Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A driver circuit 3 feeds a pulse signal to an SSR 2 every half wave of alternating-current power from a commercial power source 4, and thereby separately controls the amounts of emitted light of LED groups 1x and 1y forming an LED unit 1, the LED groups 1x and 1y being 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 group 1x and a second pulse signal for controlling the duration of light emission of the LED group 1y are fed to the SSR 2 from the driver circuit 3.

Abstract: 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.

Abstract: Two operation channels CH1 and CH2 of a bidirectional photothyristor chip 31 are disposed away from each other so as not to intersect with each other. In between a P-gate diffusion region 23 on the left-hand side and a P-gate diffusion region 23? on the right-hand side on an N-type silicon substrate, and in between the CH1 and the CH2, a channel isolation region 29 comprised of an oxygen doped semi-insulating polycrystalline silicon film 35a doped with phosphorus is formed. Consequently, a silicon interface state (Qss) in the vicinity of the channel isolation region 29 on 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 CH2 side at the point of time when the CH1 is turned off, the CH2 is turned on without incidence of light, and this allows a commutation characteristic to be enhanced.

Abstract: A driver circuit 3 feeds a pulse signal to an SSR 2 every half wave of alternating-current power from a commercial power source 4, and thereby separately controls the amounts of emitted light of LED groups 1x and 1y forming an LED unit 1, the LED groups 1x and 1y being 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 group 1x and a second pulse signal for controlling the duration of light emission of the LED group 1y are fed to the SSR 2 from the driver circuit 3.

Abstract: A channel isolation region 42 is formed over the entire width of an N-type silicon substrate 41, and photothyristors, in each of which an anode diffusion region 43, a P-gate diffusion region 44, a cathode diffusion region 45 are formed parallel to the channel isolation region 42 over almost the entire width of the N-type silicon substrate 41, are formed in a left-hand portion 40a and in a right-hand portion 40b and are wired inversely parallel. Thus, the inter-channel movement of residual holes during commutation is restrained by the channel isolation region 42, 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 42. Therefore, using this bidirectional photothyristor chip makes it possible to implement an inexpensive SSR with a main thyristor eliminated.

Abstract: Two operation channels CH1 and CH2 of a bidirectional photothyristor chip 31 are disposed away from each other so as not to intersect with each other. In between a P-gate diffusion region 23 on the left-hand side and a P-gate diffusion region 23? on the right-hand side on an N-type silicon substrate, and in between the CH1 and the CH2, a channel isolation region 29 comprised of an oxygen doped semi-insulating polycrystalline silicon film 35a doped with phosphorus is formed. Consequently, a silicon interface state (Qss) in the vicinity of the channel isolation region 29 on 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 CH2 side at the point of time when the CH1 is turned off, the CH2 is turned on without incidence of light, and this allows a commutation characteristic to be enhanced.

Abstract: A Schottky barrier diode 44 is formed between a P-gate diffusion region 33 and an N-type silicon substrate 31 in a photothyristor on a CH1 side and a photothyristor on a CH2 side. With this arrangement, the injection of minority carriers from the P-gate diffusion region 33 to the N-type silicon substrate 31 is restrained to reduce the amount of remaining carriers, and an excessive amount of carriers remaining in the N-type silicon substrate 31 during 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.

Abstract: A channel isolation region 42 is formed over the entire width of an N-type silicon substrate 41, and photothyristors, in each of which an anode diffusion region 43, a P-gate diffusion region 44, a cathode diffusion region 45 are formed parallel to the channel isolation region 42 over almost the entire width of the N-type silicon substrate 41, are formed in a left-hand portion 40a and in a right-hand portion 40b and are wired inversely parallel. Thus, the inter-channel movement of residual holes during commutation is restrained by the channel isolation region 42, 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 42. Therefore, using this bidirectional photothyristor chip makes it possible to implement an inexpensive SSR with a main thyristor eliminated.

Abstract: A Schottky barrier diode 44 is formed between a P-gate diffusion region 33 and an N-type silicon substrate 31 in a photothyristor on a CH1 side and a photothyristor on a CH2 side. With this arrangement, the injection of minority carriers from the P-gate diffusion region 33 to the N-type silicon substrate 31 is restrained to reduce the amount of remaining carriers, and an excessive amount of carriers remaining in the N-type silicon substrate 31 during 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.