Hardcopy printing device with capacitive print media monitor and methods of making and using the same
AssigneeHewlett-Packard Development Company, L.P.
InventorsBradley J. Anderson, Bruce L. Johnson
Life of this patent
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Abstract
A printing device can include a capacitive monitoring system to monitor the amount of print medium (e.g., paper) available in the printing device. The capacitive monitor includes conductive plates above and below the supply of print medium. With the print medium acting as a dielectric element, the capacitance of the system will change as print medium is removed from the supply. This change in capacitance can be used to monitor the supply of print medium in the printing device.
Claims20
A printing device with a capacitive monitoring system for monitoring an amount of print medium available, said printing device comprising:
- a capacitive monitor for measuring a capacitance in accordance with an amount of said print medium available, said capacitive monitor comprising first and second conductive elements to which a voltage is applied,
- wherein, when said printing device is in operation, a supply of said print medium is interposed between said first and second conductive elements and functions as a dielectric element;
- and
- wherein said capacitive monitor determines said amount of print medium available in accordance with capacitance measurements.
A method of monitoring an amount of print medium available in printing device using a capacitive monitoring system, said method comprising:
- monitoring changes in capacitance of first and second conductive elements to which a voltage is applied with a supply of said print medium interposed between said first and second conductive elements, said supply of print medium being depleted during operation of said printing device;
- and
- determining said amount of print medium available in accordance with said changes in capacitance.
A printing device with a capacitive monitoring system for monitoring an amount of print medium available, said printing device comprising:
- first means for determining a capacitance of first and second conductive elements to which a voltage is applied and between which a supply of said print medium is interposed;
- and
- means for determining said amount of print medium available in accordance with output from said means for determining a capacitance.
Dependencies are inferred from the claim text.