Abstract: A lighting fixture includes a power input configured to be coupled to a power source, a power output configured to be coupled to an external load and a lighting device, such as a light emitting diode (LED) device, coupled to the power input and configured to provide illumination. The lighting fixture further includes a protection circuit coupled between the power input and the power output and configured to detect a condition of a power source coupled to the power input and to control power transmission between the power input and the power output responsive to the detected condition. The power output may be configured to support daisy-chain connection of the lighting fixture to at least one other lighting fixture, and the protection circuit may be configured to control power transmission to the at least one other lighting fixture responsive to the detected condition.

Abstract: An improved LED traffic signal is provided. The LED traffic signal suitably includes a housing with an opening, a printed circuit board coupled to the housing, and a power supply system coupled to the printed circuit board. The power supply system includes a power supply module that receives an AC input voltage from an AC input line and transforms the AC input voltage into a DC voltage with a regulated current to power the LED load, and a synchronized power pulse circuit connected to the power supply that generates a synchronized power pulse representing a power consumption substantially equivalent to that of a halogen or incandescent traffic signal.

Abstract: Provided is a lighting ballast system and method for fluorescent lamps. The system and method utilize a lamp current control loop to control the light level of a fluorescent lamp. The ballast includes an open loop detector that recognizes an open current control loop as an indication of a fault or hazard condition, and causes the ballast to output a safe lamp voltage or no voltage. The fault or hazard condition may be, for example, a very high voltage at the lamp or very low current across the lamp. The ballast also includes a disable circuit that prevents the open loop detector from triggering at times when the loop is expected to be open such as during ignition and maintenance restarting of the lamp.

Abstract: A light emitting diode (LED) backlight driving circuit includes a power supply module. A controllable switch and a voltage dividing resistor module are successively connected in series between an output end of the power supply module and a grounding end of the LED backlight driving circuit. A control end of the controllable switch is coupled with a power management chip. The LED backlight driving circuit further includes a first resistor and a current regulation module, an output current of the current regulation module is regulable. One end of the first resistor is connected between the controllable switch and the voltage dividing resistor module, and another end of the first resistor is connected with a first reference voltage, the first reference voltage is constant. An output end of the current regulation module is coupled between the first resistor and the first reference voltage.

Abstract: A passive anti-arcing protection components for electronic ballasts of fluorescent lamps. This protection component is a bridge-rectifier-resistor-capacitor network, containing at least a diode, a resistor, and a capacitor. The component's circuitry is electrically connected to the ballast at the lamp side, acting as a low-resistance redirection path for any sudden change in energy. When an arcing condition is about to occur, this protection circuitry absorbs the spark energy, ceasing the arcing condition.

Abstract: A lighting system includes a plurality of LED lights having at least two different color LED lights. A controller is coupled to the LED lights for independently controlling the intensity of sets of different color LED lights. A program stored on a storage device is operable on the controller to control the intensity of each of the different sets of different color LED lights to produce light representative of color and intensity changes of outdoor daylight conditions.

Abstract: An automobile LED driving device includes a current setting portion to set multiple reference currents independently from one another for multiple respective current setting resistors connected externally, a current controller to select one of the multiple reference currents based on a control signal provided from outside, and an output transistor to control an output current to an automobile LED connected externally based on the reference current selected by the current controller.

Abstract: The present invention provides a light emitting diode (LED) driving device as a semiconductor device, which comprises: a direct current/direct current (DC/DC) controller, for controlling an output segment that is used to generate an output voltage from an input voltage and supply the output voltage to an LED; an output current driver, for generating an output current of the LED; and an LED short-circuit detection circuit, for monitoring a cathode voltage of the LED to perform an LED short-circuit detection, wherein the LED short-circuit detection circuit controls whether an action is performed or not according to a short-circuit detection enable signal input from outside the LED driving device.

Abstract: According to one or more embodiments, an inverter provides a light source with an input voltage. A protection circuit shuts down the inverter based on an overvoltage protection level that is detected based on the input voltage. A protection circuit control part shuts down the operation of the protection circuit during a predetermined interval. Abnormal operation of the protection circuit caused by a high voltage provided when the light source is turned on may be prevented. Therefore, a turn-on defect of the light source may be prevented.

