Patent ID: 7499657

Claim:
A device for measuring the quantity of residual toner received in a toner cartridge comprising: a controller for selecting one among a plurality of preset values for a correction coefficient, which is weighted increasingly depending on the length of time the toner cartridge has been in printing service, and calculating a quantity of residual toner using the selected values for a plurality of correction coefficients and a counted number of dots of a print data; and a residual toner data memory, wherein the quantity of residual toner calculated by the controller is updated and stored in the residual toner data memory, wherein the plurality of preset values for the correction coefficients further include a plurality of values for a paper-feeding mode correction coefficient (k 3 ) which is related to a quantity of transferred toner and/or waste toner and which is applied differently depending on whether single-sided printing or double-sided printing is performed.