Automated Dimming Methods and Systems For Lighting
First Claim
Patent Images
1. A system for automatically adjusting a light source in response to changes in ambient illumination level, comprisingat least one photosensor positioned to receive illumination from an area;
- a controller coupled to receive an illumination level signal from the photosensor and configured to generate a control signal varying with the illumination level;
a ballast circuit configured to be coupled to enable receipt of a time-varying DC voltage at a first node with respect to a second node, said DC voltage varying at twice a line frequency, and said DC voltage being rectified from an AC voltage power source alternating at said line frequency, wherein the ballast circuit is configured to present the DC voltage varying at twice the line frequency across said first terminal and said second terminal of a bypass capacitor, wherein the ballast circuit is further configured to allow said DC voltage to drop to 15% or less of a peak value of said DC voltage every half cycle of the line frequency, said ballast circuit comprising;
a first switch coupled to the first node operable to selectively couple the first node to a resonant circuit, the resonant circuit having a resonant frequency less than a first frequency and configured to be coupled to a light source, wherein the resonant circuit stores energy during a first portion of a cycle of the first frequency, and a second switch operable to selectively couple the resonant circuit to the second node during a second portion of the cycle of the first frequency;
said first and second switches configured to be coupled to provide an operating voltage to a light source positioned to provide illumination to the area; and
a dimming circuit coupled to the controller and to the ballast circuit, the dimming circuit configured to receive and modify an AC line voltage based on the control signal to produce the time-varying DC voltage.
2 Assignments
0 Petitions
Accused Products
Abstract
Automated control systems and methods for lighting systems are described herein. In certain embodiments, the control systems include either an improved dimmable ballast, an improved dimmer circuit, or both. The control systems are suitable for various applications including a light harvesting system and a security lighting system.
-
Citations
24 Claims
-
1. A system for automatically adjusting a light source in response to changes in ambient illumination level, comprising
at least one photosensor positioned to receive illumination from an area; -
a controller coupled to receive an illumination level signal from the photosensor and configured to generate a control signal varying with the illumination level; a ballast circuit configured to be coupled to enable receipt of a time-varying DC voltage at a first node with respect to a second node, said DC voltage varying at twice a line frequency, and said DC voltage being rectified from an AC voltage power source alternating at said line frequency, wherein the ballast circuit is configured to present the DC voltage varying at twice the line frequency across said first terminal and said second terminal of a bypass capacitor, wherein the ballast circuit is further configured to allow said DC voltage to drop to 15% or less of a peak value of said DC voltage every half cycle of the line frequency, said ballast circuit comprising; a first switch coupled to the first node operable to selectively couple the first node to a resonant circuit, the resonant circuit having a resonant frequency less than a first frequency and configured to be coupled to a light source, wherein the resonant circuit stores energy during a first portion of a cycle of the first frequency, and a second switch operable to selectively couple the resonant circuit to the second node during a second portion of the cycle of the first frequency; said first and second switches configured to be coupled to provide an operating voltage to a light source positioned to provide illumination to the area; and a dimming circuit coupled to the controller and to the ballast circuit, the dimming circuit configured to receive and modify an AC line voltage based on the control signal to produce the time-varying DC voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of automatically adjusting a light source in response to changes in ambient illumination level, comprising:
-
measuring the illumination level in an area; providing an AC line voltage at a line frequency to a dimming circuit; modifying the line voltage with the dimming circuit in response to the measured level of illumination in the area; utilizing the modified line voltage to charge energy in a non-electrolytic bypass capacitor such that the bypass capacitor is discharged every half cycle at the line frequency, the bypass capacitor coupled to a first node and a second node; storing energy in the bypass capacitor to subsequently produce a high frequency current from the bypass capacitor; selectively coupling the bypass capacitor to a resonant circuit via the first node for a first time period, wherein coupling the resonant circuit to the first node results in an operating voltage at a light source, wherein said operating voltage at the light source is the result of at least the combination of a first current from an output of the dimming circuit at the line frequency and the high frequency current from the bypass capacitor; and selectively coupling the resonant circuit to the second node for a second time period, wherein coupling the second node generates a negative voltage in the resonant circuit at the light source and allows energy from the dimming circuit to be stored in the bypass capacitor. - View Dependent Claims (14, 15, 16)
