Abstract: A lighting device that supplies current to light-emitting units includes: a DC-to-DC converter; a switch unit connected to the light-emitting units; and a control circuit which controls the DC-to-DC converter and the switch unit. The DC-to-DC converter includes: an inductor through which current from the DC-to-DC converter is provided to the light-emitting units; and a first switch element connected in series with the inductor and which switches ON/OFF. The control circuit includes: a zero-crossing detector that detects that current flowing in the inductor is substantially zero due to the first switch element switching OFF, and outputs a zero-current detection signal; and a switch controller that selects one of the light-emitting units and controls the switch unit to cause the current from the DC-to-DC converter to be supplied to the selected light-emitting unit when the first switch element subsequently switches ON, each time the switch controller receives the zero-current detection signal.

Abstract: A visible light communication modulation circuit includes a modulation resistance circuit configured to change a current flowing through an LED light source by changing a resistance thereof, a measurement circuit configured to simultaneously measure a voltage applied to the LED light source and the current flowing through the LED light source at least twice until the current is stabilized, an calculation circuit configured to obtain an equivalent series resistance of the LED light source based on at least two sets of voltage values and current values and determine a target resistance of the modulation resistance circuit based on the equivalent series resistance and a predetermined modulation degree, and a conversion circuit configured to change the resistance of the modulation resistance circuit based on the target resistance.

Abstract: A lighting system for controlling a plurality of light sources includes at least a first and a second light source, the second light source having a color temperature and relative luminous efficiency higher than those of the first light source. Further, the system includes: a driving unit configured to turn on and off each of the light sources; and a control unit configured to transmit a control signal to the driving unit in response to an input signal. In addition, the control unit transmits the control signal to the driving unit, to perform at least one of a fade-in control in which the first light source is turned on prior to the second light source when turning on the light sources and a fade-out control in which the second light source is turned off or is dimmed, prior to the first light source when turning off the light sources.

Abstract: A lighting device that supplies current to light-emitting units includes: a DC-to-DC converter; a switch unit connected to the light-emitting units; and a control circuit which controls the DC-to-DC converter and the switch unit. The DC-to-DC converter includes: an inductor through which current from the DC-to-DC converter is provided to the light-emitting units; and a first switch element connected in series with the inductor and which switches ON/OFF. The control circuit includes: a zero-crossing detector that detects that current flowing in the inductor is substantially zero due to the first switch element switching OFF, and outputs a zero-current detection signal; and a switch controller that selects one of the light-emitting units and controls the switch unit to cause the current from the DC-to-DC converter to be supplied to the selected light-emitting unit when the first switch element subsequently switches ON, each time the switch controller receives the zero-current detection signal.

Abstract: A lighting device includes: a DC converter including at least an inductor, a switching unit and a diode and being configured to output an energy accumulated in the inductor to a load via the diode by using an input from a DC power source when the switching unit is turned off; a load voltage detection unit connected to the load to detect a load voltage of the load; and an abnormality determining unit configured to determine an abnormality when the load voltage is equal to or less than a preset threshold voltage. The device further includes an output control unit configured to drive the switching unit so that oscillation of the switching unit is stopped or the output of the DC converter is decreased when the abnormality is determined.

Abstract: A lighting device for lighting a solid light-emitting element includes: a DC power source circuit configured to output DC power; a power conversion circuit including a semiconductor element connected between output terminals of the DC power source circuit, the power conversion circuit configured to supply power to the solid light-emitting element through a control of a conduction state of the semiconductor element; a first control circuit configured to control an output of the DC power source circuit; a second control circuit configured to control an output of the power conversion circuit by controlling the conduction state of the semiconductor element; and a short-circuit detection circuit configured to detect a short-circuit in the semiconductor element. The first control circuit reduces the output of the DC power source circuit when the short-circuit detection circuit detects the short-circuit in the semiconductor element.

