Image forming apparatus and image forming method

Patent metadata

Field	Value
Publication number	US-10073371-B2
Application number	US-201715656027-A
Country	US
Kind code	B2
Filing date	Jul 21, 2017
Priority date	Aug 24, 2016
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

An image forming apparatus includes a photoconductor, a light source, an optical scanning device, an image bearer, an image density sensor, an image processing circuit, and a light source driver. The plurality of images are formed with a plurality of light intensities and a plurality of image area rates on the image bearer. The image density sensor detects a plurality of image densities of the plurality of images at a plurality of positions in a main scanning direction. The image processing circuit determines a light intensity correction value to correct an image density of a target image in the main scanning direction based on the plurality of light intensities, image area rates, image densities, and positions, and the image area rate of the target image, and outputs a control signal to adjust a light intensity. The light source driver adjusts the light intensity based on the control signal.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a photoconductor;
a light source to emit a light beam onto the photoconductor;
an optical scanning device to scan the photoconductor with the light beam;
an image bearer to bear a plurality of images formed with a plurality of light intensities of the light source and a plurality of image area rates, respectively, transferred from the photoconductor;
an image density sensor to detect a plurality of image densities of the plurality of images at a plurality of positions on at least one of the image bearer and the photoconductor, respectively, in a main scanning direction of the light beam;
an image processing circuit to calculate an image area rate of a target image to be formed based on inputted image data, determine a light intensity correction value to correct an image density of the target image in the main scanning direction based on the plurality of light intensities of the plurality of images, the plurality of image area rates of the plurality of images, the plurality of image densities detected by the image density sensor, the plurality positions at which the image density sensor detects the plurality of image densities, and the image area rate of the target image, and output a control signal to adjust a light intensity of the light beam emitted by the light source; and
a light source driver to adjust the light intensity of the light beam emitted by the light source based on the control signal output by the image processing circuit.

2. The image forming apparatus according to claim 1 ,
wherein the image processing circuit calculates the image area rate in each page of the inputted image data, and the light source driver adjusts the light intensity of the light source in each page of the inputted image data.

3. The image forming apparatus according to claim 1 ,
wherein the image processing circuit calculates the image area rate in each line of the inputted image data, and the light source driver adjusts the light intensity of the light source in each line of the inputted image data.

4. The image forming apparatus according to claim 1 ,
wherein the image processing circuit calculates the image area rate in each page of the inputted image data, and the light source driver adjusts the light intensity of the light source based on the light intensity correction value determined by using the image area rate in which image density distribution in the main scanning direction is largest in the calculated image area rates of a plurality of pages of the inputted image data.

5. The image forming apparatus according to claim 1 ,
wherein the image processing circuit calculates the image area rate in each line of the inputted image data, and the light source driver adjusts the light intensity of the light source based on the light intensity correction value determined by using the image area rate in which image density distribution in the main scanning direction is largest in the calculated image area rates of a plurality of lines of the inputted image data.

6. The image forming apparatus according to claim 1 ,
wherein at least one of the plurality of images formed with the plurality of image area rates and the plurality of light intensities of the light source is formed between successive pages of the inputted image data.

7. The image forming apparatus according to claim 1 , wherein the plurality of images are image density control patterns that correspond to different image area rates.

8. An image forming method for forming an electrophotographic image with an image forming apparatus, the image forming method comprising:
forming a plurality of patterns with a plurality of image area rates and a plurality of light intensities;
detecting a plurality of image densities of the plurality of the patterns at different positions in a main scanning direction;
storing a relation between the plurality of image area rates, the plurality of light intensities, and the plurality of detected image densities of the plurality of the patterns at the different positions in the main scanning direction;
calculating an image area rate in an output image at a position in the main scanning direction from image data of the output image; and
adjusting a light intensity for the output image based on the calculated image area rate of the output image, the position in the main scanning direction, and the stored relation.

9. An image forming apparatus comprising:
a light emitting means for emitting a light beam;
an optical scanning means for scanning with the light beam;
an image bearing means for bearing a plurality of images formed with a plurality of light intensities of the light emitting means and a plurality of image area rates, respectively, transferred from a photoconductor;
an image density detecting means for detecting a plurality of image densities of the plurality of images at a plurality of positions on at least one of the image bearing means and the photoconductor, respectively, in a main scanning direction of the light beam;
an image processing means for calculating an image area rate of a target image to be formed based on inputted image data and determining a light intensity correction value to correct an image density of the target image in the main scanning direction based on the plurality of light intensities of the plurality of images, the plurality of image area rates of the plurality of images, the plurality of image densities detected by the image density detecting means, the plurality positions at which the image density detecting means detects the plurality of image densities, and the image area rate of the target image, and outputting a control signal to adjust a light intensity of the light beam emitted by the light emitting means; and
a light intensity adjusting means for adjusting the light intensity of the light beam emitted by the light emitting means based on the control signal output by the image processing means.

Assignees

• Matsuura Yuugo
• Matsumoto Kohei
• Ricoh Co Ltd

Inventors

• Matsuura Yuugo
• Matsumoto Kohei

Classifications

• G03G15/043 Primary

  with means for controlling illumination or exposure (G03G15/041 takes precedence) · CPC title

• G03G15/5041

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