Image forming apparatus and method having a forcible toner consumption process

Patent metadata

Field	Value
Publication number	US-9229399-B2
Application number	US-201414561599-A
Country	US
Kind code	B2
Filing date	Dec 5, 2014
Priority date	Dec 5, 2013
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

An image forming apparatus includes multiple image forming units each including a latent image bearer and a developing device, a transfer device to transfer toner images from the latent image bearers onto a surface of endless rotary member, a cleaner to clean the surface of the endless rotary member, and a control unit to execute a forcible toner consumption process to forcibly consume degraded toner stored in applicable one or more developing devices. The forcible toner consumption process includes a step of forming a toner image formed for forced consumption in a non-image region of the latent image bearer with an amount of toner corresponding to a difference between an image area ratio of a developed image and a prescribed threshold when the image area ratio of the developed image is lower than the prescribed threshold.

First claim

What is claimed is:

1. An image forming apparatus, comprising:
multiple image forming units each including a latent image bearer and a developing device to develop a latent image on a surface of the latent image bearer with toner;
a transfer device to transfer toner images on the multiple latent image bearers either onto a recording sheet after transferring the toner images from the multiple latent image bearers onto a surface of an endless rotary member or directly onto a recording sheet held on a surface of an endless rotary member;
a cleaner to clean the surface of the endless rotary member by removing transfer residual toner adhering thereto after a transfer process; and
a controller to execute a forcible toner consumption process to forcibly consume degraded toner stored in one or more developing devices of the multiple image forming units by forming a toner image for forced consumption in a non-image region of the latent image bearer with an amount of toner corresponding to a difference between an image area ratio of a developed image and a prescribed threshold thereof when the image area ratio of the developed image is lower than the prescribed threshold,
wherein, in the forcible toner consumption process, the controller calculates a total consumption required amount of toner by adding together amounts of consumption required toner in the respective image forming units each calculated in accordance with the image area ratio of the developed image in each of the multiple image forming units,
wherein the controller determines an amount of toner actually used to form a toner image for forced consumption in at least one of the multiple image forming units so that the total amount of actually used toner in the respective image forming units becomes less than a prescribed total maximum amount, determined in accordance with cleaning performance of the cleaner, when the total consumption required amount of toner exceeds the prescribed total maximum amount,
wherein the controller reflects a difference between the amount of toner determined to actually adhere to the toner image for forced consumption to enable the total amount of actually used toner in the respective image forming units to be less than the prescribed total maximum amount and the consumption required amount of toner calculated in accordance with the image area ratio of the developed image in at least one of the multiple image forming units to a consumption required amount of toner to be calculated in the next forcible toner consumption process in at least one of the multiple image forming units,
wherein the toner images formed for forced consumption by the respective image forming units are transferred to and superimposed on the endless rotary member.

2. The image forming apparatus as claimed in claim 1 , wherein the controller is configured to:
execute the forcible toner consumption process as needed at every printing in a continuous printing mode in which an image is continuously formed on multiple recording sheets; and
execute the forcible toner consumption process in one or more image forming units by forming the toner image for forced consumption in a region of the latent image bearer corresponding to an interval between successive recording sheets.

3. The image forming apparatus as claimed in claim 2 , wherein the controller determines amounts of toner adhering to the toner images formed for forced consumption in the respective image forming units in accordance with a ratio between the consumption required amounts of toner in the respective image forming units.

4. The image forming apparatus as claimed in claim 2 , wherein the controller is configured to:
calculate and accumulate the consumption required amount of toner at a given interval, wherein the controller determines the amount of toner adhering to the toner image for forced consumption based on an accumulated consumption required amount of toner for each of the respective image forming units; and
calculate the consumption required amount of toner negatively when the image area ratio is not less than a prescribed threshold minimum thereof.

5. The image forming apparatus as claimed in claim 1 , wherein the controller is configured to calculate the consumption required amount of toner to be less than a prescribed maximum amount in the forcible toner consumption process in one or more image forming units.

6. The image forming apparatus as claimed in claim 1 , further comprising a toner supply device to supply toner to the developing device as needed,
wherein the controller directs the toner supply device not to supply toner to the developing device when the toner image for forced consumption is presently developed in each of the multiple image forming units.

7. The image forming apparatus as claimed in claim 1 , wherein the controller adjusts the amount of toner adhering to the toner image for forced consumption by adjusting gradation thereof in the forcible toner consumption process.

8. The image forming apparatus as claimed in claim 1 , wherein the controller adjusts the amount of toner adhering to the toner image for forced consumption by adjusting a developing potential as a potential difference between an electrostatic latent image on the latent image bearer and the developing device in the forcible toner consumption process executed in one or more image forming units.

9. A method of forming an image with multiple image forming units, comprising the steps of:
bearing latent images on surfaces of multiple latent image bearers;
developing the latent images on the surfaces of the multiple latent image bearers with toner;
transferring the toner images on the multiple latent image bearers either onto a recording sheet after transferring the toner images from the multiple latent image bearers onto a surface of an endless rotary member or directly onto a recording sheet held on the surface of the endless rotary member;
forming a toner image for forced consumption in a non-image region of each of the multiple latent image bearers with an amount of toner corresponding to a difference between an image area ratio of a developed image and a prescribed threshold thereof when the image area ratio of the developed image is lower than the prescribed threshold in each of the multiple image forming units to execute a forcible toner consumption process to forcibly consume degraded toner stored in each of the developing devices;
calculating consumption required amount of toner in accordance with the image area ratio of the developed image in each of the multiple image forming units;
adding together each of the amounts of consumption required toner of the multiple image forming units to obtain a total consumption required amount of toner;
determining a prescribed amount of toner actually adhering to the toner image for forced consumption to be formed in at least one of the multiple image forming units so that the total amount of actually used toner in the respective image forming units becomes less than a prescribed total maximum amount, determined in accordance with cleaning performance of the cleaner, when the total consumption required amount of toner exceeds the prescribed total maximum amount;
reflecting a difference between the amount of toner determined to actually adhere to the toner image for forced consumption so that the total amount of actually used toner in the respective image forming units becomes less than the prescribed total maximum amount and the consumption required amount of toner calculated in accordance with the image area ratio of the developed image in at least one of the multiple image forming units to a consumption required amount of toner to be calculated in the next forcible toner consumptio

Assignees

• Kamihara Kazuaki
• Sugiyama Toshihiro
• Higa Takuma
• Nakayama Masayoshi
• Kunii Hiroyuki
• Sukesako Masaki
• Itoh Wakana
• Ricoh Co Ltd

Inventors

• Kamihara Kazuaki
• Sugiyama Toshihiro
• Higa Takuma
• Nakayama Masayoshi
• Kunii Hiroyuki
• Sukesako Masaki
• Itoh Wakana

Classifications

• G03G2215/0129

  horizontal medium transport path at the secondary transfer · CPC title

• G03G15/161

  with means for handling the intermediate support, e.g. heating, cleaning, coating with a transfer agent · CPC title

• G03G15/1605

  using at least one intermediate support (G03G15/1625 takes precedence) · CPC title

• G03G15/50 Primary

  Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control (sequencing control G03G21/14) · CPC title