Abstract: An illumination device includes a main light source block having a plurality of main light sources and a plurality of current limiters, and an auxiliary light source block having an auxiliary light source and a constant-current unit. A series circuit of the auxiliary light source and the constant-current unit is electrically connected in parallel with the main light source block, between first and second output terminals of a rectifier. A smoothing capacitor is electrically connected in parallel with a specific main light source among the plurality of main light sources. The specific main light source and a corresponding current limiter are electrically connected in parallel with the series circuit of the auxiliary light source and the constant-current unit.

Abstract: A controller circuit is configured to adjust the number of light-emitting diodes that a current flows from a rectifier circuit through so that: the number of light-emitting diodes, which are lit, of the plurality of light-emitting diodes increases according to a value of a pulsating voltage during a time period that the value of the pulsating voltage increases; and the number of light-emitting diodes, which are lit, of the plurality of light-emitting diodes decreases according to the value of the pulsating voltage during a time period that the value of the pulsating voltage decreases. Light-emitting diodes, which start to emit light by a higher voltage value, of the plurality of light-emitting diodes are disposed at a position nearer to an outside of a mounting region of a substrate than light-emitting diodes, which start to emit light by a lower voltage value, of the plurality of light-emitting diodes.

Abstract: The lighting device of the present invention includes: a power source configured to supply power to a plurality of light sources; and a cooling control circuit configured to control a plurality of cooling devices for respectively cooling the plurality of light sources. The cooling control circuit includes a power supply circuit, a plurality of output circuits, a plurality of temperature measurement circuits, and an output control circuit. The power supply circuit outputs a constant voltage by use of power from the power source. The output circuits receive the constant voltage from the power supply circuit and supply drive voltages to the plurality of cooling devices respectively. The temperature measurement circuits measure temperatures of the plurality of light sources respectively. The output control circuit regulates the drive voltages respectively supplied from the plurality of output circuits based on the temperatures respectively measured by the plurality of temperature measurement circuits.

Abstract: A lighting device includes a DC/DC converter (step-down chopper circuit) and a control circuit that includes a correction circuit. The correction circuit corrects the timing at which a switching element included in the DC/DC convertor is turned OFF based on a voltage value across a solid-state light-emitting element (LED unit). The correction is made such that an average value of a current flowing through an inductor included in the DC/DC converter is within a predetermined range regardless of a voltage value across the solid-state light-emitting element.

Abstract: A lighting device that lights up an LED and includes a DC power source, a buck converter and a control circuit. The buck converter includes a switching element, an inductor and a diode. The control circuit includes a current detection circuit that detects an electric current flowing through the switching element, a voltage detection circuit that detects a voltage across the inductor, a delay circuit that generates a delay time according to the voltage detected by the voltage detection circuit, and a drive circuit that generates and outputs a control signal to the switching element, the control signal turning OFF the switching element after a lapse of the delay time generated by the delay circuit from when the electric current detected by the current detection circuit reaches a predetermined current command value.

Abstract: A lighting device that is connected to a DC power source and supplies an electric current to a solid-state light-emitting element (LED) whose forward voltage ranges from Vfmin to Vfmax includes a DC/DC converter (buck converter) and a control unit. The DC/DC converter includes a switching element. The control unit turns OFF the switching element by peak current control, and when the solid-state light-emitting element to be connected to the lighting device has a forward voltage of Vfmax, turns ON the switching element in fixed cycles such that the DC/DC converter operates in BCM.

Abstract: The lighting device according to the present invention includes: a power source configured to supply power to a light source having a plurality of regions; a plurality of cooling devices arranged corresponding to the plurality of regions to cool the plurality of regions, respectively; and a cooling control circuit configured to control the plurality of cooling devices. The cooling control circuit includes: a plurality of output circuits configured to supply drive voltages to the plurality of cooling devices by use of power from the power source to drive the plurality of cooling devices, respectively; a plurality of temperature measurement circuits configured to respectively measure temperatures of the plurality of regions; and an output control circuit configured to regulate the drive voltages respectively supplied from the plurality of output circuits based on the temperatures respectively measured by the plurality of temperature measurement circuits.

