Sharp Kabushiki Kaisha Corporation

Mitsuru Mariyama

Hirohisa Warita

Masaru Kubo

Naoki Fukunaga

Hiroyuki Shoji

Yasuhiro Maruyama

Katsumi Inaba

Masakazu Ikeda

Takayuki Shimizu

Atsushi Kanamori

Seigo Okada

Nobuyuki Kato

Satoshi Nakajima

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 in which an alternating voltage is input and an LED is driven, and which can be connected to a phase control dimmer The LED drive circuit is provided with an edge detector for detecting an edge of the output voltage of the phase control dimmer; and a current extractor for extracting a current from a current feed line for feeding an LED drive current to the LED; wherein the value of the current extracted from the current feed line by the current extractor is varied in accordance with the detection results of the edge detector.

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

A driver circuitfeeds a pulse signal to an SSRevery half wave of alternating-current power from a commercial power source, and thereby separately controls the amounts of emitted light of LED groupsandforming an LED unit, the LED groupsandbeing connected in parallel in such a way as to point in different directions. That is, a first pulse signal for controlling the duration of light emission of the LED groupand a second pulse signal for controlling the duration of light emission of the LED groupare fed to the SSRfrom the driver circuit

LED drive circuit and LED light-emitting device

Two operation channels CHand CHof a bidirectional photothyristor chipare disposed away from each other so as not to intersect with each other. In between a P-gate diffusion regionon the left-hand side and a P-gate diffusion region' on the right-hand side on an N-type silicon substrate, and in between the CHand the CH, a channel isolation regioncomprised of an oxygen doped semi-insulating polycrystalline silicon filmdoped with phosphorus is formed. Consequently, a silicon interface state (Qss) in the vicinity of the channel isolation regionon the surface of the N-type silicon substrate increases, so that holes or minority carriers in the N-type silicon substrate are made to disappear in the region. This makes it possible to prevent such commutation failure that when a voltage of the inverted phase is applied to the CHside at the point of time when the CHis turned off, the CHis turned on without incidence of light, and this allows a commutation characteristic to be enhanced.

Bidirectional photothyristor chip, optical lighting coupler, and solid state relay

A channel isolation regionis formed over the entire width of an N-type silicon substrate, and photothyristors, in each of which an anode diffusion region, a P-gate diffusion region, a cathode diffusion regionare formed parallel to the channel isolation regionover almost the entire width of the N-type silicon substrate, are formed in a left-hand portionand in a right-hand portionand are wired inversely parallel. Thus, the inter-channel movement of residual holes during commutation is restrained by the channel isolation region, by which commutation failure is suppressed to improve a commutation characteristic. Further, an operating current large enough for controlling a load current of approx. 0.2 A is obtained although a chip is divided by the channel isolation region. Therefore, using this bidirectional photothyristor chip makes it possible to implement an inexpensive SSR with a main thyristor eliminated.

Bidirectional photothyristor chip, light-fired coupler and solid state relay

A Schottky barrier diodeis formed between a P-gate diffusion regionand an N-type silicon substratein a photothyristor on a CHside and a photothyristor on a CHside. With this arrangement, the injection of minority carriers from the P-gate diffusion regionto the N-type silicon substrateis restrained to reduce the amount of remaining carriers, and an excessive amount of carriers remaining in the N-type silicon substrateduring commutation has a reduced chance of moving toward the opposite channel side, allowing the commutation characteristic to be improved. Therefore, by a combination with an LED, there can be provided a light-fired coupler for firing and controlling the load.

Bidirectional photothyristor chip

In a bidirectional photothyristor formed on a single N type silicon substrate, a distance between a P-gate diffusion region of one thyristor and an anode diffusion region of another thyristor opposed thereto is set to be 40 to 1,000 .mu.m, preferably, 70 to 600 .mu.m, thereby eliminating a malfunction caused by a noise due to a differentiation circuit which is composed of parasitic resistors and junction capacitances. In a field portion between the P-gate diffusion region and the anode diffusion region, an oxygen-doped semi-insulating film is formed via an SiO.sub.2 film, and an Al conductor is removed to form a field light receiving portion. Unlike a P-gate light receiving portion formed in the P-gate diffusion region, the field light receiving portion does not involve a junction capacitance. Therefore, a light sensitivity can be enhanced without lowering a dV/dt resistance.

Bidirectional thyristor device

A dV/dt clamp circuit is connected to a base of a phototransistor for triggering a control electrode of a thyristor, thereby making an attempt to prevent an operation error. A control electrode voltage of the thyristor is applied to the gate of the MOSFET via a high breakdown voltage capacitor. The gate electrode voltage of the MOSFET can be continuously held at a threshold value or more by adjusting a zener voltage of a zener diode and a resistance value of a resistor. Since with a high dV/dt the MOSFET can be operated at a high speed to allow conduction between the drain and source of the MOSFET, the phototransistor does not trigger the thyristor, thereby preventing an operation error.

Semiconductor integrated circuit provided with thyristor

A switching device includes a thyristor and a MOSFET, and a voltage clamp circuit. The voltage clamp circuit includes an N.sup.+ type contact region formed in a surface layer of a N type substrate and electrically connected to a gate electrode of a MOSFET, and a P type guard ring surrounding the contact region.

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Osaka, Japan

Mitsuru Mariyama