Patent ID: 7072077

Claim:
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 capacitance indicative of 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 by (1) measuring a first capacitance attributable to said supply of print medium at a first point in time, (2) measuring a second capacitance attributable to said supply of print medium at a second point in time after a single sheet of said print medium is removed from said supply following said first point in time, and (3) differencing said first and second capacitances to determine a capacitance value attributable to said single sheet of print medium from which said amount of print medium available is determined.