Hitachi, Ltd.

International Business Machines Corporation

Hitachi Microcomputer System, Ltd.

Hitachi Video and Information System, Inc.

Kenji Kawabata

Motohiro Sugino

Ryuichi Ikeda

Hideki Miyazaki

Hiroyuki Shoji

Ikuya Nomoto

Takashi Okada

Yasuyuki Kojima

Soichiro Ogawa

Shuzo Matsumoto

Yoshiteru Watanabe

Kenichi Onda

Kunio Seki

Johji Mamiya

Hirotaka Mochizuki

Makoto Goto

Susumu Iijima

Ichiro Torii

Ryoichi Masaki

A device for turning on light allowing the brightness of an inverter-type illumination apparatus to be adjusted without having to install an additional oscillation circuit. The device comprises an active converter which generates a DC voltage from the commercial AC voltage and an inverter which switches the generated DC voltage, includes a capacitor connected in parallel with a discharge tube to be lighted, and supplies a high-frequency current to the discharge tube via a resonance circuit whose resonance frequency is determined according to the equivalent impedance of the discharge tube. The active converter has a triac adjusting the DC voltage, and switching elements of the inverter perform self-oscillation under control of the phase of the resonance current flowing through the resonance circuit.

Device for turning on light and illumination apparatus

An illumination lighting apparatus has a resonance load circuit including a discharge tube, a power supply circuit for generating DC voltage from commercial AC voltage, and an inverter for converting the generated DC voltage into an AC voltage and supplying the AC voltage to the resonance load circuit. Further, a control circuit is provided which controls electric power supplied to the resonance load circuit in response to operating parameters of the discharge tube immediately after lighting of the discharge tube.

Inverter type illumination lighting apparatus

In order to detect a fault which would result in heating or fuming of a discharge tube lighting circuit and to break the lighting circuit, input voltage and current are measured and multiplied to compute the input power. The discharge tube 3 is extinguished when an input power reaches a predetermined value.

Discharge tube lighting apparatus

A power supply apparatus which stabilizes the output by feeding it back is provided which suppresses variations of the output for abrupt variations of the input. The power supply apparatus comprises output sensing means for sensing output current and output voltage, first output control means for controlling the output with the increment or decrement of the value obtained from said output sensing means, second output control means for controlling the output from an absolute value of the input voltage, and selection means for selecting either said first output control means or said second output control means. The power supply apparatus further comprises means for detecting the variation rate of the input voltage, first monitor means for monitoring the difference between the output value of said output sensing means and the reference value, and second monitor means for monitoring both the difference between the output value of said output sensing means and a reference value, and the input voltage variation rate.

Power supply apparatus

A current feedback type discharge lamp lighting device including a switching circuit which switches an impedance of an impedance device in accordance with the number of connected discharge tubes. In the discharge lamp lighting device, a tube current for each of the connected discharge tubes is maintained constant, and the discharge lamp lighting device tends to not be effected by stray capacitance.

Discharge lamp lighting device

An information processing apparatus employs a liquid crystal display and a fluorescent lamp for backlighting the screen of the liquid crystal display. A lighting circuit for supplying alternating current lighting power to the fluorescent lamp receives input power from either a commercial alternating current power source or from a direct current battery. The level of the lighting power supplied to the fluorescent lamp is determined based upon a determination of whether the input power is being supplied from the commercial power source or from the battery.

Information processing apparatus including a control circuit for

The discharge lamp operating circuit comprises two series circuits, each including two switching devices, connected in parallel with the power supply, a series circuit, including a choke coil, a first capacitor, and a parallel circuit with a discharge lamp and a second capacitor, and connected between the middle points of the one and the other series circuit, reverse-direction rectifiers connected in parallel with the corresponding switching devices, said discharge lamp operating circuit turning on and off said discharge lamp by turning on and off the switching devices alternately. In this discharge lamp operating circuit, the timing of switching the switching devices is set from the closed condition to the open condition at a time when the current flowing through the switching devices is almost at zero level.

Discharge lamp operating circuit

A discharge lamp lighting system including at least one switch device connected between a d.c. power supply and a discharge lamp which is turned on by a high frequency power generated through turning-on and -off of the switching device. In the discharge lighting system, the discharge lamp lighting operation is allowed to start when the d.c. power supply voltage reaches a predetermined voltage value A or over, and the discharge lamp lighting operation is stopped when the d.c. power supply voltage lowers smaller than a predetermined voltage value B, where the values A and B take a relation that B is smaller than A.

Protected discharge lamp lighting system

A discharge lamp operating circuit includes at least a discharge lamp, a condenser and four switches. The condenser is charged and discharged through the discharge lamp by the turn-on and turn-off of the switches so that an AC current is caused to flow through the discharge lamp to operate the discharge lamp. A time required for the complete charging and discharging of the condenser is selected to be longer than a time scheduled for the charging and discharging of the condenser in one period. A switching frequency f.sub.0 at the time of heating of the discharge lamp and a switching frequency f at the time of operating of the discharge lamp has a relation of 2.ltoreq.f/f.sub.0 .ltoreq.10.

A compact fluorescent lamp with a screw base having a lamp with an inner tube, an outer case which is provided at one end of the lamp and includes an operating circuit section therein and has a screw base at one end of the outer case, and a molding compound having excellent insulation and good conduction of heat which is pressed and interposed into the gap between the operating circuit section and the outer case in order to transfer the heat generated in the operating circuit section to the outer case.

Growing community of inventors

Ome, Japan

Kenji Kawabata