US3857072A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Relay release timing control circuit
Assignee: AT&T Inc
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Filing: 1973-12-12
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Granted: 1974-12-24
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Expires: 1993-12-12
Abstract
Abstract The release characteristics of a relay are controlled to within a small critical range by a circuit which insures that the relay will remain operated for a period of time to bridge valid open conditions with respect to operate current and will release if the open condition exceeds another fixed period. The critical range is approximately three hundred to six hundred milliseconds and is accomplished by an RC timing circuit in combination with two zener diodes, one of which is inserted in series with the relay winding. The first zener diode acts as a reference voltage for charging the capacitor while the second zener diode acts to move the release point of the relay high enough on the RC decay curve for accurate control. The circuit is arranged such that the timing capacitor does not interfere with the operate time of the relay and is further arranged to take advantage of available components having standard tolerances.
Inventors
- 👤 D James
- 👤 J Mceowen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:36
CPC Classifications
H; H01; H01H; H01H47/00; H01H47/02; H01H47/18; H04; H04M; H04M3/00; H04M3/42; H04M3/428; H04M3/4283
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
227 words
A circuit for controlling the release time of a relay in a manner such that the relay releases only after operate current provided over a pair of leads has been removed for a fixed interval, said circuit comprising: means concurrently connected across said pair of leads and across said relay for establishing a first fixed reference voltage level derived from said current flowing between said pair of leads, said reference level voltage serving to maintain said relay operated; means concurrently connected across said reference voltage means and across said relay operable upon the removal of said line current for reducing the magnitude of said fixed reference in an RC decaying exponential manner, where R is the effective resistance of the circuit and C is the effective capacitance of the circuit; and means connected in series with the winding of said relay operable for passing current therethrough and through said relay winding only when said voltage is greater than a second fixed level, said second fixed level having a magnitude such that when said line current is removed said decaying value of said reference voltage does not reach said second fixed level until the expiration of said fixed interval, thereby maintaining said relay operated after said removal of said line current for a period of time determined by said reference voltage being reduced to said second fixed level.
Claim 2
Dependent Claim
227 words
A circuit for controlling the release time of a relay in a manner such that the relay releases only after operate current provided over a pair of leads has been removed for a fixed interval, said circuit comprising: means concurrently connected across said pair of leads and across said relay for establishing a first fixed reference voltage level derived from said current flowing between said pair of leads, said reference level voltage serving to maintain said relay operated; means concurrently connected across said reference voltage means and across said relay operable upon the removal of said line current for reducing the magnitude of said fixed reference in an RC decaying exponential manner, where R is the effective resistance of the circuit and C is the effective capacitance of the circuit; and means connected in series with the winding of said relay operable for passing current therethrough and through said relay winding only when said voltage is greater than a second fixed level, said second fixed level having a magnitude such that when said line current is removed said decaying value of said reference voltage does not reach said second fixed level until the expiration of said fixed interval, thereby maintaining said relay operated after said removal of said line current for a period of time determined by said reference voltage being reduced to said second fixed level.
Claim 3
Dependent Claim
227 words
A circuit for controlling the release time of a relay in a manner such that the relay releases only after operate current provided over a pair of leads has been removed for a fixed interval, said circuit comprising: means concurrently connected across said pair of leads and across said relay for establishing a first fixed reference voltage level derived from said current flowing between said pair of leads, said reference level voltage serving to maintain said relay operated; means concurrently connected across said reference voltage means and across said relay operable upon the removal of said line current for reducing the magnitude of said fixed reference in an RC decaying exponential manner, where R is the effective resistance of the circuit and C is the effective capacitance of the circuit; and means connected in series with the winding of said relay operable for passing current therethrough and through said relay winding only when said voltage is greater than a second fixed level, said second fixed level having a magnitude such that when said line current is removed said decaying value of said reference voltage does not reach said second fixed level until the expiration of said fixed interval, thereby maintaining said relay operated after said removal of said line current for a period of time determined by said reference voltage being reduced to said second fixed level.
Claim 4
Dependent Claim
227 words
A circuit for controlling the release time of a relay in a manner such that the relay releases only after operate current provided over a pair of leads has been removed for a fixed interval, said circuit comprising: means concurrently connected across said pair of leads and across said relay for establishing a first fixed reference voltage level derived from said current flowing between said pair of leads, said reference level voltage serving to maintain said relay operated; means concurrently connected across said reference voltage means and across said relay operable upon the removal of said line current for reducing the magnitude of said fixed reference in an RC decaying exponential manner, where R is the effective resistance of the circuit and C is the effective capacitance of the circuit; and means connected in series with the winding of said relay operable for passing current therethrough and through said relay winding only when said voltage is greater than a second fixed level, said second fixed level having a magnitude such that when said line current is removed said decaying value of said reference voltage does not reach said second fixed level until the expiration of said fixed interval, thereby maintaining said relay operated after said removal of said line current for a period of time determined by said reference voltage being reduced to said second fixed level.
Claim 5
Dependent Claim
39 words
The invention set forth in claim 1 wherein said series connected means is a breakdown device having a well-defined fixed voltage breakdown level whereby, above said level, current will flow therethrough and, below said level, current will not flow.
Claim 6
Dependent Claim
14 words
The invention set forth in claim 2 wherein said device is a zener diode.
Claim 7
Dependent Claim
52 words
The invention set forth in claim 2 wherein said device is a first transistor, the emitter thereof connected to the emitter of a second transistor, and said second transistor arranged such that when said first transistor stops passing current said second transistor begins to bypass current around said winding of said relay.
Claim 8
Dependent Claim
14 words
The invention set forth in claim 5 whereiN said device is a zener diode.
Claim 9
Dependent Claim
52 words
The invention set forth in claim 5 wherein said device is a first transistor, the emitter thereof connected to the emitter of a second transistor, and said second transistor arranged such that when said first transistor stops passing current said second transistor begins to bypass current around said winding of said relay.
References Cited (Backward Citations)
US3346779A
Cited
US3457560A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |