Fujitsu Corporation

Minoru Hirahara

Seiji Miyoshi

Yoshito Koyama

Yutaka Awata

Koji Nakamuta

Eiji Miyachika

Hiroaki Itokawa

Takuo Gotoda

A power supply device includes: a first supply section that supplies power in accordance with an extent of a load in processing in a processing device by applying a voltage to the processing device which processes data; and a second supply section that supplies, to the processing device, power smaller than the supplying power by the first supply section, in accordance with an extent of a load in processing in the processing device to increase and decrease a voltage with respect to the application voltage by the first supply section.

Method for suppressing a voltage fluctuation applying to a load by a second power section with the same or opposite voltage polarity

A thermostatic-chamber temperature control device includes: a heating element for heating a thermostatic chamber; a bridge circuit having a temperature sensitive element whose resistance value varies in accordance with the temperature of the heating element; a detection circuit for detecting an unbalanced voltage of the bridge circuit; a PWM signal generating circuit for generating a PWM signal corresponding to the unbalanced voltage detected by the detection circuit; and a switching element that has a current output terminal connected to the heating element and a current input terminal connected to a power supply circuit and is driven on the basis of the PWM signal generated by the PWM signal generating circuit.

Temperature control device

A changing-speed calculator monitors a current value of an output current flowing through a load circuit to calculate a change speed of the current value. A correction-amount obtaining unit reads from a correction-amount table a correction amount of a duty ratio corresponding to the change speed of the output current. A reference-voltage comparator compares a voltage value of an output voltage to be applied to the load circuit and a predetermined reference voltage with each other, and then notifies a duty-ratio determining unit of the comparison result. The duty-ratio determining unit performs feedback control according to the comparison result of the voltage values to correct the duty ratio. After correcting the duty ratio, the duty-ratio determining unit further corrects the duty ratio by the correction amount obtained by the correction-amount obtaining unit.

Voltage converting device and voltage converting method

An uninterruptible power supply device connects a battery for power-outage backup to the output side of an AC/DC converter. An input monitoring circuit monitors alternating current input of the AC/DC converter and outputs an alternating current input monitor signal E. An output monitoring circuit monitors the direct current output of the AC/DC converter and outputs a direct current output monitor signal E. A reactivation circuit outputs a reset signal to and reactivates protection circuits of the AC/DC converter when the state that alternating current input is provided and direct current output is not provided is determined based on the alternating current input monitor signal Eand the direct current output monitor signal Eupon turn-on of alternating current power.

Uninterruptible power supply apparatus

An analog/digital integrated subscriber circuit includes a power supply part supplying power with respect to a subscriber line, and a signal processing part carrying out a signal processing. The power supply part is provided with a D.C./D.C. converter which controls an ON-time of a switching by detecting an output voltage and an output current supplied to the subscriber line. The D.C./D.C. converter includes a switching mechanism for switching a power supply characteristic of the power supply part to a constant current characteristic up to a maximum output voltage when supplying the power with respect to a digital subscriber line and to a constant voltage characteristic having a voltage lower than the maximum output voltage when supplying the power with respect to an analog subscriber line.

Analog/digital integrated subscriber circuit

A primary control type switching power supply circuit includes a transformer having a primary side and a secondary side, a control circuit generating a control signal based on a detection signal, a circuit for switching a current flowing through the primary side in response to the control signal so as to generate an A.C. voltage on the secondary side, a rectifying and smoothing circuit for rectifying and smoothing the A.C. voltage to generate an output voltage across first and second terminals, an output voltage detection circuit including a circuit part for comparing a reference voltage and a detection voltage that is based on the output voltage, and a detection signal transmitting part supplying to the control circuit the detection signal which is indicative of an error between the reference voltage and the detection voltage so that the output voltage is maintained constant based on the control signal, and a circuit including a choke coupled to one of the first and second terminals for turning the output voltage ON/OFF via the choke at a switching frequency and for obtaining a D.C. voltage by rectifying and smoothing an induced voltage of the choke caused by the ON/OFF of the output voltage. The D.C. voltage is supplied to the detection signal transmitting part of the output voltage detection circuit as a driving voltage from a driving power supply for the detection signal transmitting part.

Primary control type switching power supply circuit

A call signal generating circuit includes a step-up transformer having a primary winding and secondary windings and a first switching circuit coupled between the primary winding of the step-up transformer and a D.C. power source for turning ON/OFF at a frequency higher than a frequency of a call signal. A rectifying circuit is coupled to the secondary windings of the step-up transformer for rectifying voltages induced at the secondary windings into a positive polarity voltage and a negative polarity voltage. A second switching circuit is coupled to the rectifying circuit for alternatively outputting the positive polarity voltage and the negative polarity voltage with a quiescent time in which both the positive and negative polarity voltages are not output. A capacitor is coupled to the second switching circuit for receiving the positive and negative polarity voltages output from the second switching circuit. A third switching circuit is provided in the call signal generating circuit for discharging the capacitor during the quiescent time. A pair of output terminals are coupled to the capacitor for outputting the generated call signal.

Call signal generating circuit

A quick charging method of secondary cell in which a secondary cell is prevented from being damaged on account of overcharging. A strain gage is bonded to the side face of a cell to be charged. A low resistor for quick charging and a high resistor for normal charging connected in parallel are inserted between a charger and the cell. The low resistor for quick charging is connected with the contact of a normally open contact relay. A voltage for measurement is generated according to the resistance of the strain gage and this voltage for measurement is compared with a reference voltage. The relay is ON/OFF controlled by the result of the comparison. Since the resistance of the strain gage is low in the beginning stage of charging, a high voltage for measurement is generated and, thereby, the relay is energized and the contact is closed so that quick charging is performed. When the cell is fully charged, the resistance of the strain gage increases and, thereby, the relay is turned OFF and the quick charging mode is switched to the normal charging mode.

Growing community of inventors

Kawasaki, Japan

Minoru Hirahara