US3925624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coupling circuit for providing bilateral protection from hazardous voltages
Assignee: AT&T Inc
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Filing: 1974-12-27
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Granted: 1975-12-09
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Expires: 1994-12-27
Abstract
Abstract A protective coupling circuit inserted between a telephone line and station equipment provides bilateral hazardous voltage protection which is normally removed in response to ringing signals on the telephone line. The hazardous voltage protection is not removed however if station generated voltages exceeding a predetermined amplitude are present when the ringing signals are received and, if removed, is reinstated in response to continuous voltages exceeding a predetermined amplitude originating from the station equipment or the telephone line.
Inventors
- 👤 Harold Westly Earle
- 👤 Joseph Robbins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:22
CPC Classifications
H; H04; H04Q; H04Q3/00; H04M; H04M1/00; H04M1/738; H04M1/74; H04M1/745
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
75 words
A circuit for providing a two-way signaling path between a telephone line and station equipment including means for limiting the amplitude of signals on the signaling path to provide hazardous voltage protection, and means responsive to ringing signals from the telephone line for disabling the limiting means, characterized in that the circuit further includes, means responsive to the presence of station generated signals exceeding a predetermined amplitude for preventing the disabling of the limiting means.
Claim 2
Dependent Claim
75 words
A circuit for providing a two-way signaling path between a telephone line and station equipment including means for limiting the amplitude of signals on the signaling path to provide hazardous voltage protection, and means responsive to ringing signals from the telephone line for disabling the limiting means, characterized in that the circuit further includes, means responsive to the presence of station generated signals exceeding a predetermined amplitude for preventing the disabling of the limiting means.
Claim 3
Dependent Claim
39 words
A circuit in accordance with claim 1 wherein the preventing means further includes means responsive to the occurrence of station generated signals exceeding the predetermined amplitude subsequent to the disabling of the limiting means for reenabling the limiting means.
Claim 4
Dependent Claim
57 words
A circuit in accordance with claim 1 wherein there is further included means operative subsequent to the disabling of the limiting means and responsive to the continuous presence of signals on the telephone line at least equal in amplitude to the amplitude of the ringing signals for reenabling the limiting means in a predetermined interval of time.
Claim 5
Dependent Claim
61 words
A circuit in accordance with claim 1 wherein there is further included means operative upon the application to the station equipment of a voltage signal greater in amplitude than the amplitude of the ringing signals and responsive to a predetermined amount of current drawn by the station equipment in response to the voltage signal applied thereto for reenabling the limiting means.
Claim 6
Dependent Claim
82 words
A circuit for normally inserting a voltage limiting device between a telephone line and a remote station to provide hazardous voltage protection including means for removing the voltage limiting device in response to ringing signals received from the telephone line, chAracterized in that the circuit further includes, means responsive to continuous signals on the telephone line at least equal in amplitude to the amplitude of the ringing signals and continuous for a predetermined interval of time for reinserting the voltage limiting device.
Claim 7
Dependent Claim
82 words
A circuit for normally inserting a voltage limiting device between a telephone line and a remote station to provide hazardous voltage protection including means for removing the voltage limiting device in response to ringing signals received from the telephone line, chAracterized in that the circuit further includes, means responsive to continuous signals on the telephone line at least equal in amplitude to the amplitude of the ringing signals and continuous for a predetermined interval of time for reinserting the voltage limiting device.
Claim 8
Dependent Claim
32 words
A circuit in accordance with claim 5 wherein there is further included means responsive to remote station generated signals exceeding a predetermined amplitude for preventing the removal of the voltage limiting device.
Claim 9
Dependent Claim
40 words
A circuit in accordance with claim 6 wherein there is further included means responsive to the occurrence of remote station generated signals exceeding the predetermined amplitude subsequent to the removal of the voltage limiting device for disabling the removing means.
