Two-wire dimmer circuit for a screw-in compact fluorescent lamp

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:

• 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 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.

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:

• 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 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 control the intensity of the second lighting load according to a second dynamic range.

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:

• 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;
• 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.