Image forming apparatus which divides image data into a plurality of regions and controls fixing temperature accordingly

1. An image forming apparatus, comprising:

a photoconductor;

an exposing unit configured to expose the photoconductor for forming a latent image on the photoconductor based on image data;

a developing unit configured to develop, by using toner, the latent image;

a transferring unit configured to transfer the image to a sheet;

a fixing unit configured to fix toner image transferred onto the sheet; and

a control unit configured to divide the image data into a plurality of regions in a sub-scanning direction based on an attribute of the sheet, determine a target temperature for each region from a result of analyzing the region, and control a temperature of the fixing unit based on the determined target temperature.

2. The image forming apparatus according to claim 1 , wherein the control unit divides the image data into the plurality of regions in a sub-scanning direction based on a process speed of the image forming apparatus.

3. The image forming apparatus according to claim 1 , wherein the control unit divides the image data into the plurality of regions in a sub-scanning direction based on a distance from the photoconductor to a nip position of the fixing unit.

4. The image forming apparatus according to claim 1 , wherein the control unit divides the image data into the plurality of regions in a sub-scanning direction based on a temperature increase rate of the fixing unit.

5. The image forming apparatus according to claim 1 , wherein the attribute of the sheet includes a length of the sheet associated with the sub-scanning direction for conveyance and types of the sheet.

6. The image forming apparatus according to claim 5 , wherein the types of sheet include thick paper, plain paper, and thin paper.

7. The image forming apparatus according to claim 1 , wherein the control unit completes adjustment of the temperature of the fixing unit before a leading end of each of the regions on the conveyed sheet reaches the nip position of the fixing unit.

8. The image forming apparatus according to claim 1 , wherein the control unit changes a target fixing temperature for the fixing unit in a case where the amount of change in toner application amount between adjacent divided regions is the same or lower than a first threshold value.

9. The image forming apparatus according to claim 1 , wherein the control unit changes a target fixing temperature for the fixing unit in a case where the amount of change in toner application amount is the same or lower than a first threshold value and a total value of the amounts of change of the divided regions are the same or lower than a second threshold value.

10. The image forming apparatus according to claim 9 , wherein the second threshold value is a lower limit value for divided regions.

11. The image forming apparatus according to claim 9 , wherein the control unit starts temperature adjustment control over the fixing unit in a case where an increase amount of the fixing temperature of the fixing unit is larger than a third threshold value and in a case where the total value of the divided regions is not higher than the second threshold value.

12. The image forming apparatus according to claim 1 , wherein the control unit increases the fixing temperature of the fixing unit to a default fixing temperature before image formation is started.

13. The image forming apparatus according to claim 12 , wherein the default fixing temperature is a fixing temperature for a maximum toner application amount.

14. The image forming apparatus according to claim 1 , wherein the developing unit includes developing units configured to develop latent images formed on photoconductors for different colors by using toners of different colors and disposed at predetermined intervals in a conveying direction of the sheet.