01), Ryback
patent: 4926398 (1990-05-01), Fincher
patent: 4961420 (1990-10-01), Cappa et al.
Gdulla Manfred
Rosert Michael
Drager Sicherheitstechnik GmbH
Lewis Aaron J.
Ottesen Walter
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