Abstract: A temperature abnormality detection method for a power conversion apparatus basically includes a detecting a first power converter temperature, a second power converter temperature and a cooling water temperature and then determining a presence of an abnormality in a preceding stage power converter based on a first temperature difference between the first power converter temperature and the cooling water temperature. The abnormality detection method further includes determining a presence of an abnormality in a subsequent stage power converter based on a second temperature difference between the second power converter temperature and an added temperature that is obtained by adding to the loss component of the preceding stage power converter converted to a temperature to the cooling water temperature.

Abstract: A temperature abnormality detection method for a power conversion apparatus basically includes a detecting a first power converter temperature, a second power converter temperature and a cooling water temperature and then determining a presence of an abnormality in a preceding stage power converter based on a first temperature difference between the first power converter temperature and the cooling water temperature. The abnormality detection method further includes determining a presence of an abnormality in a subsequent stage power converter based on a second temperature difference between the second power converter temperature and an added temperature that is obtained by adding to the loss component of the preceding stage power converter converted to a temperature to the cooling water temperature.

Abstract: An over-current detecting apparatus for a switching element includes a reference power source, a comparator circuit, a current converting element, a first resistor, and a second resistor. The comparator circuit includes a first input terminal that receives a voltage corresponding to a current flowing in the switching element and a second input terminal that receives a reference voltage supplied from the reference power source. The current converting element converts a voltage of a temperature detecting element (4) that detects a temperature of the switching element into a current corresponding to the voltage of the temperature detecting element. The first resistor is connected in series to a reference power supply side of the second input terminal of the comparator circuit. The second resistor is connected in series to a ground side of the second input terminal of the comparator circuit.

Abstract: A short-circuit protection circuit (12) configured to protect a switching element from an overcurrent includes: a potential decreasing means for decreasing a potential of a gate terminal when a main circuit current is an overcurrent; a feedback means for performing feedback control on an amount of a decrease in the gate potential caused by the potential decreasing means according to a current amount of the main circuit current; and a phase advancing means for performing phase advance compensation in a feedback loop under the feedback control.

Abstract: A short-circuit protection circuit (12) configured to protect a switching element from an overcurrent includes: a potential decreasing means for decreasing a potential of a gate terminal when a main circuit current is an overcurrent; a feedback means for performing feedback control on an amount of a decrease in the gate potential caused by the potential decreasing means according to a current amount of the main circuit current; and a phase advancing means for performing phase advance compensation in a feedback loop under the feedback control.

Abstract: An over-current detecting apparatus for a switching element (1) includes a reference power source (7), a comparator circuit (8), a current converting element (6), a first resistor (R3), and a second resistor (R2). The comparator circuit (8) includes a first input terminal that receives a voltage corresponding to a current flowing in the switching element and a second input terminal that receives a reference voltage supplied from the reference power source (7). The current converting element (6) converts a voltage of a temperature detecting element (4) that detects a temperature of the switching element (1) into a current corresponding to the voltage of the temperature detecting element (4). The first resistor (R3) is connected in series to a reference power supply side of the second input terminal of the comparator circuit (8). The second resistor (R2) is connected in series to a ground side of the second input terminal of the comparator circuit (8).

Abstract: A semiconductor laser driving circuit has a circuit protection function at low temperature and includes a voltage current converter that converts an input voltage Vin, which is determined according to a desired light brightness of the semiconductor laser to be driven, into a current. A current limiter limits an output current of the voltage current converter to a specified current value or less. An output amplifier amplifies the output current of the voltage current converter and supplies the amplified current as a drive current to the semiconductor laser. A temperature detection circuit detects a low temperature state and, in the low temperature state, decreases the specified current value of the current limiter.

Abstract: A semiconductor laser driving circuit has a circuit protection function at low temperature and includes a voltage current converter that converts an input voltage Vin, which is determined according to a desired light brightness of the semiconductor laser to be driven, into a current. A current limiter limits an output current of the voltage current converter to a specified current value or less. An output amplifier amplifies the output current of the voltage current converter and supplies the amplified current as a drive current to the semiconductor laser. A temperature detection circuit detects a low temperature state and, in the low temperature state, decreases the specified current value of the current limiter.

Abstract: A semiconductor laser driving circuit has a circuit protection function at low temperature and includes a voltage current converter that converts an input voltage Vin, which is determined according to a desired light brightness of the semiconductor laser to be driven, into a current. A current limiter limits an output current of the voltage current converter to a specified current value or less. An output amplifier amplifies the output current of the voltage current converter and supplies the amplified current as a drive current to the semiconductor laser. A temperature detection circuit detects a low temperature state and, in the low temperature state, decreases the specified current value of the current limiter.

Abstract: A voltage controlled current source outputs oscillator drive current and oscillator equivalent current. A signal oscillator outputs first source oscillation signal and second source oscillation signal. A differential amplifier outputs first amplification oscillation signal and second amplification oscillation signal. First switch circuit and second switch circuit output first current oscillation signal and second current oscillation signal, respectively. A first current value converter-amplifier circuit converts a value of the first current oscillation signal whereas a second current value converter-amplifier circuit converts a value of the second current oscillation signal, so that the thus converted values become output current finally. An adder outputs to the differential amplifier a differential amplifier drive current in which equivalent current for use with conversion is added up with the oscillator equivalent current outputted from the voltage controlled current source.

