Low line voltage detection control module and method for a fluorescent lamp
First Claim
1. A control module for use with a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized into the conductive plasma, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said control module adapted to be connected to the cathodes, said control module comprising:
- a lamp monitoring circuit for determining whether the medium of the lamp is ionized into the conductive plasma;
a line voltage monitoring circuit for determining whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium;
the lamp monitoring circuit activating the line voltage monitoring circuit in response to the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting;
a starter circuit for generating a starting voltage pulse between the cathodes sufficient to ionize the medium into the conductive plasma which the AC line voltage which is at least equal to the predetermined line voltage threshold will sustain; and
a starter initiation circuit connected to the lamp monitoring, line voltage monitoring and starter circuits, the starter initiation circuit triggering the starter circuit to generate the starting voltage pulse in response to (a) the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting and (b) the line voltage monitoring circuit determining that the AC line voltage is at least equal to the predetermined line voltage threshold to enable the AC line voltage to sustain the medium in an ionized and conductive state after application of the starting pulse.
1 Assignment
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Accused Products
Abstract
The present invention discloses a control module that provides improved control over the ignition of a fluorescent lamp. In one aspect, the control module determines whether the lamp is lit and, when the lamp is not lit, determines whether the power supply line voltage is insufficient to sustain the lamp in a lit state after ignition. When the power supply line voltage is determined to be insufficient, the control module waits until the power supply line voltage rises to a sufficient level before igniting the lamp.
23 Citations
20 Claims
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1. A control module for use with a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized into the conductive plasma, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said control module adapted to be connected to the cathodes, said control module comprising:
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a lamp monitoring circuit for determining whether the medium of the lamp is ionized into the conductive plasma; a line voltage monitoring circuit for determining whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium; the lamp monitoring circuit activating the line voltage monitoring circuit in response to the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting; a starter circuit for generating a starting voltage pulse between the cathodes sufficient to ionize the medium into the conductive plasma which the AC line voltage which is at least equal to the predetermined line voltage threshold will sustain; and a starter initiation circuit connected to the lamp monitoring, line voltage monitoring and starter circuits, the starter initiation circuit triggering the starter circuit to generate the starting voltage pulse in response to (a) the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting and (b) the line voltage monitoring circuit determining that the AC line voltage is at least equal to the predetermined line voltage threshold to enable the AC line voltage to sustain the medium in an ionized and conductive state after application of the starting pulse. - View Dependent Claims (2, 4)
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3. A control module for use with a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized into the conductive plasma, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said control module adapted to be connected to the cathodes, said control module comprising:
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a lamp monitoring circuit for determining whether the medium of the lamp is ionized into the conductive plasma; a line voltage monitoring circuit for determining whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium; the lamp monitoring circuit activating the line voltage monitoring circuit in response to the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting; and
wherein;the lamp monitoring circuit generates a transition signal indicative of the medium having transitioned from being ionized and conductive to being substantially non-ionized and non-conductive; and the line voltage monitoring circuit responds to the transition signal to determine whether the voltage across the cathodes is less than the predetermined line voltage threshold.
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5. A control module for use with a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized into the conductive plasma, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said control module adapted to be connected to the cathodes, said control module comprising:
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a lamp monitoring circuit for determining whether the medium of the lamp is ionized into the conductive plasma; a line voltage monitoring circuit for determining whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium; the lamp monitoring circuit activating the line voltage monitoring circuit in response to the lamb monitoring circuit determining that the medium is substantially non-ionized and non-conducting; and
wherein;the lamp monitoring circuit determines that the medium is substantially non-ionized and non-conductive by sensing the voltage across the cathodes and determining that the sensed voltage across the cathodes exceeds a predetermined lamp voltage threshold, the predetermined lamp voltage threshold being greater than the characteristic ionization voltage and less than the predetermined line voltage threshold. - View Dependent Claims (6, 7)
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8. A control module for use with a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized into the conductive plasma, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said control module adapted to be connected to the cathodes, said control module comprising:
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a lamp monitoring circuit for determining whether the medium of the lamp is ionized into the conductive plasma; a line voltage monitoring circuit for determining whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium; the lamp monitoring circuit activating the line voltage monitoring circuit in response to the lamp monitoring circuit determining that the medium is substantially non-ionized and non-conducting; and
wherein;the lamp monitoring circuit samples the voltage across the cathodes at a first predetermined sample time after the zero crossing point of a half cycle of the AC line voltage and compares the sampled voltage to a first reference voltage to determine whether the medium is ionized and conductive; and the line voltage monitoring circuit samples the voltage across the cathodes at a second predetermined sample time after the zero crossing point of a half cycle of the AC line voltage and compares the sampled voltage to a second reference voltage to determine whether the AC line voltage is sufficient to sustain ionization of and coduction by the medium. - View Dependent Claims (9, 10, 11)
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12. A method of controlling a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized and conductive, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said method comprising the steps of:
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determining whether the medium of the lamp is ionized and conductive; determining, in response to the medium of the lamp being determined to be substantially non-ionized and non-conductive, whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold greater than the characteristic ionization voltage of the medium; and in response to determining that the medium is substantially non-ionized and non-conductive and in response to determining that the AC line voltage is at least equal to the predetermined line voltage threshold, applying a starting voltage pulse across the cathodes sufficient to ionize the medium and ignite the medium into the conductive plasma when the AC line voltage across the cathodes is at least equal to the predetermined line voltage threshold to sustain the ionization of and conduction by the medium. - View Dependent Claims (13, 14, 19, 20)
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15. A method of controlling a fluorescent lamp having cathodes and a medium therebetween which is ionizable into a conductive plasma and which has a characteristic ionization voltage across the cathodes when the medium is ionized and conductive, the cathodes energized by an alternating (AC) power source which provides alternating half cycles of AC line voltage and AC line current to the cathodes, said method comprising the steps of:
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determining whether the medium of the lamp is ionized and conductive; determining, in response to the medium of the lamp being determined to be substantially non-ionized and non-conductive, whether the AC line voltage from the AC power source is less than a predetermined line voltage threshold, the predetermined line voltage threshold being greater than the characteristic ionization voltage of the medium; determining a first voltage across the cathodes at a first predetermined sample time after a zero crossing point of a half cycle of the AC line voltage; comparing the first voltage to a first reference voltage which is related to the characteristic ionization voltage of the medium; determining a second voltage across the cathodes at a second predetermined sample time after the zero crossing point of a half cycle of the AC line voltage; and comparing the second voltage to a second reference voltage which is related to the predetermined line voltage threshold. - View Dependent Claims (16, 17, 18)
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Specification