Patent ID: 7593664

Claim:
An image-forming device comprising: an image-carrying member that carries a developer image; a plurality of support members; an endless belt disposed in confrontation with the image-carrying member and supported on the plurality of support members to circularly move there around; a transferring member that transfers the developer image in a direction from the image-carrying member to the endless belt; a tension-adjusting mechanism that adjusts a tension generated in the endless belt between a first tension at which the developer image is transferred in the direction from the image-carrying member to the endless belt and a second tension greater than the first tension; and a cleaning unit that cleans an outer surface of the endless belt and comprises a cleaning roller disposed in opposition to the outer surface of the endless belt, and a backup roller disposed in opposition to the cleaning roller with the endless belt interposed between the backup roller and the cleaning roller, wherein the cleaning roller and the backup roller are configured to selectively provide one of a first state in which the cleaning roller and the backup roller pinch the endless belt and a second state in which the endless belt is free from the pinching by the cleaning roller and the backup roller, and wherein the tension-adjusting mechanism sets the second tension in the endless belt, and the cleaning roller and the backup roller are in the first state when the cleaning unit is cleaning the endless belt.