Abstract: A lighting device includes a voltage conversion circuit having at least a switching element connected to a positive potential side of the output terminals of the DC power source unit, and a drive unit which outputs a drive signal to the switching element. The drive unit has a first impedance element with a first impedance which is determined based on a power consumed by the drive unit before a predetermined time has elapsed after a control power source is supplied. A control capacitor for use in generating the drive signal is charged when the switching element is turned off during an on/off operation of the switching element. The lighting device further includes a second impedance element with a second impedance having a resistance component, which is arranged in a path in which the control capacitor can be charged in DC when the switching element does not perform the on/off operation.

Abstract: A control unit controls an operation of an electric power conversion unit so that load current that flows through a light source load becomes a constant value, using electric power setting value that is used to determine a size of electric power that is supplied to the light source load and a current detection value that is detected by a current detection resistor (current detection unit), and a load electric power calculation unit obtains load electric power of the light source load using the electric power setting value and a voltage detection value that is detected by a voltage detection unit, and an input electric power estimation unit corrects a circuit loss for the obtained load electric power and estimates input electric power.

Abstract: A lighting device (10) includes a voltage converter (2) for generating a predetermined DC voltage, a detector (4) for obtaining a detection voltage corresponding to a predetermined DC voltage applied across a light source (20), a controller (3) for controlling the voltage converter (2) so that a current flowing through the light source (20) is constant, and a determination unit (5) for determining whether the detection voltage is a preset first reference voltage or higher. The first reference voltage is set higher by a specified voltage than the detection voltage, and is set to vary more slowly than the detection voltage. The controller (3) stops an operation of the voltage converter (2) when the detection voltage is determined to be the first reference voltage or higher through the determination unit (5).

Abstract: An LED lighting device includes a DC/DC power converter having output terminals coupled to respective lamp sockets. A controller receives signals from a current sensor and a voltage sensor, and controls the DC/DC power converter to increase/decrease an output voltage based on a sensed output current with respect to a target value. A sensed output voltage is compared to predetermined upper and lower limit values, and the DC/DC power converter is disabled when the output voltage exceeds the predetermined upper limit value or falls below the predetermined lower limit. The controller further measures an accumulated lighting time of the device, and after the accumulated lighting time has exceeded a predetermined switching time, decreases the upper limit value monotonously or in increments as the accumulated lighting time passes.

Abstract: An LED lighting device includes a converter for converting a power source voltage into a DC voltage and outputting it to an LED unit; and a controller for controlling an output of the converter. The converter has a chopper circuit including a series circuit of an inductance element and a capacitor; a switching element connected to the inductance element in series and turned on/off by the controller; and a diode as discharging path of the inductance element during an OFF state of the switching element. The controller controls an on/off time of the switching element such that a current supplied to the LED unit during a specific time period after a lighting operation is started becomes smaller than a current supplied to the LED unit in a steady state by using a voltage generated in a secondary coil of the inductance coil as an operating voltage thereof.

Abstract: An LED lighting device includes a power converter for outputting a variable output voltage, two LED lamps being connected in series between output terminals of the power converter; a current detector for detecting an output current from the power converter; a first detector for detecting the output voltage of the power converter and generating a first detection voltage corresponding to the output voltage; a second detector for detecting an applied voltage to one of the two LED lamps and generating a second detection voltage corresponding to the applied voltage; and a controller for controlling the power converter to adjust the output voltage to thereby make the output current coincide with a target value. The controller controls the power converter to decrease the output voltage if at least one of the second detection voltage and the deference between the first and the second detection voltage does not fall within a range.

Abstract: A lighting device (10) includes a voltage converter (2) for generating a predetermined DC voltage, a detector (4) for obtaining a detection voltage corresponding to a predetermined DC voltage applied across a light source (20), a controller (3) for controlling the voltage converter (2) so that a current flowing through the light source (20) is constant, and a determination unit (5) for determining whether the detection voltage is a preset first reference voltage or higher. The first reference voltage is set higher by a specified voltage than the detection voltage, and is set to vary more slowly than the detection voltage. The controller (3) stops an operation of the voltage converter (2) when the detection voltage is determined to be the first reference voltage or higher through the determination unit (5).

