Abstract: A synchronous commutation DC-DC converter comprises a current detection transformer (51) for detecting currents (IQ1, IQ2) flowing through the primary circuit, first and second DC bias power sources (53, 54) generating bias voltages (VBS1, VBS2) larger than the voltage corresponding to the exciting current of a transformer (4), and first and second comparators (55, 57) for driving first and second commutation MOS-FETs (7, 8) when the detection voltage (VDT) of a current detection resistor (52) exceeds the bias voltages (VBS1, VBS2) of the first and second DC bias power sources (53, 54). Since each commutation MOS-FET (7, 8) in the secondary circuit is driven in synchronism with the currents (IQ1, IQ2) of the primary circuit from which the exciting current component of the transformer (4) is removed, it is possible to minimize switching loss of each commutation MOS-FET (7, 8) in the secondary circuit and enhance conversion efficiency of the synchronous commutation DC-DC converter.

Abstract: Glass for forming barrier ribs for e.g. a plasma display panel, which consists, as represented by mol % based on the following oxides, essentially of from 24 to 50% of SiO2, from 13 to 23% of B2O3, from 10 to 32% of ZnO, from 3 to 20% of Li2O, from 1 to 9% of Na2O, from 1 to 15% of Al2O3, from 0 to 20% of MgO+CaO+SrO+BaO, and from 0 to 9% of Bi2O3, wherein ((B2O3+ZnO)—Al2O3) is at least 24 mol %; in a case where ZrO2 is contained, its content is at most 2 mol %; and neither PbO nor F is contained.

Abstract: A method for producing a glass substrate for a magnetic disk by polishing a circular glass plate, which comprises a step of polishing the principal plane of the circular glass plate by using a slurry containing at least one water-soluble polymer selected from the group consisting of a water-soluble organic polymer having amino groups, a water-soluble organic polymer having amine salt groups and a water-soluble organic polymer having quaternary ammonium salt groups, and colloidal silica.

Abstract: For providing a flexible printed circuit board in which the distance between each of plural wiring patterns is a desired distance by cutting the flexible printed circuit board having plural wiring patterns, plural wiring patterns are formed so as to extend on the surface of an electrically insulative base film, and each of the plural wiring patterns is formed so as to include a portion where the distance between each of them is narrowed along the extending direction of the base film.

Abstract: A DC-DC converter of multi-output type is provided wherein a primary winding 5a is wound around core halves 5g, 5h of a transformer 5 between first and second secondary windings 5b, 5c of transformer 5 also concentrically wound around core halves 5g, 5h to form an electromagnetic sparse coupling between first and second secondary windings 5b, 5c. When on-off operation of first and second primary MOS-FETs 2, 3 generates first and second DC outputs VO1, VO2, the electromagnetic sparse coupling can reduce, attenuate or relax serge voltage induced on first secondary winding 5b.

Abstract: A discharge-lamp lighting apparatus includes first and second cold cathode fluorescent lamps (CCFLs) and first and second transformers. The first transformer has a primary winding and a secondary winding. The primary winding receives an AC voltage generated by turning on/off a first switching element pair that is connected to a first DC power source. The second transformer has a primary winding, a first secondary winding, and a second secondary winding. The primary winding of the second transformer receives an AC voltage generated by turning on/off a second switching element pair that is connected to a second DC power source. Polarities of the first and second secondary windings of the second transformer are set so that a voltages of each of the first and second secondary windings becomes additive to a voltage of the secondary winding of the first transformer.

Abstract: A discharge-lamp lighting apparatus includes first and second cold cathode fluorescent lamps (CCFLs) and first and second transformers. The second transformer has a primary winding connected in parallel to one of primary and secondary windings of the first transformer, a first secondary winding, and a second secondary winding. Each of the first and second secondary windings of the second transformer is connected to the secondary winding of the first transformer with polarities being set so that a voltage of each secondary winding of the second transformer becomes additive to a voltage of the secondary winding of the first transformer. The first CCFL is connected in parallel to a series circuit that includes the secondary winding of the first transformer and the first secondary winding of the second transformer.

