| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing an electrostatic offset and a fixing smudge effectively, while avoiding the destruction of an insulated layer which covers a fixing roll by controlling a bias voltage applied to the electrically conductive layer of the pressure roll according to a kind of recording sheet or an environmental change. SOLUTION: In a fixing device which consists of a fixing roll covered with an insulated layer, a pressure roll covered with an electrically conductive layer, and a bias control means to apply a bias voltage having a polarity reverse to toner to the electrically conductive layer of the pressure roll, and which nips a recording sheet carrying a toner image with the fixing roll and the pressure roll to fix the toner image on the recording sheet, the sheet identification means which identifies a kind of recording sheet is provided so that the bias control means selects the presence or absence of bias voltage applied to the pressure roll, or changes the magnitude of the bias voltage according to the identification result of the recording sheet by the sheet identification means.
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