Abstract: A method of controlling a pressure of a fluid in a pressure chamber, which pressure chamber is delimited by an actuator membrane having a first piezoelectric portion arranged in a central zone of the actuator membrane and at least one second piezoelectric portion arranged in at least one peripheral zone of the actuator membrane; and an ink jet printing device. In a neutral stage, a first flexure state of the actuator membrane is provided by applying first and second voltages to respective piezoelectric portions. In an activation stage, the first and second voltages are temporarily varied, without reversing their polarity, such that a curvature of the central part of the actuator membrane and a curvature of the peripheral part of the actuator membrane are changed in opposite directions, in order to expell a droplet of fluid through a nozzle.

Abstract: A system for measuring current in an H-Bridge motor drive circuit and using that current to determine the output of a device powered by the motor. A particular embodiment is disclosed for a motor-driven fluid pump. Motor current is measured at predetermined pump pressures and flow rates to create calibration tables relating motor current to pump pressure. Once calibrated, the system determines pump pressure based on motor current by referring to the calibration tables. In an embodiment, the pump is driven to achieve a predetermined fluid dispense profile. The system monitors pump pressure by measuring motor current and determines if the dispense profile is being achieved and sets alarms if predetermined thresholds are not maintained. The system also detects pump wear based on the current measurements and issues warnings to the user in such conditions.

Abstract: The present invention provides a technique using current sensing to control the pressure at constant level without the direct sensing of the pressure. This technique will help to reduce dependency solely on switch or sensor and their non linearity and other associated problems such as the non-repetitive behavior, being affected by EMI etc. The technique includes using a pump controller featuring one or more modules configured to respond to one or more input signals containing information about current provided from a pump; and configured to provide one or more output signals containing information to control the pump to operate at a substantially constant pressure without the direct sensing of pump pressure. The one or more modules control the operation of the pump based at least partly on a table of characteristics related to voltage and current that is calibrated for each pump.

Abstract: A method of charging a compressed air storage tank for a vehicle increases the pressure in the storage tank from a first pressure to a second pressure. The method includes determining the first pressure according to a first detected vehicle engine load, and starting the charge cycle when the pressure detected in the storage tank is at least as low as the first pressure. The method further includes determining the second pressure according to a second detected vehicle engine load, and stopping the charge cycle when the pressure detected in the storage tank is at least as high as the second pressure.