Sharp Kabushiki Kaisha Corporation

Yasuhiro Maruyama

Hiroyuki Shoji

Hirohisa Warita

Naoki Fukunaga

Mitsuru Mariyama

Katsumi Inaba

Masakazu Ikeda

Atsushi Kanamori

Yoshiki Ikuta

An LED drive circuit is an LED dive circuit that receives an alternating voltage to drive an LED, and includes a current remove portion that removes a current from a current supply line that supplies an LED drive current to the LED. If an input current to the LED drive circuit is an unnecessary current, the LED does not light because of current removal by the current remove portion. If the input current to the LED drive circuit turns into the LED drive current from the unnecessary current, the current remove portion decreases the amount of current removed.

LED drive circuit, LED illumination component, LED illumination device, and LED illumination system

An LED drive circuit receives an alternating-current voltage and drives an LED. The LED drive circuit has a current extractor which extracts a current from the current supply line through which an LED drive current is supplied to the LED, and a timing adjuster which adjusts the current extraction start timing and the current extraction duration in the current extractor.

LED drive circuit, LED lamp, LED lighting appliance, and LED lighting system

An LED drive circuit in which an alternating voltage is input and an LED is driven, and which is capable of connecting to a phase control dimmer. The LED circuit is provided with a current extractor for extracting a current from a power supply feed line for feeding an LED drive current to the LED; and an extraction timing adjuster for operating the current extractor for a predetermined period of time after the start of a voltage fluctuation in the power supply feed line, the voltage fluctuation accompanying output oscillation of the phase control dimmer.

LED drive circuit, LED illumination fixture, LED illumination device, and LED illumination system

An LED drive circuit that drives an LED is provided with: a rectifying circuit that converts an alternating voltage into a pulsating current; a constant current circuit; and an over-temperature protection portion that limits an output of the constant current circuit, wherein the LED and the constant current circuit are connected in series on an output side of the rectifying circuit.

LED drive circuit

The invention provides a pulse modulation photodetector, which detects, by projecting pulsed light, presence or absence of a physical object based on whether the pulsed light is received or not according to passage of the physical object. The pulsed light has a pulse width modulated according to a light emission pulse, which is generated based on a clock pulse signal and has a modulation cycle. The modulation cycle includes a light emission period during which the light emission pulse is present, and a non light emission period other than the light emission period. Further, the clock pulse signal has a pulse width being shorter in the light emission period than in the non light emission period.

Pulse modulating photodetector and electronic device

A photo-detecting method of the present invention includes the steps of projecting from a light emitting element a pulse-modulated light as pulse-modulated at a light-emitting element drive circuit toward an object; and counting a light-receiving signal, which is converted by the light-emitting element based on either reflected light reflected from the object or transmitted light transmitted through the object, plurality of times in synchronism with a modulation frequency of the pulse-modulated light projected toward the object, so as to detect the object, wherein the modulation frequency of the pulse-modulated light projected toward the object is changed while carrying out the step of counting the light-receiving signal plurality of times. With this method, it is possible to prevent faulty operation when disturbance light or noise enters the light-receiving element without the light-receiving signal.

Photo-detecting method and photo-detecting device with varying modulation frequency

A transistor includes an NPN transistor provided with an N-type emitter, a P-type base, an N-type collector, an emitter diffusion region and a collector compensation diffusion region around the base and the emitter for decreasing a saturation voltage and a parasitic PNP transistor in a region where the NPN transistor is formed, the parasitic PNP transistor operating under saturation of the NPN transistor.

Growing community of inventors

Osaka, Japan

Yasuhiro Maruyama