US-12619178-B2 - Fixing apparatus and image forming apparatus

US12619178B2US 12619178 B2US12619178 B2US 12619178B2US-12619178-B2

Abstract

A fixing apparatus includes a rotatable fixing member, a rotatable pressurizing member, a heating portion, and a circuit portion including a contact member and configured to remove electric charge from the fixing member, the contact member being in contact with the fixing member. A surface layer of the pressurizing member is electrically connected to the circuit portion via a surface layer of the fixing member. In a case where a surface resistivity of the surface layer of the pressurizing member is represented by X (Ω/□) and a surface resistivity of the surface layer of the fixing member is represented by Y (Ω/□), 4.0≤log X≤13.0, 5.0≤log Y≤14.0, log Y≥13.0−log X, and log Y≤23.0−log X are satisfied.

Inventors

Mahito Yoshioka
Tetsuichiro Fujimoto
Keisuke Mochizuki
KOHEI HAEMATSU

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20241119
Priority Date: 20220804

Claims (2)

1 . A fixing apparatus comprising: a rotatable fixing member; a rotatable pressurizing member configured to abut the fixing member at a nip portion; a heating portion configured to heat the fixing member; and a circuit portion including a contact member and configured to remove electric charge from the fixing member, the contact member being in contact with the fixing member, wherein the fixing apparatus is configured to heat an image on a recording material by the fixing member to fix the image to the recording material while nipping and conveying the recording material between the fixing member and the pressurizing member in the nip portion, wherein a surface layer of the pressurizing member is electrically connected to the circuit portion via a surface layer of the fixing member, wherein the contact member is electrically connected with an electric ground for an electric circuit configured to supply power to the heating portion, and wherein in a case where a surface resistivity of the surface layer of the pressurizing member is represented by X (Ω/□) and a surface resistivity of the surface layer of the fixing member is represented by Y (Ω/□), 4.0≤log X≤13.0, 5.0≤log Y≤14.0, log Y≥13.0−log X, and log Y≤23.0−log X are satisfied.
2 . The fixing apparatus according to claim 1 , wherein the fixing member is a tubular film, wherein the heating portion is a heater disposed in an inner space of the film, and wherein the pressurizing member is a roller sandwiching the film together with the heater to form the nip portion between the film and the roller.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a Continuation of U.S. patent application Ser. No. 18/360,925, filed Jul. 28, 2023, the entirety of which is hereby incorporated herein by reference. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a fixing apparatus that fixes an image to a recording material, and an image forming apparatus that forms an image on a recording material. Description of the Related Art An image forming apparatus of an electrophotographic system forms an image on a recording material by using toner as developer, and then fixes the image to the recording material by a fixing apparatus. A fixing apparatus of a thermal fixation system fixes an image by heating the image on a recording material while nipping and conveying the recording material between a fixing member and a pressurizing member. In a fixing apparatus of this kind, when the pressurizing member is charged by frictional charging or the like, a situation in which toner on the recording medium receives repulsive force and attaches to the fixing member, and then toner attaches to the recording material after the fixing member rotates once can occur. The image defect caused by deviation of an electrostatic force acting on the toner in the nip portion of the fixing apparatus from an appropriate range is known as electrostatic offset. Japanese Patent Application Laid-Open No. 2002-132072 discloses a technique in which the electrostatic offset is suppressed by providing a fixing film with a conductive layer having electrical conductivity, applying a voltage to the conductive layer exposed at a film end portion in the longitudinal direction by bringing a power supply brush into contact therewith, and grounding a pressurizing roller opposing the fixing film. Japanese Patent Application Laid-Open No. 2009-042303 discloses a technique in which the electrostatic offset is suppressed by bringing a conductive layer of a fixing film into contact with a conductive rubber ring provided at an end portion of a pressurizing roller and grounding a core metal of the pressurizing roller. Due to the demand for reduction of the size and cost of the image forming apparatus, there has been a demand for reducing occurrence of the electrostatic offset with a simpler configuration. SUMMARY OF THE INVENTION The present invention provides a fixing apparatus and an image forming apparatus that can reduce occurrence of the electrostatic offset with a simple configuration. According to one aspect of the invention, a fixing apparatus includes a rotatable fixing member, a rotatable pressurizing member configured to abut the fixing member at a nip portion, a heating portion configured to heat the fixing member, and a circuit portion including a contact member and configured to remove electric charge from the fixing member, the contact member being in contact with the fixing member, wherein the fixing apparatus is configured to heat an image on a recording material by the fixing member to fix the image to the recording material while nipping and conveying the recording material between the fixing member and the pressurizing member in the nip portion, wherein a surface layer of the pressurizing member is electrically connected to the circuit portion via a surface layer of the fixing member, and wherein in a case where a surface resistivity of the surface layer of the pressurizing member is represented by X (Ω/□) and a surface resistivity of the surface layer of the fixing member is represented by Y (Ω/□), 4.0≤log X≤13.0, 5.0≤log Y≤14.0, log Y≥13.0−log X, and log Y≤23.0−log X are satisfied. Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an image forming apparatus according to a first embodiment. FIG. 2 is a schematic diagram illustrating a cross-section of a fixing apparatus according to the first embodiment. FIG. 3 is a schematic view of the fixing apparatus according to the first embodiment. FIG. 4 is a diagram illustrating a layer structure of a fixing film according to the first embodiment. FIG. 5 is a diagram illustrating a charge removing mechanism of a pressurizing roller and the fixing film according to the first embodiment. FIG. 6 is a diagram illustrating a relationship between the surface resistivity of the pressurizing roller and the surface resistivity of the fixing film according to the first embodiment. FIG. 7 is a diagram illustrating how electrostatic offset occurs. FIG. 8 is a schematic view of a fixing apparatus according to a first modification example of a second embodiment. FIG. 9 is a schematic view of a fixing apparatus according to a second modification example of the second embodiment. DESCRIPTION OF THE EMBODIMENTS Embodiments of the present disclosure will be described below with reference to drawings. First Embodi