Matsushita Electric Works, Ltd.

Panasonic Intellectual Property Management Co., Ltd.

Panasonic Corporation

Akinori Hiramatsu

Hiroshi Kido

Hiroyuki Sako

Nobukazu Miki

Kazuhiro Gotoh

Shigeru Ido

Keisuke Seki

Daisuke Ueda

Junichi Hasegawa

Koji Yamada

Sana Esaki

Toshiya Kanja

Yukio Yamanaka

Koji Nishiura

Futoshi Okamoto

Atsushi Ueoka

Seiji Soga

Naokage Kishimoto

An illumination apparatus includes light sources differing from one another in terms of light-emission color and voltage drop when identical current flows therein, switches in one-to-one correspondence with the light sources, a DC power supply circuit, and a control circuit. The control circuit performs a first control of the switches through a time division control method such that an on-period of each switch is not overlapped with that of any other switch. The control circuit also performs a second control to individually control at least one of a target current magnitude, flowing through each switch in the switched-on state, and a target on-period length of each switch, and to adjust a ratio of the plurality of light sources in terms of a product of the target current magnitude and the target on-period length.

Illumination apparatus and lighting device used thereby

The light source unit includes a light source circuit including N (N&#x2267;3) pairs of a light source group including one or more solid light emitting elements and a constant current circuit connected in series with the light source group to keep, constant, current flowing through the light source group, a full-wave rectification circuit for performing full-wave rectification on AC voltage, and a control circuit. The first pair is connected to the full-wave rectification circuit. The k-th (2&#x2266;k&#x2266;N) pair is connected in parallel with the constant current circuit of the (k&#x2212;1)-th pair so that the light source groups of the k-th and (k&#x2212;1)-th pairs are in series. The control circuit terminates operations of the constant current circuits of the N pairs or limits currents flowing through the light source groups of the N pairs in response to detection of light or a signal.

Light source unit and lighting fixture

An illumination system includes: a first light-emitting element column including one of a single first light-emitting element or a plurality of first light-emitting elements connected in series; a second light-emitting element column connected in parallel with the first light-emitting element column, and including one of a single second light-emitting element or a plurality of second light-emitting elements connected in series; a constant current supply that supplies a constant current to the first light-emitting element column and the second light-emitting element column which are connected in parallel; a resistor that is connected in series with the first light-emitting element column, and detects a magnitude of current flowing through the first light-emitting element column; and a current adjuster circuit that adjusts the magnitude of the current flowing through the first light-emitting element column, according to the magnitude of the current detected by the resistor.

Illumination system and luminaire

An illumination system includes: a first light-emitting element column in which one or more first light-emitting elements are serially connected; a second light-emitting element column connected in parallel with the first light-emitting element column, and in which one or more second light-emitting elements are serially connected; a constant current supply that supplies constant current to a light source unit including the first and second light-emitting element columns; a resistor that is connected in series with the first light-emitting element column, and detects magnitude of current flowing through at least the first light-emitting element column; a bypass circuit that passes, to the resistor, at least part of current flowing through the second light-emitting element column, when a predetermined condition is satisfied; and a current adjuster circuit that adjusts the magnitude of the current flowing through the first light-emitting element column, according to the magnitude of the current detected by the resistor.

An LED lighting device is provided with output impedance control to stabilize an optical output across a wide current range. A switching power supply generates the output current, with switching control circuitry to determine switching frequency and an ON period for an associated switch, and to turn on/off the switch according to the determined frequency and ON period. An impedance element is coupled across output terminals for the lighting device, with an impedance value set so that a load current is larger than a current flowing to the impedance element at maximum on-duty of the switch and a current flowing to the impedance element is larger than the load current at minimum on-duty. The impedance element may be a variable impedance element, wherein an impedance control circuit adjusts the variable impedance such that an impedance value for minimum on-duty of the switch is smaller than that for a maximum on-duty.

