Abstract: A dual-control dimming system is disclosed. The dual-control dimming system is configured to automatically change control of an LED between two control loops as an LED output is adjusted over a dimmable range. A first control loop may take control of the LED output in a first portion of the dimmable range, while the second loop may take control of the LED output in a second portion of the dimmable range. In this way, the LED may be powered efficiently in the first portion, while providing stable (i.e., flicker-free) output in the second portion.

Abstract: A dual-control dimming system is disclosed. The dual-control dimming system is configured to automatically change control of an LED between two control loops as an LED output is adjusted over a dimmable range. A first control loop may take control of the LED output in a first portion of the dimmable range, while the second loop may take control of the LED output in a second portion of the dimmable range. In this way, the LED may be powered efficiently in the first portion, while providing stable (i.e., flicker-free) output in the second portion.

Abstract: A switched mode power supply (SMPS) receives an input voltage selectively connects and disconnects the input voltage from an inductor. The SMPS generates a charge in the inductor during a duty cycle portion while the input voltage is connected by generating control signals for selectively connecting to and disconnecting the input voltage from the inductor. Generating the control signals includes modulating a current source for a control capacitive element, selectively shorting the control capacitive element wherein a voltage VCT appears across the capacitive element when control capacitive element is not being shorted, and comparing voltage VCT to a threshold voltage generate an inverted DRIVE SIGNAL to selectively short the control capacitive element.

Abstract: A driver circuit is designed employing a current sensing circuit adapted to sense driving current being supplied to one or more light emitting devices. The driver circuit additionally employs a pulse width modulation circuit adapted to modulate a pulse width of a control signal based at least in part on an output of the current sensing circuit, the control signal being employed to adjust the driving current being supplied to the one or more light emitting devices. The driver circuit additionally employs a buck converter adapted to switch the driving current being supplied to the one or more light emitting devices.

Abstract: A driver circuit is designed employing a current sensing circuit adapted to sense driving current being supplied to one or more light emitting devices. The driver circuit additionally employs a pulse width modulation circuit adapted to modulate a pulse width of a control signal based at least in part on an output of the current sensing circuit, the control signal being employed to adjust the driving current being supplied to the one or more light emitting devices. The driver circuit additionally employs a buck converter adapted to switch the driving current being supplied to the one or more light emitting devices.

Abstract: A driver circuit is designed employing a current sensing circuit adapted to sense driving current being supplied to one or more light emitting devices. The driver circuit additionally employs a pulse width modulation circuit adapted to modulate a pulse width of a control signal based at least in part on an output of the current sensing circuit, the control signal being employed to adjust the driving current being supplied to the one or more light emitting devices. The driver circuit additionally employs a buck converter adapted to switch the driving current being supplied to the one or more light emitting devices.

Abstract: A safety interlock apparatus for an electrical device includes a DC power supply, a ballast power supply including a ballast control circuit that controls a ballast power circuit, and a lamp. A relatively low voltage electrical connection is present between the DC power supply and the ballast control circuit. A relatively high voltage electrical connection is present between the lamp and the ballast power circuit. A safety interlock switch is positioned on the relatively low voltage electrical connection, the switch having a closed state wherein the relatively low voltage is supplied to the ballast control circuit and an open disconnected state wherein the relatively low voltage electrical connection is disconnected. A panel is fixable to the electrical device frame, and is selectively movable to expose the lamp for removal.

Abstract: A safety interlock apparatus for an electrical device includes a DC power supply, a ballast power supply including a ballast control circuit that controls a ballast power circuit, and a lamp. A relatively low voltage electrical connection is present between the DC power supply and the ballast control circuit. A relatively high voltage electrical connection is present between the lamp and the ballast power circuit. A safety interlock switch is positioned on the relatively low voltage electrical connection, the switch having a closed state wherein the relatively low voltage is supplied to the ballast control circuit and an open disconnected state wherein the relatively low voltage electrical connection is disconnected. A panel is fixable to the electrical device frame, and is selectively movable to expose the lamp for removal.

Abstract: An arc discharge lamp system comprises a third electrode for igniting the arc discharge lamp in addition to first and second electrodes which provide a main discharge current path for sustaining arc discharge after the lamp has been ignited by a high-voltage, high-frequency signal applied to the third electrode. In an embodiment, an igniter circuit is connected to provide the high-voltage, high-frequency signal to the third electrode of the lamp by using a low-voltage DC power supply.

Abstract: A method and apparatus for reducing ripple current in a projector lamp comprising an electrical network comprising input terminals A and C, and output terminals B and D, including a first inductive element and a second inductive element, each inductive element having a first terminal and a second terminal, with the second terminal of the first inductive element electrically connected with the second terminal of the second inductive element at output terminal B, with the first terminal of the first inductive element connected to input terminal A, and the first terminal of the second inductive element connected to input terminal C; and a means for impressing a first source of switching potential from an external source at input terminal A, and a second source of switching potential from the external source out-of-phase with the first source of switching potential, at input terminal C such that a ripple current across the output terminals B and D is minimum.

Abstract: An igniter circuit for an arc discharge lamp comprises a DC to AC converter, a transformer, an AC to DC converter and high-voltage DC energy storage which is capable of discharging electrical energy to ignite the arc discharge lamp. In an embodiment, the igniter circuit is capable of producing arc discharge by using a low-voltage DC power supply and is suitable for implementation in a lightweight compact portable projector.