Abstract: A semiconductor laser driving circuit has a circuit protection function at low temperature and includes a voltage current converter that converts an input voltage Vin, which is determined according to a desired light brightness of the semiconductor laser to be driven, into a current. A current limiter limits an output current of the voltage current converter to a specified current value or less. An output amplifier amplifies the output current of the voltage current converter and supplies the amplified current as a drive current to the semiconductor laser. A temperature detection circuit detects a low temperature state and, in the low temperature state, decreases the specified current value of the current limiter.

Abstract: The distortion component of an oscillation signal is reduced. An oscillation signal generating circuit generates, as oscillation signals, first generation oscillation signal and second generation oscillation signal which are related to each other as a differential signal. A differential amplifier performs differential amplification on the first generation oscillation signal and the second generation oscillation signal, respectively, and outputs first amplification oscillation signal and second amplification oscillation signal. A converter circuit converts the first amplification oscillation signal and the second amplification oscillation signal into an output current oscillation signal of such a form that sink current and source current are alternately switched. In order to convert voltages of the first amplification oscillation signal and the second amplification oscillation signal into currents, a variable current source delivers a converting drive current to drive the converter circuit.

Abstract: An amplifier for amplifying an input signal, having a plurality of amplifier stages each having a gain smaller than a target gain. The plurality of amplifier stages are connected in parallel and share the load of current amplification, and add output currents obtained from their respective amplifications to achieve the target gain as a whole.

Abstract: A voltage controlled current source outputs oscillator drive current and oscillator equivalent current. A signal oscillator outputs first source oscillation signal and second source oscillation signal. A differential amplifier outputs first amplification oscillation signal and second amplification oscillation signal. First switch circuit and second switch circuit output first current oscillation signal and second current oscillation signal, respectively. A first current value converter-amplifier circuit converts a value of the first current oscillation signal whereas a second current value converter-amplifier circuit converts a value of the second current oscillation signal, so that the thus converted values become output current finally. An adder outputs to the differential amplifier a differential amplifier drive current in which equivalent current for use with conversion is added up with the oscillator equivalent current outputted from the voltage controlled current source.

Abstract: A voltage controlled current source outputs oscillator drive current and oscillator equivalent current. A signal oscillator outputs first source oscillation signal and second source oscillation signal. An amplifier outputs first amplification oscillation signal and second amplification oscillation signal. First switch circuit and second switch circuit output first current oscillation signal and second current oscillation signal, respectively. A first current value converter-amplifier circuit converts a value of the first current oscillation signal whereas a second current value converter-amplifier circuit converts a value of the second current oscillation signal, so that the thus converted values become output current finally. An adder outputs to the amplifier an amplifier drive current in which equivalent current for use with conversion is added up with the oscillator equivalent current outputted from the voltage controlled current source.

Abstract: The distortion component of an oscillation signal is reduced. An oscillation signal generating circuit generates, as oscillation signals, first generation oscillation signal and second generation oscillation signal which are related to each other as a differential signal. A differential amplifier performs differential amplification on the first generation oscillation signal and the second generation oscillation signal, respectively, and outputs first amplification oscillation signal and second amplification oscillation signal. A converter circuit converts the first amplification oscillation signal and the second amplification oscillation signal into an output current oscillation signal of such a form that sink current and source current are alternately switched. In order to convert voltages of the first amplification oscillation signal and the second amplification oscillation signal into currents, a variable current source delivers a converting drive current to drive the converter circuit.

Abstract: An amplifier for amplifying an input signal, having a plurality of amplifier stages each having a gain smaller than a target gain. The plurality of amplifier stages are connected in parallel and share the load of current amplification, and add output currents obtained from their respective amplifications to achieve the target gain as a whole.

Abstract: An optical pickup with a laser driver circuit is provided to overcome an increase in size of an optical pickup, which is caused by a ferrite bead or capacitor being provided in a drive current path to reduce EMI noise effects. In an optical disc apparatus, an optical sensor element detects a laser beam from a laser emission element included in an optical pickup circuit and then sends the detected signal to a main circuit board. An APC circuit in the main circuit board outputs a control signal to control the laser output from the laser emission element at a constant level in accordance with the detected signal from the optical sensor element. A laser driver circuit included in the optical pickup circuit incorporates a transistor and a high-frequency wave superposition circuit). The transistor produces a drive current in accordance with the control signal from the APC circuit, while the high-frequency wave superposition circuit superposes a high-frequency current on the drive current.

Abstract: An abrading device comprising two planar members that are disposed in a spaced apart relationship by at least one spacing member, a plurality of abrasive particles distributed over only the outermost surfaces of said two planar members, the space between said planar members being large enough to accommodate and protect the extended fingers of a person using the device.