Lamp bulb having integrated RFI suppression and method of restricting RFI to selected level
First Claim
1. In an incandescent lamp having a translucent housing and a filament within the housing for emitting light when energized by electrical current from an AC power source passing through the filament, an improvement in combination therewith comprising:
- a current change limiting element, comprising of an inductor assembly, located within the lamp and electrically connected to the filament and operative to limit the rate of change in current per change in time (di/dt) passing through the filament to a predetermined di/dt value in response to a substantially instantaneous change in voltage from the AC power source applied substantially instantaneously across the filament, the predetermined di/dt value limiting radio frequency interference (RFI) inherently emitted as a result of the di/dt in the filament in response to the substantially instantaneous change in voltage, the predetermined di/dt value having a value no greater than that value calculated according to the equation;
##EQU16## where;
C is a maximum permitted current amplitude;
Nn is 120 times an integer, n, where n represents the nth harmonic of the signal;
ω
is a value of the frequency at which electrical current is passed through the filament;
t2 -t1 is a time differential between the time point t1 when the substantially instantaneous change in voltage is applied across the current change limiting element and the time point t2 when the di/dt reaches a maximum magnitude; and
Ip is a value of a peak current level of the electrical current passing through the filament, established by the maximum value of the voltage of the AC power source and a resistance of the filament.
2 Assignments
0 Petitions
Accused Products
Abstract
An incandescent lamp bulb which is driven by an electronic control module (ECM) and method of manufacture characterized in that an inductor comprising a magnetic element and a winding thereon is disposed within a screw shell base of the lamp bulb and surrounds the lamp exhaust tube therein. One end of the winding on the magnetic element is connected to a filament wire within the screw shell base and the other end of the inductive winding is connected to an output terminal of the ECM control module. In this manner, the inductor significantly reduces the di/dt rise time of voltage and current when a triac within the ECM module is driven to conduction on each one half cycle of the applied AC line voltage. This operation in turn produces a substantial reduction in radio frequency interference, both of radiation transmitted into space from the lamp bulb and by direct DC coupling back into the AC line voltage source. In a preferred embodiment, the di/dt rise time is calculated mathematically based on a Fourier series transformation of the current conducted through the filament by the triac.
-
Citations
16 Claims
-
1. In an incandescent lamp having a translucent housing and a filament within the housing for emitting light when energized by electrical current from an AC power source passing through the filament, an improvement in combination therewith comprising:
-
a current change limiting element, comprising of an inductor assembly, located within the lamp and electrically connected to the filament and operative to limit the rate of change in current per change in time (di/dt) passing through the filament to a predetermined di/dt value in response to a substantially instantaneous change in voltage from the AC power source applied substantially instantaneously across the filament, the predetermined di/dt value limiting radio frequency interference (RFI) inherently emitted as a result of the di/dt in the filament in response to the substantially instantaneous change in voltage, the predetermined di/dt value having a value no greater than that value calculated according to the equation;
##EQU16## where;
C is a maximum permitted current amplitude;Nn is 120 times an integer, n, where n represents the nth harmonic of the signal; ω
is a value of the frequency at which electrical current is passed through the filament;t2 -t1 is a time differential between the time point t1 when the substantially instantaneous change in voltage is applied across the current change limiting element and the time point t2 when the di/dt reaches a maximum magnitude; and Ip is a value of a peak current level of the electrical current passing through the filament, established by the maximum value of the voltage of the AC power source and a resistance of the filament. - View Dependent Claims (2, 3, 4, 6, 7, 8)
-
-
5. A method of restricting emitted radio frequency interference emitted from an incandescent lamp having a translucent housing and a filament within the housing for emitting light when the lamp is energized by electrical current from an AC power source passing through the filament, comprising the steps of:
-
locating a current change limiting element, comprising of an inductor assembly, within the lamp; electrically connecting the filament to the current change limiting element; limiting a rate of change in current per change in time (di/dt) passing through the filament by selecting the current change limiting element to have characteristics to establish the rate of change in current per change in time (di/dt) passing through the filament to a predetermined di/dt value in response to a substantially instantaneous change in voltage from the AC power source applied substantially instantaneously across the filament; establishing the predetermined di/dt value to limit radio frequency interference (RFI) inherently emitted as a result of the di/dt in the filament in response to the substantially instantaneous change in voltage applied across the filament; and mathematically calculating a maximum value for the predetermined di/dt value according to the equation;
##EQU17## where;
C is a maximum permitted current amplitude;Nn is 120 times an integer, n, where n represents the nth harmonic of the signal; ω
is a value of the frequency at which electrical current is passed through the filament;t2 -t1 is a time differential between the time point t1 when the substantially instantaneous change in voltage is applied across the current change limiting element and the time point t2 when the di/dt reaches a maximum magnitude; and Ip is a value of a peak current level of the electrical current passing through the filament, established by the maximum value of the voltage of the AC power source and a resistance of the filament. - View Dependent Claims (9, 10, 11, 12)
-
-
13. In an incandescent lamp bulb having a light-generative filament for generating light when the lamp bulb is powered with electrical energy generated at an electrical power source and a longitudinally-extending lamp exhaust tube, a combination with the light-generative filament of a current change limiting element positionable in electrical connection with the light-generative filament for limiting rates of current level change of electrical energy applied to the light-generative filament, said current change limiting element comprising:
-
a core of ferromagnetic material having a central aperture extending therethrough to permit positioning of the core of ferromagnetic material about the lamp exhaust tube, the central aperture defining a top opening at a top surface of the core of ferromagnetic material and a bottom opening at a bottom surface of the core of ferromagnetic material; a winding wrapped about the core of ferromagnetic material; and a magnetic flux path positioned about at least a portion of the winding between the top surface of the core and the bottom surface of the core wherein the core of ferromagnetic material, the winding, and the magnetic flux path together define part of an inductor assembly of a selected inductance. - View Dependent Claims (14, 15, 16)
-
Specification