Abstract: A method for producing a glass substrate for a magnetic disk by polishing a circular glass plate, which comprises a step of polishing the principal plane of the circular glass plate by using a slurry containing a CeO2 crystal powder, the CeO2 crystal powder being obtained in such a manner that a melt containing CeO2 is quenched to obtain an amorphous material, and the amorphous material is subjected to heat treatment to obtain a CeO2 crystals-precipitated amorphous material, which is subjected to acid treatment to separate and extract the CeO2 crystal powder from the CeO2 crystals-precipitated amorphous material.

Abstract: In an overheat protection circuit for power supply devices in the present invention, overheat protection is provided by using a Schottky barrier diode (SBD) in place of a dedicated thermosensor. The overheat protection circuit is designed to flow reverse leakage current Ir resulting from temperatures of the SBD thermally coupled with a rectifier diode to a photocoupler inside an output-voltage detecting circuit in a direct-current power supply device. Thereby, where the reverse leakage current of the SBD is increased (where temperatures of the rectifier diode are elevated due to overload), a feedback signal of the output-voltage detecting circuit is increased to decrease the output voltage, thereby the direct-current power supply device is protected from overheat.

Abstract: A DC-DC converter for overvoltage protection is provided with a primary control circuit 12 which comprises an impedance controller 31 and a protective circuit 41 for ceasing operation of primary control circuit 12 when power source voltage VCC on primary control circuit 12 exceeds a predetermined voltage level. Impedance controller 31 comprises a potential detector 32 for picking out power source voltage VCC to primary control circuit 12 to produce a detection signal; and an impedance adjuster 33 for adjusting power input impedance Z in primary control circuit 12 in response to the detection signal from potential detector 32 to repress rapid rise in power source voltage on primary control circuit 12.

Abstract: A converter is provided in which the cost and size of which are reduced by a decrease in current consumption with no need of large elements or radiation fins. The converter has a switching element (Q1) being connected to a DC power source through a primary winding (P) of a transformer (T), a control circuit (4) for turning on/off the switching element (Q1), a diode (D51) and a capacitor (C51) for rectifying/smoothing the voltage induced in the secondary winding (S) of the transformer (T) to extract DC output, and a starting circuit (5) for starting the control circuit (4). The starting circuit (5) operates as a constant current circuit (Q2, R1, R2, ZD1, D1) while starting the control circuit (4), and as a constant voltage circuit (Q2, R1, R2, ZD2, D1) after starting the control circuits (4).

Abstract: A Schottky barrier diode is employed for temperature sensing, being capable of indicating temperatures above 110° C. or so by the magnitude of its reverse current. The overheat protector is disclosed as incorporated in a dc-to-dc converter in which, connected in series with the primary winding of a transformer, a current control switch is driven by a switch control circuit so as to hold the converter output voltage constant. The Schottky barrier diode is connected to the gate of a thyristor, triggering the same by its reverse current when a preselected part of the converter, to which the Schottky barrier diode is thermally coupled, heats up to a predetermined limit. The conduction of the thyristor results in disconnection of the switch control circuit from its power supply.

Abstract: A DCDC converter includes a transformer comprising primary and secondary coils. A series connection of the primary coil and a first switch is connected in parallel to a DC power. A series connection of a second switch and a capacitor is connected to both sides of the primary coil. A first control circuit controls an ON-time of the first switch. A second control circuit controls the second switch while the second control circuit is decoupled from the first control circuit. The first and second switches alternately turn ON and OFF. The second switch turns ON synchronizing with a first time period between after a charge to the capacitor is started and until the charge to the capacitor is ended. The second switch turns OFF when a second time period previously set has been elapsed after the second switch turned ON.

Abstract: A power factor corrector is connected to an AC power source, to provide a first DC voltage. A DC-DC converter supplies the first DC voltage from the power factor corrector to a primary winding of a transformer. A first rectifying/smoothing circuit rectifies and smoothes a voltage generated by a secondary winding of the transformer and supplies the rectified-and-smoothed voltage to a load. A second rectifying/smoothing circuit rectifies and smoothes a voltage generated by a control winding of the transformer. A light-load detector detects if an output ripple of the second rectifying/smoothing circuit is equal to or greater than a predetermined value, determines upon detection that the switching operation has decreased the frequency thereof or has shifted to an intermittent oscillation, and stops the power factor corrector.

