A fixing device includes a fixing member, a pressuring member, a fixing frame, a supporting member and a biasing member. The fixing member and the pressuring member forms a fixing nip. The supporting member has a bearing part which rotatably supports the pressuring member. The biasing member biases the supporting member in a pressing direction in which the pressuring member is made to come into pressure contact with the fixing member. The supporting member has a fulcrum part and a contact part. The fulcrum part is disposed separately from the bearing part and turnably engaged with the fixing frame. The contact part is disposed on an opposite side to the fulcrum part with respect to the bearing part. The fixing frame has a restriction part. The restriction part comes into contact with the contact part to restrict the supporting member from being moved in the pressing direction.

A rotatable fixing member includes an elastic layer, a primer layer provided on the elastic layer, and a parting layer provided on the primer layer. The primer layer contains a crystalline fluorocarbon polymer having a functional group and has a thickness of 850 nm or less. The parting layer is a coating layer of a crystalline fluorocarbon polymer.

A fuser having a heater, a belt, and a holder, is provided. The heater includes a metal-made base plate and a resistive-heating element and has a first face and a second face. The resistive-heating element is formed on at least one of the first face and the second face. The belt being an endless belt has an inner circumferential surface contacting the first face of the heater and rotates around the heater. The holder has a retainer face to contact the second face of the heater to retain the heater and a belt-guiding face to contact the inner circumferential surface of the belt and guide the belt there-along. The base plate has a pair of first edges located on one end and the other end of the first face in the widthwise direction extending in the lengthwise direction. The pair of first edges are rounded at ridges.

A fixing device for fixing a toner image onto a recording medium includes: an endless belt that is configured to be able to rotate; a pressure member that is in contact with an outer peripheral surface of the belt; and a sliding member that has a sliding surface in contact with an inner peripheral surface of the belt and is arranged to face the pressure member with the belt interposed between the sliding member and the pressure member, wherein a direction in which the belt rotating slides on the sliding surface is referred to as a direction of conveyance, a plurality of first grooves as well as a plurality of second grooves each allowing two of the plurality of first grooves adjacent to each other to communicate with each other are formed on the sliding surface, and the first grooves and the second grooves are formed in a non-grid pattern.

A tubular fuser device rotates and is in contact with a sheet on which a positively charged toner image is formed to fix the toner image to the sheet. The fuser device includes a tubular substrate made of a metal, a rubber layer covering the outer periphery of the substrate, an adhesion layer covering the outer periphery of the rubber layer, and a surface layer made of a resin covering the outer periphery of the adhesion layer. In the fuser device, C.Math.R/A.sup.2 is less than 1.1×10.sup.−3 FΩ/cm.sup.4 in which C.Math.R/A.sup.2 is a product of an electrostatic capacity per unit area C/A in a thickness direction of the fuser device and an electrical resistance per unit area R/A in the thickness direction of the fuser device.

According to an aspect of the invention, an elastic roll includes a base that has a circular outer circumferential line in an axial direction and includes an outer circumferential surface on which a spiral recess in the axial direction is formed; and an elastic layer that is provided to be adhered to the outer circumferential surface and has a circular outer circumferential line in the axial direction.

A fixing device includes a first belt that contacts a developer image on a recording medium; a second belt that sandwiches the recording medium with the first belt and hence forms a nip region extending in a transport direction of the recording medium; a rotational body that is provided inside the first belt in a region at a downstream side in the transport direction of the nip region, rotates, and turns the first belt; a pressing member that is provided inside the second belt and presses the second belt toward the rotational body; and a heating unit that is provided inside the first belt in a region at an upstream side in the transport direction of the nip region in a non-contact manner with respect to the first belt, and heats the developer image on the recording medium.

An image forming apparatus includes an apparatus body having an image forming unit that is configured to an image on a recording material, and a fixing unit removably attached to the apparatus body to fix the image on the recording material. The fixing unit includes a roll member having a roll body and a bearing provided at each end of the roll body to support the roll body rotatably, a pressurizing member provided in contact with the roll member to form a fixing pressurizing portion through which the recording material passes, and a storage member that stores the roll member and the pressurizing member in a state in which the roll member and the pressurizing member are pressed with a predetermined pressure. The apparatus body includes a positioning member that is in contact with the bearing to position the roll member in a transport direction of the recording material.

An image fixing device includes an elastic roller; a back-up unit forming a fixing nip with the roller therebetween, the back-up unit including a cylindrical film, a film guide, extending inside the film, for guiding the film, and an end portion guiding member including a guiding portion for guiding an inner surface of an end portion of the film. The film guide includes plural ribs contacting the film and arranged in a generatrix direction at positions upstream of the fixing nip with respect to a feeding direction of a sheet. The ribs have free end portions retracted more toward a downstream side with respect to the feeding direction of the recording material than the guiding portion of the end portion guiding member. An inside rib has a free end portion which is retracted more toward the downstream side than free end portions of the opposite end ribs.

A fuser configured to nip a sheet by a heating member and a pressurizing member and to thermally fix an image formed in a toner on the sheet, is provided. The fuser includes a supporting member, a temperature sensor, and a sensor cover. The supporting member supports the heating member. The temperature sensor is attached to the supporting member and is configured to detect a temperature of the heating member without contacting the heating member. The sensor cover is located on a side of the temperature sensor opposite to the heating member to cover the temperature sensor. The sensor cover includes a base having an opening at an upper position with respect to the temperature sensor and a windshield wall located in adjacent to the base. The windshield wall protrudes upward and extends in a lengthwise direction for the heating member.