Abstract: A method of producing a glass article includes holding a carrier having a circular shape, in which a glass substrate having a circular shape is retained, with an upper surface plate and a lower surface plate; and polishing the glass substrate by rotating the carrier with respect to the upper surface plate and the lower surface plate, to obtain the glass article. The glass substrate is disposed in the carrier such that, in a top plan view, a center of the carrier is included in a region of the glass substrate, and a center of the glass substrate is shifted from the center of the carrier.

Abstract: An electrical conductivity meter comprises a measurement tube formed of an electrical insulation material and through which a fluid of a measurement target flows, a first electrode formed on an outer peripheral surface of the measurement tube, a second electrode connected to a common potential and in contact with the fluid, a resistor in which one end is connected to the first electrode, a voltage detecting portion that detects voltages of a signal generated in the first electrode due to an input of an AC signal to the other end of the resistor, and an electrical conductivity calculating portion that calculates an electrical conductivity of the fluid based on an amplitude of the voltages detected by the voltage detection circuit.

Abstract: A pipe hole to which a measuring pipe is to be press-fitted is formed in a printed board, and a guide to be fitted to a side end portion of the printed board inserted through an opening is formed on or in an inner wall of a case.

Abstract: A preamplifier substrate on which a preamplifier is mounted, the preamplifier being configured to amplify electromotive forces detected by a pair of surface electrodes, is disposed outside a flux region where a magnetic flux is produced, and the preamplifier substrate extends in a direction intersecting a measuring tube.

Abstract: A voltage switching circuit applies a high excitation voltage to an excitation switching circuit during a period from an excitation period starting point to a rise point in an excitation period, and applies a low excitation voltage lower than the high excitation voltage to the excitation switching circuit during a period from the rise point to an excitation period ending point in the excitation period. A constant current circuit makes the current of the low excitation voltage to be input from a power supply circuit to the voltage switching circuit constant.

Abstract: A first connection line includes a first tube-side wiring pattern formed on an outer periphery of a measuring tube and connected at one end thereof to a first surface electrode, a first substrate-side wiring pattern formed on a preamplifier substrate and connected at one end thereof to a preamplifier, and a first jumper wire connecting the other end of the first tube-side wiring pattern to the other end of the first substrate-side wiring pattern; and a second connection line includes a second tube-side wiring pattern formed on the outer periphery of the measuring tube and connected at one end thereof to a second surface electrode, a second substrate-side wiring pattern formed on the preamplifier substrate and connected at one end thereof to the preamplifier, and a second jumper wire connecting the other end of the second tube-side wiring pattern to the other end of the second substrate-side wiring pattern.

Abstract: An electromagnetic flowmeter includes a measuring tube, first and second printed circuit boards fixed to the measuring tube, a housing accommodating the measuring tube and the first and second printed circuit boards and supporting the first and second printed circuit boards, joints made of an electrically conductive material and fixed to the housing, each joint having a cylindrical portion that forms a fluid passage in cooperation with the measuring tube, and connecting components each sandwiched by a corresponding one of the first and second printed circuit boards and a corresponding one of the cylindrical portions. Each connecting component is configured to elastically deform to reduce a distance between one end and the other end of the connecting component. Each connecting component electrically connects a corresponding one of the cylindrical portions to a shield pattern (electrically conductive portion) of a corresponding one of the first and second printed circuit boards.

Abstract: An electromagnetic flow meter comprises a magnetic excitation coil, first and second electrodes which are disposed opposite to each other on an outer peripheral surface of a measurement tube, an amplifying circuit that amplifies an electromotive force generated between the first electrode and the second electrode, a flow rate calculation portion that calculates a flow rate of the fluid, a third electrode formed on the outer peripheral surface of the measurement tube separated from the first electrode and the second electrode, a fourth electrode which is in contact with the fluid, a resistor in which one end is connected to the third electrode, a voltage detecting portion that measures voltages of a signal generated in the third electrode by inputting an AC signal to the other end of the resistor, and an electrical conductivity calculating portion that calculates electrical conductivity of the fluid.

Abstract: An excitation circuit includes a first switch connected between a third signal line and a first signal line supplied with a first DC voltage, a second switch connected between the third signal line and a second signal line supplied with a second DC voltage higher than the first DC voltage, third to sixth switches that reverses a polarity of a voltage on the third signal line to change a direction of an excitation current, a switching control circuit that switches the first switch at intervals shorter than intervals at which an excitation polarity is switched so that the excitation current has a first target value, and a switching control circuit that turns on the second switch when the absolute value of the excitation current is smaller than a second target value less than or equal to the first target value and that turns off the second switch when the excitation current is larger than the second target value.

Abstract: An electromagnetic flowmeter includes a board having a preamplifier circuit and a shield case mounted thereon. The preamplifier circuit amplifies an electromotive force generated between first and second electrodes disposed to be perpendicular to a magnetic field generated by an exciting coil on a measurement pipe. The preamplifier circuit includes first and second operational amplifiers, a first wiring connecting the first electrode and a non-inverting input terminal of the first operational amplifier, a second wiring connecting the second electrode and a non-inverting input terminal of the second operational amplifier, a first resistor connecting an output terminal and an inverting input terminal of the first operational amplifier, a second resistor connecting an output terminal and an inverting input terminal of the second operational amplifier, and a third resistor connecting the inverting terminals of the first and second operational amplifiers.

