Two-wire dimmer circuit for a screw-in compact fluorescent lamp
DCFirst Claim
1. A dimmer switch adapted to be coupled between an AC power source generating an AC line voltage and a lighting load, the dimmer switch controlling the intensity of the lighting load within a dynamic range bounded by a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
- a controllably conductive switching device adapted to be coupled in series electrical connection between the AC power source and the lighting load, the controllably conductive switching device controlling the amount of power delivered to the lighting load, the controllably conductive switching device having a conductive state and a non-conductive state;
a detect circuit coupled in parallel electrical connection with the controllably conductive switching device, the detect circuit operable to provide a control signal representative of whether the controllably conductive switching device is conducting a load current to the lighting load; and
a controller operatively coupled to the controllably conductive switching device and the detect circuit, the controller operable to render the controllably conductive switching device conductive at a predetermined time following a zero-crossing of the AC line voltage, and to subsequently determine in response to the control signal whether the controllably conductive switching device is conducting the load current to the lighting load;
wherein the controller is operable to automatically adjust the dimmer switch to one of a first operating mode and a second operating mode in response to the control signal, the controller operable to adjust the low-end intensity setting to a first low-end intensity setting value in the first operating mode, and to adjust the low-end intensity setting to a second low-end intensity setting value in the second operating mode.
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Abstract
A dimmer switch for controlling the intensity of a dimmable screw-in compact fluorescent lamp provides smooth dimming of the fluorescent lamp and prevents flickering of the lamp due to multiple re-strikes. The dimmer switch prevents multiple re-strikes by avoiding multiple firings of a controllably conductive switching device of the dimmer circuit by limiting the high-end light intensity of the fluorescent lamp. Specifically, the dimmer switch limits the length of a conduction interval of the controllably conductive switching device to less than approximately 75% of each half-cycle. The dimmer switch may include a user-accessible adjustment actuator for changing the dimmer switch between an incandescent operating mode and a screw-in compact fluorescent mode. The dimmer switch may also be operable to automatically change the dimmer switch between the incandescent operating mode and the screw-in compact fluorescent mode by detecting the occurrence of the multiple firings of the controllably conductive switching device.
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Citations
51 Claims
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1. A dimmer switch adapted to be coupled between an AC power source generating an AC line voltage and a lighting load, the dimmer switch controlling the intensity of the lighting load within a dynamic range bounded by a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
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a controllably conductive switching device adapted to be coupled in series electrical connection between the AC power source and the lighting load, the controllably conductive switching device controlling the amount of power delivered to the lighting load, the controllably conductive switching device having a conductive state and a non-conductive state; a detect circuit coupled in parallel electrical connection with the controllably conductive switching device, the detect circuit operable to provide a control signal representative of whether the controllably conductive switching device is conducting a load current to the lighting load; and a controller operatively coupled to the controllably conductive switching device and the detect circuit, the controller operable to render the controllably conductive switching device conductive at a predetermined time following a zero-crossing of the AC line voltage, and to subsequently determine in response to the control signal whether the controllably conductive switching device is conducting the load current to the lighting load; wherein the controller is operable to automatically adjust the dimmer switch to one of a first operating mode and a second operating mode in response to the control signal, the controller operable to adjust the low-end intensity setting to a first low-end intensity setting value in the first operating mode, and to adjust the low-end intensity setting to a second low-end intensity setting value in the second operating mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A dimmer switch adapted to be coupled between an AC power source generating an AC line voltage and a lighting load, the dimmer switch controlling the intensity of the lighting load within a dynamic range bounded by a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
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a controllably conductive switching device adapted to be coupled in series electrical connection between the AC power source and the lighting load, the controllably conductive switching device controlling the amount of power delivered to the lighting load, the controllably conductive switching device having a conductive state and a non-conductive state; a detect circuit coupled in parallel electrical connection with the controllably conductive switching device, the detect circuit operable to provide a control signal representative of whether the controllably conductive switching device is conducting a load current to the lighting load; and a controller operatively coupled to the controllably conductive switching device and the detect circuit, the controller operable to render the controllably conductive switching device conductive at a predetermined time following a zero-crossing of the AC line voltage, and to subsequently determine in response to the control signal whether the controllably conductive switching device is conducting the load current to the lighting load; wherein the controller is operable to adjust the dimmer switch to one of a first operating mode and a second operating mode in response to the control signal, the controller operable to adjust the low-end intensity setting to a first low-end intensity setting value in the first operating mode, and to adjust the low-end intensity setting to a second low-end intensity setting value in the second operating mode, wherein the first operating mode is characterized by a first dynamic range and the second operating mode is characterized by a second dynamic range, wherein the second dynamic range is less than the first dynamic range, and further wherein the dimmer switch is adapted to control the lighting intensity of a lighting load comprising a rectifier and a bus capacitor within the second dynamic range such that the dimmer switch is operable to prevent the controllably conductive switching device from being rendered conductive until after an instantaneous magnitude of the AC line voltage exceeds a voltage across the bus capacitor when the dimmer switch is operating in the second operating mode. - View Dependent Claims (23, 24)
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25. A dimmer switch adapted to be coupled between an AC power source and a lighting load for controlling the intensity of the lighting load within a dynamic range comprising a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
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a first terminal adapted to be coupled to the AC power source; a second terminal adapted to be coupled to the lighting load; a controllably conductive switching device adapted to be coupled in series electrical connection between the first and second terminals for controlling the amount of power delivered to the lighting load; a controller coupled to a control input of the controllably conductive switching device for controlling the controllably conductive switching device to be conductive for a conduction interval each half cycle of the AC power source; and a sensing circuit coupled such that the sensing circuit is operable to sense an electrical characteristic of the second terminal and adapted to provide a control signal representative of the electrical characteristic to the controller; wherein the controller is operable to automatically adjust the low-end intensity setting to one of a first low-end intensity setting value and a second low-end intensity setting value in response to the control signal from the sensing circuit. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A dimmer switch adapted to be coupled between an AC power source and a lighting load for controlling the intensity of the lighting load within a dynamic range comprising a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