Abstract: The invention relates to a spark gap having a plurality of individual spark gaps connected in series and present in a stacked arrangement, spaced apart from each other by insulating spacers (5) and nearly free of secondary current under typical operating conditions, wherein the individual spark gaps comprise electrodes (4) and outer connection electrodes are provided, and further having control elements for influencing the voltage distribution across the stacked arrangement and/or designed as an ignition aid. According to the invention, a mechanically pretensioned insulating element (8) can be inserted or pivoted between two adjacent electrodes (4) of the individual spark gaps, in order to interrupt the main current path of the spark gap in case of fault or overload.

Abstract: Output power of a laser beam emitted by a laser in an electro-optical reader is regulated by storing a killswitch byte in non-volatile memory, and by checking whether the killswitch byte is in a default state or a kill state prior to performing reading. A controller detects a fault condition and responsively changes the killswitch byte to the kill state, in order to permanently deenergize the laser and to maintain the laser permanently deenergized after the killswitch byte has been changed to the kill state.

Abstract: An LED lamp 20 according to one embodiment of the present invention includes a pair of input terminal parts 20a, 20c, a rectifier circuit unit 22, and an LED unit 24. And the LED lamp 20 has variable inductance units L50, L60 for causing an AC to flow from one of the pair of input terminal parts 20a, 20c to the other input terminal part through the rectifier circuit unit 22, a current detection unit 31 for detecting a magnitude of a DC flowing through the LED unit 24, and an inductance variable control unit 32 for making inductance values of the variable inductance units L50, L60 variable according to the magnitude of the DC detected by the current detection unit 31.

Abstract: An electric protection mechanism for a light controller includes an overload protection device. The overload protection device includes a lamplight controller, a power controller, and a load detector. A current sensor is provided between the power controller and a light. An overload detector is provided to detect the state of the electric current anytime. Once abnormal current is outputted to the light, the power controller immediately shuts its output and informs the lamplight controller of the abnormal current. The lamplight controller will reset its process, such as to shut down the power source or to press the button so as to return to normal. Thus, the lamplight controller, a light adjuster or a remote controller can be protected. The present invention provides an overload protection function, and it is safe to use the present invention.

Abstract: A system and method for streetlight control is provided. A lamp sensor inside a reflector of the streetlight is utilized to detect the output of a lamp of the streetlight. During daytime periods when the lamp is OFF, the lamp sensor is utilized to act as a day/night sensor by detecting ambient light near the lamp. When the ambient light level falls below a sufficient level indicative that night is approaching the lamp is turned ON and the lamp sensor utilized to detect the lamp output of the streetlight.

Abstract: An LED drive circuit connectable to a phase control type light adjuster includes a first reference voltage generation portion that generates a first reference voltage, a second reference voltage generation portion that generates a second reference voltage according to a phase angle of the light adjuster, an input voltage detection portion that detects a size relationship between an input voltage and a threshold value voltage, a current draw-out portion that draws out a current in accordance with the first reference voltage or the second reference voltage from an electricity supply line that supplies electricity to an LED drive portion, and a switch portion that in accordance with a detection result by the input voltage, detection portion, performs switching between an output from the first reference voltage generation portion to the current draw-out portion and an output from the second reference voltage generation portion to the current draw-out portion.

Abstract: A light-emitting-diode (LED) protection circuit, comprising: a light-emitting-diode module; two fuse elements, connected respectively to said LED module; and a discharge protection element, connected to said LED module and said two fuse elements. When current flowing through said fuse element exceeds a current protection value, said fuse element will turn into an open circuit state, to cut off an over current and prevent it from flowing to said LED module to avoid damages. In addition, when instantaneous high voltage occurs, such as incurred by a spike or a lightning, said discharge protection element can be used as an over current discharge route, to provide said LED module with a current bypass route.

Abstract: A light fixture includes a driver circuit that fully defines operational characteristics for operation outside of “Nominal Operation” of the driver circuit. The driver circuit increases a target current or set point when the current of the light source (i.e., output current of the driver circuit) or the voltage of the light source (i.e., output voltage of the driver circuit) is below a minimum operating current or minimum operating voltage of the driver circuit regardless of a command current level of the driver circuit. The driver circuit implements a soft start ramp up scheme having a default rate of increase for a set point or target current. After a shutdown, the driver circuit periodically attempts to restart operation by increasing the set point or target current from zero (i.e., shutdown) at a reduced rate as compared to the default rate.

