Fixing apparatus having uniform surface potential difference between fixing film and pressure roller and image forming apparatus thereof

1 . A fixing apparatus comprising:

a first rotating member;

an elongated heater provided with a heating element and a substrate and disposed in a space inside the first rotating member, the heating element being provided on the substrate;

a second rotating member, wherein the first rotating member is pinched by the heater and the second rotating member, and an image formed on a recording material is heated at a nip portion, via the first rotating member, to fix the image to the recording material;

a first contact member configured to come into contact with the first rotating member to ground the first rotating member; and

a second contact member configured to come into contact with the second rotating member to ground the second rotating member,

wherein, when a direction of a longer side on a surface of the substrate where the heating element is disposed is defined as a longitudinal direction and when a direction perpendicularly intersecting with the longitudinal direction on the surface of the substrate is defined as a widthwise direction, the first contact member comes into contact with an inner circumferential surface of the first rotating member at one end side in the longitudinal direction, and the second contact member comes into contact with the second rotating member at the other end side in the longitudinal direction.

2 . The fixing apparatus according to claim 1 , wherein, in the longitudinal direction, a region where a recording material with a maximum size conveyed to the nip portion passes through the nip portion is a first region and a region where the recording material does not pass through the nip portion is a second region, the first contact member comes into contact with the inner circumferential surface of the first rotating member in the first region on the one end side, and the second contact member comes into contact with an outer circumferential surface of the second rotating member in the second region on the other end side.

3 . The fixing apparatus according to claim 1 ,

wherein, in the longitudinal direction, a distance from a conveyance reference of the recording material to be conveyed to the nip portion to the first contact member is a first distance, and a distance from the conveyance reference to the second contact member is a second distance, and

wherein the first distance and the second distance are equal.

4 . The fixing apparatus according to claim 1 ,

wherein, in the longitudinal direction, a distance from a center of the first rotating member to the first contact member is a first distance, and a distance from a center to the second contact member is a second distance, and

wherein the first distance and the second distance are equal.

5 . The fixing apparatus according to claim 1 , wherein the first contact member is grounded via a first resistor and a capacitor, and the second contact member is grounded via a second resistor.

6 . The fixing apparatus according to claim 1 ,

wherein the first rotating member is a film, and the second rotating member is a pressure roller, and

wherein the heater is disposed in a space inside the film, the film is pinched by the heater and the pressure roller, and an image formed on the recording material is heated via the film at the nip portion.

7 . The fixing apparatus according to claim 6 ,

wherein the film includes a base layer, an elastic layer, and a surface layer as a mold release layer on the elastic layer, and

wherein a surface resistance of the base layer is 154.0 MΩ or less.

8 . The fixing apparatus according to claim 6 ,

wherein the pressure roller includes an elastic layer, and a surface layer as a mold release layer on the elastic layer, and

wherein a surface resistance of the surface layer of the pressure roller is 5.0 MΩ or less.

9 . The fixing apparatus according to claim 1 , wherein the second contact member is disposed on the other end side in the longitudinal direction on an outer circumferential surface of the second rotating member.

10 . An image forming apparatus comprising:

the fixing apparatus according to claim 1 ; and

an image forming unit configured to form the image on the recording material, wherein the fixing apparatus is configured to fix the image formed on the recording material to the recording material.

11 . A fixing apparatus comprising:

a cylindrical flexible member;

a heater disposed in an interior space of the cylindrical flexible member, the heater including a substrate and a heating element provided on the substrate;

a pressure roller configured to contact an outer circumferential surface of the cylindrical flexible member and, in cooperation with the heater, to form a nip portion between the cylindrical flexible member and the pressure roller, wherein a recording material bearing an image is nipped and conveyed at the nip portion and the image is fixed to the recording material at the nip portion;

a first contact member configured to contact an inner circumferential surface of the cylindrical flexible member and to electrically ground the cylindrical flexible member; and

a second contact member configured to contact an outer circumferential surface of the pressure roller and to electrically ground the pressure roller,

wherein, when a recording material having a maximum width in a longitudinal direction of the heater passes through the nip portion, a region of the nip portion through which the recording material passes is defined as a first region and another region of the nip portion through which the recording material does not pass is defined as a second region,

wherein the first contact member contacts the inner circumferential surface of the cylindrical flexible member at a position corresponding to the first region in the longitudinal direction, and

wherein the second contact member contacts the outer circumferential surface of the pressure roller at a position corresponding to the second region in the longitudinal direction.

12 . The fixing apparatus according to claim 11 ,

wherein the cylindrical flexible member includes a base layer contacting the first contact member, an elastic layer, and a surface layer contacting the pressure roller, and

wherein a surface resistance of the base layer is 154.0 MΩ or less.

13 . The fixing apparatus according to claim 12 ,

wherein the pressure roller includes an elastic layer, and a surface layer contacting the second contact member, and

wherein a surface resistance of the surface layer of the pressure roller is 5.0 MΩ or less.

14 . The fixing apparatus according to claim 11 , wherein the first contact member is electrically grounded via a first resistor and a capacitor, and the second contact member is electrically grounded via a second resistor.

15 . The fixing apparatus according to claim 11 , wherein the first contact member is made of heat-resistant resin provided with conductivity.

16 . The fixing apparatus according to claim 11 , wherein the first contact member is a polyimide film containing distributed carbon.

17 . The fixing apparatus according to claim 16 , wherein the polyimide film is disposed in the fixing apparatus such that a longer side of the polyimide film is parallel to a rotational direction of the cylindrical flexible member.

18 . The fixing apparatus according to claim 11 , wherein the second contact member is made of metal, and

wherein the second contact member is disposed in the fixing apparatus such that a longer side of the second contact member is parallel to a rotational direction of the pressure roller.

19 . An image forming apparatus comprising:

the fixing apparatus according to claim 1 ; and

an image forming unit configured to form the image on the recording material, wherein the fixing apparatus is configured to fix the image formed on the recording material to the recording material.