Abstract: An electromagnetic flow meter comprises a detector having a measurement tube, a magnetic excitation coil, and a pair of detecting electrodes; a magnetic excitation circuit; a flow rate calculation circuit that calculates the flow rate of a fluid flowing through the measurement tube; and an error detection circuit comprising a differential noise measurement circuit configured to measure a level of a magnetic flux differential noise based on an electromotive force generated between the pair of detecting electrodes disposed in the measurement tube and an index calculation circuit configured to calculate an index indicating an error in the flow rate calculated by the flow rate calculation circuit based on the level of the magnetic flux differential noise measured by the differential noise measurement circuit.

Abstract: An electromagnetic flow meter includes a measurement tube, an excitation coil, an excitation current supplying unit supplying an excitation current with an excitation frequency fex to the excitation coil, a pair of electrodes disposed inside the measurement tube, a measuring unit measuring a flow based on an emf that arises between the electrodes, a first A/D converting unit that converts the emf to a digital signal, a sampling unit sampling the digital signal, a noise evaluation value calculating unit, based on at least the sample data sampled by the sampling unit, calculating as a noise evaluation value the magnitude of the impact of a noise component owing to adherence of foreign matter to the electrodes upon the measurement of the flow, and an electrode scaling diagnosing unit determining an electrode foreign matter adherence state by comparing the noise evaluation value and a predetermined diagnostic threshold value.

Abstract: An electromagnetic flow meter comprises a detector having a measurement tube, a magnetic excitation coil, and a pair of detecting electrodes; a magnetic excitation circuit; a flow rate calculation circuit that calculates the flow rate of a fluid flowing through the measurement tube; and an error detection circuit comprising a differential noise measurement circuit configured to measure a level of a magnetic flux differential noise based on an electromotive force generated between the pair of detecting electrodes disposed in the measurement tube and an index calculation circuit configured to calculate an index indicating an error in the flow rate calculated by the flow rate calculation circuit based on the level of the magnetic flux differential noise measured by the differential noise measurement circuit.

Abstract: A magnetic excitation circuit is used as a circuit for providing a magnetic excitation electric current based on a magnetic excitation power supply voltage to a magnetic excitation coil of an electromagnetic flow meter. The magnetic excitation circuit includes four voltage storing circuits that store and output a driving voltage that is charged by a common driving voltage. The voltage storing circuits are connected respectively between the control terminals and the output terminals of four switching elements. When the four switching elements are turned ON in relation to a positive interval or a negative interval, the four switching elements operate by the driving voltages that are outputted from the respective voltage storing circuits.

Abstract: An excitation circuit, which is used in an electromagnetic flow meter, measures a flow rate value for a fluid, based on an electromotive force. An excitation coil, which is provided on an outside of a measurement tube, is supplied with an excitation current, where, in response, the electromotive force, which is perpendicular to a magnetic field of the excitation coil that is generated in the fluid within the measurement tube, is detected by a pair of electrodes provided on the measurement tube.

Abstract: In a signal amplifying circuit, a flow rate signal, inputted between flow rate signal input terminals of a connector, is inputted into one input terminal and the other input terminal of an instrumentation amplifier through resistive elements and subjected to differential amplification. The amplified output signal thereof is outputted to a sample hold circuit through a coupling capacitor. The flow rate signals, inputted between the flow rate signal input terminals, are buffered by buffer amplifiers, and output signals thereof are outputted to a fault detecting circuit. An interconnection, which connects one of the flow rate signal input terminals and a non-inverting input terminal of one of the buffer amplifiers, is guarded by a guard ring pattern. An interconnection, which connects the other one of the flow rate signal input terminals and a non-inverting input terminal of the other one of the buffer amplifiers, is guarded by another guard ring pattern.

Abstract: An excitation circuit, which is used in an electromagnetic flow meter, measures a flow rate value for a fluid, based on an electromotive force. An excitation coil, which is provided on an outside of a measurement tube, is supplied with an excitation current, where, in response, the electromotive force, which is perpendicular to a magnetic field of the excitation coil that is generated in the fluid within the measurement tube, is detected by a pair of electrodes provided on the measurement tube.

