System and method for optically detecting media feeding malfunctions in an image forming apparatus

1 . A method for optically detecting media feeding malfunctions in an image forming apparatus, the method comprising:

capturing images of a surface of a sheet of media being transported along a media feeding path as image signals;

processing the image signals of the surface of the sheet of media to detect positional changes of the sheet of media; and

determining that a media feeding malfunction has occurred when the positional changes satisfy a predefined condition.

2 . The method of claim 1 wherein the determining includes determining that the media feeding malfunction has occurred when the positional changes do not correlate with an expected amount of positional changes as a feeding mechanism of the image forming apparatus is commanded to move the sheet of media.

3 . The method of claim 1 wherein the determining includes determining that the media feeding malfunction has occurred when the positional changes include a rotational movement.

4 . The method of claim 1 wherein the determining includes determining that the media feeding malfunction has occurred when the positional changes include a lateral movement, the lateral movement being in a direction perpendicular to the direction of the media feeding path and parallel to the surface of the sheet of media.

5 . The method of claim 1 wherein the determining includes determining that the media feeding malfunction has occurred when the positional changes include a vertical movement in a direction normal to the surface of the sheet of media.

6 . The method of claim 5 wherein the determining further includes detecting optical distortion of light reflected from the surface of the sheet of media to determine whether the positional changes include the vertical movement.

7 . The method of claim 5 wherein the determining further includes determining a shift of a reflected light beam received to capture the image signals with respect to a reference point to determine whether the positional changes include the vertical movement.

8 . The method of claim 5 wherein the determining includes determining the signal strength of said image signals to determine whether the positional changes include the vertical movement.

9 . The method of claim 1 further comprising realigning the sheet of media using the positional changes derived from the image signals to correct the media feeding malfunction.

10 . A system for optically detecting media feeding malfunctions in an image forming apparatus comprising:

an optical movement tracking sensor positioned along a media feeding path to capture images of a surface of a sheet of media, the optical movement tracking sensor including an array of photosensitive elements that captures the images of the surface of the sheet of media as image signals; and

at least one processing circuit operatively connected to the optical movement tracking sensor, the at least one processing circuit being configured to process the image signals to detect positional changes of the sheet of media and to determine that a media feeding malfunction has occurred when the positional changes satisfy a predefined condition.

11 . The system of claim 10 wherein the at least one processing circuit is configured to determine that the media feeding malfunction has occurred when the positional changes do not correlate with an expected amount of positional changes as a feeding mechanism of the image forming apparatus is commanded to move the sheet of media.

12 . The system of claim 10 wherein the at least one processing circuit is configured to determine that the media feeding malfunction has occurred when the positional changes include one of a rotational movement and a lateral movement, the lateral movement being in a direction perpendicular to the direction of the media feeding path and parallel to the surface of the sheet of media.

13 . The system of claim 10 wherein the at least one processing circuit is configured to determine that the media feeding malfunction has occurred when the positional changes include a vertical movement in a direction normal to the surface of the sheet of media.

14 . The system of claim 10 wherein the at least one processing circuit includes a first processing circuit and second processing circuit, the first processing circuit being integrated in the optical movement tracking sensor, the first processing circuit being configured to detect the positional changes of the sheet of media, the second processing circuit being operatively connected to the first processing circuit, the second processing circuit being configured to determine that the media feeding malfunction has occurred when the positional changes satisfy the predefined condition.

15 . The system of claim 10 further comprising a second optical movement tracking sensor positioned along the media feeding path to capture images of a second surface of the sheet of media.

16 . The system of claim 10 further comprising a feeding mechanism to displace the sheet of media along the media feeding path, the feeding mechanism being configured to skew the sheet of media to correct the media feeding malfunction.

17 . The system of claim 16 wherein the feeding mechanism includes a roller having a varying diameter, the roller being connected to a shaft so that the roller can be moved along the length of the shaft to change the effective diameter of the roller to correct the media feeding malfunction.

18 . An image forming apparatus comprising:

a print cartridge to deposit an image forming material onto sheets of media;

a feeding mechanism to move the sheets of media along a media feeding path;

an optical movement tracking sensor positioned along the media feeding path to capture images of a surface of a sheet of media, the optical movement tracking sensor including an array of photosensitive elements that captures the images of the surface of the sheet of media as image signals; and

at least one processing circuit operatively connected to the optical movement tracking sensor, the at least one processing circuit being configured to process the image signals to detect positional changes of the sheet of media and to determine that a media feeding malfunction has occurred when the positional changes satisfy a predefined condition.

19 . The apparatus of claim 17 wherein the at least one processing circuit is configured to determine that the media feeding malfunction has occurred when the positional changes do not correlate with expected positional changes as the feeding mechanism is commanded to move the sheet of media.

20 . The apparatus of claim 17 wherein the at least one processing circuit is configured to determine that the media feeding malfunction has occurred when the positional changes include a vertical movement in a direction normal to the surface of the sheet of media.