Abstract: According to one embodiment, a luminaire includes a light-emitting module. The light-emitting module includes a light-emitting element and a capacitive element. The capacitive element is connected to the light-emitting element in parallel. The capacitive element has a withstand voltage higher than a breakdown voltage of the light-emitting element.

Abstract: Ballasts and LED drivers are presented for powering at least one light source, in which a shunt circuit provides a high impedance to allow operation of the light source when the AC input power exceeds a power threshold value, and provides a low impedance when the AC input power is below the power threshold value to prevent an output power stage from providing power to the light source.

Abstract: A driving method of a light source apparatus includes causing a primary light source to emit checking light. The checking light has light intensity sufficient to check a state of the light source apparatus and unharmful to the human body even when the checking light leaks. This emission is based on an output signal from a photodetector having detected a light radiated from a light conversion unit. The method further includes checking a state of the light source apparatus. The checking the state of the light source apparatus is based on an output signal from the photodetector having detected light radiated from the light conversion unit and entering the photodetector based on the checking light.

Abstract: Circuits useful in achieving efficient current control of LEDs based on a dimming control input are described. The circuits use a combination of PWM dimming and analog dimming to achieve a highly efficient LED driver over a wide range of dimming from near 0% to 100% light output.

Abstract: A high intensity discharge (HID) ballast circuit comprises a trigger circuit, a power half-bridge self-excited oscillation circuit, which is arranged to enable self-excited oscillation by energizing an angle capacitor Cgs with a Miller capacitor Cdg of a power MOSFET when an original single pulse output by the trigger circuit is excited, and then output self-excited oscillation signals; and a filter loop which is arranged to match impedance for the self-excited oscillation signals, thereby converting a low-impedance voltage source to a high-impedance constant current source. The inherent phase relationship of the power MOSFET is utilized, and oscillation signals are generated by a power half-bridge self-excited oscillation circuit, and then impedance matching for the oscillation signals is performed by the filter loop, and finally an HID lamp is triggered. As a result, damages to human eyes caused by stroboscopic effect can be avoided and electro magnetic compatibility test can be passed.

Abstract: A lighting arrangement comprises a checking device and a method for the control thereof, with a sensor device containing at least one light source, where the at least one light source radiates light with high radiant power which represents a danger to the eyes of operators or service personnel. A housing, which contains the at least one light source and prevents an emergence of light of the light source, is monitored as to whether the housing is open, where the at least one light source with high radiant power is switched off if there is detected upon the monitoring an opening of the housing, which permits an emergence of light of the light source. It is provided here that a lighting arrangement is switched on at the same time or later which has a radiant power not representing any danger to the eyes of operators or service personnel.

Abstract: The disclosure provides a load driving apparatus relating to an LED lamp and a method thereof and an illumination apparatus using the same. The disclosure can use a low-pass filter to filter out the high-frequency PWM signal output from the control chip and to provide a DC low voltage level to the PWM dimming pin of the control chip when the LED lamp gets short circuit. In this way, the control chip is able to entirely stop outputting the PWM signal in response to the DC low voltage level provided by the low-pass filter so as to avoid all the components in the load driving apparatus from damaging caused by the short circuit of the LED lamp.

Abstract: Embodiments of the invention provided a driving circuit for powering a light-emitting diode (LED) light source. The driving circuit includes a rectifier, a filter capacitor, and a control circuit. The rectifier converts an AC voltage from an AC power source to a rectified AC voltage. The filter capacitor coupled to the rectifier filters the rectified AC voltage to provide a DC voltage. The control circuit controls power supplied to the LED light source. The control circuit enables a discharging current periodically to discharge the filter capacitor if a switch coupled between an AC power source and a rectifier is turned off and disables the discharging current if the control circuit determines that the switch is turned on.

Abstract: The present application discloses an open circuit protecting circuit, an open circuit protecting method and an illuminating apparatus. The open circuit protecting circuit is configured in an apparatus with a LED load being supplied with power by a current source, and comprises: a switch circuit, a timer circuit and a detecting circuit. When the LED load malfunctions, the open circuit protecting circuit carries out the following operations: the detecting circuit sends an enabling signal to the timer circuit, the timer circuit sends a driving signal with a set time to the switch circuit and the switch circuit is in the on-state during the set time, so as to make the LED load be short circuited to protect the circuit from being damaged. The open circuit protecting circuit can also resume to normal work automatically after the open circuited malfunction is cleared, and thus a hot-plugging function can be realized.

