Fujitsu Ten Limited

Toyota Jidosha Kabushiki Kaisha

Keisuke Kido

Kazuhiro Komatsu

Kouji Oonishi

Junichi Sawada

Masahiko Fujimoto

Motoki Komiya

Masatoshi Watanabe

Shigeto Umeyama

Hiroto Miura

Masayoshi Kume

Satoshi Noguchi

Chiharu Morisaki

A controller of an air-fuel-ratio sensor according to an embodiment includes a current supplying unit, a sweep processing unit, and an abnormality detecting unit. The current supplying unit supplies a current to the pump cell through a first terminal connected with the pump cell so as to control the pump cell. The sweep processing unit executes a sweeping process in which a predetermined voltage or a predetermined current is applied to the detection cell through a second terminal connected with the detection cell so as to change a voltage and a current of the detection cell. The abnormality detecting unit detects a short-circuited state between the first terminal and the second terminal on the basis of a fluctuation in a voltage or a current, generated by the sweeping process, of the first terminal.

Controller and abnormality detecting method of air-fuel-ratio sensor

A controller of an air-fuel-ratio sensor includes a control unit, a voltage-abnormality detecting unit, and a short-circuit-abnormality detecting unit. The control unit controls a current and a voltage of a gas sensor element through a plurality of terminals connected with the gas sensor element. The voltage-abnormality detecting unit changes, when at least one of voltages of the plurality of terminals is out of a predetermined range, a voltage level of an output voltage. The short-circuit-abnormality detecting unit causes, when the voltage level of the output voltage changes from a first voltage into a second voltage, a control unit to perform for a predetermined time a protective operation that suppresses currents from the control unit to the plurality of terminals, and detects, when the voltage level of the output voltage is the second voltage after the protective operation is released, a short-circuit abnormality.

There is provided an abnormality detecting circuit. A clamp unit is configured to clamp an output voltage which is output from another device, such that the upper limit of the output voltage becomes a first clamp voltage which is generated on the basis of a constant voltage generated from a power supply voltage, or a second clamp voltage which is generated on the basis of the power supply voltage and which varies depending on the power supply voltage. A short-to-power detection unit is configured to compare the output voltage clamped by the clamp unit, with a predetermined threshold value which is generated on the basis of the power supply voltage, thereby detecting occurrence of a short to power.

Abnormality detecting circuit and abnormality detecting method

An overcurrent protection apparatus includes two overcurrent protection circuits. The first overcurrent protection circuit compares an electric potential on the downstream side of a first resistance element with a reference potential produced by a second resistance element by a comparator and determines that overcurrent has been caused and intercepts current flowing through a first series regulator when the electric potential on the downstream side of the first resistance element is lower than the reference potential. When the resistance value of the second resistance element is larger than the resistance value of a fourth resistance element of the second overcurrent protection circuit, e.g., 1.2 times the resistance value of the fourth resistance element, the first overcurrent protection circuit intercepts the current flowing through the first series regulator at a current value of 1.2 times a current at which a downstream second series regulator is intercepted by the second overcurrent protection circuit.

Overcurrent protection apparatus and electronic apparatus

An input terminal is electrically connected to a contact point. An anti-corrosion current supplying section is operable to supply an anti-corrosion current to the contact point through the input terminal so as to remove corrosion in the contact point. A series resistor is electrically interposed between the input terminal of the signal processing circuit and the contact point. The anti-corrosion current is supplied to the contact point through the series resistor.

Signal processing device and control unit

A circuit for preventing corrosion of a contact, includes an input terminal, a signal line, a switch, an impedance element, and a comparator. The input terminal is to be connected to the contact, which is outside the circuit. The signal line is connected to the input terminal. The switch is connected to the signal line. The impedance element is connected to the signal line in parallel to the switch. An impedance of the switching section is smaller than that of the impedance element. The comparator compares a potential of the signal line with a predetermined potential. The switch is turned on based on a comparison result output from the comparator.

Circuit for preventing corrosion of contact

A method for preventing corrosion of a contact, includes comparing a potential of a signal line connected to the contact with a predetermined potential corresponding to the corrosion of the contact; flowing a corrosion-prevention current into the contact when a result of the comparing shows that the contact is corroded; inputting into the signal line a signal used for judging a logical value of a connection state of the contact; and in the magnitude relation, setting the predetermined potential on another side of a threshold level used in the judging of the logical value of the connection state of the contact.

Method and apparatus for preventing corrosion of contact

An apparatus for preventing a contact from being corroded includes a power source, a signal line connected to the contact, a resistance connected to the signal line, a switching section, a comparator, and an overheat detecting section. The switching section has a switch between the power source and the signal line. An impedance of the switch is smaller than that of the resistance when the switch is turned on. The comparator compares a potential of the signal line with a predetermined potential to determine as to whether or not the contact is corroded. The comparator outputs a driving signal when the comparator concludes that the contact is corroded. The overheat detecting section detects whether or not temperature of the apparatus exceeds a predetermined temperature. The overheat detecting section decreases current flowing through the switching section when the temperature of the apparatus exceeds the predetermined temperature.

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Kobe, Japan

Keisuke Kido