Patent ID: 7269362

Claim:
A toner consumption calculating apparatus which calculates for each color a toner consumption demanded by image formation on a recording medium using a developer unit which comprises toner cartridges which are respectively filled with toner of a plurality of colors, comprising: a toner counter which counts a toner consumption during the image formation; a sensor which detects the density of a patch image; a calculator which calculates a cumulative count of the toner consumption; a judging device which judges whether the cumulative count of the toner consumption is equal to or smaller than a first predetermined value, and judges whether a result of the detection performed by the sensor is equal to or smaller than a second predetermined value; and a controller which corrects the cumulative count of the toner consumption when the judging device judges that the cumulative count of the toner consumption and the result of the detection are respectively equal to or smaller than the first predetermined value and the second predetermined value.