| 摘要 |
PROBLEM TO BE SOLVED: To have an adequate cleaner replacing cycle in a fixing device by providing a counter for counting the number of effective dots of printing data per color, calculating the feasible blackening ratio per color from the total printing dot number in the printing area and the counted value, and converting the standard blackening ratio into the number of pages. SOLUTION: The amount of the toner to be adhered onto a cleaning roller 56 is proportional to the amount of the toner passing through a fixing roller 50, that is, the blackening ratio. The total dot number corresponding with each paper size is stored preliminarily in a ROM. The total dot number according to the printing area information (paper size) from the host is read out from the ROM. On the other hand, the printing dot number according to the total printing area per color is read out from a printing dot count controlling part so as to calculate the printing data blackening ratio for each color by (effective printing dot number in the total printing area per color)÷(printing dot number in the total printing area). By adding a multiple with respect to the standard blackening ratio in a page number counter, the degree of fouling of the cleaning roller 56 can be administered by the page number counter.
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