Matsushita Electric Works, Ltd.

Toshiya Kanja

Katsunobu Hamamoto

Yoshinobu Murakami

Katsumi Sato

Shigeru Ido

Tomoyuki Nakano

Tokushi Yamauchi

Akinori Hiramatsu

Masahiro Yamanaka

Nobukazu Miki

Kazuhiro Nishimoto

Koji Nishiura

Hiroshi Nishimura

Tadahiro Kono

Naokage Kishimoto

Minorua Maehara

Joji Oyama

An inverter controller dives an inverter to operate at a switching frequency selectively from one of a preheating frequency (f), a starting frequency (f), and a lighting frequency (f) which are different from each other, thereby giving a preheating mode, a starting mode, and a lighting mode. A reset means is provided to make the starting mode upon lowering of a voltage supplied to the inverter below a first threshold, while an inverter stop means is provided to stop the inverter upon detection of abnormality of a discharge lamp. A timer generates a signal determining the start of the preheating, starting, and/or lighting modes, and generates a reset signal disable signal for disabling the reset means, an inverter stop disable signal for disabling the inverter stop means. The inverter controller includes a frequency sweep means for varying the switching frequency gradually from the starting frequency to the lighting frequency. The timer disables the reset means only during a period starting from the selection of the preheating frequency and ending when the switching frequency varies to the lighting frequency, and disable the inverter stop means only during a period starting from the selection of the preheating frequency and ending when the switching frequency begins to vary from the starting frequency to the lighting frequency.

Discharge lamp ballast device and lighting appliance

A discharge lamp lighting device includes a discharge lamp that is lighted through an L-C resonance induced by an oscillation output of an inverter circuit. An on-off operation of switching elements of the inverter circuit is controlled by a control IC which includes a timer circuit for determining a timing of conversion between operation status signals, an inverter control circuit for outputting a driving signal to the switching elements, an output control circuit for controlling generation of the driving signal and an operation status output circuit for outputting a status signal corresponding at least to a lighting status. Further, the discharge lamp lighting device includes an operation setting circuit for inputting a status signal from the operation status output circuit and outputting a control signal to the output control circuit.

Discharge lamp lighting device and lighting apparatus

A discharge lamp driving device capable of detecting a lamp life end reliably in a high or low temperature environment for circuit protection, yet preventing the occurrence of the cataphoresis phenomenon. Impedance elements Z and Z are inserted respectively between one filament ends of individual discharge lamps La and La and a node (the ground) having no high frequency amplitude in order to detect a difference between AC components of individual lamp voltages VLa and VLa in closed loops of the discharge lamps La and La and the impedance elements Z and Z in order to judge whether or not the depletion of the emitter occurs. Thus, it is possible to reliably judge the presence of abnormality even when the amplitudes of the lamp voltages VLa and VLa varies in a range of low to high temperature. Also, since there is no need to provide a DC blocking capacitor to a secondary winding N of a leakage transformer LT the discharge lamps La and La can be free from the DC component so as to be prevented from causing the cataphoresis phenomenon.

Discharge lamp lighting device

A discharge lamp lighting device includes an inverter circuit connected through a first impedance element across output ends of a rectifier rectifying an AC source power, a smoothing capacitor inserted through a discharging diode in a power supply path to the inverter circuit, and a series circuit of a second impedance element, discharge lamp and inductor and connected between an output end of the inverter circuit and one output end of the rectifier, wherein a path for charging the smoothing capacitor is formed through a switching element included in the inverter circuit, and the discharging diode.

A inverter AC power supply comprises a chopper connected to receive an AC voltage from a low frequency AC voltage source to provide a smoothed DC voltage, and an inverter providing a high frequency AC voltage from the smoothed DC voltage for driving a load. The chopper includes an inductor and a series connected pair of first and second switching elements which alternately turn on and off for periodically interrupting an input AC voltage to store a resulting energy to the inductor which is subsequently released to charge a smoothing capacitor to give a smoothed DC voltage there across. The inverter shares the first and second switching elements with the chopper and comprises a L-C resonant circuit which is connected across one of the first and second switching elements together with the load to provide an oscillating voltage as the high frequency AC voltage to the load. A self-excitation control circuit is included in the inverter to acknowledge a change in the oscillating voltage. The self-excitation control circuit is connected to control terminals of the first and second switching elements in order to alternately turn on and off the first and second switching elements in response to the change in the oscillating voltage.

Inverter AC power supply

An electric power source device is provided with a current compensating circuit capable of feeding to switching elements included in an inverter circuit currents substantially mutually anti-phase, the current compensating circuit thus reducing the currents flowing to the switching elements and allowing the switching elements of a small current rating to be utilizable.

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Uji, Japan

Toshiya Kanja