Abstract: A DC-DC converter of synchronous rectification type is provided which comprises: a current detector (51) for discerning electric current (IQ1, IQ2) flowing through a primary side circuit; first and second DC biasing power supplies (53, 54) for producing a bias voltage (VBS1, VBS2) higher than voltage corresponding to excitation current through transformer (4); and first and second comparators (55, 57) for activating first and second rectifying MOS-FET (7, 8) when current detector (51) produces the detection voltage (VDT) over bias voltage (VBS1, VBS2) of first and second DC biasing power supplies (53, 54). As each of first and second rectifying MOS-FETs (7, 8) in secondary side circuit is driven synchronously with electric current (IQ1, IQ2) flowing through the primary side circuit except excitation current component through transformer (4), the converter can minimize switching loss in each rectifying MOS-FET (7, 8) in secondary side circuit to improve conversion efficiency.

Abstract: A DC-DC converter of multi-output type is provided wherein first and second MOS-FETs 1 and 2 are alternately turned on and off to take a plurality of DC outputs out of a plurality of secondary windings 4b, 4c and 4d of a transformer 4 through related rectifying smoothers 12, 22 and 32. A first DC output from first secondary winding 4b is controlled by adjusting a duty ratio of first and second MOS-FETs 1 and 2. At least one magnetic amplifier 21, 31 is connected in series between each of second or more secondary windings 4c and 4d and related rectifying smoother 22 and 32 to adjust reset current to the magnetic amplifier 21, 31, thereby generating stabilized DC-outputs VO2 and VO3 from the second or more secondary windings 4c, 4d.

Abstract: A DC-DC converter of multi-output type is provided wherein a primary winding 5a is wound around core halves 5g, 5h of a transformer 5 between first and second secondary windings 5b, 5c of transformer 5 also concentrically wound around core halves 5g, 5h to form an electromagnetic sparse coupling between first and second secondary windings 5b, 5c. When on-off operation of first and second primary MOS-FETs 2, 3 generates first and second DC outputs VO1, VO2, the electromagnetic sparse coupling can reduce, attenuate or relax serge voltage induced on first secondary winding 5b.

Abstract: The ON duration of an N channel MOS transistor is set based on a target voltage at a node between a resistor and a light receiving element of a photocoupler. A comparator compares the target voltage with a reference voltage at a node between a variable resistor and a resistor. A normal mode and a low frequency operation mode are switched from one to the other based on an output signal from the comparator. The resistance of the variable resistor becomes low when an input voltage from a power source is high. Even when the input voltage is high, therefore, the ON duration of the N channel MOS transistor at the transition between the normal mode and the low frequency operation mode becomes short. This reduces the switching energy in low frequency operation mode, thereby suppressing noise.

Abstract: When an AC power supply (9) is powered up, a constant current supply section (14) supplies a constant current to a capacitor (C3) to charge the capacitor (C3). When a voltage across the capacitor (C3) becomes equal to or greater than a predetermined voltage, a switch control section (17) sets a switch (13) off. When an output current drops to lead to a light load, a load detecting circuit (15) stops the operation of a PWM control circuit (12) and activates a timer (16). The timer (16) supplies a switch-ON signal to the switch control section (17) when it is activated and a predetermined time measured elapses. When supplied with the switch-ON signal, the switch control section (17) sets the switch (13) on. When the switch (13) is set on, the capacitor (C3) is charged again, applying a voltage to the PWM control circuit (12).

Abstract: A boost quantity detecting section (103) detects a boost quantity of an inductor (L11). An operational amplifier (113) of a control section (106) compares the boost quantity detected by the boost quantity detecting section (103) with a reference voltage (ES12). When a supply voltage supplied from an AC power source (100) reduces and an output voltage is unchanged, the boost quantity detected by the boost quantity detecting section (103) increases. When a signal level of a boost quantity detection signal is higher than the reference voltage (ES12), a control section (106) reduces a target level of a switching current. The target level of the switching current decreases, so that the output voltage decreases and energy loss due to boosting reduces.