Abstract: In a signal amplifying circuit, a flow rate signal, inputted between flow rate signal input terminals of a connector, is inputted into one input terminal and the other input terminal of an instrumentation amplifier through resistive elements and subjected to differential amplification. The amplified output signal thereof is outputted to a sample hold circuit through a coupling capacitor. The flow rate signals, inputted between the flow rate signal input terminals, are buffered by buffer amplifiers, and output signals thereof are outputted to a fault detecting circuit. An interconnection, which connects one of the flow rate signal input terminals and a non-inverting input terminal of one of the buffer amplifiers, is guarded by a guard ring pattern. An interconnection, which connects the other one of the flow rate signal input terminals and a non-inverting input terminal of the other one of the buffer amplifiers, is guarded by another guard ring pattern.

Abstract: A magnetic excitation circuit is used as a circuit for providing a magnetic excitation electric current based on a magnetic excitation power supply voltage to a magnetic excitation coil of an electromagnetic flow meter. The magnetic excitation circuit includes four voltage storing circuits that store and output a driving voltage that is charged by a common driving voltage. The voltage storing circuits are connected respectively between the control terminals and the output terminals of four switching elements. When the four switching elements are turned ON in relation to a positive interval or a negative interval, the four switching elements operate by the driving voltages that are outputted from the respective voltage storing circuits.

Abstract: A wave ring spring is provided between a top face of a battery case and an inner wall of an equipment case. A plurality of silicone rubber pieces is provided between a bottom face of the battery case and an inner wall of the equipment case. A plurality of elastic tabs is provided between the outer peripheral surfaces that connect between the top face and the bottom face of the battery case and inner walls of the equipment case. The elastic tabs are formed integrally with the outer peripheral surfaces of the battery case.

Abstract: With the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the positive magnetic excitation period to the non-magnetic-excitation period defined as a first period T1 and the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the negative magnetic excitation period to the non-magnetic-excitation period defined as a second period T2, the sum of a voltage produced at a detecting electrode and a voltage produced at a detecting electrode, at the time of each first period T1 and second period T2, is calculated as a sum of voltages between electrodes, and a fault in an electromagnetic flow meter, such as detection of an empty state, adhesion of an electrically insulating object to an electrode, and so forth, is evaluated based on the sum of voltages between electrodes.

Abstract: An electromagnetic flow meter includes a measurement tube, an excitation coil, an excitation current supplying unit supplying an excitation current with an excitation frequency fex to the excitation coil, a pair of electrodes disposed inside the measurement tube, a measuring unit measuring a flow based on an emf that arises between the electrodes, a first A/D converting unit that converts the emf to a digital signal, a sampling unit sampling the digital signal, a noise evaluation value calculating unit, based on at least the sample data sampled by the sampling unit, calculating as a noise evaluation value the magnitude of the impact of a noise component owing to adherence of foreign matter to the electrodes upon the measurement of the flow, and an electrode scaling diagnosing unit determining an electrode foreign matter adherence state by comparing the noise evaluation value and a predetermined diagnostic threshold value.

Abstract: A liquid crystal display part includes a seven segment display group and first and second switches. If the first switch “on”, a display provided by the seven segment display group is switched to a normal direction display having an upward orientation. In addition, if the second switch is “on,” then the display provided by the seven segment display group is switched to an inverse direction display having a downward direction. In addition, a first character pattern that indicates the unit of the measurement value is displayed for the normal direction display, and a second character pattern that indicates the unit of the measurement value is displayed for the inverse direction display. A cover is openably, closably, and rotatably provided to the liquid crystal display part, and the display direction of the measurement value is switched according to the position of the cover.

Abstract: A wave ring spring is provided between a top face of a battery case and an inner wall of an equipment case. A plurality of silicone rubber pieces is provided between a bottom face of the battery case and an inner wall of the equipment case. A plurality of elastic tabs is provided between the outer peripheral surfaces that connect between the top face and the bottom face of the battery case and inner walls of the equipment case. The elastic tabs are formed integrally with the outer peripheral surfaces of the battery case.

