US3721887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Battery protection circuit
Assignee: AT&T Inc
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Filing: 1971-11-24
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Granted: 1973-03-20
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Expires: 1991-11-24
Abstract
Abstract A protection circuit for an AC powered unregulated power supply having a rechargeable battery means comprising nickel-cadmium cells comprises a two-state circuit which is energized by the presence of AC power supplied to the unregulated power supply. The protection circuit is arranged to disconnect the load from the power supply in the event that AC power fails and the terminal voltage of the battery means falls below a predetermined minimum value. Furthermore, the load will not be picked up until AC power is restored.
Inventors
- 👤 C Nickerson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:24
CPC Classifications
H; H02; H02J; H02J7/00; H02J7/60; H02J7/663; H02J9/00; H02J9/04; H02J9/06; H02J9/061
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
337 words
A battery protection circuit for an unregulated source of power which comprises: power source first and second output terminals for connection to a load circuit, a primary source of power comprising: a rectifier circuit having input terminals connectable to a source of alternating current power and first and second rectifier output terminals, standby battery means comprising first and second battery terminals, and switching means responsive to ON control signals at a control terminal thereof for selectively connecting said first rectifier output terminal and said first battery terminal to said power source first terminal; and said protection circuit comprises bistable circuit means comprising an output terminal connected to said switching means control terminal, a control terminal, and a power terminal, said power terminal, said second battery terminal, and said rectifier second output terminal connected electrically; resistive means coupling said first output terminal of said rectifier to said control terminal and means including a portion of said last-named means coupling said first terminal of said battery to said control terminal, said control terminal also connected to the input terminal of said rectifier, and asymmetrical circuit means connected between said first terminal of said battery means and said first terminal of said rectifier and connected so that current flows from said battery means if the potential at said first terminal of said rectifier means falls below the potential of said battery means; and said bistable circuit means is proportioned so as to be in a first state and generate at the output terminal thereof an ON control signal in response to a potential in excess of the potential of said battery and to retain that state in response to a potential equal to or greater than a potential which represents a safe discharge potential for said battery and to be in the second state in response to a potential below said safe discharge potential at the control terminal thereof said bistable circuit means remaining in said second state until an AC signal is again applied at the rectifier input terminal.
Claim 2
Dependent Claim
337 words
A battery protection circuit for an unregulated source of power which comprises: power source first and second output terminals for connection to a load circuit, a primary source of power comprising: a rectifier circuit having input terminals connectable to a source of alternating current power and first and second rectifier output terminals, standby battery means comprising first and second battery terminals, and switching means responsive to ON control signals at a control terminal thereof for selectively connecting said first rectifier output terminal and said first battery terminal to said power source first terminal; and said protection circuit comprises bistable circuit means comprising an output terminal connected to said switching means control terminal, a control terminal, and a power terminal, said power terminal, said second battery terminal, and said rectifier second output terminal connected electrically; resistive means coupling said first output terminal of said rectifier to said control terminal and means including a portion of said last-named means coupling said first terminal of said battery to said control terminal, said control terminal also connected to the input terminal of said rectifier, and asymmetrical circuit means connected between said first terminal of said battery means and said first terminal of said rectifier and connected so that current flows from said battery means if the potential at said first terminal of said rectifier means falls below the potential of said battery means; and said bistable circuit means is proportioned so as to be in a first state and generate at the output terminal thereof an ON control signal in response to a potential in excess of the potential of said battery and to retain that state in response to a potential equal to or greater than a potential which represents a safe discharge potential for said battery and to be in the second state in response to a potential below said safe discharge potential at the control terminal thereof said bistable circuit means remaining in said second state until an AC signal is again applied at the rectifier input terminal.
Claim 3
Dependent Claim
251 words
In combination: a primary source of direct current of at least a first potential value connectable to an alternating current source and comprising first and second primary source output terminals; standby battery means comprising first and second battery terminals; a power source output terminal for connection to a load circuit; switching means responsive to ON control signals applied thereto for selectively connecting said first output terminal of said primary source and said first battery terminal to said power source output terminal; bistable circuit means comprising an output terminal connected to a control terminal of said switcHing means, a control terminal and a power terminal; said power terminal, said second battery terminal, and said second output terminal of said primary source connected electrically; resistive means coupling said first output terminal of said primary source to said control terminal; means including a portion of said resistive means coupling said first battery terminal to said control terminal; said control terminal also connected to the input terminal of said rectifier, and asymmetrical circuit means connected between said first battery terminal and said first terminal of said primary source and poled so that current flows from said battery means through said asymmetrical circuit means if the potential at said first terminal of said primary source falls below the potential of said battery means said bistable means keeping said switching means in an off condition upon a drop in battery potential and turning said switching means on thereafter only upon receiving a signal from the AC source.
Claim 4
Dependent Claim
251 words
In combination: a primary source of direct current of at least a first potential value connectable to an alternating current source and comprising first and second primary source output terminals; standby battery means comprising first and second battery terminals; a power source output terminal for connection to a load circuit; switching means responsive to ON control signals applied thereto for selectively connecting said first output terminal of said primary source and said first battery terminal to said power source output terminal; bistable circuit means comprising an output terminal connected to a control terminal of said switcHing means, a control terminal and a power terminal; said power terminal, said second battery terminal, and said second output terminal of said primary source connected electrically; resistive means coupling said first output terminal of said primary source to said control terminal; means including a portion of said resistive means coupling said first battery terminal to said control terminal; said control terminal also connected to the input terminal of said rectifier, and asymmetrical circuit means connected between said first battery terminal and said first terminal of said primary source and poled so that current flows from said battery means through said asymmetrical circuit means if the potential at said first terminal of said primary source falls below the potential of said battery means said bistable means keeping said switching means in an off condition upon a drop in battery potential and turning said switching means on thereafter only upon receiving a signal from the AC source.
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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |