Method and apparatus for non-saturated switching for firing energy control in an inkjet printer
AssigneeHewlett-Packard Company
InventorKirkpatrick William Norton
Life of this patent
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Abstract
A method and apparatus for controlling firing energy in an inkjet printer are embodied in a control circuit and a regulated pen voltage source for an inkjet printer pen. The control circuit includes switches connected between the nozzle resistors of the pen and a low voltage rail. The control circuit is configured to control the voltages across the switches within a known tolerance, independent of variations in the switch current, integrated circuit process variations, temperature variations, and variations in the resistances of the nozzle resistors. The voltage provided to each nozzle resistor by the pen voltage source is adjusted to compensate for changes in the voltages across the switches.
Claims15
A method for controlling firing energy in an inkjet printer with a printer pen, the method comprising the steps of:
- controlling a switch voltage across a switch which is electrically connected to a first side of a nozzle resistor of the printer pen, and
- adjusting a pen supply voltage which is electrically connected to a second side of the nozzle resistor to compensate for changes in the switch voltage;
- wherein the switch voltage is controlled such that the switch operates in a non-saturated mode.
An apparatus for controlling firing energy in an inkjet printer with an inkjet pen including a nozzle resistor, the apparatus comprising:
- a control circuit including a switch electrically connected between a first side of the nozzle resistor and a low voltage rail, the control circuit being configured to control a switch voltage across the switch;
- and
- a regulated pen voltage source which provides a pen voltage to a second side of the nozzle resistor, the pen voltage being adjusted to compensate for changes in the switch voltage;
- wherein the control circuit is configured to control the switch voltage such that the switch operates in a non-saturated mode.
Dependencies are inferred from the claim text.