Dionex Corporation

Impact Systems, Inc.

Peak Systems, Inc.

David A Wolze

Michael William Recknor

A present invention and method provides a pressure injection apparatus (20) that injects a quantitatively defined volume of liquid sample (21) from a container (22) into a capillary device (23). A servo pressure primary regulator (26) is included which precisely regulates the fluid from a supply pressure (P.sub.S) to a substantially constant regulated pressure (P.sub.R) in communication with the liquid sample (21) for a predetermined period of time. A feedback mechanism cooperates with a valving assembly (31) to continuously monitor and adjust the regulated pressure (P.sub.R) to be substantially constant and precise for delivery to the container (21).

Pressure injection apparatus and method for injecting a sample into an

Flowrate in a precision pump used for liquid chromatography employs a digital control system incorporating artificial intelligence. The pump system operates in a default flow mode, wherein real-time pressure feedback is not used to control motor speed, or in pressure mode, wherein motor speed is controlled by the pump system pressure point. The artificial intelligence commands mode changes to pressure mode when the constant displacement flow measurement time is within a threshold relative to commanded flowrate, and when the higher pressure piston is being measured. Flow mode pressure ripple is minimized by monitoring pressure points and commanding motor speed change at appropriate positions during the motor cam rotation. Pressure mode uses the higher pressurized piston as a reference for constant displacement flow measurement and provides accurate flowrate even if one piston is leaky. In pressure mode, the artificial intelligence monitors for intake cycle oscillation and optimizes a highest system pressure gain dynamically. By determining the duration of hydraulic intake and activating proportioning only during the constant intake flow portion of an intake cycle, constant flowrate proportioning is provided. The present invention compensates for a variety of system and environmental variables including leaky valves, air bubbles, a leaky cylinder head, pressure changes, and variations in anticipated compliance and can maintain a flowrate constant within about .+-.1% without using real-time pressure feedback.

Bimodal liquid chromatography pump employing artificial intelligence

A controller for a load such as the heater elements of an actuator for drying the various zones or slices of a moving sheet of a papermaking machine includes silicon controlled rectifiers for each zone or slice of the moving sheet whose firing angle is controlled by an external power command signal. This power command signal is processed by a digital signal processor which strobes at a high rate the line voltage and load current to provide a closed loop feedback control technique for power being applied to the load and in addition, the processor, at the same time, has an open loop firing angle control routine which has a fast response time to protect against abnormal conditions within one-half cycle of load voltage.

Power controller for heater load

An improved high power (40,000 watt) high intensity arc discharge power supply which provides reliable, automatic ignition control and enables precise variation of lamp power in dual AC and DC modes of operation over an extended dynamic range from 400 watts to 40,000 watts. A capacitive boost circuit is provided to supply the high voltage necessary to ignite the lamp. Upon start-up, the voltage on a boost circuit capacitor is monitored by an ignition circuit which automatically enables the ignitor when the voltage is at the required level and switches the ignitor off when the lamp starts. After ignition the boost charging circuit is disabled and the power supply operates in a normal mode. The power supply operates on a three phase alternating voltage input through a three phase bridge, switches it through a drive transistor and then supplies it to an inductor. The signal is then supplied through an H-bridge commutator to the boost circuit, the ignitor and the arc lamp itself. The circuit operates under the control of an analog computer which determines the switching rate, monitors the voltage and current, provides power feedback and generally controls the power supply. A power command input signal determines the power level at which the arc lamp will operate. Below a certain lamp current level, an oscillator circuit controlling the commutator is disabled so the lamp will operate on DC power in a 'simmer' or low temperature mode. The lamp is thus operated over a large dynamic range.

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San Jose, CA, United States of America

David A Wolze