1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of Related Art
A conventional electro-photographic image forming apparatus such as a printer, a copier, a fax machine, and a multifunction machine thereof forms an image through the following process. In a case of, for example, the printer, a surface of a photosensitive drum or an image supporting member is charged with a charging roller. Then, an LED head exposes the surface of the photosensitive drum to form a latent image. A developing roller electrostatically attaches a thin layer of toner to the latent image to form a toner image; and a transfer roller transfers the toner image to a sheet, thereby forming an image or printing. After transferring the toner image, a cleaning blade cleans toner remaining on the photosensitive drum. Afterward, the sheet with the toner image transferred thereon is sent to a fixing device, thereby fixing the toner image to the sheet.
In a color printer, four image forming units are arranged for forming a toner image in each color. The photosensitive drum is arranged in each of the image forming units, and a transferring device is arranged facing each of the image forming units. The transferring device has a driving roller; an idle roller; an endless belt tensely provided between the driving roller and the idle roller; and a transfer roller provided facing the photosensitive drum with the endless belt inbetween.
In the transferring device, the endless belt moves to transport a sheet, and a toner image in each color is transferred onto the sheet by overlaying the toner images with the transfer roller, thereby forming a color toner image. Then, the color toner image is fixed to the sheet, thereby forming a color image.
In the color printer described above, the endless belt may be provided with a reinforcing tape along an edge thereof in order to prevent a crack from forming in the edge while the endless belt is running (refer to Patent Reference). Patent Reference Japan Patent Publication No. 11-219046
In the conventional image forming device, it is troublesome to put the reinforcing tape on the endless belt. The reinforcing tape tends to twine around each roller and deform each time the endless belt passes the driving roller and the idle roller. When the reinforcing tape repeatedly twines and deforms, the reinforcing tape comes off from the endless belt. Once the reinforcing tape comes off, the endless belt directly receives a stress due to repetitive deformation, so that the endless belt is damaged from the edge thereof and cracked, and even broken later. As a result, durability of the endless belt is impaired.
In view of the problems described above, an object of the invention is to provide an image forming apparatus having a belt with improved durability.
Further objects and advantages of the invention will be apparent from the following description of the invention.