-
-
17. A system for automatically adjusting a light source in response to a control signal, comprising
a controller configured to generate a control signal based on a parameter associated with an area a light source is positioned to illuminate; -
a ballast circuit configured to be coupled to receive a time-varying DC voltage at a first node with respect to a second node, said DC voltage varying at twice a line frequency, and said DC voltage being rectified from an AC voltage power source alternating at said line frequency, wherein the ballast circuit is configured to present the DC voltage varying at twice the line frequency across said first terminal and said second terminal of said bypass capacitor, wherein the ballast circuit is further configured to allow said DC voltage to drop to 15% or less of a peak value of said DC voltage every half cycle of the line frequency, and said ballast circuit comprising; a first switch coupled to the first node operable to selectively couple the first node to a resonant circuit, the resonant circuit having a resonant frequency and configured to be coupled to a light source, wherein the resonant circuit stores energy during a first portion of a cycle of the first frequency, and a second switch operable to selectively couple the resonant circuit to the second node, the second switch allowing all or some of the energy stored in the resonant circuit to be recirculated into the resonant circuit during a second portion of the cycle of the first frequency; said first and second switches being configured to be coupled to provide an operating voltage to the light source positioned to provide illumination to the area; and a dimming circuit coupled to the controller and to the ballast circuit, the dimming circuit configured to receive and modify an AC line voltage based on the control signal to produce the time-varying DC voltage. - View Dependent Claims (18, 19, 20, 21)
-
-
22. A method of automatically controlling a gas-discharge lamp in response to a control signal, comprising:
-
generating a control signal based on a parameter associated with an area the lamp is illuminating; providing an AC line voltage at a line frequency; rectifying the AC line voltage and modifying the rectified AC voltage at the line frequency in response to the control signal; selectively switching at a switching frequency by a first solid state switch the modified rectified AC voltage at the line frequency thereby providing a plurality of switched DC voltages to a resonant circuit; producing a plurality of alternating lamp voltages by said resonant circuit to said lamp wherein; a first portion of said plurality of alternating lamp voltages increase in magnitude of voltage for a first time period during which said lamp is not ionized, a second portion of said plurality of alternating lamp voltages remain at a steady state ionization voltage for a second time period due to ionization occurring in said lamp, a third portion of said plurality of alternating lamp voltages decrease in magnitude of voltage for a third time period during which said lamp is becomes nonionized, and wherein said first time period, said second time period, and said third time period occur during a half cycle of said line frequency; said step of modifying the rectified AC line voltage resulting in altering the light output of said lamp.
-
-
23. A system for automatically adjusting illumination of an area in response to a control signal, comprising:
-
a ballast circuit coupled to a light source, the ballast circuit coupled to receive a time-varying DC voltage at a first node with respect to a second node, said DC voltage varying at twice a line frequency, and said DC voltage being rectified from an AC voltage power source alternating at said line frequency, wherein the ballast circuit is configured to present the DC voltage varying at twice the line frequency across a first terminal and a second terminal of a bypass capacitor, wherein the ballast circuit is further configured to allow said DC voltage to drop to 15% or less of a peak value of said DC voltage every half cycle of the line frequency, and said ballast circuit comprising; a first switch coupled to the first node operable to selectively couple the first node to a resonant circuit, the resonant circuit having a resonant frequency less than a first frequency and configured to be coupled to a light source, wherein the resonant circuit stores energy during a first portion of a cycle of the first frequency, and a second switch operable to selectively couple the resonant circuit to the second node during a second portion of the cycle of the first frequency; said first and second switches being coupled to provide an operating voltage to said light source; a power switch coupled to the ballast circuit, the power switch being selectively alterable from a first state in which the power switch allows an AC line voltage to said ballast circuit to a second state in which the power switch prevents said AC line voltage to said ballast circuit based on a control signal; and a controller configured to generate said control signal and to provide said control signal to said power switch so as to selectively alter the state of said power switch based on a parameter associated with an area the light source is positioned to illuminate. - View Dependent Claims (24)
-
Specification