Image forming apparatus capable of stabilizing image density on a short-term and long-term basis

Patent metadata

Field	Value
Publication number	US-9280113-B2
Application number	US-201113697899-A
Country	US
Kind code	B2
Filing date	May 13, 2011
Priority date	May 18, 2010
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

An image forming apparatus capable of stabilizing image density on a long-term basis by compensating for an error in prediction of toner particle charge amount, while reducing variation in image density on a short-term basis by the prediction. A CPU predicts an amount of electrostatic charge of toner particles in a developer container and sets an exposure condition and causes a toner image to be fixed on a recording medium and a pattern image for detecting image density, to be each formed on a photosensitive drum according to the set exposure condition, while performing gradation correction based on the gradation conversion table. The CPU updates the gradation conversion table such that a detected density of the pattern image becomes closer to a target density. The CPU sets the exposure condition based on a result of the prediction such that toner image density becomes constant.

First claim

The invention claimed is:

1. An image forming apparatus comprising:
a predicting unit configured to predict an amount of electrostatic charge of toner particles in a developer container;
a determining unit configured to determine an exposure condition based on the amount of electrostatic charge of the toner particles predicted by the predicting unit;
a storage unit configured to store a gradation conversion table;
a converting unit configured to convert image data based on the gradation conversion table stored in the storing unit;
an image forming unit configured to form an image based on the converted image data converted by the converting unit, the image forming unit having an image bearing member, an exposure unit configured to expose the image bearing member using light according to the exposure condition determined by the determining unit to form an electrostatic latent image on the image bearing member, and a development unit configured to develop the electrostatic latent image using toner particles;
a measuring unit configured to measure a pattern image formed by the image forming unit;
a controlling unit configured to control the converting unit to convert pattern image data based on the gradation conversion table, control the exposure unit to expose the image bearing member based on the converted pattern image data using light according to the exposure condition determined by the determining unit to form a pattern image, and control the measuring unit to measure the pattern image; and
an updating unit configured to correct the gradation conversion table stored in the storage unit based on the measurement result of the pattern image, and to update the gradation conversion table stored in the storage unit to the corrected gradation conversion table.

2. An image forming apparatus comprising:
a converting unit configured to convert image data based on a gradation conversion condition; and
an image forming unit configured to form a toner image based on the image data converted by the converting unit, the image forming unit having an exposure unit configured to irradiate light based on the image data to form an electrostatic latent image and a developing unit configured to develop the electrostatic latent image;
an acquiring unit configured to acquire a consumption amount of toner consumed by the developing unit;
a determining unit configured to determine, based on the consumption amount acquired by the acquiring unit, a replenishment amount of toner to be replenished to the developing unit;
a setting unit configured to set intensity of light to be irradiated by the exposure unit based on the consumption amount acquired by the acquiring unit and the replenishment amount determined by the determining unit;
a controller configured to control the converting unit to convert measuring image data based on the gradation conversion condition, and control the image forming unit to form a measuring image corresponding to the converted measuring image data with the intensity of light set by the setting unit;
a measuring unit configured to measure the measuring image; and
an updating unit configured to update the gradation conversion condition based on a measurement result of the measuring unit.

3. The image forming apparatus according to claim 2 , wherein the setting unit is configured to determine a predictive amount of electrostatic charge of toner in the developing unit based on the consumption amount acquired by the acquiring unit and the replenishment amount determined by the determining unit and set the intensity of light to be irradiated by the exposure unit in accordance with the predictive determined amount of electrostatic charge.

4. The image forming apparatus according to claim 3 , wherein the developing unit is configured to contain toner and carrier, and
wherein the setting unit is configured to determine the predictive amount of electrostatic charge of toner in the developing unit based on the consumption amount acquired by the acquiring unit, the replenishment amount determined by the determining unit, and a mixture ratio between the toner and the carrier in the developing unit.

5. The image forming apparatus according to claim 3 , wherein the setting unit is configured to determine the predictive amount of electrostatic charge of toner in the developing unit based on the consumption amount acquired by the acquiring unit, the replenishment amount determined by the determining unit, and an environmental humidity.

6. The image forming apparatus according to claim 2 , wherein the developing unit has a container unit containing toner and a toner bearing member bearing the toner in the container unit, and
wherein the setting unit is configured to set the intensity of light to be irradiated by the exposure unit based on the consumption amount acquired by the acquiring unit, the replenishment amount determined by the determining unit, and driving information on the toner bearing member.

Assignees

• Hirabayashi Jun
• Canon Kk

Inventors

• Hirabayashi Jun

Classifications

• G03G15/5041 Primary

  Detecting a toner image, e.g. density, toner coverage, using a test patch (G03G15/553 takes precedence) · CPC title

• G03G2215/00042

  Optical detection · CPC title