公开(公告)号：US3474197A

公开(公告)日：1969-10-21

申请号：US3474197D

申请日：1965-10-13

Applicant: TESLA NP

Inventor： KOUKAL VLASTIMIL ,  KRAKORA OTOKAR

IPC: C04B35/468 ,  H01G7/02 ,  H04R19/00 ,  H04R19/04

CPC classification number: H04R19/005 ,  C04B35/4684 ,  H01G7/026 ,  H04R19/04

公开(公告)号：US3624312A

公开(公告)日：1971-11-30

申请号：US3624312D

申请日：1969-08-04

Applicant: TESLA NP

Inventor： KOUKAL VLASTIMIL ,  KRAKORA OTOKAR

IPC: H04R19/00 ,  H04R19/04 ,  H04R23/00

CPC classification number: H04R19/005

Abstract: The electret member of an electret microphone is a substantially cylindrical body of barium titanate composition having a first flat end face opposite the microphone diaphragm and a second end face covered with a fixedly attached electrode which extends into a blind axial bore centered in the second end face. The electret member is attached to a supporting plate by a bolt soldered to the electrode in the bore and fastened to the support plate by a nut. The bolt provides the conductive lead for the electret.