Azbil Corporation

Hitachi-high-technologies Corporation

Yamatake Corporation

Kouji Okuda

Hiroaki Nagoya

Kouichirou Murata

Tetsuya Kajita

Ichiro Mitsutake

Yutaka Harada

Shin Suzuki

Motohiro Tanaka

Naoki Nagashima

Takashi Nomiyama

Kazuumi Tanaka

Taka Inoue

Kentaro Ohya

Yoshio Maehana

Seita Nashimoto

Gas ring for a plasma processing apparatus

Gas diffusion plate for a plasma processing apparatus

In a comparing circuit, the value of a control signal from a higher-level device and a normal range that is set for the control signal are compared, and the result is sent to a control unit. The control unit, when sent the result indicating that the value of the control signal is outside of the normal range, forcibly adjusts the electric current signal (the adjusted electric current) to the electropneumatic converter to zero, regardless of the deviation between the value indicated by the control signal and the value indicated by the valve opening signal. The adjustment of the electric current in the control unit is performed using a normal function that is possessed by the control unit, that is, the function for changing continuously the value of the electric current signal in accordance with the deviation.

Positioner

A field device has a primary power supply generating circuit that generates a primary power supply from an electric current that is supplied through a pair of electric wires from a higher-level system, and a calculation processing portion and various functional circuit portions, which operate based on a supply of an operating power supply electric current produced from the primary power supply. The field device also has an operating power supply electric current supplying unit that supplies the operating power supply electric current to a calculation processing portion with maximum priority. The calculation processing portion receives the operating power supply electric current supplied with maximum priority, clears a self-reset operation after starting up itself, and then directs sequentially, following a predetermined sequence, supply of the operating power supply electric current to each of the various functional circuit portions.

Field device

The range of electric currents that can be assumed by a supply electric current is categorized into a plurality of electric current ranges, where, for each electric current range category, there are combinations of functions, wherein the total value for the electric current required is less than the upper limit value, and no less than the lower limit value, for the electric current range established, and a table wherein these combinations are established is stored in memory. An actual value is detected for a supply current I to ascertain the category of electric current to which the supply electric current I applies, the combination of functions established for the applicable category of electric currents is read out from the table, and operation of the function circuit portions for the functions of the combination that has been read out is enabled, and operation of the other function circuit portions is disabled.

A voltage/current converting circuit is provided in a stage prior to a communication circuit. An over-current preventing circuit is incorporated into the voltage/current converting circuit. The voltage/current converting circuit converts a DC voltage signal into a DC electric current signal, and converts an AC voltage signal into an AC electric current signal. Moreover, the voltage/current converting circuit keeps the excessively large electric current that would flow into the internal circuitry thereof to no more than a predetermined electric current value (for example, no more than 30 mA) when the positioner is connected in error to the voltage source side without a load resistance connected.

A coil of an electro-pneumatic converting portion is connected in parallel with a constant voltage circuit. An electric current regulating portion is provided in a supply line for an electric current to the coil. The regulating value for the electric current in this electric current regulating portion is controlled by an instruction from a CPU. The CPU detects, as a present supply electric current, an actual value for the supply electric current from a higher-level system, and evaluates whether or not there is, in the present supply electric current, a surplus electric current that can be directed to the electro-pneumatic converting portion. The supply electric current can be in excess of 4 mA and is the surplus electric current, and if there is a surplus electric current, then a command is sent to the electric current regulating portion so as to allocate that surplus electric current to the coil.

Valve positioner with current allocating device

A power supply controlling function is provided in a controlling portion. The power supply controlling function defines a first pressure sensor, a second pressure sensor, a third pressure sensor, and an oscillation detecting sensor as sensors to which power may be supplied, and turns switches that are provided in the supply circuits of the power supply to the individual sensors to which power may be supplied ON and OFF so that a plurality of these sensors to which power may be supplied does not operate simultaneously.

To provide reliable notification of a fault state when a power supply to a calculation processing portion is in the OFF state when a power supply to a communication processing portion is in the ON state. An isolating circuit, an inverting circuit inverting a signal branch-outputted through an output line of the isolating circuit, and a selecting circuit that uses the signal outputted from the output line of the isolating circuit as a first input and the inverted signal from the inverting circuit as a second input, to select either the first input or the second input, depending on a selection setting status thereof, to output the selected signal to the communication processing portion are provided. A +5 V voltage is applied through a resistor to the output line of the isolating circuit. This +5 V voltage is produced through the power supply supplied from the second double-wire transmission path.

A variable impedance circuit is provided as an active load between an input line L1 and an output line L2. This circuit has low impedance with respect to a DC electric current signal and has high impedance with respect to an AC electric current signal, structured from a series circuit of resistors R1, R2, and R3 connected between lines L1 and L2; a transistor Q1 having the collector connected to the line L1 and the base connected between the resistors R2 and R3; a resistor R4 connected between the emitter of the transistor Q1 and the line L2; a capacitor C1 with one end connected between the resistors R2 and R3; a resistor R5 connected between the other end of the capacitor C1 and the line L2; a capacitor C2 having one end connected between the resistors R1 and R2; and a resistor R6 connected between the other end of the capacitor C2 and the line L2.

The disclosed device easily and precisely satisfies a requested output range, and is provided with: a &#x394;&#x3a3;-modulator () which converts a digital input signal to a pulse signal; an input comparison device () which compares an input value that corresponds to the digital input signal, and a pre-set threshold value; and a thinned output control unit () which, when the result of the comparison by the input comparison device () shows that the input value is less than the threshold value, reduces the output value corresponding to the input value in accordance with the size of the difference between the input value and the threshold value, and sets the output value to 0 when the input value is 0.

Modulator and &#x394;&#x3a3;-type D/A converter

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.

Capacitive electromagnetic flowmeter

An electromagnetic flowmeter includes a coil, exciting section, noise eliminating section, and arithmetic processing section. The coil applies a magnetic field to a fluid flowing in a pipe line. The exciting section supplies an exciting current to the coil. The noise eliminating section eliminates noise from a measurement signal detected from the fluid under excitation by using a differential frequency component between a commercial power frequency and an exciting frequency. The arithmetic processing section calculates a measurement flow rate on the basis of the measurement signal output from the noise eliminating section.

Growing community of inventors

Tokyo, Japan

Kouji Okuda