Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Panasonic Electric Works Co., Ltd.

Katsuyoshi Nakada

Koji Watanabe

Junichi Hasegawa

Tomoyuki Nakano

Hirofumi Konishi

Toshiaki Sasaki

Nobuo Ukita

Kiyoaki Uchihashi

Hisanaga Onishi

Kenichi Fukuda

Satoshi Yagi

Akihiro Kishimoto

Keisuke Ueda

Kei Mitsuyasu

Shinichiro Goto

Tomohiro Sugiura

Hisaji Ito

A lighting device which outputs a DC current to a load, the lighting device including: a downconverter circuit which includes a switching element and steps down a DC voltage input to the downconverter circuit; and a controller which controls turning on and off of the switching element, wherein the controller has operating modes including a detection mode in which the controller detects a time taken for a current through the switching element to reach a predetermined value after the switching element turns on, the current through the switching element representing the DC current output to the load.

Lighting device and lighting fixture for current control with a solid-state lighting element

A dimming lighting circuit includes: a rectifier circuit; a phase detection circuit which outputs a dimming signal having a signal level corresponding to a conduction phase angle of an AC voltage; and a DC-DC converter which receives a DC voltage output from the rectifier circuit and supplies a light source with a DC current corresponding to the signal level of the dimming signal output from the phase detection circuit. If the conduction phase angle detected when the dimming lighting circuit receives the AC voltage at power-on is less than or equal to a predetermined angle, the phase detection circuit outputs, as the dimming signal, a substitute signal having a signal level corresponding to a conduction phase angle greater than the conduction phase angle of the AC voltage, for a predetermined time period.

Dimming lighting circuit and luminaire

A lighting device includes a switching regulator having an inductor and a switching device, and a controller. The controller includes a peak current detector that outputs a peak detection signal when detecting that a current flowing through the switching device reaches a threshold, a zero-cross detector that outputs a zero-cross detection signal when a current discharged from the inductor reaches a predetermined lower limit value or less, a synchronization signal controller that outputs a periodic synchronization signal, and a switching controller. The switching controller turns on the switching device in synchronization with a start of an on-period of the synchronization signal and the zero-cross detection signal, and turns off the switching device in synchronization with the peak detection signal. The peak current detector reduces the threshold when an on-period of the synchronization signal finishes, and increases the threshold to an original value when an on-period of the synchronization signal starts.

Lighting device and luminaire

The controller changes an applied time (ON-time) of a DC voltage while keeping an intermittent period in which the DC voltage is supplied intermittently constant, when adjusting an average value of currents to a predetermined reference value or more, and changes a stopped time (OFF-time) of the DC voltage together with the intermittent period while keeping the applied time constant, when adjusting the average value to a value less than the predetermined reference value. Therefore, the lighting device can reduce variation in emission color compared with the conventional lighting device adopting DC Dimming Method, and can reduce variation in amount of light compared with the case where ON-time is changed until the dimming level reaches a lower limit. As a result, the lighting device can modulate light even at a low dimming level while reducing variation in emission color and variation in amount of light.

Lighting device and lighting fixture

In order to suppress a peak of an excessive current and suppress a variation in a resonance voltage of a resonator, which are likely to occur immediately after a discharge lamp starts lighting, in a case where a high-frequency current continuously flows asymmetrically with respect to a zero current instead of flowing symmetrically on positive and negative sides immediately after the lighting since electrodes of the discharge lamp are not evenly warmed, the resonance voltage and the high-frequency current are finely adjusted in a resonance voltage and high-frequency current setting method including setting a drive frequency of an inverter circuit and varying output from a down-converter.

Discharge lamp lighting apparatus

A high pressure discharge lamp ballast is provided with a control operation for stable transition from a lamp ignition mode into a preheating mode. An inverter is coupled across a DC source and has a plurality of switching elements coupled to the high pressure discharge lamp. A series resonant LC circuit is coupled to the inverter outputs and to the high pressure discharge lamp. A control circuit is coupled to the switching elements and configured to control switching operation. An ignition mode has one or more time periods during each of which a driving frequency of the switching elements is swept through a predetermined range of frequencies and then controlled at a first driving frequency less than the predetermined range of frequencies. A preheating mode follows wherein the switching elements are controlled at a second driving frequency less than the predetermined range of frequencies.