Abstract: A visible light communication modulation circuit includes a modulation resistance circuit configured to change a current flowing through an LED light source by changing a resistance thereof, a measurement circuit configured to simultaneously measure a voltage applied to the LED light source and the current flowing through the LED light source at least twice until the current is stabilized, an calculation circuit configured to obtain an equivalent series resistance of the LED light source based on at least two sets of voltage values and current values and determine a target resistance of the modulation resistance circuit based on the equivalent series resistance and a predetermined modulation degree, and a conversion circuit configured to change the resistance of the modulation resistance circuit based on the target resistance.

Abstract: A lighting apparatus includes a power supply unit and a control unit configured to control the power supply unit. The control unit determines, at a time of activation of the lighting apparatus, a first color temperature of the load at an initial stage of lighting based on a command value. Thereafter, the control unit controls the power supply unit such that the light quantity and the color temperature of the load change according to a second output characteristic during a period in which the color temperature of the load changes from the first color temperature to a second color temperature. The second color temperature is a color temperature, in the first output characteristic, corresponding to the command value. A correspondence relationship between a plurality of light quantities and a plurality of color temperatures defined by the second output characteristic is different from that of the first output characteristic.

Abstract: A lighting apparatus includes a chopper circuit and a control circuit that controls the chopper circuit. The control circuit includes a determining unit that determines a duty ratio of a dimming signal, and an output control unit that outputs a drive signal. The control circuit outputs a drive signal from the output control unit according to a result of a determination by the determining unit and causes the solid state light-emitting element to be lighted in a normal mode. In the charging mode, the control circuit sets an average value of a current flowing through an inductor to be higher than in the normal mode and charges a smoothing capacitor until a voltage across the smoothing capacitor reaches a prescribed voltage. When power is supplied, the control circuit charges the smoothing capacitor in the charging mode and subsequently lights the solid state light-emitting element in the normal mode.

Abstract: A lighting apparatus includes a chopper circuit and a control circuit that controls the chopper circuit. The control circuit includes a determining unit that determines a duty ratio of a dimming signal, and an output control unit that outputs a drive signal. The control circuit outputs a drive signal from the output control unit according to a result of a determination by the determining unit and causes the solid state light-emitting element to be lighted in a normal mode. In the charging mode, the control circuit sets an average value of a current flowing through an inductor to be higher than in the normal mode and charges a smoothing capacitor until a voltage across the smoothing capacitor reaches a prescribed voltage. When power is supplied, the control circuit charges the smoothing capacitor in the charging mode and subsequently lights the solid state light-emitting element in the normal mode.

Abstract: A light emitting device includes a set of light source units including multiple types of solid state light emitting elements having different light colors, each of the light source units comprising the same type of the solid state light emitting elements connected in series and; and an information storage unit which stores information about electrical characteristic of the set of light source units. The information stored in the information storage unit represents a relationship between a light output and a drive current in the set of light source units.

Abstract: A lighting device includes an AC to DC conversion unit for receiving a setting signal and converting it into a DC voltage having a predetermined voltage, voltage conversion units for converting the DC voltage inputted from the AC to DC conversion unit and driving the light source modules according to drive signals, a PWM signal generating unit for generating a PWM signal having a duty ratio corresponding to the setting signal, and a control unit, by outputting the drive signals to the voltage conversion units based on a command value determined according to the duty ratio, for controlling output powers of the voltage conversion units such that a characteristic curve of the sum of the output powers of the voltage conversion units has the maximum or at least one inflection point within an adjustment range of the conduction angle.

Abstract: A lighting device for lighting a solid light-emitting element includes: a DC power source circuit configured to output DC power; a power conversion circuit including a semiconductor element connected between output terminals of the DC power source circuit, the power conversion circuit configured to supply power to the solid light-emitting element through a control of a conduction state of the semiconductor element; a first control circuit configured to control an output of the DC power source circuit; a second control circuit configured to control an output of the power conversion circuit by controlling the conduction state of the semiconductor element; and a short-circuit detection circuit configured to detect a short-circuit in the semiconductor element. The first control circuit reduces the output of the DC power source circuit when the short-circuit detection circuit detects the short-circuit in the semiconductor element.