Abstract: An LED lighting device includes: a power source unit for supplying the DC output voltage to a light-emitting diode; a control unit for adjusting the DC output voltage; and a control power source unit for supplying a control power to the control unit. The control power source unit generates the control power with the DC output voltage and has: a current-limiting resistor for limiting an electric current that flows from the power source unit to the control unit; a constant voltage unit for converting a voltage to be applied to the control unit through the current-limiting resistor unit to a constant voltage; and a switching unit for switching a resistance value of the current-limiting resistor unit among a plurality of resistance values.

Abstract: A control unit controls an operation of an electric power conversion unit so that load current that flows through a light source load becomes a constant value, using electric power setting value that is used to determine a size of electric power that is supplied to the light source load and a current detection value that is detected by a current detection resistor (current detection unit), and a load electric power calculation unit obtains load electric power of the light source load using the electric power setting value and a voltage detection value that is detected by a voltage detection unit, and an input electric power estimation unit corrects a circuit loss for the obtained load electric power and estimates input electric power.

Abstract: An LED lighting device includes a step-up chopper which includes a first switching element and increases an output voltage applied from a DC power supply, a step-down chopper which includes a second switching element and decreases the output voltage from the step-up chopper to apply the decreased output voltage to a light source unit having light emitting diodes, a controller which controls operations of the first and the second switching element, a current limiter which includes a current limiting element and a switch; and a voltage detection unit. The controller stops an operation of the first switching element when the voltage detection unit detects the voltage applied to the light source unit exceeding a predetermined voltage value, and the switch allows a current to flow through the path passing through the current limiting element when the operation of the first switching element is stopped.

Abstract: An LED lighting device includes: a power source unit for supplying the DC output voltage to a light-emitting diode; a control unit for adjusting the DC output voltage; and a control power source unit for supplying a control power to the control unit. The control power source unit generates the control power with the DC output voltage and has: a current-limiting resistor for limiting an electric current that flows from the power source unit to the control unit; a constant voltage unit for converting a voltage to be applied to the control unit through the current-limiting resistor unit to a constant voltage; and a switching unit for switching a resistance value of the current-limiting resistor unit among a plurality of resistance values.

Abstract: An LED lighting device includes a DC/DC power converter having output terminals coupled to respective lamp sockets. A controller receives signals from a current sensor and a voltage sensor, and controls the DC/DC power converter to increase/decrease an output voltage based on a sensed output current with respect to a target value. A sensed output voltage is compared to predetermined upper and lower limit values, and the DC/DC power converter is disabled when the output voltage exceeds the predetermined upper limit value or falls below the predetermined lower limit. The controller further measures an accumulated lighting time of the device, and after the accumulated lighting time has exceeded a predetermined switching time, decreases the upper limit value monotonously or in increments as the accumulated lighting time passes.

Abstract: An LED lighting device includes a power converter for outputting a variable output voltage, two LED lamps being connected in series between output terminals of the power converter; a current detector for detecting an output current from the power converter; a first detector for detecting the output voltage of the power converter and generating a first detection voltage corresponding to the output voltage; a second detector for detecting an applied voltage to one of the two LED lamps and generating a second detection voltage corresponding to the applied voltage; and a controller for controlling the power converter to adjust the output voltage to thereby make the output current coincide with a target value. The controller controls the power converter to decrease the output voltage if at least one of the second detection voltage and the deference between the first and the second detection voltage does not fall within a range.

Abstract: An LED lighting device includes a converter for converting a power source voltage into a DC voltage and outputting it to an LED unit; and a controller for controlling an output of the converter. The converter has a chopper circuit including a series circuit of an inductance element and a capacitor; a switching element connected to the inductance element in series and turned on/off by the controller; and a diode as discharging path of the inductance element during an OFF state of the switching element. The controller controls an on/off time of the switching element such that a current supplied to the LED unit during a specific time period after a lighting operation is started becomes smaller than a current supplied to the LED unit in a steady state by using a voltage generated in a secondary coil of the inductance coil as an operating voltage thereof.

Abstract: An LED lighting device includes a step-up chopper which includes a first switching element and increases an output voltage applied from a DC power supply, a step-down chopper which includes a second switching element and decreases the output voltage from the step-up chopper to apply the decreased output voltage to a light source unit having light emitting diodes, a controller which controls operations of the first and the second switching element, a current limiter which includes a current limiting element and a switch; and a voltage detection unit. The controller stops an operation of the first switching element when the voltage detection unit detects the voltage applied to the light source unit exceeding a predetermined voltage value, and the switch allows a current to flow through the path passing through the current limiting element when the operation of the first switching element is stopped.