Tdk Corporation

Takakazu Imai

Takeshi Uematsu

Hiroshi Kawasaki

Ken Matsuura

Koichiro Miura

Takeo Gokita

Reiji Okuno

Kei Tanabe

Junya Fukuda

Hiraku Hirabayashi

Masanori Sakai

Naoki Ohta

Tsuyoshi Umehara

Satoshi Abe

Hiroyoshi Nakajima

Yosuke Komasaki

Hayato Miyashita

Takuya Daigo

A movement detection unit includes a movable body, a first sensor, a second sensor, and a signal processor. The movable body performs a movement in a first direction. The first sensor detects a first magnetic field change which is caused by the movement of the movable body and outputs a first signal. The second sensor is provided in the first direction at a location different from a location of the first sensor. The second sensor detects a second magnetic field change which is caused by the movement of the movable body and outputting a second signal. The signal processor includes a signal generating circuit that generates a third signal and a fourth signal on a basis of the first signal. The third signal and the fourth signal have waveforms different from each other.

Movement detection unit

A magnetic sensor includes a magnetic detection element circuit that includes first and second magnetic detection elements, which are connected in series, and an output terminal, which is positioned between the first and second magnetic detection elements; an impedance matching device, which has a prescribed input voltage range and is connected to an output terminal of the magnetic detection element circuit; a first current supply source, which supplies an electric current to the magnetic detection element circuit; and a second current supply source, which supplies an electric current to the impedance matching device. A resistor is provided between the output terminal of the magnetic detection element circuit and the first current supply source and/or a reference electric potential point.

Magnetic sensor

A movement detection unit includes a movable body, a first sensor, a second sensor, and a signal processor. The movable body performs a movement in a first direction. The first sensor detects a first magnetic field change which is caused by the movement of the movable body and outputs a first signal. The second sensor is provided in the first direction at a location different from a location of the first sensor. The second sensor detects a second magnetic fled change which is caused by the movement of the movable body and outputting a second signal. The signal processor includes a signal generating circuit that generates a third signal and a fourth signal on a basis of the first signal. The third signal and the fourth signal have waveforms different from each other.

Provided is a magnetic field detection device and a current sensor capable of increasing the degree of freedom in selecting the type of the magnetic field detection element. A magnetic field detection deviceincludes a conductorthat generates a magnetic field; a C coreprovided so as to surround the conductor; and a magnetic field detection elementthat detects a magnetic field. The C corehas a gap G, and the magnetic field detection elementis disposed at a position where the magnetic field generated from the conductorcan be detected, the position being outside the gap G. Since the direction of the magnetic flux varies outside of the gap Gfrom place to place, the direction of the magnetic flux that passes through the magnetic field detection elementcan be arbitrarily selected by arbitrarily selecting the installation location of the magnetic field detection element. Therefore, the degree of freedom in selecting the type of the magnetic field detection elementis increased.

Magnetic field detection device and current sensor

A magnetic coupling-type isolator includes a primary coil configured to generate a first magnetic field in accordance with an input signal, a bias coil configured to generate a second magnetic field in accordance with a bias signal, a first magneto-resistive element having a magnetic resistance increased by the first magnetic field and decreased by the second magnetic field, a second magneto-resistive element having a magnetic resistance decreased by the first magnetic field and increased by the second magnetic field, and a comparator configured to output an output signal in accordance with a difference between the magnetic resistance of the first magneto-resistive element and the magnetic resistance of the second magneto-resistive element.

Signal transmitting device having output circuit for voltage comparison

The magnetic field measurement method has: a step of preparing a magnetic sensor which includes: a magneto-resistive effect element having a magnetization-free layer and a magnetization fixed layer, and having a longitudinal direction; and magnetic field application means, wherein the magnetization direction of the magnetization fixed layer is fixed in a direction which forms an angle equal to or less than 45 degrees to the longitudinal direction, and a magnetic field generated by the magnetic field application means forms an angle equal to or less than 45 degrees to the longitudinal direction; a step of saturating the magnetization of the magnetization-free layer by the magnetic field application means and magnetizing the magnetization-free layer in one direction in the longitudinal direction; and a step of measuring the strength of an external magnetic field by applying the external magnetic field to the magnetization-free layer in the other direction in the longitudinal direction.

Magnetic field measurement method and magnetic sensor

The magnetic sensor according to the present invention includes: a magneto-resistive effect element which has a stacked body in which a magnetization-free layer, a nonmagnetic layer, and a magnetization fixed layer are stacked in this order, and the longitudinal direction of which is a direction perpendicular to the stacking direction; and a current path layer which is provided on the magneto-resistive effect element via an insulation layer so as to be spaced apart from the magneto-resistive effect element in the stacking direction, and which generates a magnetic field by being supplied with a current. The current path layer extends in a direction which forms an angle between 0 and 45 degrees to the longitudinal direction of the magneto-resistive effect element when viewed from the stacking direction.