Abstract: A lighting device includes an AC to DC conversion unit for receiving a setting signal and converting it into a DC voltage having a predetermined voltage, voltage conversion units for converting the DC voltage inputted from the AC to DC conversion unit and driving the light source modules according to drive signals, a PWM signal generating unit for generating a PWM signal having a duty ratio corresponding to the setting signal, and a control unit, by outputting the drive signals to the voltage conversion units based on a command value determined according to the duty ratio, for controlling output powers of the voltage conversion units such that a characteristic curve of the sum of the output powers of the voltage conversion units has the maximum or at least one inflection point within an adjustment range of the conduction angle.

Abstract: A lighting apparatus includes a power supply unit and a control unit configured to control the power supply unit. The control unit determines, at a time of activation of the lighting apparatus, a first color temperature of the load at an initial stage of lighting based on a command value. Thereafter, the control unit controls the power supply unit such that the light quantity and the color temperature of the load change according to a second output characteristic during a period in which the color temperature of the load changes from the first color temperature to a second color temperature. The second color temperature is a color temperature, in the first output characteristic, corresponding to the command value. A correspondence relationship between a plurality of light quantities and a plurality of color temperatures defined by the second output characteristic is different from that of the first output characteristic.

Abstract: An illumination system includes a lighting apparatus having a solid-state light emitting element as a light source; and a dimmer including a bidirectional switching element having a self-sustaining function and connected to a serial circuit of the lighting apparatus and an external power source. The dimmer varies a conduction angle of the bidirectional switching element by controlling a phase of an AC voltage of the external power source, wherein the lighting apparatus performs dimming of the light source based on the conduction angle of the bidirectional switching element, and the dimmer continues to apply driving current to the bidirectional switching element during a first period, which is a part of a second period, the bidirectional switching element being allowed to conduct throughout the second period.

Abstract: In a conventional example, even if a duty cycle of the burst dimming is changed during an OFF-period of a switching element, current flowing to an LED is maintained constant. On the other hand, in the present embodiment, an accumulated value of ON-periods of a switching element is increased or decreased so as to be linked to a minimum variation width for a duty cycle (a dimming level) of a dimming signal, regardless of a timing of when the duty cycle is changed. Therefore, a lighting system (an LED drive device) according to the present embodiment can change smoothly a light output of a solid-state light-emitting element (a light source) with respect to a change in a duty cycle of the burst dimming while preventing the switching frequency from increasing.

Abstract: A solid-state light-emitting element drive device includes a switching regulator and a control circuit. The switching regulator includes a series circuit of a switching element and an inductor, a regenerative element configured to allow a regenerative current to flow therethrough from the inductor when the switching element is turned off, and output terminals configured so that a solid-state light-emitting element is connected therebetween. The control circuit is configured to control a switching operation of the switching element of the switching regulator. The control circuit is configured to suppress an output power of the switching regulator if a parameter obtained from at least one of an ON-period and an OFF-period of the switching element is out of a prescribed range.

Abstract: A lighting device includes: a series circuit of an inductor and a switching element; a diode which regenerates and supplies an energy of the inductor; and a control circuit which controls on/off of the switching element. The control circuit includes a drive signal generator which outputs a high frequency pulse drive signal; and a drive control section which turns on and off the switching element based on the high frequency drive signal and a PWM signal. The drive signal generator changes an ON time of the high frequency drive signal such that, after the PWM signal is changed from OFF to ON, a peak value of the load current gradually drops along an envelope of a specific slope, and the specific slope of the envelope is changed based on a duty ratio of the PWM signal.

Abstract: A lighting device includes lighting control units respectively provided for controlling lighting of solid state light emitting element groups irradiating light of different chromaticities and a color ratio setting unit for setting a target output ratio of the solid state light emitting element groups. In an xy chromaticity diagram of an XYZ color system, a straight line connecting chromaticity coordinates of lights irradiated by a first and a second solid state light emitting element group intersects a black body locus. Further, the lighting control units include a first and a second lighting control unit for controlling lighting of the first and the second solid state light emitting element group, and the first and the second control unit perform a feedback control such that an output ratio of the second to the first solid state light emitting element group becomes equal to the target output ratio thereof.