Image forming apparatus and control method thereof

• US 8,531,497 B2
• Filed: 06/24/2008
• Issued: 09/10/2013
• Est. Priority Date: 06/26/2007
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Motoyama, Masanao
• Primary Examiner(s): Le, Uyen Chau N
• Assistant Examiner(s): Bedtelyon, John M
• Application Number:
  US12/145,421
• Publication Number:
  US 20090003861A1
• Time in Patent Office: 1,904 Days
• Field of Search: 347/116, 347/229, 347/234, 347/235, 347248-250, 347/243, 347/259, 347/260
• US Class Current: 347/243
• CPC Class Codes: G03G 15/0415 and means for controlling illumination or exposure
• CPC Class Codes: G03G 15/043 with means for controlling illumination or exposure G03G15/041 takes precedence
• CPC Class Codes: G03G 15/0435 by introducing an optical element in the optical path, e.g. a filter
• CPC Class Codes: G03G 15/326 by application of light, e.g. using a LED array
• CPC Class Codes: G03G 2215/0404 Laser

Abstract

An image forming apparatus includes a light beam output unit configured to output a light beam, a deflection unit for deflection scanning in a main scanning direction of a photosensitive member by reflecting the light beam from the light beam output unit, a timing information detection unit configured to detect timing information of the deflection scanning by the deflection unit, a calculation unit configured to calculate a correction amount of the main scanning direction for a next scan based on the timing information, a light beam modulation control unit configured to generate a light beam modulation signal based on image data and the correction amount, and a drive unit configured to drive the light beam output unit based on the light beam modulation signal.

Claims

1. An image forming apparatus comprising:

a light beam output unit configured to output a light beam;

a deflection unit configured to deflection scan a photosensitive member in a main scanning direction by vibrating a mirror to reflect the light beam output from the light beam output unit onto the photosensitive member;

a timing information detection unit configured to detect timing information for a first scan of the deflection scanning by the deflection unit during an image forming;

a calculation unit configured to calculate a difference between;

a target maximum wave amplitude of a frequency component of an angle between the mirror and the photosensitive member, and

an maximum wave amplitude of the frequency component of the angle between the mirror and the photosensitive member in the first scan,

the calculated difference calculated using the timing information for the first scan, the calculation unit further configured to calculate a correction amount of the main scanning direction for a next scan, the correction amount for attenuating non-periodic jitter of the minor caused by at least one of air resistance and turbulence, the correction amount calculated based on the calculated difference;

a light beam modulation control unit configured to generate a light beam modulation signal for a second scan of image forming during the image forming based on image data and the correction amount calculated based on the timing information for the first scan; and

a drive unit configured to drive the light beam output unit based on the light beam modulation signal.

2. The image forming apparatus according to claim 1, wherein the correction amount is a magnification in the main scanning direction of the image data.

3. The image forming apparatus according to claim 1, wherein the correction amount is a deletion interval or an insertion interval of a pixel in the main scanning direction.

4. The image forming apparatus according to claim 1, wherein the calculation unit calculates the correction amount for the next scan for each scan in the main scanning direction.

5. The image forming apparatus according to claim 1, wherein the calculation unit is configured to calculate an angular velocity of the deflection unit for a current scan based on the timing information, and to determine, based on the calculated angular velocity, a target angular velocity, a first drawing time for actually drawing one pixel on the photosensitive member, and a second drawing time of one pixel for resolving an error between the angular velocity and the target angular velocity to calculate the correction amount based a difference between the first drawing time and the second drawing time.

6. A method for controlling an image forming apparatus which has:

a light beam output unit configured to output a light beam for exposing a photosensitive member; and

a deflection unit configured to deflection scan a photosensitive member in a main scanning direction by vibrating a mirror to reflect the light beam output from the light beam output unit onto the photosensitive member;

the method comprising;

detecting timing information for a first scan of the deflection scanning by the deflection unit during an image forming;

calculating a difference between;

a target maximum wave amplitude of a frequency component of an angle between the mirror and the photosensitive member, and

an maximum wave amplitude of the frequency component of the angle between the mirror and the photosensitive member in the first scan,

the calculated difference calculated using the timing information for the first scan, and

calculating a correction amount of the main scanning direction for a next scan, the correction amount for attenuating non-periodic jitter of the mirror caused by at least one of air resistance and turbulence, the correction amount calculated based on the calculated difference;

generating a light beam modulation signal for a second scan of image forming during the image forming based on image data and the correction amount calculated based on the timing information for the first scan; and

driving the light beam output unit based on the light beam modulation signal.

7. The method according to claim 6, wherein the correction amount is a magnification in the main scanning direction of the image data.

8. The method according to claim 6, wherein the correction amount is a deletion interval or an insertion interval of a pixel in the main scanning direction.

9. The method according to claim 6, further comprising calculating the correction amount for the next scan for each scan in the main scanning direction.

10. The method according to claim 6, further comprising:

calculating an angular velocity of the deflection unit for a current scan based on the timing information; and

determining, based on the calculated angular velocity, a target angular velocity, a first drawing time for actually drawing one pixel on the photosensitive member, and a second drawing time of one pixel for resolving an error between the angular velocity and the target angular velocity to calculate the correction amount based a difference between the first drawing time and the second drawing time.

11. A storage medium storing a computer program for executing the method according to claim 6 in a computer.