Claim 10
Dependent Claim
92 words
A circuit for connecting station equipment to a telephone line including means for limiting the amplitude of signals applied to the station equipment and means responsive to ringing signals on the telephone line for removing the limiting means, characterized in that the circuit further includes, means responsive to the application of a voltage signal to the station equipment greater in amplitude than the amplitude of the ringing signals for detecting a predetermined amount of current drawn by the station equipment, and means responsive to the detecting means for reinstating the limiting means.
Claim 11
Dependent Claim
92 words
A circuit for connecting station equipment to a telephone line including means for limiting the amplitude of signals applied to the station equipment and means responsive to ringing signals on the telephone line for removing the limiting means, characterized in that the circuit further includes, means responsive to the application of a voltage signal to the station equipment greater in amplitude than the amplitude of the ringing signals for detecting a predetermined amount of current drawn by the station equipment, and means responsive to the detecting means for reinstating the limiting means.
Claim 12
Dependent Claim
41 words
A circuit in accordance with claim 8 further including means responsive to continuous signals on the telephone line at least equal in amplitude to the amplitude of the ringing signals for enabling the reinstating means in a predetermined interval of time.
Claim 13
Dependent Claim
30 words
A circuit in accordance with claim 8 wherein there is further included means responsive to station generated signals exceeding a predetermined amplitude for preventing the removal of the limiting means.
Claim 14
Dependent Claim
75 words
A circuit for connecting a telephone line to a remote station including means responsive to the remote station going off-hook for signaling the occurrence of the off-hook condition via the telephone line to a telephone central office, characterized in that, the circuit further includes, means for detecting the absence of ringing signals on the telephone line, and means responsive to the detecting means for rendering the signaling means unresponsive to the remote station going off-hook.
Claim 15
Dependent Claim
75 words
A circuit for connecting a telephone line to a remote station including means responsive to the remote station going off-hook for signaling the occurrence of the off-hook condition via the telephone line to a telephone central office, characterized in that, the circuit further includes, means for detecting the absence of ringing signals on the telephone line, and means responsive to the detecting means for rendering the signaling means unresponsive to the remote station going off-hook.
Claim 16
Dependent Claim
64 words
A circuit in accordance with claim 11 wherein the detecting means includes means for charging a capacitor in response to the presence of ringing signals on the telephone line and means for discharging the capacitor in response to the absence of ringing signals on the telephone line, the rendering means being operative in response to the discharge of the capacitor to a predetermined level.
Claim 17
Independent Claim
65 words
A method for protecting a telephone line from voltages generated by station equipment connected to the telephone line, comprising the steps of, normally inserting a voltage limiting device between the telephone line and the station equipment, removing the voltage limiting device in response to ringing signals on the telephone line, reinserting the voltage limiting device in response to station generated voltages exceeding a predetermined amplitude.
Claim 18
Independent Claim
65 words
A method for protecting a telephone line from voltages generated by station equipment connected to the telephone line, comprising the steps of, normally inserting a voltage limiting device between the telephone line and the station equipment, removing the voltage limiting device in response to ringing signals on the telephone line, reinserting the voltage limiting device in response to station generated voltages exceeding a predetermined amplitude.
Claim 19
Independent Claim
71 words
A method for protecting station equipment from voltages originating from a telephone line connected to the station equipment, comprising the steps of, normally inserting a voltage limiting device between the telephone line and the station equipment, removing the voltage limiting device in response to ringing signals on the telephone line, reinserting the voltage limiting device in response to the continuous presence of voltages on the telephone line exceeding a predetermined amplitude.
Claim 20
Independent Claim
71 words
A method for protecting station equipment from voltages originating from a telephone line connected to the station equipment, comprising the steps of, normally inserting a voltage limiting device between the telephone line and the station equipment, removing the voltage limiting device in response to ringing signals on the telephone line, reinserting the voltage limiting device in response to the continuous presence of voltages on the telephone line exceeding a predetermined amplitude.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |