Abstract: A no-load detection circuit includes an inductance device, an impedance device and a switch circuit. The inductance device is interposed between a choke coil and a first output terminal, which is at a high potential side, so as to be magnetically coupled to the choke coil. The impedance device is connected in series with the inductance device between the inductance device and the first output terminal. The switch circuit is configured to be turned on when a value of electric potential at the first output terminal exceeds a predetermined reference value. The control circuit is configured to stop the switching control if the switch circuit is turned on.

Abstract: A no-load detection circuit includes an inductance device, an impedance device and a switch circuit. The inductance device is interposed between a choke coil and a first output terminal, which is at a high potential side, so as to be magnetically coupled to the choke coil. The impedance device is connected in series with the inductance device between the inductance device and the first output terminal. The switch circuit is configured to be turned on when a value of electric potential at the first output terminal exceeds a predetermined reference value. The control circuit is configured to stop the switching control if the switch circuit is turned on.

Abstract: A lighting device includes a switching regulator having an inductor and a switching device, and a controller. The controller includes a peak current detector that outputs a peak detection signal when detecting that a current flowing through the switching device reaches a threshold, a zero-cross detector that outputs a zero-cross detection signal when a current discharged from the inductor reaches a predetermined lower limit value or less, a synchronization signal controller that outputs a periodic synchronization signal, and a switching controller. The switching controller turns on the switching device in synchronization with a start of an on-period of the synchronization signal and the zero-cross detection signal, and turns off the switching device in synchronization with the peak detection signal. The peak current detector reduces the threshold when an on-period of the synchronization signal finishes, and increases the threshold to an original value when an on-period of the synchronization signal starts.

Abstract: The controller changes an applied time (ON-time) of a DC voltage while keeping an intermittent period in which the DC voltage is supplied intermittently constant, when adjusting an average value of currents to a predetermined reference value or more, and changes a stopped time (OFF-time) of the DC voltage together with the intermittent period while keeping the applied time constant, when adjusting the average value to a value less than the predetermined reference value. Therefore, the lighting device can reduce variation in emission color compared with the conventional lighting device adopting DC Dimming Method, and can reduce variation in amount of light compared with the case where ON-time is changed until the dimming level reaches a lower limit. As a result, the lighting device can modulate light even at a low dimming level while reducing variation in emission color and variation in amount of light.

Abstract: A lighting device includes a switching regulator having an inductor and a switching device, and a controller. The controller includes a peak current detector that outputs a peak detection signal when detecting that a current flowing through the switching device reaches a threshold, a zero-cross detector that outputs a zero-cross detection signal when a current discharged from the inductor reaches a predetermined lower limit value or less, a synchronization signal controller that outputs a periodic synchronization signal, and a switching controller. The switching controller turns on the switching device in synchronization with a start of an on-period of the synchronization signal and the zero-cross detection signal, and turns off the switching device in synchronization with the peak detection signal. The peak current detector reduces the threshold when an on-period of the synchronization signal finishes, and increases the threshold to an original value when an on-period of the synchronization signal starts.

Abstract: A lighting device is capable of realizing a stable dimming control in a wide range of light output. The lighting device includes a DC power circuit for providing power to a switching element of the lighting device. A current controller switches the switching element to enable a current to flow from the DC power circuit through a solid state light source and maintain the current from the DC power circuit through the solid state light source current controller at a predetermined current. The current controller includes a first switching controller operable to change a width of an on-pulse provided to the switching element and a second switching controller operable to determine a burst-on time during which the on-pulses determined by the first switching controller are provided to the switching element. The burst-on time is longer than an on-pulse period of the first switching controller.

Abstract: A discharge lamp ballast and method of operation are provided for generating a DC component in an output voltage during a lamp starting operation having a predetermined duration. The ballast includes an inverter having four switches arranged in a full-bridge configuration, a resonant circuit having a resonant frequency, and a control circuit. The method includes a step of sweeping an inverter operating frequency within a predetermined frequency range including the resonant frequency, wherein a high voltage is generated for igniting the lamp. The method further includes periodically and alternately repeating a first state of turning on a first set of diagonally positioned switching elements and turning off a second set of diagonally positioned switching elements, and a second state of turning on only one of the second set of switching elements and turning off the remaining three switching elements, respectively.

Abstract: The controller changes an applied time (ON-time) of a DC voltage while keeping an intermittent period in which the DC voltage is supplied intermittently constant, when adjusting an average value of currents to a predetermined reference value or more, and changes a stopped time (OFF-time) of the DC voltage together with the intermittent period while keeping the applied time constant, when adjusting the average value to a value less than the predetermined reference value. Therefore, the lighting device can reduce variation in emission color compared with the conventional lighting device adopting DC Dimming Method, and can reduce variation in amount of light compared with the case where ON-time is changed until the dimming level reaches a lower limit. As a result, the lighting device can modulate light even at a low dimming level while reducing variation in emission color and variation in amount of light.

