US3883777A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for automatically compensating failure of a lamp
Assignee: Tokai Rika Co Ltd
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Filing: 1973-08-01
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Granted: 1975-05-13
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Expires: 1993-08-01
Abstract
Abstract A device for automatically compensating failure of a lamp in which voltage drop across a series resistor is applied to the emitter of a transistor for detecting failure of a lamp and the forward voltage drop across a diode is applied to the base of said transistor to restrain the voltage drop across the series resistor, and the main current of a transistor circuit controlled by the failure detecting transistor is made to flow through a resistor to form a positive feedback to said failure detecting transistor within the range controlled by said diode and resistor thereby to further lower the voltage drop across the series resistor. The failure detecting transistor is sufficiently turned on by the above-mentioned circuit arrangement to energize a backup lamp.
Inventors
- 👤 Masayuki Morita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:04
CPC Classifications
B; B60; B60Q; B60Q11/00; B60Q11/005; H; H05; H05B; H05B39/00; H05B39/10
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
218 words
An apparatus for automatically detecting and compensating failure of a first lamp normally energizable from a power supply, comprising in combination: means including a series resistor connecting said first lamp across said power supply and responsive to conduction through said first lamp for creating a voltage drop in said series resistor; first and second normally non-conductive transistors of opposite polarity; means connecting a main current electrode of said normally nonconductive first transistor between said first lamp and series resistor and responsive to loss of said voltage drop upon failure of said first lamp for turning on said first transistor; bias means connecting the base of said first transistor to said power supply for enabling said main current electrode to control turn on of said first transistor; means coupling said first transistor to the base of said second transistor and responsive to first transistor conduction for turning on said second transistor; feedback means coupling a main current electrode of said second transistor to said bias means and responsive to conduction of said second transistor for increasing conductive bias on said first transistor base and accelerating switching of said first and second transistors into conduction; and a back-up lamp and means coupling same to said second transistor and responsive to conduction of said second transistor for energizing said back-up lamp.
Claim 2
Independent Claim
218 words
An apparatus for automatically detecting and compensating failure of a first lamp normally energizable from a power supply, comprising in combination: means including a series resistor connecting said first lamp across said power supply and responsive to conduction through said first lamp for creating a voltage drop in said series resistor; first and second normally non-conductive transistors of opposite polarity; means connecting a main current electrode of said normally nonconductive first transistor between said first lamp and series resistor and responsive to loss of said voltage drop upon failure of said first lamp for turning on said first transistor; bias means connecting the base of said first transistor to said power supply for enabling said main current electrode to control turn on of said first transistor; means coupling said first transistor to the base of said second transistor and responsive to first transistor conduction for turning on said second transistor; feedback means coupling a main current electrode of said second transistor to said bias means and responsive to conduction of said second transistor for increasing conductive bias on said first transistor base and accelerating switching of said first and second transistors into conduction; and a back-up lamp and means coupling same to said second transistor and responsive to conduction of said second transistor for energizing said back-up lamp.
Claim 3
Dependent Claim
49 words
An apparatus according to claim 1 in which said series resistor is of resistance sufficiently small that said voltage drop thereacross is less than the threshold voltage of said first transistor, whereby to minimize power loss in said series resistor during normal current flow through the ignited first lamp.
Claim 4
Dependent Claim
102 words
An apparatus according to claim 2 in which said bias means comprises a further resistor and a diode in series between said power supply and said base of said first transistor, said main electrode of said second transistor being connected at least through said further resistor to said power supply to provide positive feedback from said second transistor upon conduction thereof to said first transistor, whereby said series diode and further resistor and said positive feedback provide rapid and positive actuation of said transistors despite the relatively small change in voltage drop across said series resistor upon failure of said first lamp.
Claim 5
Dependent Claim
134 words
The apparatus of claim 1 in which the emitter is the electrode of said first transistor connected between said series resistor and first lamp, the collector of said first transistor is direct connected to the base of said second transistor, said bias means comprises a diode and further resistor in series, one end of said bias means being connected to said power supply and the other end being connected to the base of said first transistor and the collector of second transistor, said means coupling said back-up lamp to said second transistor comprising a conductive path connected to the emitter of said second transistor and including a path to circuit ground for said back-up lamp and first lamp and resistance means connecting the base and collector of said second transistor to said circuit ground.
Claim 6
Dependent Claim
98 words
An apparatus according to claim 1 in which said bias means comprises a diode and further resistor in series, the first recited coupling means comprising a resistor connecting the first transistor collector to the second transistor base, said feedback means including an additional resistor connecting the second transistor collector to the first transistor base, the remaining said coupling means comprising a third transistor connected in series between said back-up lamp and power supply and having a base electrode coupled to the collector of said second transistor for actuation of said third transistor upon actuation of said second transistor.
Claim 7
Dependent Claim
103 words
An apparatus according to claim 1 in which said bias means comprises a further resistor and diode in series between said power supply and said first transistor base, the diode-connected end of said further resistor being connected by said feedback means in series with the main current electrodes of said second transistor and thence through said last mentioned coupling means with said back-up lamp, said last mentioned coupling means comprising a conductive connection between the emitter of said second transistor and said back-up lamp, the first mentioned coupling means comprising a resistor connected between said first transistor collector and said second transistor base.
Claim 8
Independent Claim
198 words
A device for automatically detecting and compensating failure in a lamp normally energizable from a power supply, which comprises: a first lamp, the failure of which is to be detected and compensated; a back-up lamp energizable in the place of said first lamp, when said first lamp is burnt out; a series resistor connected between said power supply and said first lamp; a PNP transistor having a collector, an emitter connected between said series resistor and said first lamp, and a base connected to said power supply through a bias path including a further resistor and diode in series; an NPN transistor having a base; means connecting said base of said NPN transistor to the collector of said PNP transistor for turning on said NPN transistor when the potential at the emitter of said PNP transistor is higher than the potential at the base thereof, said NPN transistor having main current electrodes and means coupling one thereof to said bias path for further lowering the potential of said PNP transistor base upon conduction of said NPN transistor; means coupling said NPN transistor and back-up lamp and responsive to conduction of said NPN transistor for energizing said back-up lamp.
Claim 9
Independent Claim
198 words
A device for automatically detecting and compensating failure in a lamp normally energizable from a power supply, which comprises: a first lamp, the failure of which is to be detected and compensated; a back-up lamp energizable in the place of said first lamp, when said first lamp is burnt out; a series resistor connected between said power supply and said first lamp; a PNP transistor having a collector, an emitter connected between said series resistor and said first lamp, and a base connected to said power supply through a bias path including a further resistor and diode in series; an NPN transistor having a base; means connecting said base of said NPN transistor to the collector of said PNP transistor for turning on said NPN transistor when the potential at the emitter of said PNP transistor is higher than the potential at the base thereof, said NPN transistor having main current electrodes and means coupling one thereof to said bias path for further lowering the potential of said PNP transistor base upon conduction of said NPN transistor; means coupling said NPN transistor and back-up lamp and responsive to conduction of said NPN transistor for energizing said back-up lamp.
Claim 10
Dependent Claim
27 words
A device according to claim 7 including an amplification transisTor conductive in response to the turning on of said NPN transistor for energizing said back-up lamp therethrough.
Claim 11
Dependent Claim
41 words
A device according to claim 7 wherein said diode is connected at its cathode to the base of said PNP transistor and at its anode to said power supply through said further resistor and to the collector of said NPN transistor.
References Cited (Backward Citations)
US3076123A
Cited
US3562580A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |