# US 2014/0153950 A1 · Image forming apparatus

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- Number: US 2014/0153950 A1
- Document ID: US20140153950A1
- Status: Published application
- Kind: A1
- Application number: 14/092,734
- Filed: 2013-11-27
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Shogo Kan; Akimichi Suzuki; Satoshi Nishida; Hideo Nanataki; Takanori Mitani
- Web page: https://patentgrep.com/patent/US20140153950A1

## CPC

- G03G 15/2046: {specially for the influence of heat loss, e.g. due to the contact with the copy material or other roller}
- G03G 15/2039: {with means for controlling the fixing temperature}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An image forming apparatus configured to form a toner image on a recording material, includes: an image forming unit configured to form a unfixed toner image on the recording material; a fixing unit configured to heat the recording material where the unfixed toner image is formed while conveying the recording material using a nip portion, and to fix the unfixed toner image on the recording material; and a control unit configured to perform control so that temperature of the fixing unit is maintained in target temperature, with the target temperature (Tn) of a n'th page in consecutive printing being set to the highest temperature of the target temperatures (Tn to Tn+k) according to each of image densities (Dn to Dn+k) at (n to (n+k))'th pages, where integer k21.

## Claims

### Claim 1

An image forming apparatus configured to form a toner image on a recording material, comprising:
an image forming unit configured to form a unfixed toner image on the recording material;
a fixing unit configured to heat the recording material where the unfixed toner image is formed while conveying the recording material using a nip portion, and to fix the unfixed toner image on the recording material; and
a control unit configured to perform control so that temperature of the fixing unit is maintained in target temperature,
wherein the target temperature (Tn) of a n'th page in consecutive printing is set to the highest temperature of the target temperatures (Tn to Tn+k) according to each of image densities (Dn to Dn+k) at (n to (n+k))'th pages, where integer k≧1.

### Claim 2 (depends on 1)

The apparatus according to claim 1,
wherein the higher the image densities (Dn to Dn+k), the higher the target temperatures (Tn to Tn+k).

### Claim 3 (depends on 1)

The apparatus according to claim 1,
wherein the fixing unit includes
a cylindrical film,
a nip portion forming member configured to be in contact with an inner face of the film, and
a pressing member configured to form the nip portion along with the nip portion forming member, across the film.

### Claim 4 (depends on 2)

The apparatus according to claim 2,
wherein the nip portion forming member is a heater.

### Claim 5

An image forming apparatus configured to form a toner image on a recording material, comprising:
an image forming unit configured to form a unfixed toner image on the recording material;
a fixing unit configured to heat the recording material where the unfixed toner image is formed while conveying the recording material using a nip portion, and to fix the unfixed toner image on the recording material; and
a control unit configured to perform control so that temperature of the fixing unit is maintained in target temperature,
wherein the target temperature (Tn) of a n'th page in consecutive printing is set to the highest temperature of the target temperature (Tn) according to image density Dn at the n'th page, and corrected target temperatures (Tn+1′ to Tn+k′) obtained by correcting the target temperatures (Tn+1 to Tn+k) according to each of image densities (Dn+1 to Dn+k) at ((n+1) to (n+k))'th pages respectively, according to the number of pages from the n page of the pages ((n+1) to (n+k)) respectively, where integer k≧1.

### Claim 6 (depends on 5)

The apparatus according to claim 5,
wherein the higher the image densities (Dn to Dn+k), the higher the target temperatures (Tn to Tn+k).

### Claim 7 (depends on 5)

The apparatus according to claim 5,
wherein the corrected target temperatures (Tn+1′ to Tn+k′) are obtained by performing correction to subtract, the greater the number of pages of each of the target temperatures (Tn+1 to Tn+k), a greater value therefrom.

### Claim 8 (depends on 5)

The apparatus according to claim 5,
wherein the fixing unit includes
a cylindrical film,
a nip portion forming member configured to be in contact with an inner face of the film, and
a pressing member configured to form the nip portion along with the nip portion forming member, across the film.

### Claim 9 (depends on 8)

The apparatus according to claim 8,
wherein the nip portion forming member is a heater.

### Claim 10

An image forming apparatus configured to form a toner image on a recording material, comprising:
an image forming unit configured to form a unfixed toner image on the recording material;
a fixing unit configured to heat the recording material where the unfixed toner image is formed while conveying the recording material using a nip portion, and to fix the unfixed toner image on the recording material; and
a control unit configured to perform control so that temperature of the fixing unit is maintained in target temperature,
wherein the target temperature (Tn) of a n'th page in consecutive printing is set to lower temperature in a case where the highest image density of each of image densities (Dn to Dn+k) of (n to (n+k))'th pages respectively is a first image density than a case where the highest image density is a second image density higher than the first image density, where integer k≧1.