Abstract: An electric protection mechanism for a light controller includes an overload protection device. The overload protection device includes a lamplight controller, a power controller, and a load detector. A current sensor is provided between the power controller and a light. An overload detector is provided to detect the state of the electric current anytime. Once abnormal current is outputted to the light, the power controller immediately shuts its output and informs the lamplight controller of the abnormal current. The lamplight controller will reset its process, such as to shut down the power source or to press the button so as to return to normal. Thus, the lamplight controller, a light adjuster or a remote controller can be protected. The present invention provides an overload protection function, and it is safe to use the present invention.

Abstract: Methods and apparati for controlling bleed current (IBLEED) in a driver circuit (20) for a lighting device (23). A method embodiment of the present invention comprises the steps of coupling a dimmer (21) to an input of the driver circuit (20), and forcing the bleed current (IBLEED) to be inversely proportional to the time-averaged voltage (VLEDP) at said lighting device (23). The dimmer (21) consumes power even when the lighting device (23) is not emitting light.

Abstract: An apparatus, method and system are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). A representative apparatus comprises: a plurality of LEDs coupled in series to form a plurality of segments of LEDs; first and second current regulators; a current sensor; and a controller to monitor a current level through a series LED current path, and to provide for first or second segments of LEDs to be in or out of the series LED current path at different current levels. A voltage regulator is also utilized to provide a voltage during a zero-crossing interval of the AC voltage. In a representative embodiment, first and second segments of LEDs are both in the series LED current path regulated at a lower current level compared to when only the first segment of LEDs is in the series LED current path.

Abstract: The driving circuit includes a power module, a plurality of LED modules, and a constant current component. Each LED module includes a bypass circuit and at least one light emitting diode. The light emitting diode is serially connected between a first end and a second end of the bypass circuit. The first end of each bypass circuit is coupled to the power module or a third end of an adjacent upstream bypass circuit for serially connecting the constant current component electrically, thereby achieving the illumination of different total numbers of LED units in accordance with various voltage changes, and cascade light emitting diodes having increased power efficiency.

Abstract: According to one embodiment, a marker lamp is supplied with electric power from an alternating constant-current power supply device via a saturable device. The marker lamp includes a solid-state light-emitting circuit functioning as a light source and a lighting circuit configured to subject the solid-state light-emitting circuit to lighting control. The marker lamp further includes an abnormality monitoring device configured to monitor a state of the solid-state light-emitting circuit and open, if detecting an abnormal state, an output side of the saturable device corresponding to the marker lamp.

Abstract: An LED driving circuit for driving an LED module is provided. The LED module is coupled to an inductor and a flywheel unit to provide a continuous current conduction of the inductor. A terminal of a converting switch is coupled to the LED module, and another terminal thereof is coupled to ground through a current detection unit that generates a current feedback signal to a controller, so as to stabilize a current flowing through the LED module. The LED driving circuit also includes a protecting circuit, which detects a potential of one end of the LED module to generate a detection signal and makes/has the converting switch to be turned off responsive to the detection signal. If the converting switch is turned off, driving of the LED module is stopped.

Abstract: An LED driver circuit prevents an increase in output voltage of a DC/DC converter in an open circuit condition associated with removal or failure of an LED lighting device. A DC power source provides a first DC voltage across positive and negative voltage rails. A DC/DC converter includes a switching element which when turned ON/OFF provides a second DC voltage across first and second ends of a capacitor which further define first and second LED lighting device connection terminals. A control circuit, upon receiving a drive power signal, turns ON/OFF the switching element to provide constant current control. A power supply circuit is coupled between the second LED lighting device connection terminal and the negative voltage rail and generates the drive power signal to the control circuit during a detected lighting condition. The power supply circuit further disables the drive power signal during a detected open circuit condition.

Abstract: A retained and a removable circuit connect together to form a closed circuit. A switching mechanism is connected between the retained and removable circuits and to a circuit break load. Upon disconnection of the circuit break load and/or the removable circuit, the switching mechanism automatically switches from an open circuit to a closed circuit to form a closed circuit with the retained circuit.

