Abstract: According to one embodiment, a lighting device includes a lighting circuit. The lighting circuit includes a direct-current power supply and a DC-DC converter, and lights an illumination lamp by constant-current control. An output capacitor is connected in parallel to an output end of the DC-DC converter. A capacitance of the output capacitor is set to such a value that a peak value of a pulse-like current flowing when the illumination lamp is instantaneously detached from and attached to the output end of the DC-DC converter is one or more and four or less times a load current of the illumination lamp.

Abstract: According to one embodiment, a lighting device includes a lighting circuit and a control circuit. The lighting circuit includes an output end to which an illumination lamp is connected, and lights the illumination lamp by a direct-current power. The control circuit controls the lighting circuit so that power consumption caused by a contact resistance at a connection part between the illumination lamp and the output end of the lighting circuit during whole light lighting of the illumination lamp does not exceed a specified value set to 8 W or less.

Abstract: A DC power source unit 37 is provided which boosts source voltage from a power source portion 36. A lighting circuit 38 is provided which supplies DC voltage to loads, the DC voltage being obtained by stepping down output current of the DC power source circuit 37. A control circuit 39 is provided which controls the lighting circuit 38 in accordance with at least either voltage or current of LEDs 25 and controls the DC power source unit 37 so that a ratio of output voltage to voltage of the LEDs 25 becomes a preset fixed ratio.

Abstract: A dedicated power source for LED lamps capable of reliably detecting attachment of an LED lamp is provided. A dedicated power source has a DC power source portion, and includes a lighting circuit which receives power supplied from the DC power source portion and light-controls an LED lamp including an LED element and a detection resistor connected in parallel to the LED element and an attachment detecting portion for detecting attachment of the LED lamp based on a voltage level changing in accordance with attachment/detachment of the detection resistor by attachment/detachment of the LED lamp.

Abstract: The LED lighting device includes a lighting circuit unit, a current detecting unit, a voltage detecting unit, and a control unit. The lighting circuit unit is adapted in use to be connected to a lamp socket to be connected to a LED lamp, and is configured to provide an output voltage in the form of a DC voltage to the lamp socket in a manner to turn on the LED lamp. The current detecting unit is configured to detect an output current which is caused by the output voltage and is supplied from said lighting circuit unit to said lamp socket. The voltage detecting unit is configured to detect the output voltage of said lighting circuit unit. The control unit configured to control the lighting circuit unit.

Abstract: An LED lamp system which suppresses flickering of an LED element is provided. The LED lamp system includes straight-tube type LED lamps each having LED elements and a dedicated power source for lighting the LED elements. The dedicated power source full-wave rectifies and smoothes a commercial AC power source, outputs constant current having a ripple factor of 1.3 or smaller and thus lights the LED elements.

Abstract: According to one embodiment, there is provided a lighting fixture including a fixture body, straight-tube type LED lamps each having semiconductor light emitting elements, and a dedicated power source for lighting the semiconductor light emitting elements. The dedicated power source outputs current having a trapezoidal waveform a period of a peak portion of which is 54% or more of one cycle, and thus lights the semiconductor light emitting elements.

Abstract: In one embodiment, a DC power supply unit includes a DC power supply source; a load circuit connected to an output end of the DC power supply source; a load state detection device to detect a load voltage or an electric quantity corresponding to the load voltage; and a control device to receive the detected output of the load state detection device. The control device controls a maximum output voltage of the DC power supply source so that the voltage difference between the maximum output voltage of the DC power supply source and the load voltage at the time of normal operation falls within a predetermined range in which arc discharge is suppressed.

Abstract: Certain embodiments provide an LED lighting equipment including a lighting main body. An LED power device has a DC power source and a DC-DC converter having an input terminal connected to the DC power source and the DC-DC converter having an output terminal. An LED light source has a board and a plurality of LED packages; each including a plurality of LED chips connected in series. The LED packages are mounted on the board and connected in series to the output terminal of the DC-DC converter.

Abstract: A light-emitting device and an illumination apparatus are disclosed. A plurality of LED elements are connected in series between positive and negative lines, and first bypass capacitor is connected in parallel to the LED elements respectively. Each series circuit of a predetermined number of LED elements is connected in parallel to second bypass capacitors. As a result, with the negative power line set as a grounding point, the AC impedance at connection points of the series circuit of the LED elements against the ground is reduced. Thus, the erroneous lighting or “flicker” of each LED which otherwise might be caused by an external noise is prevented.

Abstract: In a power supply unit, if a dimmer rate is changed within a range of k1, k2, . . . k7 by a dimmer signal k of a dimmer signal generator, light-emitting diodes are controlled to be lighted by a constant current characteristic in an area where the dimmer rate is small according to a load characteristic corresponding to the dimmer rates k1, k2, . . . k7. As the dimmer rate becomes deeper, a tendency of a constant voltage characteristic is gradually strengthened from a constant current characteristic so that the light-emitting diodes are lighted at the deeper dimmer rate.

Abstract: An LED lighting device includes light emitting diode, a current control circuit having a first series circuit of first and second switching elements, a second series circuit of third and fourth switching elements, and a condenser, which is configured so that the first and second series circuits are parallel connected and the condenser is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements, and a control circuit for alternatively on-off controlling a pair of the first and fourth switching elements and a pair of the second and third switching elements.

Abstract: An electronic ballast comprises a direct current power supply configured to provide a direct current voltage. A switching circuit, including first and second switching elements, is connected in parallel with the direct current power supply, and is configured to convert the direct current voltage to a high-frequency alternating current. A load circuit, including a discharge lamp, a resonance inductor, and a resonance capacitor, is operated by the high-frequency alternating current. A driving circuit is arranged between the switching circuit and the load circuit. A driving circuit is provided with feedback windings magnetically connected to a detecting winding of the current transformer. A driving circuit is configured to control a switching frequency of the first and second switching elements according to a detected current of the detecting winding. A magnetic energy control means is configured to control a magnetic energy of the current transformer.

Abstract: An electronic ballast comprises a direct current power supply configured to provide a direct current voltage.