Determining an out-of-liquid condition
AssigneeHewlett-Packard Development Company, L.P.
InventorsMatthew Jason Janssen, James William Ring, James Ronald Cole
Life of this patent
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Abstract
In one example, a method for determining an out-of-liquid condition of a liquid supply for an inkjet printer. The method includes acquiring, during printing, a sequence of data points, each data point comprising a differential liquid/air pressure at the liquid supply measured with a sensor and a corresponding cumulative amount of liquid delivered from the liquid supply. The method further includes generating a curve using the data points. The method also includes determining, from a predetermined characteristic of the curve, whether the out-of-liquid condition exists. The characteristic is independent of at least one of a gain and an offset of the sensor.
Claims15
A method for determining an out-of-liquid condition of a liquid supply for an inkjet printer, comprising:
- acquiring, during printing, a sequence of data points, each data point comprising a differential liquid/air pressure at the liquid supply measured with a sensor and a corresponding cumulative amount of liquid delivered from the liquid supply;
- generating a curve using the data points;
- and
- determining, from a predetermined characteristic of the curve, whether the out-of-liquid condition exists, the characteristic independent of at least one of a gain and an offset of the sensor.
An inkjet printing device, comprising:
- a liquid channel to deliver liquid from a liquid supply to a printhead;
- an air pump to pressurize the liquid supply through an air channel;
- and
- a controller coupled to the liquid channel and the air channel to
- periodically measure, during printing, a differential liquid/air pressure between the liquid channel and the air channel using a differential pressure sensor disposed at the liquid supply, the sensor having an indeterminate gain and offset,
- correlate each measured pressure to a cumulative amount of liquid delivered from the liquid supply,
- generate a curve from the measured pressures and the correlated cumulative amounts of delivered ink, and
- determine, from a predetermined characteristic of the curve, when an out-of-liquid condition of the liquid supply occurs.
A non-transitory computer-readable storage medium having an executable program stored thereon, wherein the program instructs a processor to:
- periodically measure a differential liquid/air pressure at a liquid supply of an inkjet printing device during printing;
- correlate each measured pressure to a cumulative amount of liquid delivered from the liquid supply;
- generate a curve from the measured pressures and the correlated cumulative amounts of delivered ink;
- and
- determine whether an out-of-liquid condition of the liquid supply occurs using a characteristic of the curve, the characteristic different from a predefined differential liquid/air pressure value.
Dependencies are inferred from the claim text.