Abstract: A lighting device is capable of realizing a stable dimming control in a wide range of light output. The lighting device includes a DC power circuit for providing power to a switching element of the lighting device. A current controller switches the switching element to enable a current to flow from the DC power circuit through a solid state light source and maintain the current from the DC power circuit through the solid state light source current controller at a predetermined current. The current controller includes a first switching controller operable to change a width of an on-pulse provided to the switching element and a second switching controller operable to determine a burst-on time during which the on-pulses determined by the first switching controller are provided to the switching element. The burst-on time is longer than an on-pulse period of the first switching controller.

Abstract: A discharge lamp ballast and method of operation are provided for generating a DC component in an output voltage during a lamp starting operation having a predetermined duration. The ballast includes an inverter having four switches arranged in a full-bridge configuration, a resonant circuit having a resonant frequency, and a control circuit. The method includes a step of sweeping an inverter operating frequency within a predetermined frequency range including the resonant frequency, wherein a high voltage is generated for igniting the lamp. The method further includes periodically and alternately repeating a first state of turning on a first set of diagonally positioned switching elements and turning off a second set of diagonally positioned switching elements, and a second state of turning on only one of the second set of switching elements and turning off the remaining three switching elements, respectively.

Abstract: A lighting device for lighting a high-pressure discharge lamp 2 having an outer tube, an interior of which is substantially under vacuum. The lighting device includes a ballast 3 having at least a current limiting element and a high-voltage pulse generating circuit 4 for generating a high-voltage pulse, and also includes a lighting discriminating means 8 for discriminating between lighting and non-lighting of the discharge lamp 2, a timer circuit 9 for setting a predetermined period of time, and a pulse-stop control means 10 for stopping generation of the high-voltage pulse. When the lighting discriminating means 8 discriminates non-lighting after lighting has been discriminated, generation of the high-voltage pulse is stopped within the predetermined period of time set by the timer circuit 9.

Abstract: A lighting device for lighting a high-pressure discharge lamp 2 having an outer tube, an interior of which is substantially under vacuum. The lighting device includes a ballast 3 having at least a current limiting element and a high-voltage pulse generating circuit 4 for generating a high-voltage pulse, and also includes a lighting discriminating means 8 for discriminating between lighting and non-lighting of the discharge lamp 2, a timer circuit 9 for setting a predetermined period of time, and a pulse-stop control means 10 for stopping generation of the high-voltage pulse. When the lighting discriminating means 8 discriminates non-lighting after lighting has been discriminated, generation of the high-voltage pulse is stopped within the predetermined period of time set by the timer circuit 9.

Abstract: An inverter circuit produces a proper electric power to be supplied to a discharge lamp. A feedback control system detects a lamp voltage and a lamp current, or a lamp power of the discharge lamp, and feedback-controls the inverter circuit based on the detected at least one of the lamp voltage, lamp current and lamp power. A response switching circuit switches a response speed of the feedback control system so that the response speed is high in a low luminous efficiency region, and is low in a high luminous efficiency region.

Abstract: A discharge-lamp lighting device stably lights and controls a discharge lamp suitable for use in a vehicle. In the discharge-lamp lighting device, an inverter for receiving DC power from a DC step-up circuit supplies AC power to the discharge lamp. Further, a start-discharging circuit applies a high voltage for effecting start discharging to the discharge lamp. A lamp current controlling circuit decides the value of a current to be supplied to the discharge lamp, based on both the luminous efficiency of the discharge lamp, which varies depending on a voltage applied to the discharge lamp and a voltage for the discharge lamp, which has been detected by a voltage detector circuit. A step-up controlling circuit controls a voltage output from the DC step-up circuit in such a manner that the decided value of current coincides with the value of a current to be supplied to the discharge lamp, which has been detected by a current detector circuit.

Abstract: A discharging lamp lighting apparatus is provided with predicting means for predicting final discharging lamp voltage of a discharging lamp, and discharging lamp control means including a discharging lamp voltage-discharging lamp current corresponding characteristic to instruct current applied to the discharging lamp by discharging lamp voltage fed to the discharging lamp, for performing lighting control by using a value predicted by the predicting means. It is thereby possible to feed the optimal power to the discharging lamp according to a variation in the final discharging lamp voltage due to quality or an operating time, and reduce a time required for stability of luminous flux.

Abstract: An apparatus for lighting a discharge lamp is provided with an inverter circuit 3 for causing an input power supply 2 to generate the voltage required for a discharge lamp 1, a rectifying smoothing circuit 4 for rectifying and smoothing the output of the invertor circuit 3, a feedback control circuit 8 for computing the power required for the discharge lamp 1 so as to control the feedback control circuit 8 in the feedback mode, a polarity switching circuit 9 for switching the polarity of the rectified and smoothed output to apply the output to the discharge lamp 1 with a low-frequency square wave, and an ignitor 11 for superposing a high-voltage pulse on the discharge lamp 1 when the discharge lamp 1 is started.