Abstract: An electromagnetic flowmeter that prevents fluctuations in the frequency of synchronized pulse signals due to momentary fluctuations of the power source voltage. The comparator of an AC synchronizing circuit that generates pulse signals synchronized to the frequency of a commercial power source is given a hysteresis function in which a first threshold value Vth1 and a second threshold value Vth2 are set up in the comparator. The comparator compares the level of divided AC signals from a dividing circuit with the first threshold value Vth1, and if the level of the divided AC signals exceeds the first threshold value Vth1, the level of the synchronized pulse signals is inverted from the “L” level to the “H” level; and if the level of the divided AC signals falls below the second threshold value Vth2, the level of the synchronized pulse signals is inverted from the “H” level to the “L” level.

Abstract: With the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the positive magnetic excitation period to the non-magnetic-excitation period defined as a first period T1 and the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the negative magnetic excitation period to the non-magnetic-excitation period defined as a second period T2, the sum of a voltage produced at a detecting electrode and a voltage produced at a detecting electrode, at the time of each first period T1 and second period T2, is calculated as a sum of voltages between electrodes, and a fault in an electromagnetic flow meter, such as detection of an empty state, adhesion of an electrically insulating object to an electrode, and so forth, is evaluated based on the sum of voltages between electrodes.

Abstract: In a constant current circuit, a constant current is caused to flow through a resistor, thereby causing a constant voltage to occur across the resistor. This constant voltage is then superimposed on an output signal of an operational amplifier that is to be fed back to the drain of a field effect transistor, thereby maintaining the same potential in an AC manner between the output terminal of the operational amplifier and the drain of the field effect transistor. In this way, the gate and drain of the field effect transistor is caused to exhibit the same potential in an AC manner, so that no current will occur through the stray capacitance between the gate and drain of the field effect transistor. As a result, similarly to a case of using a feedback capacitor, the input impedance of the field effect transistor can be raised.

Abstract: In a constant current circuit, a constant current is caused to flow through a resistor, thereby causing a constant voltage to occur across the resistor. This constant voltage is then superimposed on an output signal of an operational amplifier that is to be fed back to the drain of a field effect transistor, thereby maintaining the same potential in an AC manner between the output terminal of the operational amplifier and the drain of the field effect transistor. In this way, the gate and drain of the field effect transistor is caused to exhibit the same potential in an AC manner, so that no current will occur through the stray capacitance between the gate and drain of the field effect transistor. As a result, similarly to a case of using a feedback capacitor, the input impedance of the field effect transistor can be raised.

Abstract: An electromagnetic flowmeter that prevents fluctuations in the frequency of synchronized pulse signals due to momentary fluctuations of the power source voltage. The comparator of an AC synchronizing circuit that generates pulse signals synchronized to the frequency of a commercial power source is given a hysteresis function in which a first threshold value Vth1 and a second threshold value Vth2 are set up in the comparator. The comparator compares the level of divided AC signals from a dividing circuit with the first threshold value Vth1, and if the level of the divided AC signals exceeds the first threshold value Vth1, the level of the synchronized pulse signals is inverted from the “L” level to the “H” level; and if the level of the divided AC signals falls below the second threshold value Vth2, the level of the synchronized pulse signals is inverted from the “H” level to the “L” level.

Abstract: A liquid crystal display part includes a seven segment display group and first and second switches. If the first switch “on”, a display provided by the seven segment display group is switched to a normal direction display having an upward orientation. In addition, if the second switch is “on,” then the display provided by the seven segment display group is switched to an inverse direction display having a downward direction. In addition, a first character pattern that indicates the unit of the measurement value is displayed for the normal direction display, and a second character pattern that indicates the unit of the measurement value is displayed for the inverse direction display. A cover is openably, closably, and rotatably provided to the liquid crystal display part, and the display direction of the measurement value is switched according to the position of the cover.