IMAGE FORMING APPARATUS

Abstract

The present invention is an image forming apparatus containing an image holding body, a developer holding body for holding developer that forms a developer image by being affixed to the electrostatic latent image formed on the image holding body, a transfer unit for transferring the developer image to a medium, a fusion apparatus for fusing the transferred developer image onto the medium, an idle time judgment process section for making a judgment as to whether an idle time, from when printing is completed to when printing is initiated, of the image forming apparatus is long, and a surface potential setting process section for changing and setting a surface potential of the image holding body to a reference value at which fogging is not generated in a case where the idle time is long.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

This invention may take physical form in certain parts and arrangements of parts, a preferred embodiment and method of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof, and wherein:

FIG. 1 is a block diagram showing the controls of the printer according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of the printer according to the first embodiment of the present invention;

FIG. 3 is a diagram showing the change of a fogging level;

FIG. 4A is a diagram showing a condition of the fogging generated on the surface of a photosensitive drum 11;

FIG. 4B is a diagram showing a potential resulting from application of a toner potential on a development roller to a voltage applied to the development roller;

FIG. 5 is a time chart showing the performance of the printer according to the first embodiment of the present invention;

FIG. 6 is a block diagram showing the controls of the printer according to a second embodiment of the present invention;

FIG. 7 is a diagram showing the change of the fogging level after the printer is idle;

FIG. 8 is a time chart showing the performance of the printer according to the second embodiment of the present invention;

FIG. 9 is a block diagram showing the controls of the printer according to a third embodiment of the present invention; and

FIG. 10 is a time chart showing the performance of the printer according to the third embodiment of the present invention.

Claims

1. An image forming apparatus, comprising: an image holding body;a developer holding body for holding developer that forms a developer image by being affixed to an electrostatic latent image formed on said image holding body;a transfer unit for transferring the developer image to a medium;a fusion apparatus for fusing the transferred developer image onto said medium;an idle time judgment process unit for making a judgment as to whether an idle time, from when printing is completed to when printing is initiated, of said image forming apparatus is long; anda surface potential setting process unit for changing and setting a surface potential of said image holding body to a reference value at which fogging is not generated in a case where the idle time is long.

2. The image forming apparatus according to claim 1, further comprising an idle time calculation process unit for calculating the idle time, from when printing is completed to when printing is initiated, of said image forming apparatus, wherein said idle time judgment process unit makes a judgment that the idle time is long in a case where a calculated idle time is greater than a threshold value.

3. The image forming apparatus according to claim 1, wherein said surface potential setting process unit changes the surface potential to the reference value according to a number of printed pages or printing time after the surface potential is changed to the reference value at which fogging is not generated.

4. The image forming apparatus according to claim 1, further comprising a temperature detection unit for detecting a fusion device temperature expressing a temperature of a fusion device and an apparatus surrounding temperature representing a temperature surrounding said image forming apparatus, wherein said idle time judgment process unit makes a judgment that the idle time is long in a case where a temperature difference between the apparatus surrounding temperature and the fusion device temperature is greater than the threshold value.

5. The image forming apparatus according to claim 1, wherein the idle time from when printing is completed to when printing is initiated is a time during which a print job is not received from an upper level apparatus.

6. The image forming apparatus according to claim 1, further comprising a secondary power source for providing power to said image forming apparatus in a case where a main power source is turned off.

7. An image forming apparatus, comprising: an image holding body;a developer holding body for holding developer that forms a developer image by being affixed to an electrostatic latent image formed on said image holding body;a transfer unit for transferring the developer image to a medium;a fusion apparatus for fusing the transferred developer image onto said medium; anda surface potential changing unit for changing the surface potential before the surface potential reaches a point at which fogging is generated.

8. The image forming apparatus according to claim 7, wherein the surface potential changing unit comprises a timer for measuring a time from when printing is completed and a surface potential setting process unit for changing and setting a surface potential of said image holding body to a reference value at which fogging is not generated in a case where the idle time is long.

9. The image forming apparatus according to claim 7, further comprising an idle time calculation process unit for calculating the idle time, from when printing is completed to when printing is initiated, of said image forming apparatus, wherein said idle time judgment process unit makes a judgment that the idle time is long in a case where a calculated idle time is greater than a threshold value.

10. The image forming apparatus according to claim 7, wherein said surface potential setting process unit changes the surface potential to the reference value according to a number of printed pages or printing time after the surface potential is changed to the reference value at which fogging is not generated.

11. The image forming apparatus according to claim 7, further comprising a temperature detection unit for detecting a fusion device temperature expressing a temperature of a fusion device and an apparatus surrounding temperature representing a temperature surrounding said image forming apparatus, wherein said idle time judgment process unit makes a judgment that the idle time is long in a case where a temperature difference between the apparatus surrounding temperature and the fusion device temperature is greater than the threshold value.