Matsushita Electric Works, Ltd.

Masahiro Yamanaka

Katsunobu Hamamoto

Kazuhiro Nishimoto

Hiroyuki Sako

Tokushi Yamauchi

Kei Mitsuyasu

Toshiya Kanja

Yukio Yamanaka

Katsumi Sato

Koji Nishiura

Yoshifumi Kuroki

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

The ballast of the present invention includes a DC power supply, an inverter circuit, a load circuit, and an integrated control circuit. The integrated control circuit controls the switching elements of the DC power supply and the inverter circuit. The integrated control circuit includes a first control unit, a second control unit, and a driver circuit. The first control unit generates a first control signal for control of the switching element of the DC power supply. The second control unit generates a second control signal for control of the switching elements of the inverter circuit. The driver circuit provides drive signals for driving each one of the switching elements of said DC power supply and the inverter circuit in accordance with the first control signal and the second control signal. As mentioned above, control circuits for controlling the DC power supply and the inverter circuit are integrated into a single component, the number of components which are mounted on a printed circuit board is reduced.

Ballast for a discharge lamp with integrated control circuit for controlling switching element of dc power supply and inverter circuit

A power supply device in which an inverter circuit is supplied with power directly from a rectification circuit, the inverter circuit has a pair of switching elements connected in series with each other and connected between both ends of the rectification circuit through an impedance element, a series circuit of the impedance element, two capacitors and an inductor is connected in parallel to one of the switching elements of the inverter circuit connected to positive polarity one of the both ends of the rectification circuit, a load is connected across one of the capacitor, a valley filling circuit receives an output of the inverter circuit through a diode provided in the valley filling circuit and supplies it to a power supply capacitor provided therein and, when a DC output voltage of the rectification circuit drops, the valley filling circuit supplies power to the inverter circuit via the power supply capacitor and another diode provided therein. Thereby, fluctuations in a current supplied to the load can be effectively reduced.

Power supply device

A power supply with a full-wave rectifier and a chopper having an inductor and a transistor connected in series across the rectifier. The transistor is switched on and off providing an interrupted voltage which is applied across a smoothing capacitor, via a blocking diode, to produce a smoothed DC voltage for driving a load. When the transistor is turned on, current from the rectifier is drawn through the inductor. When the transistor is turned off, the current through the inductor is conducted, in a positive direction, to the smoothing capacitor. The inductor and parasitic capacitance inherently present in the chopper create oscillations which allow current to flow through the inductor in a negative direction. A controller turns the transistor on at a time when the current flows in the negative direction and turns the transistor off after a predetermined on-period so as to release the current through the inductor, thereby causing the current to first flow in the negative direction and then in the positive direction through the inductor during the on-period. An input current wave shaping circuit is provided so that for each on-period, the amount of current flowing continuously through the inductor in the negative direction occurring immediately after the turning on of the transistor is less than the amount of current flowing through the inductor in the positive direction.

Power supply having a chopper with an improved power factor

Growing community of inventors

Otsu, Japan

Masahiro Yamanaka