Abstract: The invention discloses an illumination controlling circuit coupled between a household electricity input and an illumination lamp. The illumination controlling circuit includes a dimmer module, a sampling-and-holding circuit, a differential circuit, an integrator circuit and a clamping circuit. The dimmer circuit is used for generating a dimming signal which includes a plurality of waveform pulses. The sampling-and-holding circuit samples from the dimming signal, so as to obtain an average waveform pulse. The differential circuit is used for extracting a voltage difference of the average waveform pulse. The integrator circuit performs integration on the average waveform pulse according to the voltage difference, so as to generate a direct current voltage signal. When a level of the direct current voltage signal exceeds a threshold voltage level of the clamping circuit, the direct current voltage signal is used for driving the illumination lamp.

Abstract: A light source package for selectively interrupting power to a light source is provided. An optical element is positioned to reflect a reflected portion of the light from the light source. The reflected portion impinges upon a base that includes a roof panel with a light source side and a sensor side that is opposite to the light source side. The light source side of the roof panel receives the reflected portion of the light and transmits a transmitted portion of the light through the roof panel. The sensor side of the roof panel includes a recess in which a sensing component is located. The sensing component receives the transmitted portion of the light and is be configured to interrupt power to the light source when the transmitted portion of the light is below a threshold.

Abstract: A self-heating thermal protector operates to disconnect a load control device for a lighting load from an AC power source when insulation is present around the insulation detector independent of the magnitude of an AC mains line voltage of the AC power source. The insulation detector comprises a temperature-sensitive switch and a constant power circuit that are located in a thermally-conductive enclosure. The temperature-sensitive switch is coupled between the AC power source and the load control device and is rendered conductive and non-conductive in response to a temperature inside the enclosure. The constant power circuit is coupled in parallel with the AC power source and dissipates a constant amount of power independent of the magnitude of the AC mains line voltage when the temperature-sensitive switch is conductive. Restricted airflow over the thermal protector causes the temperature inside the enclosure to increase, such that the temperature-sensitive switch is rendered non-conductive.

Abstract: An organic light emitting display device includes a display panel including an organic light emitting diode, a power supply including a DC-DC converter that generates a driving voltage for the organic light emitting diode and that provides the driving voltage to the display panel, the DC-DC converter including an inductor and a switch, and an over-current prevention unit that blocks supply of the driving voltage when a value of a current flowing through the inductor is greater than a reference value.

Abstract: A light control apparatus and a lighting appliance using the same enable increased luminous efficiency in light control and elongated operative life of a light source. The lighting appliance includes a light source and a light control apparatus. The light control apparatus comprises an electric current output circuit that outputs a constant electric current for lighting to a light source configured of an organic electroluminescence device, and a light control circuit that performs light control of the light source by intermittently supplying the constant electric current outputted from the electric current output circuit. The light control apparatus also comprises an electric discharge prevention circuit (diode) that prevents electric discharge of an electric charge charged in a capacitive component of the organic electroluminescence device.

Abstract: A bypass circuit is provided for each LED in a series to permit continued operation with reduced lighting in the event of an LED failure. The bypass circuit is provided in parallel to the LED and comprises a Zener Diode provided in parallel to a thyristor. Upon LED failure, the voltage across the Zener Diode is increased thereby triggering the thyristor which is maintained in a triggered mode as long as current flows through the series circuit.

Abstract: Methods of protecting an electrical device, such as a ballast, from damage due to an inrush current, and devices incorporating such methods, are disclosed. A loss of input power received by the ballast is detected. In response, the ballast is entered into a standby mode. The ballast is able to remain in the standby mode for a standby period of time. The input power is monitored during the standby period of time to measure a start time. Measurement of the start time is triggered by the ballast receiving input power again. The ballast is entered into an active mode when the measured start time exceeds a protection time. The protection time corresponds to an amount of time needed for an inrush current to dissipate following input power again being received by the ballast, protecting the ballast from possible damage due to the inrush current.

Abstract: A backlight protection circuit includes a driving circuit, two lamps, a pulse modulator, and a feedback circuit. The pulse modulator controlling the operating state of the driving circuit includes an over-voltage sampling end. Each of the two lamps includes a high voltage end connected to the driving circuit, and a low voltage end connected to the over-voltage sampling end through the feedback circuit. The pulse modulator stops the operation of the driving circuit when the voltage of the low voltage end exceeds a reference voltage.