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a first terminal adapted to be coupled to the AC power source; a second terminal adapted to be coupled to the lighting load; a controllably conductive switching device adapted to be coupled in series electrical connection between the first and second terminals for controlling the amount of power delivered to the lighting load; a controller coupled to a control input of the controllably conductive switching device for controlling the controllably conductive switching device to be conductive for a conduction interval each half cycle of the AC power source; and a sensing circuit coupled such that the sensing circuit is operable to sense an electrical characteristic of the second terminal and adapted to provide a control signal representative of the electrical characteristic to the controller, wherein the sensing circuit comprises a voltage detect circuit operable to provide a control signal representative of the magnitude of a voltage across the controllably conductive switching device; wherein the controller is operable to adjust the low-end intensity setting to one of a first low-end intensity setting value and a second low-end intensity setting value in response to the control signal from the sensing circuit, wherein the electrical characteristic of the second terminal comprises one of a current and a voltage, wherein the controller is operable to determine the magnitude of the voltage across the controllably conductive switching device at a predetermined time after the controller controls the controllably conductive switching device to be conductive, wherein the controllably conductive switching device comprises a triac, wherein a first dynamic range is characterized by the first low-end intensity setting value and a second dynamic range is characterized by the second low-end intensity setting value, wherein the second dynamic range is less than the first dynamic range, and further wherein the dimmer switch is adapted to control the lighting intensity of a lighting load comprising a rectifier and a bus capacitor within the second dynamic range such that the dimmer switch is operable to prevent the triac from being controlled to be conductive until after an instantaneous magnitude of the AC line voltage exceeds a voltage across the bus capacitor. - View Dependent Claims (39)
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40. A dimmer switch adapted to be coupled between an AC power source and at least one of a plurality of lighting loads, the plurality of lighting loads comprising a first lighting load including an incandescent light source and a second lighting load including a rectifier and a bus capacitor, the dimmer switch controlling the intensity of the at least one lighting load within a dynamic range including a high-end intensity setting and a low-end intensity setting, the dimmer switch comprising:
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a controllably conductive switching device adapted to be coupled in series electrical connection between the AC power source and the at least one lighting load, the controllably conductive switching device controlling the amount of power delivered to the at least one lighting load, the controllably conductive switching device having a conductive state and a non-conductive state; a detect circuit coupled in parallel electrical connection with the controllably conductive switching device, the detect circuit operable to provide a control signal representative of whether the controllably conductive switching device is conducting a load current to the at least one lighting load; and a controller operatively coupled to the controllably conductive switching device and the detect circuit, the controller operable to render the controllably conductive switching device conductive at a predetermined time following a zero-crossing of the AC line voltage, and to subsequently determine in response to the control signal whether the at least one lighting load comprises the first lighting load or the second lighting load; wherein upon determining that the at least one lighting load comprises the first lighting load, the controller is operable to automatically control the intensity of the first lighting load according to a first dynamic range; and
upon determining that the at least one lighting load comprises the second lighting load, the controller is operable to automatically control the intensity of the second lighting load according to a second dynamic range. - View Dependent Claims (41, 42, 43)
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44. A method of controlling a dimmer switch adapted to be coupled between a lighting load and an AC power source generating an AC line voltage, the dimmer switch adapted to control the intensity of the lighting load between a high-end intensity setting and a low-end intensity setting, the method comprising the steps of:
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rendering a controllably conductive switching device conductive, the controllably conductive switching device adapted to be coupled in series electrical connection between the AC line voltage and the lighting load for controlling the amount of power delivered to the lighting load; automatically determining if the controllably conductive switching device is conducting a load current to the lighting load at a predetermined period of time after the step of rendering the controllably conductive switching device conductive; automatically adjusting the low-end intensity setting to a first low-end intensity setting value if the controllably conductive switching device is conducting the load current; and automatically adjusting the low-end intensity setting to a second low-end intensity setting value if the controllably conductive switching device is not conducting the load current. - View Dependent Claims (45, 46, 47, 48, 49, 50)
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51. A method of controlling a dimmer switch adapted to be coupled between a lighting load and an AC power source generating an AC line voltage, the dimmer switch adapted to control the intensity of the lighting load between a high-end intensity setting and a low-end intensity setting, the method comprising the steps of:
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rendering a controllably conductive switching device conductive, the controllably conductive switching device adapted to be coupled in series electrical connection between the AC line voltage and the lighting load for controlling the amount of power delivered to the lighting load; determining if the controllably conductive switching device is conducting a load current to the lighting load at a predetermined period of time after the step of rendering the controllably conductive switching device conductive; automatically adjusting the low-end intensity setting to a first low-end intensity setting value if the controllably conductive switching device is conducting the load current; automatically adjusting the low-end intensity setting to a second low-end intensity setting value if the controllably conductive switching device is not conducting the load current; detecting the magnitude of a voltage across the controllably conductive switching device at the predetermined time after the controller renders the controllably conductive switching device conductive; wherein the controllably conductive switching device comprises a triac; comparing the magnitude of the voltage detected across the triac to a predetermined threshold; determining that the triac is conducting the load current if the magnitude of the voltage does not exceed the predetermined threshold; and determining that the triac is not conducting the load current if the magnitude of the voltage does exceed the predetermined threshold.
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Specification