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公开(公告)号：US1781795A
公开(公告)日：1930-11-18
申请号：US19243027
申请日：1927-05-18
Applicant: RCA CORP
Inventor： ROELOF VERMEULEN , URK AREND THOMAS VAN , HENDRICUS HERMANS THEODORUS
IPC: H04R11/00
CPC classification number: H04R11/00
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