Method and apparatus for compensating image skew and electro-photographic image froming apparatus incorporating the same

Abstract

A method and apparatus for compensating image skew and an electro-photographic image forming apparatus including the same are provided. Image skew of a toner image transferred onto a paper is compensated for by inclining a photosensitive medium onto which a light beam is scanned to be parallel to a scanning line of the light beam. A first inclination member including a first inclined surface facing upward and a second inclination member including a second inclined surface contacting and facing the first inclined surface are provided, wherein a position of a shaft of the photosensitive medium is adjusted by moving at least one of the first and second inclination members. Image skew of a toner image is sensed, and a photosensitive medium onto which a light beam is scanned is inclined to correspond to a scanning line skew of the light beam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other exemplary features and advantages of certain exemplary embodiments of the present invention will become more apparent from the following detailed description of certain exemplary embodiments thereof when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates scanning skew and image skew caused thereby;

FIG. 2 is a cross-sectional view of an electro-photographic image forming apparatus according to an exemplary embodiment of the present invention;

FIG. 3 is a cross-sectional view of an image skew compensating apparatus included in the electro-photographic image forming apparatus of the exemplary embodiment of FIG. 2, according to an exemplary embodiment of the present invention;

FIG. 4 illustrates image skew compensation in the case of the image skew compensating apparatus of the exemplary embodiment of FIG. 3;

FIG. 5 is a cross-sectional view of the image skew compensating apparatus of the exemplary embodiment of FIG. 2 according to another exemplary embodiment of the present invention; and

FIG. 6 is a cross-sectional view of the image skew compensating apparatus of the exemplary embodiment of FIG. 2 according to another exemplary embodiment of the present invention.

Claims

1. An image skew compensating apparatus for compensating for image skew of a toner image transferred onto paper, the image skew compensating apparatus comprising: a first inclination member comprising a first inclined surface facing upward; anda second inclination member comprising a second inclined surface contacting and facing the first inclined surface,wherein a position of a shaft of a photosensitive medium onto which a light beam is scanned is adjusted by moving at least one of the first and second inclination members.

2. The apparatus of claim 1, further comprising: a motor; anda screw extended from a rotation axis of the motor and inserted into at least one of the first and second inclination members;wherein a rotation of the screw moves at least one of the first and second inclination members back and forth according to the rotation direction of the motor.

3. The apparatus of claim 2, further comprising: a sensor for sensing an image skew; anda controller for controlling driving of the motor based on signals sensed by the sensor.

4. The apparatus of claim 1, wherein the second inclination member supports the shaft of the photosensitive medium.

5. The apparatus of claim 1, wherein the second inclination member supports one side of a developing unit comprising the photosensitive medium.

6. The apparatus of claim 1, wherein the second inclination member supports one side of a frame that links and supports a plurality of developing units, which respectively include a photosensitive medium.

7. The apparatus of claim 1, wherein a rise and fall of the photosensitive medium by moving at least one of the first and second inclination member is within 1 mm.

8. An electro-photographic image forming apparatus comprising: at least one photosensitive medium on which an electrostatic latent image is formed by light beam scanning and a toner image is developed by toner supplied to the electrostatic latent image; andan image skew compensating apparatus for compensating for image skew of a toner image transferred onto a paper by inclining the photosensitive medium,wherein the image skew compensating apparatus comprises:a first inclination member comprising a first inclined surface facing upward; anda second inclination member comprising a second inclined surface contacting and facing the first inclined surface,wherein a position of a shaft of the photosensitive medium is adjusted by moving at least one of the first and second inclination members.

9. The apparatus of claim 8, further comprising: a motor; anda screw extended from a rotation axis of the motor and inserted into at least one of the first and second inclination members; andwherein a rotation of the screw moves at least one of the first and second inclination members back and forth according to the rotation direction of the motor.

10. The apparatus of claim 9, wherein the image skew compensating apparatus further comprises: a sensor for sensing an image skew; anda controller for controlling driving of the motor based on signals sensed by the sensor.

11. The apparatus of claim 8, wherein the second inclination member supports the shaft of the photosensitive medium.

12. The apparatus of claim 8, further comprising a developing unit in which the photosensitive medium is installed, wherein the second inclination member supports one side of the developing unit.

13. The apparatus of claim 8, further comprising: a plurality of developing units comprising a plurality of photosensitive mediums, respectively; anda frame for linking and supporting the developing units,wherein the second inclination member supports one side of the frame.

14. The apparatus of claim 8, further comprising: a plurality of photosensitive mediums; anda plurality of the image skew compensating apparatuses corresponding to the number of the photosensitive mediums.

15. The apparatus of claim 8, wherein a toner image developed on the photosensitive medium is directly transferred to paper.

16. The apparatus of claim 8, wherein a toner image developed on the photosensitive medium is transferred to paper via an intermediate transfer medium.

17. The apparatus of claim 8, wherein a rise and fall of the photosensitive medium by moving at least one of the first and second inclination members is within 1 mm.

18. A method of compensating for image skew, the method comprising: sensing image skew of a toner image; andinclining a photosensitive medium onto which a light beam is scanned to correspond to scanning line skew of the light beam.

19. The method of claim 18, wherein the inclining of the photosensitive medium comprising inclining the photosensitive medium to make the skewed scanning line and a longitudinal axis of the photosensitive medium essentially parallel to each other.

20. The method of claim 18, wherein, the inclining of the photosensitive medium comprises inclining a plurality of photosensitive mediums for printing a color image.

21. The image skew compensating apparatus of claim 1 wherein the photosensitive medium onto which a light beam is scanned is inclined to be essentially parallel to a scanning line of the light beam.

22. The method of claim 20, wherein the photosensitive mediums are connected to each other and inclined together to minimize bad color registration.

23. A sensor for sensing an image skew in an image forming apparatus, the sensor comprising: a first light emitting element for emitting a first light onto a first portion of a transfer belt of an image forming apparatus;a second light emitting element for emitting a second light onto a second portion of the transfer belt;a first light sensing element for sensing the first light reflected from the first portion of the transfer belt; anda second light sensing element for sensing the second light reflected from the second portion of the transfer belt;wherein the first portion of the transfer belt is spaced apart from the second portion of the transfer belt in a width direction of the transfer belt, and an output of the first and second light sensing elements comprises at least one of an indication of a skew of an image transferred by the transfer belt and an indication of color registration of the image.

24. The sensor of claim 23, wherein at least on of the first and second light sensing elements comprises a photosensor.

25. The sensor of claim 23, wherein: the first light emitting element and the first light sensing element are positioned approximately in a vicinity of the first portion of the transfer belt;the second light emitting element and the second light sensing element are positioned approximately in a vicinity of the second portion of the transfer belt; andthe first and second portions are at opposite ends of the transfer belt in the width direction of the transfer belt.

26. A method of sensing an image skew in an image forming apparatus, the method comprising: emitting a first light onto a first portion of a transfer belt of an image forming apparatus;emitting a second light onto a second portion of the transfer belt;sensing the first light reflected from the first portion of the transfer belt;sensing the second light reflected from the second portion of the transfer belt, wherein the first portion of the transfer belt is spaced apart from the second portion of the transfer belt in a width direction of the transfer belt; andoutputting based on the first and second sensed reflected light at least one of an indication of a skew of an image transferred by the transfer belt and an indication of color registration of the image.

27. The method of claim 26, wherein at least on of the first and second light sensing elements comprises a photosensor.

28. The method of claim 26, further comprising: positioning the first light emitting element and the first light sensing element approximately in a vicinity of the first portion of the transfer belt; andpositioning the second light emitting element and the second light sensing element approximately in a vicinity of the second portion of the transfer belt;wherein the first and second portions are at opposite ends of the transfer belt in the width direction of the transfer belt.

