Image forming device

Abstract

The invention provides an image forming device preventing transfer unevenness caused by change of a water content in a recording sheet during both-side printing. The image forming device has a both-side printing function, electrostatically transfers, by application of a transfer voltage, an unfixed image from an image carrier provided with the unfixed image when a transferred recording sheet passes through a transfer position, and then thermally fixes the unfixed image through a heating rotating body provided with a fixing position. During both-side printing, the image forming device acquires an index value (S805) of the water content at each of a plurality of sheet-passing-direction positions of the recording sheet having undergone thermal fixing of an unfixed image electrostatically transferred onto a first side thereof, and controls a transfer voltage applied for eletrostatically transferring an unfixed image onto a second side of the recording sheet, so that the lower the water content represented by the index value of the position, the greater an absolute value (S809) of the transfer voltage.

Description

technical field [0001] The present invention relates to an image forming apparatus, such as a printer and a copying machine, which has a double-sided printing function and performs printing processing by thermally fixing the unfixed image after electrostatically transferring the unfixed image to a recording sheet, and particularly relates to controlling electrostatic transfer during double-sided printing The technique of applying the transfer voltage when the image is not fixed. Background technique [0002] In image forming apparatuses such as printers and copiers, there is a double-sided recording sheet in which an unfixed image is electrostatically transferred and thermally fixed on the first surface (one surface, such as the front surface) and the second surface (the other surface, such as the back surface) Devices with a printing function have gained widespread popularity. [0003] In addition, the fixing temperature required to thermally fix the unfixed image differs ...

AI Technical Summary

Problems solved by technology

[0004] However, in the case of setting the temperature as described above, excessive power will be consumed when thermally fixing the unfixed image on the page that does not require the most amount of heating, which is undesirable from the viewpoint of energy saving. satisfying

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