Rejecting noise transients while turning off a fluorescent lamp using a starter unit
First Claim
1. A method for operating a lamp, comprising:
- (a) stopping an illuminating current from flowing through a gas of a lamp by closing a switch in a starter unit;
(b) taking samples of a shunt current that flows through the switch when the switch is closed, wherein the samples of the shunt current are decreasing; and
(c) opening the switch at a predetermined time interval after the samples of the shunt current first begin to increase after the samples of the shunt current are decreasing in (b).
1 Assignment
0 Petitions
Accused Products
Abstract
A local minimum of a current monitoring signal is identified by a starter unit that turns off a fluorescent lamp without using a wall switch. Closing a main switch in the starter unit stops an illuminating current from flowing through a gas in the lamp. The local minimum of the current monitoring signal is reached when an increasing valid sample is identified following four valid samples. A sample is valid if it does not differ from the preceding valid sample by more than a threshold difference based on known properties of the signal. By skipping invalid samples, the local minimum is accurately determined to have been reached despite transient noise spikes in the signal that would trip any voltage threshold used to locate the local minimum. When the main switch is opened at a predetermined time after the local minimum, the illuminating current does not again flow through the gas.
-
Citations
17 Claims
-
1. A method for operating a lamp, comprising:
-
(a) stopping an illuminating current from flowing through a gas of a lamp by closing a switch in a starter unit; (b) taking samples of a shunt current that flows through the switch when the switch is closed, wherein the samples of the shunt current are decreasing; and (c) opening the switch at a predetermined time interval after the samples of the shunt current first begin to increase after the samples of the shunt current are decreasing in (b). - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. An apparatus for operating a lamp, comprising:
-
a ballast adapted to receive an alternating current from an AC line voltage supply; a fluorescent lamp coupled to the ballast, wherein the alternating current has a waveform and flows through a switch in a starter unit when the switch is closed, and wherein the alternating current flows through a gas of the fluorescent lamp when both the switch is open and the fluorescent lamp is on; and means for opening the switch when a predetermined time interval elapses following a local minimum of the waveform of the alternating current by determining when samples of the alternating current begin to increase, wherein the means is also for stopping the alternating current from flowing through the gas when the switch is open without disconnecting the AC line voltage supply from the fluorescent lamp. - View Dependent Claims (9, 10, 11)
-
-
12. A method for operating a lamp, comprising:
-
(a) stopping an illuminating current from flowing through a gas of a lamp by closing a switch in a starter unit; (b) taking samples of a shunt current that flows through the switch when the switch is closed, wherein the samples of the shunt current are decreasing; and (c) opening the switch after the samples of the shunt current first begin to increase after the samples of the shunt current are decreasing in (b). - View Dependent Claims (13, 14, 15, 16, 17)
-
Specification