29. An image skew compensating apparatus for compensating for image skew of a toner image transferred onto an image recording medium, the image skew compensating apparatus comprising: a sensor for sensing an image skew;an inclination adjusting element for changing inclination of a photosensitive element onto which a light beam is scanned; anda controller for controlling the inclination adjusting element based on the image skew sensed by the sensor.

30. The image skew compensating apparatus of claim 29, wherein the inclination adjusting element comprises: a first inclination member comprising a first inclined surface facing upward; anda second inclination member comprising a second inclined surface contacting and facing the first inclined surface,wherein a position of a shaft of the photosensitive medium onto which the light beam is scanned is adjusted by moving at least one of the first and second inclination members.

31. The image skew compensating apparatus of claim 29, wherein the sensor comprises: a first light emitting element for emitting a first light onto a first portion of a transfer belt of an image forming apparatus;a second light emitting element for emitting a second light onto a second portion of the transfer belt;a first light sensing element for sensing the first light reflected from the first portion of the transfer belt; anda second light sensing element for sensing the second light reflected from the second portion of the transfer belt;wherein the first portion of the transfer belt is spaced apart from the second portion of the transfer belt in a width direction of the transfer belt, and an output of the first and second light sensing elements comprises at least one of an indication of a skew of an image transferred by the transfer belt and an indication of color registration of the image.

32. A method for compensating for image skew of a toner image transferred onto an image recording medium, the image skew compensating apparatus comprising: sensing an image skew; andchanging an inclination of a photosensitive element onto which a light beam is scanned based on the sensed image skew.

33. The method of claim 32, wherein the changing of the inclination comprises adjusting a position of a shaft of the photosensitive medium onto which the light beam is scanned.

34. The method of claim 33 wherein the adjusting comprises moving at least one of a first inclination member comprising a first inclined surface facing upward and a second inclination member comprising a second inclined surface contacting and facing the first inclined surface.

35. The method of claim 32, wherein the sensing of the image skew comprises: emitting a first light onto a first portion of a transfer belt of an image forming apparatus;emitting a second light onto a second portion of the transfer belt;sensing the first light reflected from the first portion of the transfer belt; andsensing the second light reflected from the second portion of the transfer belt;wherein the first portion of the transfer belt is spaced apart from the second portion of the transfer belt in a width direction of the transfer belt, and an output of the first and second light sensing elements comprises at least one of an indication of a skew of an image transferred by the transfer belt and an indication of color registration of the image.

36. An image forming apparatus comprising: at least one photosensitive medium on which an electrostatic latent image is formed by light beam scanning and a toner image is developed by toner supplied to the electrostatic latent image; andan image skew compensating apparatus as claimed in claim 29 for compensating for image skew of a toner image transferred onto an image recording medium by inclining the photosensitive medium.

37. An image forming apparatus comprising: a plurality photosensitive mediums on which an electrostatic latent image is formed by light beam scanning and a toner image is developed by toner supplied to the electrostatic latent image;a sensor for sensing an image skew;at least one inclination adjusting element for changing inclination of at least one of the plurality of photosensitive elements onto which a light beam is scanned; anda controller for controlling the inclination of the at least one adjusting element based on the image skew sensed by the sensor.

38. The image forming apparatus of claim 37, further comprising a plurality of inclination adjusting elements for changing inclination of each of the plurality of respective photosensitive elements, wherein the controller controls the inclination of at least one of the plurality of the adjusting elements based on the image skew sensed by the sensor.

39. The image forming apparatus of claim 38, wherein the controller controls the inclination of each of the plurality of the adjusting elements based on the image skew sensed by the sensor.

40. A method for forming and an image by an electro-photographic image forming apparatus, the method comprising: forming an electrostatic latent image on a plurality photosensitive mediums by light beam scanning and developing a toner image by toner supplied to the electrostatic latent image;sensing an image skew; andchanging inclination of at least one of the plurality of photosensitive elements onto which a light beam is scanned based on the sensed image skew.