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Patent US3663860A successfully refreshed from Google Patents.
US3663860A
Expired / Lapsed
US
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Short circuit proof flasher circuit
Assignee: Motorola Solutions Inc
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Filing: 1970-02-25
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Granted: 1972-05-16
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Expires: 1990-02-25
Abstract
Abstract Load current control circuitry including means for generating a driving signal with a predetermined duty cycle. Current control circuit means are connected between a load terminal and the generating means and provide different and selected levels of load current to an electrical load which is connected to the load terminal. The first level of current is that required during the initial energization of the load, and this initial current is provided by a starting network within the current control circuit means. The current control circuit means also includes a load steady state current supply and short circuit protection circuit which is connected between the generating means and the electrical load. The latter circuit is responsive to a predetermined voltage developed across the electrical load for providing a steady state DC current to the load after the latter has been initially energized.
Inventors
- 👤 Robert A Phillips
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:39
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/20; H05; H05B; H05B39/00; H05B39/09
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
180 words
Electrical load current control circuitry including, in combination: a. means for generating a driving signal having a predetermined duty cycle, b. load starting network means connected between said generating means and a load terminal and responsive to said driving signal for providing a first predetermined energizing turn-on current to an electrical load connectable to said load terminal, and c. load steady state current supply means coupled to said means for generating a driving signal, connected to said load terminal and responsive to the simultaneous occurrence of a driving signal from said driving means and a predetermined change in voltage across said load for supplying said load with a second predetermined steady state current greater than said first predetermined energizing turn-on current subsequent to an initial current surge when said load is energized, whereby whenever said load is shorted there exists an insufficient change in voltage across said load to cause said load steady state current supply means to supply said load with current, the only current then being supplied being said first predetermined current of said load starting network means.
Claim 2
Dependent Claim
180 words
Electrical load current control circuitry including, in combination: a. means for generating a driving signal having a predetermined duty cycle, b. load starting network means connected between said generating means and a load terminal and responsive to said driving signal for providing a first predetermined energizing turn-on current to an electrical load connectable to said load terminal, and c. load steady state current supply means coupled to said means for generating a driving signal, connected to said load terminal and responsive to the simultaneous occurrence of a driving signal from said driving means and a predetermined change in voltage across said load for supplying said load with a second predetermined steady state current greater than said first predetermined energizing turn-on current subsequent to an initial current surge when said load is energized, whereby whenever said load is shorted there exists an insufficient change in voltage across said load to cause said load steady state current supply means to supply said load with current, the only current then being supplied being said first predetermined current of said load starting network means.
Claim 3
Dependent Claim
54 words
Circuitry defined in claim 1 wherein said load steady state current supply means includes a gating circuit connected between said generating means and said load terminal and responsive to both said driving signal and to said predetermined change in voltage developed across said load for supplying said second predetermined load current to said load.
Claim 4
Dependent Claim
77 words
Circuitry defined in claim 1 wherein said load starting network means includes pulse forming circuitry connected between said generating means and said load terminal and responsive to said driving signal for supplying said first predetermined turn-on current to said load to bring the voltage across said load up to said predetermined change in value, said pulse forming circuit being monostable and reverting to its original state a predetermined time after the application thereto of said driving signal.
Claim 5
Dependent Claim
43 words
Circuitry defined in claim 1 wherein said generating means is an astable flip-flop for providing a square wave output driving signal having a predetermined duty cycle for periodically driving both said load starting network means and said load steady state current supply means.
Claim 6
Dependent Claim
46 words
Circuitry defined in claim 1 wherein said load starting network means includes a pulse amplifier circuit including a current limiting impedance connected between said generating means and said load terminal for providing predetermined said first turn-on current to aN electrical load connected to said load terminal.
Claim 7
Dependent Claim
70 words
Circuitry defined in claim 1 wherein: said load steady state current supply means includes a power transistor connected between a power supply terminal and said load terminal, and means connected to said power transistor for biasing said power transistor into conduction to connect said power supply through said power transistor and to said load terminal to supply said second predetermined current to an electrical load connected to said load terminal.
Claim 8
Dependent Claim
78 words
Circuitry defined in claim 1 which further includes feedback means connected between said load terminal and one input of said load steady state current supply means for providing a voltage transition at the input of said load steady state current supply means responsive to said predetermined change in voltage across said load to energize said steady state current supply means to apply said second predetermined current to said load terminal after said electrical load has been initially energized.
Claim 9
Dependent Claim
80 words
Circuitry defined in claim 2 wherein said electrical load is a lamp having a given temperature coefficient of resistance so that the voltage developed across said lamp varies with the current through said lamp, said load steady state current supply means further includes a power transistor connected between said power supply terminal and said load terminal and responsive to a signal at the output of said gating circuit to become conductive and connect said second predetermined current to said lamp.
Claim 10
Dependent Claim
96 words
Circuitry defined in claim 8 wherein: a. said load starting network means includes a pulse forming circuit responsive to said driving signal at the output of said generating means for providing a periodic turn on pulse at the output thereof, and b. said load starting network means further includes a pulse amplifier serially connected to a current limiting impedance between said power supply terminal and said load terminal so that said pulse amplifier is biased conductive upon receiving an output pulse from said pulse forming network to thereby provide said first predetermined current to said lamp.
Claim 11
Dependent Claim
85 words
Circuitry defined in claim 9 wherein: a. said generating means is an astable flip-flop for producing a square wave output signal having a predetermined duty cycle, and b. said circuitry further including voltage sensitive feedback means connected between said load terminal and one input of said gating circuit for coupling a voltage transition to said gating circuit in response to said predetermined change in voltage across said load to thereby turn-on said power transistor a predetermined time after current begins to flow through said lamp.
Claim 12
Dependent Claim
48 words
Circuitry defined in claim 10 wherein said voltage sensitive feedback means includes: a. an integrating network connected across said electrical load for delaying the voltage rise, there across, and b. a zener diode clamp connected across said integrating network for limiting the voltage applied to said gating circuit.
References Cited (Backward Citations)
US3263119A
Cited
US3461399A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |