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A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float9floating according to a liquid le

A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float9floating according to a liquid level, an insulating substrate6having a plurality of conductor electrodes4connected with a resistor5, and a movable contact interlocked with a movement of the float9to come in contact with the conductor electrodes4on the insulating substrate6, in which a material containing silver is used as a material of the conductor electrodes4or the movable contact, a voltage dividing resistance11is connected with a power source BA in series with the resistor5, and a voltage of a connection point between the voltage dividing resistance11and the resistor5is outputted as a signal corresponding to the liquid level, and resistance values of the voltage dividing resistance11and the resistor5are set so that a voltage drop VS due to silver sulfide generated between the conductor electrode4and the movable contact becomes15% or less, preferably10% or less with respect to a difference between a voltage VF equivalent to a full tank of the liquid level and a voltage VE equivalent to a low region.

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A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float9floating according to a liquid le

A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float9floating according to a liquid level, an insulating substrate6having a plurality of conductor electrodes4connected with a resistor5, and a movable contact interlocked with a movement of the float9to come in contact with the conductor electrodes4on the insulating substrate6, in which a material containing silver is used as a material of the conductor electrodes4or the movable contact, a voltage dividing resistance11is connected with a power source BA in series with the resistor5, and a voltage of a connection point between the voltage dividing resistance11and the resistor5is outputted as a signal corresponding to the liquid level, and resistance values of the voltage dividing resistance11and the resistor5are set so that a voltage drop VS due to silver sulfide generated between the conductor electrode4and the movable contact becomes15% or less, preferably10% or less with respect to a difference between a voltage VF equivalent to a full tank of the liquid level and a voltage VE equivalent to a low region. 20021100, Kingsley et al., 324/096 inals thereof to said device and in series between an input terminal and an output terminal to a load, said device comprising: a switching control unit that switches the switching transistor in accordance with a switching control signal based on an output voltage of the output terminal;a state detection unit that detects a gate-source voltage of the switching element to determine whether or not the switching transistor is in an ON state;a voltage detection unit that is connected to the opposite terminals of the switching element to detect a voltage generated across the switching element and that determines whether or not the voltage across the switching transistor is higher than a predetermined voltage and outputs a detection signal if said voltage is greater than the predetermined voltage during the ON-state of the switching element; anda gate unit that stops supplying the switching control signal to the switching transistor when the switching transistor is in the ON state and the voltage detected by the voltage detection unit is higher than the predetermined voltage.9. A power supply device, comprising: a switching element which is connected in series with a load and which controls an output voltage;a power supply control unit that controls the switching element based on the output voltage;an ON-state detection unit that detects a gate-source voltage of the switching element to determine whether or not the switching element is in the ON state; anda voltage detection unit that is connected to the opposite terminals of the switching element to detect a voltage generated across the switching element and that detects the voltage generated across the switching element when the switching element is in the ON state.10. The power supply device as claimed in claim 9, wherein the ON-state detection unit determines whether or not the switching element is in the ON state in accordance with a control signal for controlling the switching element.11. The power supply device as claimed in claim 9, wherein the ON-state detection unit comprises a comparison unit that compares a gate-source voltage of the switching element with a predetermined voltage.12. The power supply device as claimed in claim 11, wherein the predetermined voltage can be set based on an externally supplied voltage.13. The power supply device as claimed in claim 9, wherein the ON-state detection unit comprises:an error detection unit that detects a potential difference between the output voltage and a first predetermined voltage; anda comparison unit that compares the potential difference detected by the error detection unit with a second predetermined voltage.14. The power supply device as claimed in claim 13, wherein the second predetermined voltage can be set based on an externally supplied voltage.15. The power supply device as claimed in claim 9, wherein the ON-state detection unit comprises a comparison unit that compares a drain-source voltage of the switching element with a predetermined voltage.16. A power supply control method employing a switching element connected at opposite terminals thereof in series between a power supply source and a load, comprising the steps of: detecting a gate-source voltage of the switching element to determine whether or not the switching element is in an ON state;detecting a voltage generated across the switching element at the opposite terminals thereof when the switching element is in the ON-state and outputting a detection signal if said detected voltage is greater than a predetermined voltage during the ON-state of the switching element; andcontrolling an output voltage based on the detected voltage generated across the switching element.17. The power supply control method as claimed in claim 16, wh erein the step of determining whether or not the switching element is in the ON state is performed in accordance with a control signal for controlling the switching element.18. The power supply control method as claimed in claim 16, wherein the step of determining whether or not the switching element is in the ON state is performed in accordance with a result of a comparison between a gate-source voltage of the switching element and a predetermined voltage.19. The power supply control method as claimed in claim 18, wherein the predetermined voltage can be set based on an externally supplied voltage.20. The power supply control method as claimed in claim 16, further comprising the step of detecting a potential difference between the output voltage and a first predetermined voltage,wherein the step of determining whether or not the switching element is in the ON state is performed based on a result of a comparison between the potential difference and a second predetermined voltage.21. The power supply control method as claimed in claim 20, wherein the second predetermined voltage can be set based on an externally supplied voltage.22. The power supply control method as claimed in claim 16, wherein the step of determining whether or not the switching element is in the ON state is performed in accordance with a result of a comparison between a drain-source voltage of the switching element and a predetermined voltage.23. An electronic apparatus comprising: a switching element connected at opposite terminals thereof in series between a power source and a load; anda power supply control device that converts an input voltage into a predetermined driving voltage and supplies the predetermined driving voltage to an internal device,wherein the power supply control device detects a gate-source voltage of the switching element to determine whether or not the switching element is in an ON-state, detects a voltage generated across the switching element at the opposite terminals thereof when the switching element is in the ON state and outputs a detection signal if said voltage is greater than a predetermined voltage during the ON-state of the switching element, and controls the driving voltage in accordance with detection signal.24. The electronic apparatus as claimed in claim 23, wherein the power supply control device determines whether or not the switching element is in the ON state, in accordance with a control signal for controlling the switching element.25. The electronic apparatus as claimed in claim 23, wherein the power supply control device determines whether or not the switching element is in the ON state, in accordance with a result of a comparison between a gate-source voltage of the switching element and a predetermined voltage.26. The electronic apparatus as claimed in claim 25, wherein the predetermined voltage can be set based on an externally supplied voltage.27. The electronic apparatus as claimed in claim 23, wherein the power supply control device detects a potential difference between the output voltage and a first predetermined voltage, and then determines whether or not the switching element is in the ON state, in accordance with a result of a comparison between the potential difference and a second predetermined voltage.28. The electronic apparatus as claimed in claim 27, wherein the second predetermined voltage can be set based on an externally supplied voltage.29. The electronic apparatus as claimed in claim 23, wherein the power supply control device determines whether or not the switching element is in the ON state, in accordance with a result of a comparison between a drain-source voltage of the switching element and a predetermined voltage.30. A power supply circuit having a switching element connected in series with a load and supplying a control signal to the switching element to switch from an OFF-state to an ON-state to provide power sup