Abstract: A lighting device includes a constant-current circuit, a smoothing capacitor, a bypass circuit, a detection unit, and a bypass control unit. The constant-current circuit supplies a constant current to a plurality of solid-state light-emitting elements connected in series. The smoothing capacitor is connected between output terminals of the constant-current circuit. The bypass circuit is connected in parallel to one or more of the plurality of solid-state light-emitting elements. The detection unit detects whether the one or more solid-state light-emitting elements are open-circuited. When the detection unit detects that at least one of the one or more solid-state light-emitting elements is open-circuited, the bypass control unit discharges the smoothing capacitor during a discharge period to then bypass the one or more solid-state light-emitting elements through the bypass circuit.

Abstract: An electronic ballast includes an AC-DC converter, a DC-DC converter, a cooling device and a power supply. The cooling device is configured to cool the light source. The power supply includes a first power supply configured to generate a first operating voltage from a first voltage obtained from a chopper circuit included in the AC-DC converter to supply the first operating voltage to at least one of the AC-DC converter and the DC-DC converter. The power supply further includes a second power supply configured to generate a second operating voltage from a second voltage obtained from the chopper circuit to supply the second operating voltage to at least the cooling device of the AC-DC converter, the DC-DC converter and the cooling device.

Abstract: A lighting device that is connected to a DC power source and supplies an electric current to a solid-state light-emitting element (LED) whose forward voltage ranges from Vfmin to Vfmax includes a DC/DC converter (buck converter) and a control unit. The DC/DC converter includes a switching element. The control unit turns OFF the switching element by peak current control, and when the solid-state light-emitting element to be connected to the lighting device has a forward voltage of Vfmax, turns ON the switching element in fixed cycles such that the DC/DC converter operates in BCM.

Abstract: A lighting device includes a DC/DC converter (step-down chopper circuit) and a control circuit that includes a correction circuit. The correction circuit corrects the timing at which a switching element included in the DC/DC convertor is turned OFF based on a voltage value across a solid-state light-emitting element (LED unit). The correction is made such that an average value of a current flowing through an inductor included in the DC/DC converter is within a predetermined range regardless of a voltage value across the solid-state light-emitting element.

Abstract: A lighting device that lights up an LED and includes a DC power source, a buck converter and a control circuit. The buck converter includes a switching element, an inductor and a diode. The control circuit includes a current detection circuit that detects an electric current flowing through the switching element, a voltage detection circuit that detects a voltage across the inductor, a delay circuit that generates a delay time according to the voltage detected by the voltage detection circuit, and a drive circuit that generates and outputs a control signal to the switching element, the control signal turning OFF the switching element after a lapse of the delay time generated by the delay circuit from when the electric current detected by the current detection circuit reaches a predetermined current command value.

Abstract: The lighting device according to the present invention includes a power supply circuit, a temperature detection circuit, and a temperature control circuit. The power supply circuit supplies operation power to a light source including a solid state light emitting device. The temperature detection circuit measures a surrounding temperature of the light source and outputs the measured surrounding temperature as a detection temperature. The temperature control circuit determines whether an increase rate of the surrounding temperature exceeds a predetermined criterion value. When determining that the increase rate exceeds the criterion value, the temperature control circuit performs a process of decreasing a temperature of the light source.

Abstract: The lighting device of the present invention includes: a power source configured to supply power to a plurality of light sources; and a cooling control circuit configured to control a plurality of cooling devices for respectively cooling the plurality of light sources. The cooling control circuit includes a power supply circuit, a plurality of output circuits, a plurality of temperature measurement circuits, and an output control circuit. The power supply circuit outputs a constant voltage by use of power from the power source. The output circuits receive the constant voltage from the power supply circuit and supply drive voltages to the plurality of cooling devices respectively. The temperature measurement circuits measure temperatures of the plurality of light sources respectively. The output control circuit regulates the drive voltages respectively supplied from the plurality of output circuits based on the temperatures respectively measured by the plurality of temperature measurement circuits.