LED lighting device with output impedance control

An electronic ballast for hot cathode discharge lamp comprises a DC voltage source, a chopper, and an inverter. The chopper includes a switching element connected in series with an inductor across the DC voltage and driven to turn on and off for providing a periodically interrupted voltage which is smoothed by a capacitor to produce a smoothed DC voltage as a chopper output. The inverter includes at least one switching element which is coupled to the chopper output to produce therefrom a high frequency AC voltage as an inverter output to be applied to cathodes of the discharge lamp for lighting the discharge lamp. The ballast is characterized to include an inverter controller and a delay circuit. The inverter controller controls the inverter to operate selectively in a normal mode of providing the inverter output of a first level and in a limited mode of providing the inverter output of a second level which is lower than the first level and is determined to give a preheating current to the cathodes. The delay circuit delays the start-up of the inverter for a time period from the start-up of the chopper. The inverter controller controls the inverter to operate in the limited mode after the start-up of the inverter for a predetermined period for preheating the discharge lamp after which the inverter controller allows the inverter to operate in the normal operation mode for lighting the discharge lamp.

Electronic ballast for hot cathode discharge lamps

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

A power supply for driving one or more loads includes a DC voltage source, an inverter connected to the DC voltage source for providing a high frequency AC voltage at its output end, and an output transformer having a primary winding and a secondary winding. The primary winding is coupled to the output end of the inverter through a tuning inductor, while the secondary winding is coupled to the load. A tuning capacitor, which constitutes a resonant circuit in cooperation with the resonance inductance for supplying a resonance current to the load, is connected across the secondary winding of the output transformer in parallel relation to the load. The tuning capacitor is arranged in circuit on the opposite side of the secondary winding from the load such that the tuning capacitor is open-circuited when the load is disconnected from the secondary winding.

Power supply

A power supply with an inverter capable of avoiding the inverter from producing excessive high voltage when a load is detached or the load impedance is greatly increased. The inverter is energized by a fixed DC voltage source and includes at least one switching element and an L-C resonant circuit. The switching element is driven to turn on and off and cooperative with the L-C resonant circuit to produce a high frequency AC voltage at an inverter output for driving a load. The inverter includes first and second clamping diodes connected in series across the DC voltage source in anti-parallel relation thereto with the first and second diodes defining therebetween a first connection point. Also included in the inverter is a pair of first and second impedance elements which are connected in series across the inverter output to provide a divided voltage indicative of an output voltage of the inverter with the first and second impedance elements defining therebetween a second connection point. The first and second connection points are connected to each other so as to keep the points at a voltage level nearly equal to a fixed voltage of the DC voltage source, in such a manner as to limit the output voltage of the inverter below a predetermined level by allowing a clamping current to flow through the first and second diodes and impedance elements and through the DC voltage source to escape the excessive voltage developed in response to the increase in the impedance of the load.

Inverter power supply

An inverter device has a full-wave rectifier providing a pulsating DC voltage from an input AC voltage, a smoothing circuit. The smoothing circuit includes a choke coil, a smoothing capacitor and a switching element chopping the pulsating DC voltage through the choke coil into a smoothed DC voltage at the smoothing capacitor. An inverter is included to have the element common to the smoothing circuit and operating to switch the smoothed DC voltage to apply a resulting voltage to a load circuit including a load, inductance and capacitor. The inductance and capacitor define an oscillation circuit providing to the load an oscillating current composed of first and second currents of opposite directions. The oscillating current alternating to flow for a nominal on-time duration determined by a circuit constant of the oscillation circuit itself. A controller is included to detect the termination of the second current and excites the common switching element at a timing dependent upon the termination of the second current so as to start flowing the first current. The controller includes a timer for separately controlling an actual on-time duration for flowing the first current within the nominal on-time duration, whereby enabling to regulate the accumulated DC voltage in the smoothing capacitor at a desired level by controlling to vary the actual on-time duration of the common switching element.

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Nara, Japan

Akinori Hiramatsu