Abstract: A power factor correction circuit includes a filter capacitor interposed between AC input terminals, a first inductor interposed between the first end of the filter capacitor and an input of a first rectifying bridge circuit, and a second inductor interposed between the second end of the filter capacitor and another input of the first rectifying bridge circuit. The power factor correction circuit further includes a second rectifying bridge circuit including inputs connected to AC input terminals, and outputs connected to a smoothing capacitor. A control circuit controls switching devices in the first rectifying bridge circuit. The power factor correction circuit can facilitate preventing an overcurrent from flowing through diodes and parasitic diodes in the switching devices, using a simple configuration.

Abstract: A switching power supply apparatus which includes a DC power supply, an isolation transformer having primary, secondary and tertiary windings, and a switching element, and in which, by turning the switching element on and off, the high-frequency voltage appearing in the secondary windings of the isolation transformer is rectified to obtain a DC output, power consumption can be decreased during standby (in burst mode) in particular by means of a control circuit which controls the turn-on and turn-off of the element and similar.

Abstract: A switching power supply device has a drive circuit that can minimize a loss while being compact. The drive circuit turns on and off a high-side switching element (MOSFET) according to a positive or negative voltage developed at a tertiary winding of a transformer. The drive circuit includes a control unit that detects the development time, during which the negative voltage is developed at the tertiary winding, as the on time of a low-side switching element, and makes the on time of the high-side switching element nearly or substantially equal to the development time.

Abstract: A control system for a power factor correction circuit performs stabilized oscillation operation and suppresses switching frequency variation due to change of the AC power source. A control system includes a voltage error amplifier for outputting a voltage error signal obtained by amplifying a difference between a DC output voltage Vo and a command value Vref of the DC output voltage, a current command value generating circuit for outputting a current command value Vi for controlling the input current Iin, a comparator comparing an inductor current signal obtained by detecting an inductor current running in the switching element by a current detecting resistor with a magnitude of the output signal Vi from the multiplier, a timer circuit for setting an off-period of the switching element corresponding to the voltage Vd, and a reset-set type flip-flop circuit for setting an off-timing of the switching element after an elapse of the off-period.

Abstract: A switching power supply includes a control circuit controlling ON and OFF of switching devices Q1 and Q2 and having an error amplifying circuit that controls a DC output voltage at a constant preset value, an oscillator circuit that controls the switching frequency in response to the output signal level FB of an error amplifying circuit, and a pulse width control circuit PWM that controls the pulse width in response to the output signal such that the ON-periods of switching devices Q1 and Q2 are equal to each other. The ON and OFF of switching devices Q1 and Q2 is controlled based on the output from oscillator circuit VCO when the output signal is higher than a threshold level. The switching frequency is fixed when the output signal level FB is lower than the threshold level.

Abstract: A computerized tomography apparatus and program for obtaining a cross-sectional image corresponding to projections are provided in which, for a temporary cross-sectional image f(x, y) obtained in some manner, an evaluation function E is defined which includes differences between projections calculated from f(x, y) and measured projections, and f(x, y) is changed in a manner which substantially decreases E. The computerized tomography apparatus and program are characterized in which a back projection operation, which is required by conventional computerized tomography, is not essentially required. The computerized tomography apparatus and program are particularly effective in removal or reduction of metal artifacts, aliasing artifacts and the like.

Abstract: A power converter includes a small-sized inductor connected to an AC voltage input line for power factor correction and a filter for suppressing conduction noise. The inductor is connected to a rectifier and comprises first and second windings and that are wound on a common magnetic core and loosely coupled with each other. A leakage inductance component of the inductor functions as an energy storage element in a main conversion operation and an excitation inductance component of the inductor functions as a noise reduction element for suppressing an conduction noise caused by on-off operation of a switching element.

Abstract: A control circuit for controlling a subsidiary (high-side) switching device in an insulating electric power converter having a half-bridge structure includes a first series circuit of a resistor and a diode, a second series circuit of a resistor and a diode, and a transistor. The control circuit turns the subsidiary switching device ON and OFF using the voltage generated in a transformer winding for a signal voltage. The control circuit also turns the transistor ON and OFF with the voltages generated in the first and second series circuits so as not to make the gate voltage of subsidiary switching device exceed the gate breakdown voltage thereof in all the operation modes.

Abstract: A switching power supply, which operates intermittently under a light load for suppressing electric power consumption, reduces output voltage variations caused when a load current increases rapidly from a light load state, and reduces output voltage ringing. The switching power supply includes a comparator that compares a feedback signal obtained by isolating the output from an error amplifier with a burst threshold value and a comparator that compares the feedback signal with a power-supply-interruption threshold value preset to be lower than the burst threshold value. The switching power supply stops output of a driving pulse from a driver circuit when the feedback signal is lower than the burst threshold value. The switching power supply also stops the output of operation power from first power supply circuit when the feedback signal is lower than the power-supply-interruption threshold value.

Abstract: A switching power supply exhibits high conversion efficiency and facilitates reducing the size thereof. The switching power supply includes a half-bridge circuit including a first series circuit formed of switching devices Q1 and Q2 and connected between the output terminals of a DC power supply; and a second series circuit connecting primary inductance Lr1 of transformer T1, primary inductance Lr2 of transformer T2 and capacitor Cr in series. The second series circuit is connected between the output terminals of the half-bridge circuit, and is made to conduct a series resonance operation. The switching devices Q1 and Q2 is controlled at the ON-duties of 0.5 for reducing the breakdown voltages of rectifying diodes D1 and D2 on the secondary side of transformers T1 and T2 and for improving the conversion efficiency of the switching device.