Abstract: The present invention provides a light emitting diode (LED) driving device as a semiconductor device, which comprises: a direct current/direct current (DC/DC) controller, for controlling an output segment that is used to generate an output voltage from an input voltage and supply the output voltage to an LED; an output current driver, for generating an output current of the LED; and an LED short-circuit detection circuit, for monitoring a cathode voltage of the LED to perform an LED short-circuit detection, wherein the LED short-circuit detection circuit controls whether an action is performed or not according to a short-circuit detection enable signal input from outside the LED driving device.

Abstract: A lighting apparatus for a fluorescent tube and a driving method thereof are provided. The lighting apparatus includes a fluorescent tube, an open-loop protection unit and a driving device. The driving device includes an inverter and a power unit. The open-loop protection unit detects and determines an open-loop situation of two nodes of the fluorescent tube to produce an open-loop protection signal. The inverter receives a power voltage to light the fluorescent tube with a dual high-voltage method according to a trigger signal. The power unit coupled to the open-loop protection unit and the inverter provides the power voltage and determines whether to turn off the inverter according to the open-loop protection signal. When the open-loop situation of the fluorescent tube is occurred or driving voltage of the fluorescent tube is greater than a rated operating voltage, the inverter is turned off immediately to avoid components from overheating or burning.

Abstract: A electronic ballast according includes a DC power source circuit for generating a DC voltage from an AC power source, a pair of switching elements, an LC series resonance circuit, an inverter circuit for converting the DC voltage into a high frequency voltage to supply to a fluorescent lamp FL, and means such as a current transformer for detecting a current flowing into the fluorescent lamp FL, wherein oscillation of the inverter circuit is stopped when a value of a current flowing into the fluorescent lamp exceeds a predetermined value.

Abstract: Disclosed is an organic EL illuminating apparatus which can detect a short-circuit when the short-circuit is generated in one area between the anode and the cathode. The organic EL illuminating apparatus is provided with: an organic EL illuminating device (1); a drive circuit (2) which turns on the organic EL illuminating device (1); an illuminance detection monitor (3) which monitors the lighting state of the organic EL illuminating device (1); and a monitor detection signal feedback circuit (4) which makes the drive circuit (2) turn off the organic EL illuminating device (1), on the basis of monitor information obtained from the illuminance detection monitor (3) .

Abstract: According to one embodiment, there is provided a light emitting device including an organic electroluminescent device that includes a first electrode, a light emitting layer arranged above the first electrode, and a second electrode arranged above the light emitting layer, a drive circuit that supplies a drive current between the first electrode and the second electrode to drive the organic electroluminescent device, and a drive stop circuit that stops the driving of the organic electroluminescent device when a value of the drive current falls below a predetermined value.

Abstract: A circuit that can detect computer states. When the computer in a S3 state, a S3 state pin of the computer is at low level, and a S4 state pin of the computer is at high level. A first light emitting diode is turned on and emits light, indicating that the computer is in the S3 state. The circuit also detects an S4 state, a network state, a hard disk state, a network awakening state, a network booting state, a low power state, and a management engine state of the computer according to seven other light emitting diodes.

Abstract: An LED driving circuit for driving an LED module is provided. The LED module is coupled to an inductor and a flywheel unit to provide a continuous current conduction of the inductor. A terminal of a converting switch is coupled to the LED module, and another terminal thereof is coupled to ground through a current detection unit that generates a current feedback signal to a controller, so as to stabilize a current flowing through the LED module. The LED driving circuit also includes a protecting circuit, which detects a potential of one end of the LED module to generate a detection signal and makes/has the converting switch to be turned off responsive to the detection signal. If the converting switch is turned off, driving of the LED module is stopped.

Abstract: A lighting apparatus includes a lighting circuit unit, a timer unit, a life judgment unit, a timing adjustment unit, and an indication unit. The lighting circuit unit is configured to activate a light source. The timer unit is configured to measure accumulated operation time of the lighting circuit unit. The life judgment unit is configured to store a first judgment time and a second judgment time longer than the first judgment time. The life judgment unit is configured to compare the accumulated operation time with the first judgment time and output a first judgment signal when the accumulated operation time becomes equal to the first judgment time. The life judgment unit is configured to compare the accumulated operation time with the second judgment time and output a second judgment signal when the accumulated operation time becomes equal to the second judgment time. The timing adjustment unit is configured to vary timing at which the life judgment unit outputs the first judgment signal.