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 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: 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: 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 power source apparatus includes a DC voltage generator (1, 2, 3) to generate a DC voltage, a plurality of voltage converters connected in parallel with one another and each having a switching element (5a/5b) to convert the DC voltage generated by the DC voltage generator into a predetermined DC voltage, a first controller 10 to generate a first control signal for controlling ON/OFF of one of the switching elements contained in the plurality of voltage converters, and a second controller 20 to control, according to the first control signal, the switching elements other than the switching element controlled by the first controller.

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: A dropper type regulator of the invention, in which a semiconductor device is connected in series between a DC power supply and a voltage output terminal, extracts a second voltage from the first voltage of the DC power supply; when the driving voltage of the semiconductor device is detected as being larger than a preset first threshold value, the voltage difference occurring between the input and output terminals of the semiconductor device is detected, and when this voltage difference is detected as being larger than a second threshold value, an overload protection circuit performs overload protection.

Abstract: A current resonant DC-DC converter of multi-output type is provided which comprises an output-regulatory MOS-FET 40 connected between a secondary winding 5c of a transformer 5 and a smoothing capacitor 16 in a second rectifying smoother 17, and an output control circuit 41 for controlling the on-off operation of output-regulatory MOS-FET 40 based on voltage VO2 from smoothing capacitor 16 in second rectifying smoother 17. By turning the on-off operation of output-regulatory MOS-FET 40 in synchronization with switching frequency of first or second MOS-FETs 1, 2, an ideal cross regulation among respective DC outputs can be obtained, providing the inexpensive converter with simple circuit alteration capable of producing highly stable DC outputs with high power conversion efficiency, high accuracy and less power conversion loss.

Abstract: In the production of a glass substrate for magnetic disks, in a step of polishing a main surface of a circular glass plate, roll-off is reduced without reducing the polishing rate. The process comprises a step of polishing a main surface of a circular glass plate by using an acidic polishing fluid containing colloidal silica or fumed silica, and a water-soluble polymer having at least one member selected from a group consisting of a carboxylic acid group, a carboxylate group, a sulfonic acid group and a sulfonate group, bonded to its main chain, or an acidic polishing fluid containing 100 parts by mass of colloidal silica or fumed silica, and from 0.02 to 0.1 part by mass of a surfactant having a sulfonic acid group.

Abstract: A power factor correcting converter includes a rectifier to rectify an AC voltage of an AC power source into a pulsating voltage, a voltage converter having a switching element, to convert the pulsating voltage into a predetermined DC voltage with the switching element being turned on/off according to a control signal, an smoothing circuit to smooth the control signal, and a control signal generator to generate the control signal and change a switching frequency of the control signal according to an output from the smoothing circuit.

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 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: An AC-DC converter includes a rectifier DB for rectifying an alternating current supplied from an alternating power source AC, a power factor controller 11a connected to an output side of the rectifier DB to improve a power factor and also output either a power or a current limited to a predetermined value, a DC-DC converter 12 that converts a voltage outputted from the power factor controller 11 to another voltage, a capacitor EDLC for storing an energy and a two-way converter 13 having one input/output terminals connected to the output side of the power factor controller 11a and the other input/output terminals connected to the capacitor to carry out a two-way power conversion.

Abstract: An AC-DC converter includes a rectifier DB for rectifying an alternating current supplied from an alternating power source AC, a power factor controller 11 connected to an output side of the rectifier DB to improve a power factor, a DC-DC converter 12 that converts a voltage outputted from the power factor controller 11 to another voltage and also outputs either a power or a current limited to a predetermined value, a capacitor for storing an energy and a two-way converter 13 having one input/output terminals connected to output terminals of the DC-DC converter 12 and the other input/output terminals connected to the capacitor to carry out a two-way power conversion.

Abstract: A power source apparatus has a series circuit connected between output terminals of a DC power source, the series circuit including a primary winding of a transformer and a switching element; a controller configured to control an ON/OFF operation of the switching element; and an output diode connected between terminals of a second winding of the transformer and configured to rectify an alternating current that is induced on the secondary winding when the controller turns on/off the switching element. The output diode includes a plurality of diodes that are connected in parallel with one another and are made of wide-gap semiconductor.

Abstract: A DC-DC converter includes a series circuit of a switch element Q1 and a switch element Q2 connected to a DC power source, a series circuit of a primary winding P1 of a transformer and a capacitor connected in parallel with one of the switch elements, a rectifying-smoothing circuit of a voltage generated by a secondary winding (S1, S2) of the transformer, a controller to alternately turn on/off the switch elements according to an output of the rectifying-smoothing circuit, first and second timing detectors to detect ON/OFF states of the switch elements, and an ON time storing part to operate in response to a detection signal from the second timing detector and store an ON time of the switch element Q1 based on an OFF time of the switch element Q2. The controller turns on the switch element Q2 only during the stored ON time.

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 cold cathode fluorescent lamp inverter apparatus includes a series circuit connected to a DC power source and including first and second switching elements, a series circuit connected between a connection point of the first and second switching elements and the DC power source and including a primary winding of a transformer, a reactor, and a capacitor, a cold cathode fluorescent lamp connected to a secondary winding of the transformer, a current detector connected to the cold cathode fluorescent lamp and to the secondary winding, to detect a value of a current passed through the cold cathode fluorescent lamp, and a controller to turn on/off the first and second switching elements alternately with each other according to the detected current value. The current detector detects a ripple component in the DC power source, and corrects the current of the cold cathode fluorescent lamp according to the detected ripple component.

Abstract: A diode chip is sealed by a glass material. There are provided a light emitting diode chip and a glass member in close contact with at least one portion of the surface of the light emitting diode chip. The glass member has a surface shape containing a curved surface at least a portion thereof. The curved surface is preferably a portion of a spherical surface or a spheroidal surface. The glass member has a surface shape containing a spherical portion and a flat portion, and the diode chip is preferably disposed on the flat portion.

Abstract: A dropper type regulator of the invention, in which a semiconductor device is connected in series between a DC power supply and a voltage output terminal, extracts a second voltage from the first voltage of the DC power supply; when the driving voltage of the semiconductor device is detected as being larger than a preset first threshold value, the voltage difference occurring between the input and output terminals of the semiconductor device is detected, and when this voltage difference is detected as being larger than a second threshold value, an overload protection circuit performs overload protection.