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公开(公告)号:US1746729A
公开(公告)日:1930-02-11
申请号:US23800927
申请日:1927-12-06
Applicant: BELL TELEPHONE LABOR INC
Inventor: IVES HERBERT E
IPC: H04N1/036
CPC classification number: H04N1/036
公开(公告)号:US1746729A
公开(公告)日:1930-02-11
申请号:US23800927
申请日:1927-12-06
Applicant: BELL TELEPHONE LABOR INC
Inventor: IVES HERBERT E
IPC: H04N1/036
CPC classification number: H04N1/036