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Expired
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Carl Gustaf Ferdinand Holmgren
August Emanuel Brahm
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Individual
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Publication of GB190618944ApublicationCriticalpatent/GB190618944A/en
18,944. Holmgren, C. G. F., and Brahm, A. E. March 9, [date applied for under Patents Act, 1901]. Telephones.-In a hand set, the microphone 6 is provided with a substantial metal cover 1. The sound waves reach the microphone diaphragm 3 through apertures 4 protected by an overhanging flange 5. The apertures are preferably formed only on the side facing the receiver 7. Saliva being prevented from entering the interior of the microphone, i t c a n b e kept in hygienic condition by external cleaning.
GB190618944D1906-03-091906-08-24Improvements in Compound Telephones
ExpiredGB190618944A
(en)