
US Patent No: 4,809,317
Number of patents in Portfolio can not be more than 2000
Telephone line exclusion device
Stats
-
Feb 28, 1989
Issued date -
Apr 22, 1987
filing date -
07/041,236
serial no -
Expired
status
Importance
Abstract
A device is disclosed for use on a telephone line where there is two or more telephones or other instruments connected in parallel to the same telephone line whereby when one of the instruments goes off-hook (in a telephone, raises the receiver) the telephone line exclusion device automatically locks out all other instruments connected in parallel with the instrument that went off-hook. Such a result is achieved by a pair of interconnected two-coil polarized normally closed reed relays which interface the incoming telephone line and the two instruments. The two lines which normally connect to each instrument on the telephone line utilizes the normally closed contacts of one relay to energize the coils of the other relay and thereby inhibit the other instrument on the telephone line by opening the normally closed contact of the second relay which is in line with the other instrument. Upon the first instrument going on-hook (in a telephone, returning the receiver to the cradle), the telephone line exclusion device returns to its quiescent state where either instrument upon the line may be utilized.
First Claim
Related Publications
International Classification(s)
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Cited Art
| Patent Info | (Count) | # Cites | Year |
|---|---|---|---|
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| 4,660,218 Apparatus for switching telephone line a response device, a data terminal or a telephone | 107 | 1985 | |
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| 4,591,662 Telephone set-computer terminal assembly with a single decimal keyboard and a switchable local power supply | 18 | 1984 | |
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| 4,604,499 Computer telephone access security processor | 27 | 1984 | |
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| 4,367,374 Modem telephone interface circuit | 45 | 1981 | |
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| 4,596,021 Modem for switching between voice and data communications on a single telephone call | 89 | 1984 | |
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| 4,640,988 Telephone interrupter | 16 | 1984 | |
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| 4,394,540 Remote meter reader and method for reading meters over non-dedicated telephone lines | 53 | 1981 | |
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| 4,444,999 Automatic electronic disconnector for subscriber terminal equipment | 38 | 1982 | |
| 4,469,917 Time synchronized data transmission system | 24 | 1982 | |