Patent ID: 7835654
Filing Date: 2010-11-16
Classification: G03G

Abstract:
1. A fixing apparatus that fixes a toner image formed on a sheet by passing the sheet through a fixing nip, comprising: a roller that is rotatably held; a belt that revolves; a pressing member disposed on an inner face of the belt, the pressing member pressing the belt from the inner face against a surface of the roller so that the fixing nip is formed between the belt and the roller; and a pressure controller that, in accordance with information indicating a measurement of the sheet in a roller axis direction, changes a pressure distribution in the roller axis direction, the pressure distribution being a distribution of the pressure applied to the roller by the pressing member; wherein if the measurement of the sheet that is to pass through the fixing nip is of a first size, the pressure controller causes the pressing member to use a first pressure distribution in which a pressure on a site through which the sheet of the first size is anticipated to pass is greater than or equal to a necessary fixing pressure and a pressure on other sites is below the necessary fixing pressure, and if the measurement of the sheet that is to pass through the fixing nip is of a second size that exceeds the first size, the pressure controller causes the pressing member to use a second pressure distribution in which a pressure on all sites is greater than or equal to the necessary fixing pressure; and wherein the pressing member is made of an elongated, bendable bar material, a plurality of pectinate projections being formed on one face thereof, a central one of the projections, with respect to a length direction of the pressing member, projecting farther than ones of the projections in a vicinity of ends of the pressing member, the pressure controller includes a support member that supports the pressing member, and a pressure applicator, the support member supporting the pressing member so as to at least be in contact with the central projection, the pressure applicator applying pressure to the pressing member via the support member, and if the sheet is of the first size, the pressure applicator applies a first pressure, and if the sheet is of the second size, the pressure applicator applies a second pressure that is greater than the first pressure.