Abstract: A lighting device includes: a DC power source circuit; an output control circuit including a chopping switch to adjust an output current by chopping of the chopping switch; light source switches respectively connected to the light sources; and a control unit for controlling a time period for which a current flows in the light sources. The control unit controls the output control circuit such that an operation period for which the chopping is conducted and a stop period for which the chopping is stopped are repeated alternately and performs switchover of the light source switches to be sequentially and selectively turned on, and the switchover is conducted during the stop period with a time interval from a beginning of the stop period.

Abstract: A control circuit is configured to convert a DC voltage that is outputted from a DC power supply to a square wave voltage by switching the switching element according to a PWM signal having a duty ratio that corresponds to a light modulation level of the light source unit, and cause the square wave voltage to be outputted to the light source unit. The control circuit includes a voltage controller configured to control an operating voltage for operating the switching element such that at least one of a rising time and a falling time of a current that flows through the switching element is 1 microsecond or more.

Abstract: A light source circuit includes light-emitting diodes and a constant current circuit that controls current flowing through light-emitting diodes to a fixed level. A DC power supply circuit outputs a DC voltage having a voltage value capable of causing light-emitting diodes to emit light. A light modulation control unit includes: a MOSFET electrically connected between DC power supply circuit and light source circuit; and a control circuit configured to control MOSFET. Control circuit is configured to turn MOSFET on and off with a duty ratio corresponding to a light modulation level such that DC voltage that is outputted from DC power supply circuit is converted to a square wave voltage, and the square wave voltage is outputted to light source circuit. The square wave voltage has an amplitude equal to the voltage value of the DC voltage that is outputted from DC power supply circuit.

Abstract: A control unit of a light source device after activation time is configured to turn on switches respectively connected in series with light sources, in prescribed order. The light source device and a lighting device are configured to transmit characteristics of the light sources, based on a voltage change depending on a pattern of on and off of the switches.

Abstract: A lighting device is configured such that only one of a first current control circuit and a charging current control circuit operates in any of operation modes from a first mode to a fourth mode. The lighting device is configured such that the first current control circuit and the charging current control circuit are not included in the same closed circuit.

Abstract: In a first control mode, a control circuit turns a switching element on and off at a predetermined oscillating frequency and an On time so that a current flows through inductor in continuous mode without a sleep interval. In a second control mode, control circuit fixes oscillating frequency of switching element and changes On time of switching element. In a third control mode, control circuit fixes On time of switching element and changes oscillating frequency of switching element. Second control mode and third control mode are allocated for at least two intervals of intervals into which a dimming range is divided. Control circuit selects first control mode to fully light a light source load, and then, if a dimming ratio is designated, control circuit selects one of second and third control modes according to the interval, to which the dimming ratio corresponds, to dim light source load.

Abstract: A lighting device includes a power conversion unit, an impedance adjustment unit, a first control unit, and a second control unit. The power conversion unit is configured to convert input power to direct-current power used for a light source. The impedance adjustment unit is formed of a series circuit of a resistor element and a switch element and is coupled to the light source in parallel, relative to the power conversion unit. The second control unit is configured to cause the power conversion unit to operate, for each burst cycle, for an operation period which is not longer than the burst cycle, and increase and reduce the ratio of the operation period to the burst cycle. The first control unit is configured to make the switch element conductive for a predetermined adjustment period which is not longer than the operation period, during the operation period.

Abstract: A lighting device includes a lighting unit which controls a current being supplied to a load, in which light emitting modules, each having one or more semiconductor light emitting elements connected in series, are connected in parallel, to be a constant current; a current detector which detects a current flowing through one of the light emitting modules; and an abnormality detector which compares a detected value from the current detector with an upper limit and a lower limit of a predetermined current range to detect an abnormality in the load. The abnormality detector detects the abnormality in the load if the detected value from the current detector is larger than the upper limit or smaller than the lower limit, and if the abnormality in the load is detected, the lighting unit reduces the current being supplied to the load.