Abstract: An igniter circuit for an arc discharge lamp comprises a DC to AC converter, a transformer, an AC to DC converter and high-voltage DC energy storage which is capable of discharging electrical energy to ignite the arc discharge lamp. In an embodiment, the igniter circuit is capable of producing arc discharge by using a low-voltage DC power supply and is suitable for implementation in a lightweight compact portable projector.

Abstract: An arc discharge lamp system comprises a third electrode for igniting the arc discharge lamp in addition to first and second electrodes which provide a main discharge current path for sustaining arc discharge after the lamp has been ignited by a high-voltage, high-frequency signal applied to the third electrode. In an embodiment, an igniter circuit is connected to provide the high-voltage, high-frequency signal to the third electrode of the lamp by using a low-voltage DC power supply.

Abstract: A safety interlock apparatus for an electrical device includes a DC power supply, a ballast power supply including a ballast control circuit that controls a ballast power circuit, and a lamp. A relatively low voltage electrical connection is present between the DC power supply and the ballast control circuit. A relatively high voltage electrical connection is present between the lamp and the ballast power circuit. A safety interlock switch is positioned on the relatively low voltage electrical connection, the switch having a closed state wherein the relatively low voltage is supplied to the ballast control circuit and an open disconnected state wherein the relatively low voltage electrical connection is disconnected. A panel is fixable to the electrical device frame, and is selectively movable to expose the lamp for removal.

Abstract: A frame sequential color display projection system (110) of this invention includes an arc lamp (112) having a predetermined power rating for providing a source of polychromatic light that propagates through a color wheel (120) that sequentially provides R, G, B, and optionally, W light colors during respective sequential time periods. A display controller (131) is synchronized with the color wheel to generate color image data during the respective time periods. A light valve, such as a DMD (130), receives the color image data for generating the frame sequential color display. A lamp ballast (156) is also synchronized with the color wheel to provide nominal and boosted power levels (212) to the arc lamp during selected ones of the time periods such that the projector provides a brighter, color-adjusted display without requiring the arc lamp to operate at an average power level exceeding its predetermined power rating.

Abstract: A method and apparatus for reducing ripple current in a projector lamp comprising an electrical network comprising input terminals A and C, and output terminals B and D, including a first inductive element and a second inductive element, each inductive element having a first terminal and a second terminal, with the second terminal of the first inductive element electrically connected with the second terminal of the second inductive element at output terminal B, with the first terminal of the first inductive element connected to input terminal A, and the first terminal of the second inductive element connected to input terminal C; and a means for impressing a first source of switching potential from an external source at input terminal A, and a second source of switching potential from the external source out-of-phase with the first source of switching potential, at input terminal C such that a ripple current across the output terminals B and D is minimum.

Abstract: A method and apparatus for reducing ripple current in a projector lamp comprising an electrical network comprising input terminals A and C, and output terminals B and D, including a first inductive element and a second inductive element, each inductive element having a first terminal and a second terminal, with the second terminal of the first inductive element electrically connected with the second terminal of the second inductive element at output terminal B, with the first terminal of the first inductive element connected to input terminal A, and the first terminal of the second inductive element connected to input terminal C; and a means for impressing a first source of switching potential from an external source at input terminal A, and a second source of switching potential from the external source out-of-phase with the first source of switching potential, at input terminal C such that a ripple current across the output terminals B and D is minimum.

Abstract: A portable image projector is provided with a fan having a control system for cooling a metal-halide arc lamp. The arc lamp cooling system of the present invention includes a fan having a fan control to operate the fan at an initially reduced level during lamp start-up to allow the temperature of the arc lamp to increase to its full operating temperature. The fan control includes a microcontroller to operate the fan at a reduced voltage over a period of time after which the voltage is increased to operate the fan at full capacity. Power to the fan may be increased in incremental time steps or linearly over a period of time as determined by the microcontroller.

Abstract: A frame sequential color display projection system (110) of this invention includes an arc lamp (112) having a predetermined power rating for providing a source of polychromatic light that propagates through a color wheel (120) that sequentially provides R, G, B, and optionally, W light colors during respective sequential time periods. A display controller (131) is synchronized with the color wheel to generate color image data during the respective time periods. A light valve, such as a DMD (130), receives the color image data for generating the frame sequential color display. A lamp ballast (156) is also synchronized with the color wheel to provide nominal and boosted power levels (212) to the arc lamp during selected ones of the time periods such that the projector provides a brighter, color-adjusted display without requiring the arc lamp to operate at an average power level exceeding its predetermined power rating.

Abstract: A frame sequential color display projection system (110) of this invention includes an arc lamp (112) having a predetermined power rating for providing a source of polychromatic light that propagates through a color wheel (120) that sequentially provides R, G, B, and optionally, W light colors during respective sequential time periods. A display controller (131) is synchronized with the color wheel to generate color image data during the respective time periods. A light valve, such as a DMD (130), receives the color image data for generating the frame sequential color display. A lamp ballast (156) is also synchronized with the color wheel to provide nominal and boosted power levels (212) to the arc lamp during selected ones of the time periods such that the projector provides a brighter, color-adjusted display without requiring the arc lamp to operate at an average power level exceeding its predetermined power rating.