Abstract: A first connection line includes a first tube-side wiring pattern formed on an outer periphery of a measuring tube and connected at one end thereof to a first surface electrode, a first substrate-side wiring pattern formed on a preamplifier substrate and connected at one end thereof to a preamplifier, and a first jumper wire connecting the other end of the first tube-side wiring pattern to the other end of the first substrate-side wiring pattern; and a second connection line includes a second tube-side wiring pattern formed on the outer periphery of the measuring tube and connected at one end thereof to a second surface electrode, a second substrate-side wiring pattern formed on the preamplifier substrate and connected at one end thereof to the preamplifier, and a second jumper wire connecting the other end of the second tube-side wiring pattern to the other end of the second substrate-side wiring pattern.

Abstract: A voltage switching circuit applies a high excitation voltage to an excitation switching circuit during a period from an excitation period starting point to a rise point in an excitation period, and applies a low excitation voltage lower than the high excitation voltage to the excitation switching circuit during a period from the rise point to an excitation period ending point in the excitation period. A constant current circuit makes the current of the low excitation voltage to be input from a power supply circuit to the voltage switching circuit constant.

Abstract: A preamplifier substrate on which a preamplifier is mounted, the preamplifier being configured to amplify electromotive forces detected by a pair of surface electrodes, is disposed outside a flux region where a magnetic flux is produced, and the preamplifier substrate extends in a direction intersecting a measuring tube.

Abstract: An electromagnetic flowmeter includes a measuring tube, first and second printed circuit boards fixed to the measuring tube, a housing accommodating the measuring tube and the first and second printed circuit boards and supporting the first and second printed circuit boards, joints made of an electrically conductive material and fixed to the housing, each joint having a cylindrical portion that forms a fluid passage in cooperation with the measuring tube, and connecting components each sandwiched by a corresponding one of the first and second printed circuit boards and a corresponding one of the cylindrical portions. Each connecting component is configured to elastically deform to reduce a distance between one end and the other end of the connecting component. Each connecting component electrically connects a corresponding one of the cylindrical portions to a shield pattern (electrically conductive portion) of a corresponding one of the first and second printed circuit boards.

Abstract: A pipe hole to which a measuring pipe is to be press-fitted is formed in a printed board, and a guide to be fitted to a side end portion of the printed board inserted through an opening is formed on or in an inner wall of a case.

Abstract: An excitation circuit includes a second switch and a third switch that are respectively connected between a third signal line and a first end of an excitation coil and between the first end of the excitation coil and a fourth signal line and that are switched in accordance with intervals at which an excitation polarity is switched, a fourth switch and a fifth switch that are respectively connected between the third signal line and a second end of the excitation coil and between the second end of the excitation coil and the fourth signal line and that are switched in accordance with the intervals at which the excitation polarity is switched, a switching control circuit that controls a first switch connected between a first signal line and the third signal line at intervals shorter than the intervals at which the excitation polarity is switched.

Abstract: To realize a stable operation and the suppression of heat generation in the case where an excitation current supplied from a converter is used to generate a power source voltage, a standard signal generator is provided. The standard signal generator includes an input circuit that includes: a rectification circuit that rectifies an excitation current; a resistor that is provided between a power source voltage output terminal for supplying a power source voltage and an output terminal of the rectification circuit; an amplification circuit that outputs an output voltage obtained by amplifying a voltage across both ends of the resistor; and a constant voltage circuit that performs control such that the power source voltage is constant. A power source voltage switch switches the power source voltage with the constant voltage circuit being controlled in accordance with the result of a comparison between the output voltage and a prescribed threshold value.

Abstract: An input circuit includes a rectifier circuit that rectifies an excitation current obtained from a converter, and a constant voltage circuit that receives output of the rectifier circuit and performs control so that a power supply voltage is maintained constant. A power supply voltage source switching unit switches the source of a power supply voltage used in a calibrator to the constant voltage circuit when the converter is a converter of a four-wire electromagnetic flowmeter, and switches the source of the power supply voltage to a battery when the converter is a converter of a two-wire electromagnetic flowmeter. A remaining capacity indicator provides a remaining battery capacity indication in accordance with the voltage of the battery. When the converter is a converter of a four-wire electromagnetic flowmeter and it is determined that the battery is not in a battery holder, the remaining capacity indicator stops providing a remaining battery capacity.

Abstract: An electromagnetic flow meter comprises a magnetic excitation coil, first and second electrodes which are disposed opposite to each other on an outer peripheral surface of a measurement tube, an amplifying circuit that amplifies an electromotive force generated between the first electrode and the second electrode, a flow rate calculation portion that calculates a flow rate of the fluid, a third electrode formed on the outer peripheral surface of the measurement tube separated from the first electrode and the second electrode, a fourth electrode which is in contact with the fluid, a resistor in which one end is connected to the third electrode, a voltage detecting portion that measures voltages of a signal generated in the third electrode by inputting an AC signal to the other end of the resistor, and an electrical conductivity calculating portion that calculates electrical conductivity of the fluid.

Abstract: An electrical conductivity meter comprises a measurement tube formed of an electrical insulation material and through which a fluid of a measurement target flows, a first electrode formed on an outer peripheral surface of the measurement tube, a second electrode connected to a common potential and in contact with the fluid, a resistor in which one end is connected to the first electrode, a voltage detecting portion that detects voltages of a signal generated in the first electrode due to an input of an AC signal to the other end of the resistor, and an electrical conductivity calculating portion that calculates an electrical conductivity of the fluid based on an amplitude of the voltages detected by the voltage detection circuit.