US4461980A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protection circuit for series resonant electronic ballasts
Assignee: Individual
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Filing: 1982-08-25
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Granted: 1984-07-24
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Expires: 2002-08-25
Abstract
Abstract For protection against potentially serious electric shock hazard to a person removing and/or replacing a fluorescent lamp in a fluorescent lighting fixture having an inverter-type electronic ballast, a special protection circuit is provided as part of this ballast. This protection circuit operates to disable the ballast inverter within about one second after a fluorescent lamp is removed from at least one of its sockets, thereby removing the potentially hazardous voltage present at the fixture's lamp sockets.
Inventors
- 👤 Ole K. Nilssen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:42
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/26; H05B41/28; H05B41/282; H05B41/285; H05B41/2851; H05B41/2856; H05B41/2855; Y; Y10; Y10S; Y10S315/00; Y10S315/07
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
245 words
A ballasting means for a gas discharge lamp, said ballasting means being adapted to be powered from an ordinary electric utility power line and comprising: rectification means connected in circuit with said power line and operative to supply a DC voltage; inverter means operative to convert said DC voltage into a substantially squarewave voltage, said squarewave voltage having a fundamental frequency and being provided across a pair of squarewave output terminals; an L-C circuit comprising an inductor and a capacitor effectively connected in series with one another, said L-C circuit being resonant at or near said fundmental frequency and connected across said pair of squarewave output terminals; connect means operative to permit connection of said lamp in parallel circuit with said capacitor; voltage limiting means operative, whenever said lamp is not effectively connected in parallel with said capacitor, to limit the voltage developed across said capacitor to a magnitude lower than that dictated by the L-C circuit's Q-multiplication effect, but yet high enough to provide for effective lamp starting, said magnitude never-the-less being of a level high enough to represent a serious electric shock hazard to humans; and safety means operative, whenever said voltage limiting means has been limiting the voltage developed across said capacitor for but a relatively brief period, to disable said inverter means, thereby to reduce the magnitude of the voltage developed across said capacitor to a level that is not high enough to represent a serious electric shock hazard to humans.
Claim 2
Dependent Claim
245 words
A ballasting means for a gas discharge lamp, said ballasting means being adapted to be powered from an ordinary electric utility power line and comprising: rectification means connected in circuit with said power line and operative to supply a DC voltage; inverter means operative to convert said DC voltage into a substantially squarewave voltage, said squarewave voltage having a fundamental frequency and being provided across a pair of squarewave output terminals; an L-C circuit comprising an inductor and a capacitor effectively connected in series with one another, said L-C circuit being resonant at or near said fundmental frequency and connected across said pair of squarewave output terminals; connect means operative to permit connection of said lamp in parallel circuit with said capacitor; voltage limiting means operative, whenever said lamp is not effectively connected in parallel with said capacitor, to limit the voltage developed across said capacitor to a magnitude lower than that dictated by the L-C circuit's Q-multiplication effect, but yet high enough to provide for effective lamp starting, said magnitude never-the-less being of a level high enough to represent a serious electric shock hazard to humans; and safety means operative, whenever said voltage limiting means has been limiting the voltage developed across said capacitor for but a relatively brief period, to disable said inverter means, thereby to reduce the magnitude of the voltage developed across said capacitor to a level that is not high enough to represent a serious electric shock hazard to humans.
Claim 3
Dependent Claim
20 words
The ballasting means of claim 1 wherein said relatively brief period of time is on the order of one second.
Claim 4
Dependent Claim
31 words
The ballasting means of claim 2 and restoring means operative to restore the inverter to operation after a pre-determined length of time after it has been disabled by said safety means.
Claim 5
Dependent Claim
19 words
The ballasting means of claim 3 wherein said pre-determined length of time is on the order of 30 seconds.
Claim 6
Dependent Claim
216 words
A ballasting means for a gas discharge lamp, said ballasting means comprising: a source of DC voltage; an inverter operative to convert said DC voltage into a substantially squarewave voltage, said squarewave voltage having a fundamental frequency and being provided across a pair of squarewave output terminals; an L-C circuit comprising an inductor and a capacitor effectively connected in series with one another, said L-C circuit being resonant at or near said fundamental frequency and connected across said pair of squarewave output terminals; connect means operative to permit connection of said lamp in circuit with said capacitor; clamping means operative, whenever the lamp is not effectively connected in circuit with said capacitor, to extract energy from said resonant L-C circuit, thereby to limit the voltage developed across said capacitor to a magnitude lower than that dictated by the L-C circuit's Q-multiplying effect, yet appropriate for effective lamp starting, said magnitude never-the-less being of a level high enough to represent a serious electric shock hazard to humans; and safety means operative, whenever said clamping means has been extracting energy from said resonant L-C circuit for more than a relatively brief time period, to reduce the magnitude of the voltage developed across said capacitor to a level that does not represent a serious electric shock hazard to humans.
