Image forming apparatus and method of correcting image positional deviation

Patent metadata

Field	Value
Publication number	US-12061433-B2
Application number	US-202117197219-A
Country	US
Kind code	B2
Filing date	Mar 10, 2021
Priority date	Mar 31, 2020
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

An image forming apparatus includes a light beam scanner to scan an image bearer by a light beam according to data on a pattern for image positional deviation correction and a developing device to develop a latent image of the pattern. The pattern is formed on the image bearer by scanning performed by the light beam scanner. The image forming apparatus includes a transfer belt to transfer the pattern to a medium, a sensor to read the pattern to obtain an amount of image positional deviation, a skew correction device to adjust a tilt of an optical member of the light beam scanner according to a skew amount to correct a skew and perform the image positional deviation correction according to the amount of image positional deviation, and circuitry to drive the skew correction device before the image positional deviation correction.

First claim

The invention claimed is:

1. An image forming apparatus, comprising:
a light beam scanner configured to scan an image bearer by a light beam according to data on a pattern for image positional deviation correction;
a developing device configured to develop a latent image of the pattern for positional deviation correction, the pattern for positional deviation correction being formed on the image bearer by scanning performed by the light beam scanner;
a sensor configured to read the pattern for image positional deviation correction to obtain an amount of image positional deviation;
a skew correction device configured to adjust a tilt of an optical member of the light beam scanner according to a skew amount to correct a skew and perform the image positional deviation correction according to the amount of image positional deviation, the skew correction device including,
a stepping motor,
a rotation shaft extending from the stepping motor in a first direction perpendicular to the stepping motor, and
an adjuster attached to the optical member and an outside of the rotation shaft of the stepping motor, the adjuster configured to change the tilt of the optical member by moving a center of the adjuster towards or away from the stepping motor in the first direction, the center of the adjuster being coincident with an axis of rotation of the rotation shaft and the movement being caused by a rotation of the stepping motor; and

circuitry configured to
drive the skew correction device before the image positional deviation correction, and
cause the stepping motor to rotate, from a starting position of the stepping motor at a start of a skew correction operation, by a given amount in a positive direction and by the given amount in a negative direction prior to reading the pattern for image positional deviation correction in a same skew correction operation.

2. The image forming apparatus of claim 1 ,
wherein the adjuster is attached to the outside of the rotation shaft of the stepping motor so as to have a backlash.

3. The image forming apparatus of claim 1 ,
wherein the positive direction is a same direction as a rotation direction at an end of a previous operation performed by the image forming apparatus most recently prior to a correction.

4. The image forming apparatus of claim 3 ,
wherein the direction to which the adjuster pushes the optical member depends upon the rotation direction.

5. The image forming apparatus of claim 1 , wherein the optical member is attached to the adjuster at a first end of the optical member, and
a second end of the optical member, opposite from the first end, is fixed in position.

6. The image forming apparatus of claim 1 , wherein a full rotation of the stepping motor includes four steps.

7. The image forming apparatus of claim 1 , wherein the pattern for positional deviation correction includes at least one horizontal line with respect to a scanning direction and at least one diagonal line with respect to the scanning direction.

8. The image forming apparatus of claim 1 , wherein the circuitry is configured to determine the amount of image positional deviation in a second direction perpendicular to a belt-moving direction of the image bearer.

9. The image forming apparatus of claim 1 , wherein the circuitry is configured to determine the amount of image positional deviation in a second direction corresponding to a belt-moving direction of the image bearer.

10. The image forming apparatus of claim 9 , wherein
the pattern for positional deviation correction includes first and second patterns corresponding to a first color and third and fourth patterns corresponding to a second color, and
the circuitry is configured to determine the skew amount based on a difference between a time from the first pattern to the third pattern and a time from the second pattern to the fourth pattern.

11. An image forming apparatus, comprising:
means for scanning an image bearer by a light beam according to data on a pattern for image positional deviation correction;
means for developing a latent image of the pattern for positional deviation correction, the pattern for positional deviation correction being formed on the image bearer by the means for scanning;
means for transferring the pattern for positional deviation correction formed on the image bearer to a medium;
means for reading the pattern for image positional deviation correction to obtain an amount of image positional deviation;
means for adjusting a tilt of an optical member of the means for scanning according to a skew amount to correct a skew and performing the image positional deviation correction according to the amount of image positional deviation, the means for adjusting including,
a stepping motor,
a rotation shaft extending from the stepping motor in a first direction perpendicular to the stepping motor, and
an adjuster attached to the optical member and an outside of the rotation shaft of the stepping motor, the adjuster configured to change the tilt of the optical member by moving a center of the adjuster towards or away from the stepping motor in the first direction, the center of the adjuster being coincident with an axis of rotation of the rotation shaft and the movement being caused by a rotation of the stepping motor; and

means for driving the means for adjusting before the image positional deviation correction,
wherein the means for driving is configured to rotate the stepping motor, from a starting position of the stepping motor at a start of a skew correction operation, by a given amount in a positive direction and by the given amount in a negative direction prior to reading the pattern for image positional deviation correction in a same skew correction operation.

12. A method of correcting image positional deviation, comprising:
scanning an image bearer by a light beam according to data on a pattern for image positional deviation correction;
developing a latent image of the pattern for positional deviation correction, the pattern for positional deviation correction being formed on the image bearer by the scanning;
reading the pattern for image positional deviation correction to obtain an amount of image positional deviation;
adjusting a tilt of an optical member of a light beam scanner according to a skew amount to correct a skew via a skew correction device, the skew correction device including,
a stepping motor,
a rotation shaft extending from the stepping motor in a first direction perpendicular to the stepping motor, and
an adjuster attached to the optical member and an outside of the rotation shaft of the stepping motor, the adjuster configured to change the tilt of the optical member by moving a center of the adjuster towards or away from the stepping motor in the first direction, the center of the adjuster being coincident with an axis of rotation of the rotation shaft and the movement being caused by a rotation of the stepping motor;

performing the image positional deviation correction according to the amount of image positional deviation after the tilt of the optical member is changed; and
rotating the stepping motor, from a starting position of the stepping motor at a start of a skew correction operation, by a given amount in a positive direction and by the given amount in a negative direction prior to reading the pattern for image positional deviation correction in a same skew correction operation.

13. The method of claim 12 , wherein the optical member is attached to the adjuster at a first end of the optical member, and
a second end of the optical member, opposite from the first end, is fixed in position.

Assignees

• Maeda Katsuhiko
• Ricoh Co Ltd

Inventors

• Maeda Katsuhiko

Classifications

• G03G15/043

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

• G03G15/6567 Primary

  for deskewing or aligning · CPC title

• G03G15/5058 Primary

  using a test patch · CPC title