Startup control for a high pressure discharge lamp ballast

An electronic ballast is provided for powering a high intensity discharge lamp. A voltage step-down circuit is arranged to reduce an input DC voltage. An inverter circuit includes at least one high frequency switching element is and arranged to convert the reduced voltage to a high frequency AC voltage. A resonant circuit receives the high frequency voltage and is further coupled to the discharge lamp. A voltage step-down control circuit controls the DC voltage output from the voltage step-down circuit. A driving circuit supplies a driving signal to the switching element of the inverter, and further adjusts a driving frequency of the driving signal, thereby controlling the high-frequency voltage. The high frequency voltage in a first operating mode is controlled to a low level wherein the lamp is prevented from starting. The high frequency voltage in a second operating mode is controlled to a high level wherein the discharge lamp can be started.

HID lamp ballast with controlled DC step down circuit

A lamp ballast is provided requiring less size and cost for powering a discharge lamp. An inverter circuit converts a DC voltage from a DC power source into a voltage having a determined frequency, and supplies the converted voltage to the discharge lamp inserted between a pair of output ends of the inverter. A resonant circuit includes an auto-transformer and a resonant capacitor, and supplies an output voltage corresponding to a frequency of the rectangular wave voltage of the power supply circuit to the discharge lamp. A voltage detection circuit detects an output voltage of the resonant circuit based on a potential of the resonant capacitor. A control circuit has a startup control mode to set the frequency of the rectangular wave voltage based on the detected voltage from the voltage detection circuit, wherein the output voltage of the resonant circuit exceeds a starting voltage of the discharge lamp.

Discharge lamp ballast having an auto-transformer for high voltage detection

A discharge lamp ballast having a starting circuit including a second inductor connected between a first end of a discharge lamp and the positive voltage side of a first capacitor; a second capacitor forming a resonance circuit together with the second inductor; a second switching element connected between the positive terminal of a DC power source and the second end of the lamp; a third switching element connected between the second end of the lamp and the negative voltage side of the first capacitor; and a starting controller that controls both switching elements. The starting controller alternately turns both switching elements on and off so as to contribute resonance voltage of the resonance circuit for starting of the lamp in case of the starting mode.

Discharge lamp ballast, lighting system and projector

A DC-DC converterwith a switching element Qchanges a supply of power to a HID lamp DL. On/off of the element Qis controlled with a control circuit. The circuitcontrols an on/off state of the element Qwith constant lamp power control on stable operation of the lamp. The circuitcontrols the on/off state of the element Qso as to provide the lamp with lamp power larger than lamp power by the constant lamp power control based on high power control for a period of time that the lamp is on. It is possible to keep temperature of electrodes and within a bulb of the lamp in a proper state through simple control, and to prevent flicker generation and electrode degradation.

Discharge lamp ballast and projector

In a chopper circuit, output power is controllable with a direct current power source as a power source, and a smoothing capacitor is connected between output terminals of the chopper circuit. A polarity inversion circuit applies an alternating voltage to a high pressure discharge lamp with a voltage across the smoothing capacitor as a power source. The output power of the chopper circuit and an inversion frequency of the polarity inversion circuit are controlled by a control circuit based upon a terminal voltage of the smoothing capacitor, which is detected by a voltage detecting circuit. In the control circuit, a switch voltage is set for defining a range of voltages detected by the voltage detecting circuit, and the inversion frequency is changed in plural stages according to the magnitude relation between the detected voltage and the switch voltage. The inversion frequency corresponding to electric power applied to the high pressure discharge lamp is set with respect to each range of lamp voltages, to thereby inhibit occurrence of an arc jump.

Discharge lamp lighting device, illumination device, and projector

A discharge lamp lighting apparatus comprising a d.c. power source section which rectifies and smoothes an a.c. voltage; a current detecting circuit which detects a current which flows through a discharge lamp; a power source ripple detecting circuit which detects a voltage change of power supplied from the d.c. power source section and outputs a voltage obtained by superimposing the detected voltage over a detected voltage which is available from the current detecting circuit; and a control circuit which controls, based on the output voltage from the power source ripple detecting circuit, an output voltage to the discharge lamp so that the current flowing through the discharge lamp becomes a constant current. A rate of superimposition of the output voltage from the power source ripple detecting circuit may be switched in accordance with the discharge lamp voltage.

Growing community of inventors

Kyoto, Japan

Katsuyoshi Nakada