Matsushita Electric Industrial Co., Ltd.

Matsushita Electric Industrial

Masataka Ozawa

Koji Miyazaki

Kazuhiko Ito

Masayoshi Gyoten

Shigeru Horii

Takayuki Kamitani

Kazutaka Koyama

Atsuo Waki

Takeshi Saito

Masanobu Murakami

Nobuhisa Yoshikawa

Makoto Horiuchi

Kazushige Sugita

Kouji Miyazaki

Hiroki Nakagawa

Takashi Katsura

Yoshiro Ogata

Tetsuya Tahara

Masakatsu Kichibayashi

Youji Tashiro

A ballast for a fluorescent lamp includes a high frequency power source circuit for supplying a preheat start type fluorescent lamp with preheating and lighting current via an inductor. The high frequency power source circuit includes at least two switching elements for controlling application of voltages of different polarity to the fluorescent lamp, a self-exciting type switching element driving circuit for driving the switching elements so as to alternate on and off repeatedly; and a timer circuit for detecting lapse of a predetermined time from start of the ballast for the fluorescent lamp. The switching element driving circuit shortens an ON-period of at least one of the switching elements to restrict an increase of an amplitude of current flowing in the inductor during a period until the timer circuit detects lapse of a predetermined time.

Ballast for fluorescent lamp

A ballast for a discharge lamp comprises a smoothing capacitor, an inverter circuit including at least one switching device connected in parallel to the smoothing capacitor, a driving circuit for driving the inverter circuit, an activating circuit for activating the driving circuit, a resonance circuit including first and second capacitors and an inductor connected to output terminals of the inverter circuit, a discharge lamp connected to output terminals of the resonance circuit, a third capacitor connected in parallel to the discharge lamp. A fourth capacitor and first and second rectifying elements connected in series are connected in parallel to the smoothing capacitor. Between both terminals of the fourth capacitor and terminals for connection to an AC power source, a filter and a rectifier are inserted. A terminal of the first capacitor other than that connected to the inverter circuit is connected to a junction of the first and second rectifying elements.

Ballast for a discharge lamp

The fluorescent lamp lighting apparatus of the present invention includes: a first serial connection including a first switching device and a second switching device which are connected to a power supply circuit; a second serial connection including a first inductor, a first capacitor and a fluorescent lamp which are connected between one terminal of the power supply circuit and an intermediate point of the first and the second switching devices; a third serial connection including a second inductor, a second capacitor and a third inductor which is electromagnetically coupled to the first inductor, the third serial connection supplying a control voltage to a control terminal of the first switching device or a control terminal of the second switching device; and a constant voltage device connected in parallel to the second capacitor. In the fluorescent lamp lighting apparatus, the constant voltage device supplies a positive control voltage and a negative control voltage to the control terminal, the positive control voltage is positive with respect to a cathode terminal corresponding to the control terminal, the negative control voltage is negative with respect to the cathode terminal, and an absolute value of the positive control voltage is larger than an absolute value of the negative control voltage.

Fluorescent lamp lighting apparatus

A high pressure discharge lamp is disclosed. The high pressure discharge lamp includes: a discharge tube which is filled with gas; a first electrode having a first end, the first electrode being provided in the discharge tube; and a second electrode having a second end which is positioned away from the first end by a certain distance, the second electrode being provided in the discharge tube. In the high pressure discharge lamp, arc discharge is induced by a voltage applied between the first end of the first electrode and the second end of the second electrode. The high pressure discharge lamp further includes a convection regulating member which is electrically insulating and provided in the discharge tube. The convection regulating member suppresses the deformation of the arc discharge caused by the convection of the gas in the discharge tube.

High pressure discharge lamp having improved convection regulating means

The present invention relates to an inverter driven lamp arrangement. The arrangement provides for the sensing of both lamp voltage and current. The arrangement also provides for a large current during times of low voltage and a small current during times of high voltage. The sensing of lamp current is done by a current detector that is connected to a resonance circuit whose output is applied in signal form to a lamp start control circuit. The resonant circuit is a series connected resonant circuit composed of a choke coil and a first capacitor. This series connected arrangement is further connected in series with a second non-resonant capacitor. Also the arrangement includes circuitry to gradually reduce the frequency of the inverter just after the lamp starts.

An inverter driven lamp arrangement having a current detection circuitry

In a discharge-lamp lighting apparatus for lighting a discharge lamp such as a metal halide lamp, there is provided a lighting control circuit which controls its output in a starting time of the discharge lamp in response to at least a length of the last off-time and an on-time after the start of discharging; and a power supplied to the discharge lamp is controlled in accordance with this output of the lighting control circuit.

Apparatus for controlling the power to a discharge-lamp

When a discharge lamp is started, high voltage pulses which superpose the voltage due to LC resonance of a resonance circuit are supplied to the discharge lamp, and breakdown occurs in the discharge lamp. The pulse energy needed for the high voltage pulses is small and the output power of the resonance circuit can be decreased. After the breakdown, the energy needed for the transfer from glow discharge to arc discharge is supplied by the resonance, and the high voltage pulses used to supply the starting energy are allowed to be stopped. Thus, the starting and restriking of a discharge lamp is sure, and the starting circuit for a discharge lamp can be made more compact.

Discharge lamp starting circuit

A discharge lamp apparatus is capable of securely detecting the decrease of emission in the terminal stage of the life of a discharge lamp by connecting a voltage detecting circuit to the discharge lamp, and a discharge lamp apparatus for securely starting, operating and dimming the discharge lamp, and is also capable of protecting the lamp in the event of abnormality; the apparatus includes two timer circuits, a reset circuit, a dimmer circuit, an abnormality detecting circuit, and a stopping circuit.

Discharge lamp operation apparatus

A high-pressure sodium lamp is connected to a d.c. power supply through a ballast, to operate it with a current containing a d.c. component. The relation between the ratio l/d of the inter-electrode distance l (mm) to the inner diameter d (mm) of the arc tube of the high-pressure sodium lamp and the sodium vapor pressure P.sub.Na (kPa) in the arc tube is maintained at P.sub.Na .gtoreq.6.0 (l/d-5.8), thus making it possible to operate the high-pressure sodium lamp with a current containing a d.c. component without causing a significant color separation which otherwise might be the result of cataphoresis.

Growing community of inventors

Takarazuka, Japan

Masataka Ozawa