Abstract: A switch mode power supply according to the invention that can improve the reliability thereof includes a series circuit connected between the positive and negative electrodes of a DC power supply 3, the series circuit including a capacitor 4, a main switching device 1, and a subsidiary switching device 2; a main control circuit 13; a subsidiary control circuit 10; control circuits 13 and 10 turning main switching device 1 and subsidiary switching device 2 alternately ON and OFF to obtain a DC output via a transformer 6; and subsidiary control circuit 10 preventing a voltage exceeding the gate breakdown voltage of subsidiary switching device 2 from being applied to the gate electrode of subsidiary switching device 2.

Abstract: A switching power supply apparatus which includes a DC power supply, an isolation transformer having primary, secondary and tertiary windings, and a switching element, and in which, by turning the switching element on and off, the high-frequency voltage appearing in the secondary windings of the isolation transformer is rectified to obtain a DC output, power consumption can be decreased during standby (in burst mode) in particular by means of a control circuit which controls the turn-on and turn-off of the element and similar.

Abstract: Various metal oxide nanosheets with uniform thickness under mild conditions and in a short time are provided. A mixed solution containing a surfactant such as laurylamine and a metal alkoxide are allowed to flow over water surface to obtain a composite nanosheet. The composite nanosheet comprises a lamella molecular film consisting of a surfactant, and a metal oxide nanosheet formed along the surface of the molecular film. If necessary, the composite nanosheet was separated and then immersed in a solvent in which the surfactant can be dissolved, to separate the metal oxide nanosheet from the molecular film.

Abstract: A switching power supply device includes a first series circuit of first and second switching elements connected in parallel with a DC power supply. An isolation transformer has primary and secondary windings and first and second auxiliary windings, a first layer including the primary windings between a second layer of the two auxiliary windings, and a third layer of the secondary windings. A capacitor in series with the primary windings defines a second series circuit in parallel with the second switching element. A rectifying and smoothing circuit includes a rectifying diode and a smoothing capacitor, connected to the secondary windings. First and second control circuits turn on and off the first and second switching elements based on voltages generated in the two auxiliary windings, to obtain a DC output from the rectifying and smoothing circuit, enabling an adequate auxiliary windings voltage and stable switching operation including stable zero-voltage turn-on.

Abstract: A switching power supply device has a drive circuit that can minimize a loss while being compact. The drive circuit turns on and off a high-side switching element (MOSFET) according to a positive or negative voltage developed at a tertiary winding of a transformer. The drive circuit includes a control unit that detects the development time, during which the negative voltage is developed at the tertiary winding, as the on time of a low-side switching element, and makes the on time of the high-side switching element nearly or substantially equal to the development time.

Abstract: A power conversion device has a series circuit of a main switching element and a sub-switching element connected to both ends of a DC power supply, an insulating transformer, and control circuits. The main switching and sub-switching elements are alternately turned on and off by the respective control circuits such that voltage generated in the secondary coil is subjected to smoothing rectification and supplied to a load. The insulating transformer includes a primary coil, and the main control circuit takes voltage of the primary coil as signal voltage to cause the main switching element to turn on and off such that DC voltage supplied to the load is constant. The sub-control circuit turns on the sub-switching element when the voltage at both ends of the sub-switching element becomes lower than a reference voltage or when the voltage of the primary coil exceeds a predetermined value.

Abstract: A control method for controlling a switching power supply circuit has a control circuit including a setting device that limits the exciting current of a transformer at the time of changeover from a switching delay to a switching period. The setting value set by the setting device is changed slowly to prevent the exciting current of transformer from changing rapidly and to reduce the excitation noise of transformer, and the setting value is changed gradually to prevent the output voltage from lowering even when the load becomes heavier than a certain value during the light load operation. The control method facilitates reducing the electric power consumption of the switching power supply circuit under a light load, reducing the transformer excitation noise and preventing the output voltage from lowering when the load is light.

Abstract: A control circuit for controlling a subsidiary (high-side) switching device in an insulating electric power converter having a half-bridge structure includes a first series circuit of a resistor and a diode, a second series circuit of a resistor and a diode, and a transistor. The control circuit turns the subsidiary switching device ON and OFF using the voltage generated in a transformer winding for a signal voltage. The control circuit also turns the transistor ON and OFF with the voltages generated in the first and second series circuits so as not to make the gate voltage of subsidiary switching device exceed the gate breakdown voltage thereof in all the operation modes.

Abstract: A control method for controlling a switching power supply circuit has a control circuit including a setting device that limits the exciting current of a transformer at the time of changeover from a switching delay to a switching period. The setting value set by the setting device is changed slowly to prevent the exciting current of transformer from changing rapidly and to reduce the excitation noise of transformer, and the setting value is changed gradually to prevent the output voltage from lowering even when the load becomes heavier than a certain value during the light load operation. The control method facilitates reducing the electric power consumption of the switching power supply circuit under a light load, reducing the transformer excitation noise and preventing the output voltage from lowering when the load is light.

Abstract: A power conversion device has a series circuit of a main switching element and a sub-switching element connected to both ends of a DC power supply, an insulating transformer, and control circuits. The main switching and sub-switching elements are alternately turned on and off by the respective control circuits such that voltage generated in the secondary coil is subjected to smoothing rectification and supplied to a load. The insulating transformer includes a primary coil, and the main control circuit takes voltage of the primary coil as signal voltage to cause the main switching element to turn on and off such that DC voltage supplied to the load is constant. The sub-control circuit turns on the sub-switching element when the voltage at both ends of the sub-switching element becomes lower than a reference voltage or when the voltage of the primary coil exceeds a predetermined value.