Light dimmer for LED and incandescent lamps
AssigneeRadiant Power Corporation
InventorStephen Elliott
Life of this patent
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Abstract
The light output intensity of incandescent lamps and LEDs connected to a common lamp power bus are controlled using a composite waveform having two power components: a pulse-width modulated (PWM) component and a direct current DC component. The DC component is maintained below the turn-on voltage for the LEDs. The PWM component controls the light intensity of the LEDs; and the DC component is calculated as a quadrature power series, taking into account that the PWM component contributes to the light intensity of the incandescent lamps. The frequency and slew rate of the PWM component are selected to minimize EMI. A small steady state power component is provided to keep the LEDs slightly turned on to minimize EMI.
Claims25
Method of dimming both incandescent lamps and LEDs connected to a common lamp power bus, comprising:
- connecting incandescent lamps to the power bus;
- connecting LEDs to the power bus;
- with a composite waveform on the power bus, causing light output intensities of the incandescent lamps and of the LEDs to track each other, when being dimmed;
- wherein:
- the composite waveform comprises two power components:
- a pulse-width modulated (PWM) component (V1) having a duty cycle (D) and an alternating current (AC) component (V2).
Method of dimming both incandescent lamps and LEDs connected to a common lamp power bus, comprising:
- connecting incandescent lamps to the power bus;
- connecting LEDs to the power bus;
- with a composite waveform on the power bus, causing light output intensities of the incandescent lamps and of the LEDs to track each other, when being dimmed;
- wherein:
- the composite waveform comprises two power components:
- a first pulse-width modulated (PWM) component (V1) and a second pulse-width modulated (PWM) component (V2).
Method of dimming both incandescent lamps and LEDs connected to a common lamp power bus, comprising:
- connecting incandescent lamps to the power bus;
- connecting LEDs to the power bus;
- with a composite waveform on the power bus, causing light output intensities of the incandescent lamps and of the LEDs to track each other, when being dimmed;
- wherein:
- the composite waveform comprises two power components:
- a pulse-width modulated (PWM) component (V1) having a duty cycle (D) and a direct current (DC) component (V2).
Dimmer for controlling light intensity of LEDs and incandescent bulbs connected to a common power bus comprising:
- a common power bus to which the LEDs and incandescent bulbs are connected;
- means for providing a composite signal on the power bus comprising a first component (V1) and a second component (V2), wherein:
- the first component is PWM and controls the intensity (L) of the LEDs in direct proportion to the PWM duty cycle (D), and contributes to the intensity of the incandescent bulbs;
- and
- the second component is selected from the group comprising DC, AC and PWM, and is selected such that the second component contributes to the intensity of the incandescent bulbs and does not contribute to the intensity of the LEDs.
Dependencies are inferred from the claim text.