专利快速检索-快速检索全球专利，免费商用专利数据库-IPRDB

1. 发明专利

JPS5234601A CALLING CIRCUIT 失效
公开(公告)号：JPS5234601A
公开(公告)日：1977-03-16
申请号：JP10999575
申请日：1975-09-12
申请人： IWATSU ELECTRIC CO LTD
发明人： KITA GUNZOU
IPC分类号： H04Q3/58 , H04M1/72
摘要： PURPOSE:Even if office receiving and extension calling occurs during the same period of time, the extension calling of the telephone other than office receiving is never interrupted.

2. 发明专利

JPS53114304A KEY TELEPHONE SET 失效
公开(公告)号：JPS53114304A
公开(公告)日：1978-10-05
申请号：JP2807477
申请日：1977-03-16
申请人： IWATSU ELECTRIC CO LTD
发明人： KITA GUNZOU , OOISHI KOUJI
IPC分类号： H04Q3/58 , H04M9/00
摘要： PURPOSE:To improve efficiency from the viewpoint of construction and economical point with the number of lines connecting a trunk circuit with a key telephone set reduced by providing an independent bettery.

3. 发明专利

JPS577659A EXTENSION SECRET CALL SYSTEM OF KEY TELEPHONE SET 失效
公开(公告)号：JPS577659A
公开(公告)日：1982-01-14
申请号：JP8085280
申请日：1980-06-17
申请人： IWATSU ELECTRIC CO LTD
发明人： KITA GUNZOU
IPC分类号： H04M1/70 , H04M3/16 , H04M9/00 , H04Q3/58
摘要： PURPOSE:To eliminate influence of a loop resistance and to detect an answer from a called subscriber securely by providing a control line other than a calling line and by further providing an outflow and an inflow source for currents. CONSTITUTION:The internal calling operation of a key telephone set 1 turns on an SCR1. Consequently, a transistor (TR) Q11 turns on while a TRQ10 turns off, and a contact 1p is still closed, thereby connecting a calling network to extension channels P1 and P2. If a key telephone set (not shown in the figure) is provided at a called extension side, it is connected to the extension channels P1 and P2 as well as the calling operation of the key telephone set 1. Currents flowing through the paths from the key telephone sets 1 and 2 join together on a line P3 to reach -V via TRQn3 and Rn7. The current value of the confluence is nearly equal to that of a constant current In determined by ZDn1 and the Rn7 in a key telephone set (n). Therefore, the 3rd key telephone set, even if intend to interrupt the extension calling, fails.

4. 发明专利

JPS5247305A EXTENSION CALLING SYSTEMOF BUTTON TELEPHONE SYSTEM 失效
公开(公告)号：JPS5247305A
公开(公告)日：1977-04-15
申请号：JP12306275
申请日：1975-10-13
申请人： IWATSU ELECTRIC CO LTD
发明人： KITA GUNZOU , SEKIGUCHI KOUICHI
IPC分类号： H04Q3/58 , H04M1/12 , H04M9/08 , H04M11/02 , H04Q3/00
摘要： PURPOSE:The DC loop of office line is held by non-linear circuit under office line survice. Thus, internal communication can be quickly performed without retaining office line.

你已经成功收藏专利！

检索式保存成功!

IPRDB