US 5,844,490 AGranted

Monitoring device for a chemical reagent supply system

AssigneeUnited Microelectronics Corp.

InventorsChung-Chien Lu, Eric Liu, His-Huang Lee, Tien-Tsai Lu

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Abstract

A monitoring device for a chemical reagent supply system includes a position voltage generator, mounted to a pump of the supply system, to monitor the expansion state of a bellows. The actual outflow of the chemical reagent is calculated by the position voltage generator. According to a demand signal from equipment needing the chemical reagent, which is processed to consider the viscosity of the chemical reagent, a theoretic demand outflow is calculated by the monitoring device. When the difference between the actual outflow and the theoretic demand outflow exceeds a permissible tolerance, the monitoring device raises an alarm signal to warn an operator and thereby to assure the accuracy of the chemical reagent supply system.

Claims10

Dependent claims

A monitoring device for a fluid chemical reagent supply system, the chemical reagent supply system including a compressed air source, a pump having a cylinder, a piston, a piston rod mounted to the piston, and a bellows mounted to the piston rod, a regulator valve mounted to the compressed air source and the cylinder to govern the travel of the piston, and a signal source which is coupled to the regulator valve, and the system generating a demand signal to drive the regulator valve, the monitoring device comprising:

a position voltage generator for generating a position voltage according to a state of expansion of the bellows;
a processing circuit, responsive to the position voltage, a theoretical demand signal based on the viscosity of fluid in the bellows and a demand for the fluid reagent, to produce a difference signal indicative of a difference between an actual outflow of the reagent fluid and a theoretical demand outflow;
a comparator for producing an overriding signal indicative of whether the difference signal is within a predetermined signal range;
and
an alarm responsive to the overriding signal.

2 more elements

A monitoring device for a fluid chemical reagent supply system, the chemical reagent supply system including a compressed air source, a pump having a cylinder, a piston, a piston rod mounted to the piston, and a bellows mounted to the piston rod, a regulator valve mounted to the compressed air source and the cylinder to govern the travel of the piston, and a signal source which is coupled to the regulator valve, and the system generating a first signal to drive the regulator valve, the monitoring device comprising:

a pre-treatment circuit coupled to the signal source, for pre-treating the first signal, to convert the first signal to a second signal;
a position voltage generator for mounting to the bellows, the position voltage generator generating a first voltage according to a state of expansion of the bellows;
a voltage generating device, responsive to the second signal for generating a second voltage according to a viscosity of a fluid reagent in the bellows;
a voltage buffer amplifier coupled to the position voltage generator for offsetting, adjusting and amplifying the first voltage to produce a third voltage;
a subtracter, coupled to the voltage generating device and the voltage buffer amplifier, for generating a fourth voltage according to a difference between the second voltage and the third voltage;
a comparator coupled to the subtracter, the comparator having settings of a maximum voltage and a minimum voltage, the comparator being responsive to the fourth voltage for generating an overriding signal based on a comparison of the fourth voltage with the minimum voltage and the maximum voltage, the overriding signal having a lock period;
an overriding mode selector coupled to the pre-treatment circuit, the overriding mode selector being responsive to the second signal for generating a control signal;
an overriding device coupled to the comparator and the overriding mode selector to receive the control signal and the overriding signal, the overiding device locking the overriding signal according to the control signal and continually outputting an alarm signal;
and
an alarm device coupled to the overriding device to receive the alarm signal, for outputting an alarm according to the alarm signal.

7 more elements

Dependencies are inferred from the claim text.