Triac dimmable compact fluorescent lamp with dimming interface
First Claim
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1. A ballast for powering at least one lamp in combination with a triac dimmer having a cut-in angle, the ballast comprising:
- a driver for controlling the level of lamp illumination based on a dimming signal; and
a dimming interface for supplying the dimming signal to the driver and including threshold means for establishing a minimum cut-in angle corresponding to a maximum level for the dimming signal, the threshold means acting upon pulses appearing in the dimming interface which have a cut-in angle actually determined by the triac dimmer to produce a modified signal representing the cut-in angle of the triac dimmer but with the minimum cut-in angle being imposed, the dimming interface supplying a dimming signal to the driver based on the cut-in angle of the modified signal, whereby the ballast can effectively interface with triac dimmers with different minimum cut-in angles.
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Abstract
A dimming interface for translating the conduction pulse width of a signal produced by a triac dimmer into a proportional rectified average voltage serving as a dimming signal. The dimming signal is supplied as an input to an IC driver for controlling the level of lamp illumination. The proportional rectified average voltage can be converted into a signal representing a duty cylce whereby a variation in the mains line voltage does not affect the dimming signal.
102 Citations
22 Claims
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1. A ballast for powering at least one lamp in combination with a triac dimmer having a cut-in angle, the ballast comprising:
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a driver for controlling the level of lamp illumination based on a dimming signal; and
a dimming interface for supplying the dimming signal to the driver and including threshold means for establishing a minimum cut-in angle corresponding to a maximum level for the dimming signal, the threshold means acting upon pulses appearing in the dimming interface which have a cut-in angle actually determined by the triac dimmer to produce a modified signal representing the cut-in angle of the triac dimmer but with the minimum cut-in angle being imposed, the dimming interface supplying a dimming signal to the driver based on the cut-in angle of the modified signal, whereby the ballast can effectively interface with triac dimmers with different minimum cut-in angles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 11, 21)
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8. A ballast for powering at least one lamp in combination with a triac dimmer having a cut-in angle, the ballast comprising:
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a driver for controlling the level of lamp illumination based on a dimming signal; and
a dimming interface for supplying the dimming signal to the driver and including a zener diode for establishing a minimum cut-in angle corresponding to a maximum level for the dimming signal, the zener diode reducing the voltage of a pulse signal representing the cut-in angle of the triac dimmer as a pulse width to thereby limit the pulse width of said pulse signal, and converting means for converting the pulse width of the reduced pulse voltage signal into a proportional average rectified voltage which serves as the dimming signal, whereby the ballast can effectively interface with triac dimmers with different minimum cut-in angles.
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9. A compact fluorescent lamp in combination with a triac dimmer having a cut-in angle, comprising:
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a driver for controlling the level of lamp illumination based on a dimming signal; and
a dimming interface for supplying the dimming signal to the driver and including threshold means for establishing a minimum cut-in angle corresponding to a maximum level for the dimming signal, the threshold means acting to effectively limit the cut-in angle of pulses having a cut-in angle actually determined by the triac dimmer to a cut-in angle no less than the established minimum cut-in angle, the dimming interface supplying a dimming signal to the driver based on the cut-in angle of the pulses as limited if necessary by said threshold means, wherein an effective interface with triac dimmers with different minimum cut-in angles is achieved.
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10. A method for powering at least one lamp, comprising:
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controlling the level of lamp illumination based on a dimming signal supplied to an inverter driver;
supplying the dimming signal as an input to the inverter driver based on a cut-in angle of a triac dimmer, which cut-in angle of the triac dimmer may be less than a desired minimum cut-in angle; and
reducing the voltage level of a signal representing the cut-in angle of the triac dimmer by a predetermined amount to thereby form a modified signal in which the cut-in angle represented by the modified signal is limited to the desired minimum cut-in angle, the desired minimum cut-in angle corresponding to a maximum level for the dimming signal, the dimming signal supplied as the input to the inverter driver being formed from the modified signal, wherein an effective interface with triac dimmers with different minimum cut-in angles is achieved.
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12. A ballast for powering at least one lamp in combination with a triac dimmer having a cut-in angle, the ballast comprising:
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a driver for controlling the level of lamp illumination based on a dimming signal; and
a dimming interface for supplying the dimming signal to the driver, the dimming interface receiving pulses having a pulse width determined by the cut-in angle of the triac dimmer, the dimming interface including threshold means for establishing a minimum cut-in angle corresponding to a maximum level for the dimming signal, said threshold means acting to effectively limit the cut-in angle of any received pulses having a cut-in angle less than the established minimum cut-in angle to a cut-in angle equal to the established minimum cut-in angle, the dimming interface supplying a dimming signal to the driver based on the cut-in angle of the received pulses as limited if necessary by said threshold means wherein the ballast can effectively interface with different minimum cut-in angles. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 22)
a voltage-divider, a capacitor coupling the voltage-divider to an output of the triac dimmer, a rectifier coupled to the voltage-divider via said threshold means, and an RC circuit coupled to the rectifier for deriving a proportional average rectified voltage as said dimming signal.
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15. The ballast as claimed in claim 14 wherein said threshold means comprises a zener diode which reduces the proportional average rectified voltage of the dimming signal by the value of its zener voltage.
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16. The ballast as claimed in claim 12 wherein the triac dimmer supplies an input of the dimming interface with an unrectified signal having a DC voltage component, and the dimming interface includes a rectifier, and a zener diode threshold converter as said threshold means.
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17. The ballast as claimed in claim 16 further comprising a DC blocking capacitor coupling the input of the dimming interface to an output of the triac dimmer.
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18. The ballast as claimed in claim 16 wherein the dimming interface further comprises;
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a voltage-divider coupled to said zener diode threshold converter, said rectifier produces a rectified voltage, and a circuit coupled to the rectifier for deriving a proportional average rectified voltage as the dimming signal, and said voltage-divider and said zener diode determine the proportional average rectified voltage based upon the triac dimmer firing angle.
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19. The ballast as claimed in claim 12 wherein the threshold means establishes said minimum cut-in angle by a reduction in the voltage of a signal representing the cut-in angle.
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20. The ballast as claimed in claim 12 wherein the triac dimmer supplies an input of the dimming interface with an unrectified signal having a DC voltage component,
the threshold means establishes said minimum cut-in angle by a reduction in the voltage of a signal representing the cut-in angle, and the dimming interface further comprises a single pulse rectifier and a DC blocking capacitor coupling the input of the dimming interface to an output of the triac dimmer. -
22. The ballast as claimed in claim 12 further comprising:
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a rectifier circuit having an input coupled to a dimmer terminal, and means coupling said dimmer terminal to an input of the dimming interface and to an output of the triac dimmer.
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Specification