Abstract: The lighting device according to the present invention includes: a power source configured to supply power to a light source having a plurality of regions; a plurality of cooling devices arranged corresponding to the plurality of regions to cool the plurality of regions, respectively; and a cooling control circuit configured to control the plurality of cooling devices. The cooling control circuit includes: a plurality of output circuits configured to supply drive voltages to the plurality of cooling devices by use of power from the power source to drive the plurality of cooling devices, respectively; a plurality of temperature measurement circuits configured to respectively measure temperatures of the plurality of regions; and an output control circuit configured to regulate the drive voltages respectively supplied from the plurality of output circuits based on the temperatures respectively measured by the plurality of temperature measurement circuits.

Abstract: A high pressure discharge lamp lighting device in this invention comprises a converter, an inverter, an igniter, a controller, and a pulse voltage detection circuit. The converter outputs the direct current voltage. The inverter converts the direct current voltage into the lighting voltage which is alternating current voltage, and applies the lighting voltage to the high pressure discharge lamp through an output terminal. The igniter is configured to output the pulse voltage superimposed on the lighting voltage, whereby the starting voltage is applied to the high pressure discharge lamp. The controller is configured to control the igniter to allow the igniter to superimpose the pulse voltage on the lighting voltage. The pulse voltage detection circuit detects the starting voltage to output the detection signal. The starting voltage regulation circuit regulates the starting voltage to the desired voltage value of the voltage on the basis of the detection signal.

Abstract: An electronic ballast provides controlled preheating for a discharge lamp. A power converting circuit receives a DC power input and converts it into an AC power output. A starting circuit coupled to the power converting circuit generates a high voltage for starting the lamp. A control circuit controls the power converting circuit to generate AC power output to the lamp dependent on a mode of operation. A symmetry detecting circuit determines a positive-negative symmetrical state of the output power provided to the discharge lamp with respect to ground. The control circuit has a starting mode wherein the discharge lamp is triggered to start with a high voltage generated by the starting circuit, an electrode heating mode wherein the AC power output of the power converting circuit is controlled to a first frequency for heating each lamp electrode, and a steady-state mode wherein the AC power output of the power converting circuit is controlled to a second frequency for maintaining lighting of the discharge lamp.

Abstract: A high pressure discharge lamp lighting device comprising an inverter, an igniter, a controller, a pulse voltage detection circuit, and the starting pulse voltage regulation circuit. The inverter applies a lighting voltage to a high pressure discharge lamp. The controller applies the starting pulse voltage generated by the igniter to the high pressure discharge lamp. The pulse voltage detection circuit is configured to detect a voltage indicative of the starting pulse voltage to output a detection signal. The starting pulse voltage regulation circuit is configured to regulate the starting pulse voltage to a desired value of the starting pulse voltage on the basis of the detection signal. The pulse voltage detection circuit is configured to detect either one of the voltage developed in the specified circuit component of the igniter and the starting pulse voltage as the voltage indicative of the voltage indicative of the starting pulse voltage.

Abstract: An electronic ballast is provided for controlled preheating of filaments in a discharge lamp. A power converter has a plurality of switching elements and converts DC power from a DC power source into AC power for the lamp. A starting circuit generates a high voltage for starting the lamp. A half-wave discharge detecting circuit detects an absolute value for each polarity peak of a lamp current, calculates an asymmetrical current value from the detected peaks with respect to a predetermined current threshold, and detects a half-wave discharge of the lamp wherein an absolute value of the asymmetrical current value is equal to or more than the current threshold for a predetermined determination time.

Abstract: A high pressure discharge lamp lighting device includes a DC power source circuit; a power supply circuit for converting an output from the DC power source circuit into a square wave AC output to be supplied to a high pressure discharge lamp; a starting circuit for applying a high voltage output for lamp startup to the high pressure discharge lamp; a control circuit; and a half-wave discharge detection circuit for detecting a half-wave discharge. The detection circuit detects the half-wave discharge at an initial stage of the lamp startup and the control circuit controls the magnitude of a voltage of a square wave half period of one polarity having a load voltage of a larger magnitude and that of a square wave half period of the other polarity having a load voltage of a smaller magnitude to approximate to each other.