Image forming apparatus and image forming method

1. An image forming apparatus comprising:

an image transfer unit that transfers an image to continuous paper provided with a plurality of sprocket holes along a paper length direction on both sides in a paper width direction;

an image fixing unit that fixes the image transported to the continuous paper by the image transfer unit;

a transport unit that includes a plurality of protruding parts inserted into the sprocket holes on both sides in the paper width direction, that is placed downstream in a paper transport direction from the image fixing unit for moving the protruding parts in the paper transport direction, and that transports the continuous paper;

a change unit that changes the spacing between the protruding parts in the paper width direction; and

a control unit that controls drive of the change unit so that the spacing between the protruding parts in the paper width direction becomes narrower than the spacing between the sprocket holes in the continuous paper before image fixing in the paper width direction during image formation processing of the image transfer unit and the image fixing unit,

wherein the control unit sets automatically a change amount for changing the spacing between the protruding parts in the paper width direction in response to the type of the continuous paper.

2. The image forming apparatus as claimed in claim 1 ,

wherein

the control unit sets the change amount for changing the spacing between the protruding parts in the paper width direction in response to a user's input operation.

3. The image forming apparatus as claimed in claim 1 , further comprising:

a post-processing unit that includes a handling unit cutting the continuous paper.

4. The image forming apparatus as claimed in claim 1 , further comprising:

a paper thickness detection unit that detects a thickness of the continuous paper,

wherein

the control unit recognizes the thickness of the continuous paper based on detection result of the paper thickness detection unit.

5. The image forming apparatus as claimed in claim 1 , wherein the image fixing unit uses a flash fixing technique.

6. An image forming method comprising:

transferring an image to continuous paper provided with a plurality of sprocket holes along a paper length direction on both sides in a paper width direction;

fixing the image transported to the continuous paper;

transporting the continuous paper by inserting a plurality of protruding parts into the sprocket holes and moving the plurality of protruding parts;

changing a spacing between the protruding parts in the paper width direction; and

controlling drive of the change unit so that the spacing between the protruding parts in the paper width direction becomes narrower than a spacing between the sprocket holes in the continuous paper before image fixing in the paper width direction during image formation processing,

wherein a change amount for changing the spacing between the protruding parts in the paper width direction is set automatically in response to the type of the continuous paper.

7. The image forming apparatus as claimed in claim 1 ,

wherein the image forming apparatus obtains the type of the transported continuous paper, and

wherein the control unit sets automatically the change amount for changing the spacing between the protruding parts in the paper width direction using the obtained type of the continuous paper.

8. The image forming method as claimed in claim 6 further comprising:

obtaining the type of the transported continuous paper,

wherein the change amount for changing the spacing between the protruding parts in the paper width direction is set automatically using the obtained type of the continuous paper.

9. The image forming apparatus as claimed in claim 7 , wherein the type of the continuous paper is classified according to at least one of a thickness of the continuous paper and a paper quality.

10. The image forming method as claimed in claim 8 , wherein the type of the continuous paper is classified according to at least one of a thickness of the continuous paper and a paper quality.

11. The image forming apparatus as claimed in claim 7 ,

wherein the image forming apparatus stores a control table which comprises a plurality of types of continuous paper in association with a change amount for changing the spacing between the protruding parts in the paper width direction for each of the respective types, and

wherein the control unit sets automatically the change amount for changing the spacing between the protruding parts in the paper width direction by retrieving the change amount associated with the obtained type of the continuous paper from the control table.

12. The image forming method as claimed in claim 8 further comprising:

storing a control table which comprises a plurality of types of continuous paper in association with a change amount for changing the spacing between the protruding parts in the paper width direction for each of the respective types,

wherein the change amount for changing the spacing between the protruding parts in the paper width direction is automatically set by retrieving the change amount associated with the obtained type of the continuous paper from the control table.