Magnetic sensor and magnetic field strength measurement method saturating magnetization of magnetization-free layer

A digital signal transmitting apparatus includes an encoder which converts parallel input signals of multiple channels into serial data in a manner synchronized with a first clock signal, and a decoder which converts the serial data into parallel output signals of the multiple channels in a manner synchronized with a second clock signal operating in a manner asynchronous with the first clock signal. The serial data has a different period and a different duty factor corresponding to each combination of the logical values of the parallel input signals of the multiple channels.

Digital signal transmitting apparatus and digital signal transmitting method

A DC-DC converter has a switching circuit including switching elements at the high-side and at the low-side, an inductor connected to the output end of the switching circuit, a smoothing capacitor connected to the inductor, a switching control circuit for supplying a switching pulse to the switching elements, and a circuit. The circuit detects that a state that the switching element at the high side is switched off and the switching element at the low side is switched on is maintained for a predetermined period or longer. In this case, the circuit forcibly switches off the switching element at the low side.

DC-DC converter and control method thereof

A current flowing through a measuring target coil increases when a pulse signal is high. A voltage corresponding to instantaneous value of the current through the coil is input to input terminal. A blanking signal generator circuit generates signal which has predetermined pulse width and rises in synchronization with rise of the pulse signal. During period in which this signal is high, first switch becomes ON and first capacitor holds the voltage at the input terminal. A second switch becomes ON when first switch becomes OFF to connect second capacitor to connection node between resistors, and disconnects second capacitor from connection node when the pulse signal becomes low. Second capacitor is charged with voltage corresponding to average value of an amount of increase in the current through the coil. A voltage obtained by adding the voltage charged in first capacitor to this charged voltage is supplied to third capacitor.

Average current detector circuit

A selector sets respective phases of pulse driving signals in reverse when a proportion signal or integration signal does not exceed a threshold. Shifting the respective phases of the pulse driving signals from each other lowers the ripple voltage. When the load current increases drastically, the output voltage Vo tends to decrease remarkably because of the shortage of capacity in the power supply. In this case, when the proportion signal or integration signal exceeds its corresponding threshold, a phase control unit causes the pulse driving signals to synchronize their phases, i.e., the selector supplies the same ramp wave to the comparators, so that respective output voltages supplied from the DC voltage converter circuits attain the same phase, thereby restraining the output voltage supplied to the load from decreasing remarkably.

Power supply apparatus and control circuit therefor

A controllerA for generating a drive signal (PWM signal) PS for controlling a switching power supply, comprises control signal setting meansfor setting a control signal CS on the basis of an output voltage Vo and a target voltage Vr; current estimating meansfor estimating an inductor current on the basis of the drive signal PS and for generating an estimated current signal PC; DC component removing meansfor extracting a DC component DC included in the estimated current signal PC and for removing the DC component DC from the estimated current signal PC; DC component resetting meansfor resetting the extracted DC component DC every predetermined time; and comparing meansfor comparing the control signal CS with the estimated current signal PC' after the removal of the DC component DC.

Switching power supply controller and switching power supply

An output voltage of a switching power supply is regulated to a target value. When the target value of the output voltage is altered, the reference value is changed monotonously and linearly a plurality of times at a plurality of gradients to the altered target value. An input voltage of the power supply is switched in response to a switching pulse with the duty ratio calculated according to a difference between the reference value and the output voltage.

Switching power supply, and method and circuit for regulating output of the same

This invention provides a switching power supply control circuit based on the parallel operation scheme that suppresses ripples in the output voltage. The control circuit comprises switching circuit blocksandconnected in parallel, output reactorsandconnected in parallel corresponding to the switching circuit blocksand, and a control circuitthat controls the operation of the switching circuit blocksand. The control circuitcomprises: means of calculating the difference between the reactor currents Iand Iflowing through the output reactorsandand the average value of the reactor currents, means of generating control voltages Vand Vcorresponding to the switching circuit blocksandbased on the calculated differences and the output voltage Vcomparatorsandthat compare the control voltages Vand Vagainst the reference voltage Vand latch circuitsandthat latch the outputs of the comparatorsandin response to the clock signal CLK.

Switching power supply control circuit and switching power supply using same

An adderoutputs a signal VS indicating a value of (Vr&#x2212;Vo), and a multiplieroutputs a control signal GS indicating a value of G(Vr&#x2212;Vo) on the basis of the signal VS. An adderoutputs a signal HS on the basis of the control signal GS and a signal FS outputted from an operation circuit, and a PWM signal generating circuitgenerates a PWM signal KS on the basis of the signal HS and a ramp signal RS outputted from a ramp signal circuit, and outputs this signal KS to a switching power supply. A countercounts an on time of the PWM signal KS and retains a count value at a time of receiving a sample signal SMP. The operation circuithas a high-pass filterand an integrator, performs an operation based on a signal DS indicating the count value outputted from the counter, and outputs the signal FS after the operation.

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Tokyo, Japan

Takakazu Imai