Claim 7
Dependent Claim
216 words
A ballasting means for a gas discharge lamp, said ballasting means comprising: a source of DC voltage; an inverter operative to convert said DC voltage into a substantially squarewave voltage, said squarewave voltage having a fundamental frequency and being provided across a pair of squarewave output terminals; an L-C circuit comprising an inductor and a capacitor effectively connected in series with one another, said L-C circuit being resonant at or near said fundamental frequency and connected across said pair of squarewave output terminals; connect means operative to permit connection of said lamp in circuit with said capacitor; clamping means operative, whenever the lamp is not effectively connected in circuit with said capacitor, to extract energy from said resonant L-C circuit, thereby to limit the voltage developed across said capacitor to a magnitude lower than that dictated by the L-C circuit's Q-multiplying effect, yet appropriate for effective lamp starting, said magnitude never-the-less being of a level high enough to represent a serious electric shock hazard to humans; and safety means operative, whenever said clamping means has been extracting energy from said resonant L-C circuit for more than a relatively brief time period, to reduce the magnitude of the voltage developed across said capacitor to a level that does not represent a serious electric shock hazard to humans.
Claim 8
Dependent Claim
222 words
A ballasting means for a gas discharge lamp, comprising: a source of DC voltage; an inverter operative to convert said DC voltage into an AC voltage provided across a pair of output terminals, said AC voltage having a frequency; an L-C series-circuit resonant at or near said frequency and connected across said pair of output terminals; connect means operative to permit connection of said lamp in loading relationship with said L-C series-circuit; clamping means operative, whenever the loading provided for said L-C series-circuit by said lamp is lower than a given level, to extract energy from said L-C series-circuit, thereby preventing the voltages developed within said L-C series-circuit, as well as the current drawn by said L-C series-circuit, from reaching magnitudes that might be damaging to components in said L-C series-circuit or in said inverter, yet in spite of the presence of said clamping means the magnitudes of the voltages developed within said L-C series-circuit will be high enough to constitute a serious electric shock hazard to humans; and safety means operative, whenever said clamping means has been extracting energy from said L-C series-circuit for longer than a relatively brief period of time, to effect a reduction in magnitudes of the voltages developed within said L-C series-circuit to a level low enough not to constitute a serious electric shock hazard to humans.
Claim 9
Dependent Claim
222 words
A ballasting means for a gas discharge lamp, comprising: a source of DC voltage; an inverter operative to convert said DC voltage into an AC voltage provided across a pair of output terminals, said AC voltage having a frequency; an L-C series-circuit resonant at or near said frequency and connected across said pair of output terminals; connect means operative to permit connection of said lamp in loading relationship with said L-C series-circuit; clamping means operative, whenever the loading provided for said L-C series-circuit by said lamp is lower than a given level, to extract energy from said L-C series-circuit, thereby preventing the voltages developed within said L-C series-circuit, as well as the current drawn by said L-C series-circuit, from reaching magnitudes that might be damaging to components in said L-C series-circuit or in said inverter, yet in spite of the presence of said clamping means the magnitudes of the voltages developed within said L-C series-circuit will be high enough to constitute a serious electric shock hazard to humans; and safety means operative, whenever said clamping means has been extracting energy from said L-C series-circuit for longer than a relatively brief period of time, to effect a reduction in magnitudes of the voltages developed within said L-C series-circuit to a level low enough not to constitute a serious electric shock hazard to humans.
Claim 10
Dependent Claim
18 words
The ballasting means of claim 6 wherein said reduction in magnitudes is accomplished by disablement of the inverter.
Claim 11
Dependent Claim
48 words
The ballasting means of claim 7 wherein said inverter includes a pair of alternatingly switching power transistors capable of continuous self-oscillating operation once having been triggered and until being manifestly disabled, and where said disablement is effected by momentarily shorting the base-emitter junction of one of these transistors.
Claim 12
Dependent Claim
22 words
The ballasting means of claim 8 wherein said inverter also includes means for automatic re-triggering of oscillation some pre-determined time after disablement.
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) | 1987-07-24 | 1988-01-23 | 1988-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-24 | 1992-01-23 | 1992-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-24 | 1996-01-23 | 1996-07-24 | $7700.00 | Window Closed / Lapsed |