Abstract: A lighting device includes: a lighting unit which outputs a direct current; a smoothing unit having a capacitor which smoothes the direct current outputted from the lighting unit and supplies it; and a control unit for performing an intermittent control which alternately repeats a first time period in which the direct current is supplied to the smoothing unit and a second time period in which the direct current decreases to be smaller than that in the first time period. In the lighting device, a product of a frequency (Hz) and a capacitance (?F) of the capacitor is equal to or greater than 0.05 in which one cycle of the frequency corresponds to a sum of the first time period and the second time period.

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: 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: 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: A lighting device includes a rectifier, a constant current regulator and a charge-discharge circuit. The constant current regulator is electrically connected in series with first and second solid-state light-emitting element arrays between a pair of output terminals of the rectifier. The constant current regulator is configured to adjust a current flowing through the second solid-state light-emitting element array to a constant current. The charge-discharge circuit is electrically connected in series with the first solid-state light-emitting element array between the pair of output terminals of the rectifier. The charge-discharge circuit includes a charge storage element, and is configured so that a charge current flows to the charge storage element through the first solid-state light-emitting element array, and so that a discharge current flows from the charge storage element to the second solid-state light-emitting element array.

Abstract: A lighting device includes: a plurality of DC power supply circuits. A plurality of light sources and switching units are connected to each of the DC power supply circuits, the switching units being configured to respectively switch electrical connection between the light sources and said each of the DC power supply circuits. A difference in rated voltage between any two light sources connected to one of the plurality of DC power supply circuits in common is smaller than a difference in rated voltage between two light sources respectively connected to different DC power supply circuits of the plurality of DC power supply circuits.

Abstract: A light source circuit includes light-emitting diodes and a constant current circuit that controls current flowing through light-emitting diodes to a fixed level. A DC power supply circuit outputs a DC voltage having a voltage value capable of causing light-emitting diodes to emit light. A light modulation control unit includes: a MOSFET electrically connected between DC power supply circuit and light source circuit; and a control circuit configured to control MOSFET. Control circuit is configured to turn MOSFET on and off with a duty ratio corresponding to a light modulation level such that DC voltage that is outputted from DC power supply circuit is converted to a square wave voltage, and the square wave voltage is outputted to light source circuit. The square wave voltage has an amplitude equal to the voltage value of the DC voltage that is outputted from DC power supply circuit.

Abstract: A control circuit selects a first control mode in which a switching element is turned on and off so that a current flows through an inductor in a critical or discontinuous mode, thereby fully lighting a light source load. The control circuit selects one of a second control mode in which On time of the switching element is changed and a third control mode in which an oscillating frequency is changed according to an interval, to which a designated dimming ratio corresponds, to dim the light source load. An output capacitor connected between output terminals of a step-down chopper circuit smoothes pulsation component of an output current supplied to the light source load and has capacity set so that a ripple ratio of the output current is less than 0.5 at full lighting of the light source load.

Abstract: A controller has a first mode and a second mode. First mode is of generating a PWM signal that has a duty ratio to be changed according to a luminous level for a light emitting element and has a constant amplitude. Second mode is of generating a PAM signal that has a constant duty ratio and has an amplitude to be changed according to the luminous level for the light emitting element. Controller is configured to apply one of PWM signal in first mode and PAM signal in second mode to a control terminal of a switching element, when the luminous level is a predetermined level or more. Controller is configured to apply the other of PWM signal in first mode and PAM signal in second mode to the control terminal of the switching element, when the luminous level is less than the predetermined level.

Abstract: In first mode, controller is configured, when receiving a dimming instruction signal, to control voltage-adjusting part to provide a DC voltage with a magnitude corresponding to a luminous level, across output ends of DC power supply, and apply a control voltage with a magnitude kept constant to a control terminal of switching element. In second mode, controller is configured, when receiving the dimming instruction signal, to apply the control voltage with a magnitude corresponding to luminous level to the control terminal of switching element, and control voltage-adjusting part to provide the DC voltage with a magnitude kept constant, across the output ends of DC power supply. Controller is configured to operate in one of first and second modes when luminous level is predetermined level or more, and in the other of first and second modes when luminous level is less than predetermined level.

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.