Patent ID: 8995853
Filing Date: 2015-03-31
Classification: G03G

Abstract:
1. A transfer device comprising: an intermediate transfer belt disposed to face a plurality of image carriers each carrying a toner image on a circumferential surface of the image carrier and moreover rotationally driven at an equal speed, the intermediate transfer belt being circumferentially and rotationally driven in one direction, the toner images being transferred from the plurality of image carriers onto a surface of the intermediate transfer belt in a superimposed manner; a driving roller around which the intermediate transfer belt is supported and which circumferentially and rotationally drives the intermediate transfer belt; an environment sensor detecting a temperature or a humidity around the intermediate transfer belt; a density detecting section detecting a density of a belt surface of the intermediate transfer belt; and a speed ratio adjusting section controlling a rotation speed of the driving roller according to results of detection by the environment sensor and the density detecting section, thereby adjusting a speed ratio Vb/Vd between a circumferential rotating speed Vb of the intermediate transfer belt and a rotation speed Vd of the image carrier, wherein the speed ratio adjusting section: sets the speed ratio Vb/Vd to a first speed ratio when the temperature or humidity detected by the environment sensor is lower than a preset threshold, sets the speed ratio Vb/Vd to a second speed ratio that is higher than the first speed ratio when the temperature or humidity is equal to or higher than a preset threshold, and sets the speed ratio Vb/Vd to a third speed ratio that is higher than the first speed ratio and lower than the second speed ratio when the density detecting section detects that the density of the belt surface of the intermediate transfer belt is greater than a preset threshold.