# US 11,079,702 B2 · Image forming apparatus

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- Number: US 11,079,702 B2
- Document ID: US11079702B2
- Status: Granted
- Kind: B2
- Application number: 16/703,373
- Filed: 2019-12-04
- Published: 2020-06-18
- Granted: 2021-08-03
- Earliest claimed: 2018-12-14
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Tomohiro Saito; Kenta Matsuzaki; Shozo Aiba
- Web page: https://patentgrep.com/patent/US11079702B2

## CPC

- G03G 15/162: {details of the the intermediate support, e.g. chemical composition}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An image forming apparatus includes a photosensitive member, a rotatable intermediate transfer belt configured to come into contact with a photosensitive member at a first contact portion on an outer peripheral surface thereof, and, a transfer member configured to come into contact with an inner peripheral surface of the intermediate transfer belt at a second contact portion. The transfer member is disposed such that an upstream end of the second contact portion is positioned downstream of a downstream end of the first contact portion in the rotation direction of the intermediate transfer belt. In a case where a surface resistivity measured on the outer peripheral surface of the intermediate transfer belt is G and a surface resistivity measured on the inner peripheral surface of the intermediate transfer belt is N, 0.75≤N/G≤1.2 is satisfied.

## Claims

### Claim 1

An image forming apparatus comprising:
a photosensitive drum configured to bear a toner image;
a rotatable intermediate transfer belt configured to come into contact with the photosensitive drum at a first contact area on an outer peripheral surface thereof, bear the toner image transferred thereto from the photosensitive drum, and transfer the toner image onto a recording material at a secondary transfer area; and
a transfer roller configured to come into contact with an inner peripheral surface of the intermediate transfer belt at a second contact area, and transfer the toner image on the photosensitive drum onto the intermediate transfer belt by being applied a transfer bias,
wherein the transfer roller is disposed such that an upstream end of the second contact area is positioned downstream of a downstream end of the first contact portion in the area and upstream of the secondary transfer area with respect to a rotation direction of the intermediate transfer belt,
wherein the intermediate transfer belt comprises a base layer and a surface layer provided on an outer peripheral surface of the base layer,
wherein, in a case where a surface resistivity measured on the outer peripheral surface of the intermediate transfer belt is G and a surface resistivity measured on the inner peripheral surface of the intermediate transfer belt is N, 0.75≤N/G≤1.2 is satisfied, and
wherein 1.0×109Ω/□≤N≤1.0×1013Ω/□ is satisfied.

### Claim 2 (depends on 1)

The image forming apparatus according to claim 1, wherein the intermediate transfer belt satisfies 0.8≤N/G<1.0.

### Claim 3 (depends on 1)

The image forming apparatus according to claim 1, wherein the intermediate transfer belt satisfies 0.9<N/G<1.0.

### Claim 4 (depends on 1)

The image forming apparatus according to claim 1, wherein a thickness D of the base layer satisfies 30 μm≤D≤100 μm.

### Claim 5 (depends on 1)

The image forming apparatus according to claim 1, wherein a surface resistivity β of the surface layer itself satisfies 4.0×109 Ω/□≤β≤5.0×1010Ω/□.

### Claim 6 (depends on 1)

The image forming apparatus according to claim 1, wherein a thickness E of the surface layer satisfies 1 nm≤E≤20.0 μm,
wherein a thickness D of the base layer satisfies 30 μm≤D≤100 μm,
wherein 1.9×109Ω/□≤G≤1.5×1010Ω/□ is satisfied, and
wherein 1.4×109Ω/□≤N≤1.8×1010Ω/□ is satisfied.

### Claim 7 (depends on 1)

The image forming apparatus according to claim 1, wherein a transfer current Itg that flows between the transfer roller and the photosensitive drum when the transfer bias is applied to the transfer roller satisfies 5.0 μA≤Itg≤40 μA.

### Claim 8 (depends on 1)

The image forming apparatus according to claim 1, wherein an offset amount F of a rotation center of the transfer roller with respect to a rotation center of the photosensitive drum in a rotation direction of the intermediate transfer belt satisfies 4.0 mm≤F≤7.0 mm.

### Claim 9 (depends on 1)

The image forming apparatus according to claim 1, wherein a contact angle θ of n-hexadecane on the surface layer satisfies 10°≤θ≤90°.

### Claim 10 (depends on 1)

The image forming apparatus according to claim 1, wherein 1.4×109 Ω/□≤N≤1.8×1010Ω/□ is satisfied.

### Claim 11 (depends on 1)

The image forming apparatus according to claim 1, wherein 1.9×109 Ω/□≤G≤1.5×1010Ω/□ is satisfied.

### Claim 12 (depends on 1)

The image forming apparatus according to claim 1, wherein the base layer contains at least one of polyimide, polyamide, polyphenylene sulfide, polyetherimide, and polyether ether ketone.

### Claim 13 (depends on 1)

The image forming apparatus according to claim 1, wherein the surface layer contains at least a binder resin and perfluoropolyether.

### Claim 14 (depends on 1)

The image forming apparatus according to claim 1, wherein the transfer roller is a metal roller.

### Claim 15

An image forming apparatus comprising:
a photosensitive drum configured to bear a toner image;
a rotatable intermediate transfer belt configured to come into contact with the photosensitive drum at a first contact area on an outer peripheral surface thereof, bear the toner image transferred thereto from the photosensitive drum, and transfer the toner image onto a recording material at a secondary transfer area; and
a transfer roller configured to come into contact with an inner peripheral surface of the intermediate transfer belt at a second contact area, and transfer the toner image on the photosensitive drum onto the intermediate transfer belt by being applied a transfer bias,
wherein the transfer roller is disposed such that an upstream end of the second contact area is positioned downstream of a downstream end of the first contact area and upstream of the secondary transfer area with respect to a rotation direction of the intermediate transfer belt,
wherein the intermediate transfer belt is formed to have different resistivities on the outer peripheral surface side and the inner peripheral surface side thereof, and in a case where a surface resistivity measured on the outer peripheral surface of the intermediate transfer belt is G and a surface resistivity measured on the inner peripheral surface of the intermediate transfer belt is N, 0.75≤N/G≤1.2 is satisfied, and
wherein 1.0×109Ω/□≤N≤1.0×1013Ω/□ is satisfied.

### Claim 16 (depends on 15)

The image forming apparatus according to claim 15, wherein the transfer roller is a metal roller.

### Claim 17 (depends on 15)

The image forming apparatus according to claim 15, wherein 1.4×109 Ω/□≤N≤1.8×1010Ω/□ is satisfied.

### Claim 18 (depends on 15)

The image forming apparatus according to claim 15, wherein 1.9×109 Ω/□≤G≤1.5×1010Ω/□ is satisfied.