Image forming apparatus and image forming method

Patent metadata

Field	Value
Publication number	US-9448514-B2
Application number	US-201414564291-A
Country	US
Kind code	B2
Filing date	Dec 9, 2014
Priority date	Mar 15, 2013
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

An image forming apparatus includes a first heater disposed opposite and heating at least a center of a fixing belt in an axial direction thereof and a second heater disposed opposite and heating at least a lateral end of the fixing belt in the axial direction thereof. A power supply supplies power to the first heater and the second heater. A controller that controls the power supply includes a calculator to calculate an elapsed time elapsed after at least one of the first heater and the second heater starts heating the fixing belt. The controller controls the power supply to supply power to the first heater and the second heater such that a power density of the second heater is greater than a power density of the first heater when the elapsed time calculated by the calculator is smaller than a predetermined time.

First claim

What is claimed is:

1. An image forming apparatus comprising:
an endless fixing belt rotatable in a predetermined direction of rotation;
a first heater disposed opposite and heating at least a center of the fixing belt in an axial direction thereof;
a second heater disposed opposite and heating at least a lateral end of the fixing belt in the axial direction thereof;
a power supply connected to the first heater and the second heater to supply power to the first heater and the second heater;
a guide separably contacting an inner circumferential surface of the lateral end of the fixing belt in the axial direction thereof to guide the fixing belt as the fixing belt rotates; and
a controller operatively connected to the power supply to control the power supply,
the controller including a calculator to calculate an elapsed time elapsed after at least one of the first heater and the second heater starts heating the fixing belt,
the controller to control the power supply to supply a non-zero amount of power to the first heater and a non-zero amount of power to the second heater such that a power density of the second heater is greater than a power density of the first heater when the elapsed time calculated by the calculator is smaller than a predetermined time,

wherein after the predetermined time, the controller controls the power supply to change the amount of non-zero power supplied to the first heater, and to change the amount of non-zero power supplied to the second heater.

2. The image forming apparatus according to claim 1 ,
wherein the first heater includes:
a first center heat generator disposed opposite the center of the fixing belt in the axial direction thereof; and
a first lateral end heat generator disposed opposite the lateral end of the fixing belt in the axial direction thereof and having a decreased power density as compared to a power density of the first center heat generator, and
wherein the second heater includes:
a second center heat generator disposed opposite the center of the fixing belt in the axial direction thereof; and
a second lateral end heat generator disposed opposite the lateral end of the fixing belt in the axial direction thereof and having an increased power density as compared to a power density of the second center heat generator.

3. The image forming apparatus according to claim 1 , wherein a power density ratio between the power density of the first heater and the power density of the second heater is constant during warm-up and during an initial period of a print job for printing on a plurality of recording media continuously.

4. The image forming apparatus according to claim 1 , wherein, if the controller determines that power supplied by the power supply to one of the first heater and the second heater exceeds a maximum output of the one of the first heater and the second heater, the controller controls the power supply to change a power density ratio between the power density of the first heater and the power density of the second heater to supply a maximum power available to the first heater and the second heater thereto.

5. The image forming apparatus according to claim 1 , further comprising a temperature detector disposed opposite the fixing belt to detect a temperature of the fixing belt,
wherein the controller is operatively connected to the temperature detector and further includes a power detector to detect power available to the first heater and the second heater, and
wherein, when the temperature of the fixing belt detected by the temperature detector is smaller than a preset second temperature by at least a predetermined value, the controller controls the power supply to supply power to the first heater and the second heater such that the first heater and the second heater output heat at preset fixed outputs, respectively, based on the power detected by the power detector.

6. The image forming apparatus according to claim 1 , wherein, when the power detected by the power detector is greater than a preset power, the controller controls the power supply to supply power to the first heater and the second heater such that the power density of the second heater is greater than the power density of the first heater.

7. The image forming apparatus according to claim 1 , wherein:
the controller controls the power supply such that the power density of the second heater is less than the power density of the first heater when the elapsed time calculated by the calculator is greater than the predetermined time.

8. The image forming apparatus according to claim 1 , wherein:
the controller controls the power supply such that the power density of the first heater when the elapsed time calculated by the calculator is greater than the predetermined time is greater than the power density of the first heater when the elapsed time calculated by the calculator is smaller than the predetermined time.

9. An image forming method of an image forming apparatus including a fixing device, the image forming method comprising:
determining that a difference ΔT between a target fixing temperature and a temperature of a fixing belt is higher than a setting temperature Ta;
calculating a non-zero power to be applied to a first heater for heating a center of the fixing belt in an axial direction thereof and a non-zero power to be applied to a second heater for heating a lateral end of the fixing belt in the axial direction thereof according to input voltage and an operation condition of a peripheral device of the fixing device;
applying the non-zero powers which have been calculated to the first heater and the second heater, respectively;
determining that a time t has elapsed after the first heater and the second heater starts heating the fixing belt;
calculating another non-zero power to be applied to the first heater and another non-zero power to be applied to the second heater based on a reference table for a latter portion of a print job; and
applying the another non-zero powers which have been calculated to the first heater and the second heater, respectively.

10. The image forming method of claim 9 , wherein:
the calculating of the non-zero power to be applied to the first heater and the non-zero power to be applied to the second heater is performed such that a power density of the first heater is less than a power density of the second heater, and
the calculating, after the time t has elapsed, of the another non-zero power to be applied to the first heater and the another non-zero power to be applied to the second heater is performed such that a power density of the second heater is less than a power density of the first heater.

Assignees

• Ikebuchi Yutaka
• Yoshinaga Hiroshi
• Seki Takayuki
• Arai Yuji
• Mimbu Ryuuichi
• Tamaki Shuntaro
• Saito Kazuya
• Yuasa Shuutaroh
• Shimokawa Toshihiko
• Yoshikawa Masaaki
• Hachisuka Toshiharu
• Ricoh Co Ltd

Inventors

• Ikebuchi Yutaka
• Yoshinaga Hiroshi
• Seki Takayuki
• Arai Yuji
• Mimbu Ryuuichi
• Tamaki Shuntaro
• Saito Kazuya
• Yuasa Shuutaroh
• Shimokawa Toshihiko
• Yoshikawa Masaaki
• Hachisuka Toshiharu

Classifications

• G03G15/2082

  Physics · mapped topic

• G03G15/2042 Primary

  specially for the axial heat partition · CPC title

• G03G2215/2035

  the fixing nip having a stationary belt support member opposing a pressure member · CPC title

• G03G15/205

  specially for the mode of operation, e.g. standby, warming-up, error (G03G15/2046 takes precedence) · CPC title

• G03G15/2039 Primary

  with means for controlling the fixing temperature · CPC title