US4636704A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Battery charging circuit
Assignee: Ryobi Ltd
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Filing: 1985-07-09
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Granted: 1987-01-13
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Expires: 2005-07-09
Abstract
Abstract A circuit for charging a battery having a charge-completion signal generator, e.g., a thermostat, that is turned off when the temperature of a rechargeable battery or cell has reached the level corresponding to charge completion. A constant-current circuit controls the charging current. A light-emitting element is lit by current for controlling the constant-current circuit. A silicon-controlled rectifier operates in conjunction with a switching element upon receiving an external charge-completion signal to cause the constant-current circuit to stop operating and remain off by detecting the cell voltage even after the external charge-completion signal has been cut off.
Inventors
- 👤 Shinichi Nakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:21
CPC Classifications
H; H02; H02J; H02J7/00; H02J7/90; H02J7/971; H02J7/975; H02J7/977
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
232 words
A circuit for charging a battery, comprising: a constant-circuit for controlling current to the battery; means for generating a charge completion signal upon completion of the charge of the battery; means responsive to the battery voltage when it reaches a predetermined point for generating a control signal; a switching element having a pair of output terminals and an input terminal, said switching element input terminal being connected to said responsive means and establishing a low-impedance path across said switching element input terminals upon generation of said control signal; a silicon-controlled rectifier comprising a pair of output terminals connected in series with said switching element output terminals, said silicon-controlled rectifier having an input terminal connected to said charge-completion signal generating means and establishing a low-impedance path across said silicon-controlled rectifier output terminals upon generation of said charge completion signal and maintaining a low-impedance path across said silicon-controlled rectifier output terminals while said low impedance path is established across said switching element output terminals; and said switching and said silicon-controlled rectifier being coupled to said constant-current circuit and causing said constant-current to interrupt charging current to the battery whenever a low-impedance path is present across the series combination of said switching element output terminals and silicon-controlled rectifier output terminals; whereby charging current to the battery remains off even after said charge completion signal is deactivated at times when said control signal is being generated.
Claim 2
Dependent Claim
232 words
A circuit for charging a battery, comprising: a constant-circuit for controlling current to the battery; means for generating a charge completion signal upon completion of the charge of the battery; means responsive to the battery voltage when it reaches a predetermined point for generating a control signal; a switching element having a pair of output terminals and an input terminal, said switching element input terminal being connected to said responsive means and establishing a low-impedance path across said switching element input terminals upon generation of said control signal; a silicon-controlled rectifier comprising a pair of output terminals connected in series with said switching element output terminals, said silicon-controlled rectifier having an input terminal connected to said charge-completion signal generating means and establishing a low-impedance path across said silicon-controlled rectifier output terminals upon generation of said charge completion signal and maintaining a low-impedance path across said silicon-controlled rectifier output terminals while said low impedance path is established across said switching element output terminals; and said switching and said silicon-controlled rectifier being coupled to said constant-current circuit and causing said constant-current to interrupt charging current to the battery whenever a low-impedance path is present across the series combination of said switching element output terminals and silicon-controlled rectifier output terminals; whereby charging current to the battery remains off even after said charge completion signal is deactivated at times when said control signal is being generated.
Claim 3
Dependent Claim
20 words
A circuit as recited in claim 1 wherein said charge completion signal generating means comprises circuit means including a thermostat.
Claim 4
Dependent Claim
14 words
A circuit as recited in claim 1 wherein said switching element comprises a transistor.
Claim 5
Dependent Claim
22 words
A circuit as recited in claim 1 further comprising light-emitting means for providing an indication of the presence of said charging current.
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) | 1990-01-12 | 1990-07-14 | 1991-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-12 | 1994-07-14 | 1995-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-12 | 1998-07-14 | 1999-01-13 | $7700.00 | Window Closed / Lapsed |