Image forming apparatus and layer thickness calculating method

Abstract

An image forming apparatus includes: an image carrier that rotates and carries a toner image by a surface layer disposed on a surface thereof; a charging roll that charges the surface layer while the image carrier completes one or more rotations; a power supply unit that supplies a current to the charging roll; a detector that samples and detects the current that the power supply unit outputs; a leak current detector that detects a leak current included in the current that the detector has detected; a layer thickness calculating unit that calculates a numerical value relating to the thickness of the surface layer on the basis of the current that the detector has detected; and a current leak state determining unit that determines a current leak state on the basis of the current that the detector has detected and the leak current that the leak current detector has detected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a side view showing an image forming apparatus pertaining to the exemplary embodiment of the invention;

FIG. 2 is a block diagram showing the details of an image carrier, a charging roll, and their vicinity;

FIG. 3 is a graph showing three charging current characteristics that a charging current detector has sampled and detected in a state where an eliminator lamp has been switched OFF;

FIG. 4 is a graph showing a leak current that is used in order for a charge amount detector to calculate an accumulated charge amount; and

FIG. 5 is a flowchart showing processing (S10) where the image forming apparatus calculates the thickness of a photoconductor layer.

Claims

1. An image forming apparatus comprising: an image carrier that rotates and carries a toner image by a surface layer disposed on a surface thereof;a charging roll that charges the surface layer of the image carrier while the image carrier completes one or more rotations;a power supply unit that supplies a current to the charging roll;a detector that detects the current that the power supply unit outputs;a leak current detector that detects a leak current included in the current that the detector has detected;a layer thickness calculating unit that calculates a numerical value relating to the thickness of the surface layer of the image carrier on the basis of the current that the detector has detected; anda current leak state determining unit that determines a current leak state on the basis of the current that the detector has detected and the leak current that the leak current detector has detected.

2. The image forming apparatus of claim 1, wherein the layer thickness calculating unit determines whether or not it should calculate the numerical value relating to the thickness of the surface layer in accordance with the determination result of the current leak state determining unit.

3. The image forming apparatus of claim 2, wherein the current leak state determining unit determines the current leak state by comparing a predetermined threshold with the leak current that the leak current detector has detected.

4. The image forming apparatus of claim 3, wherein the current leak state determining unit sets the threshold to be equal to or less than the periodic leak current that the leak current detector has first detected when the leak current that the leak current detector has detected is a periodic leak current that is reproducible.

5. The image forming apparatus of claim 2, wherein the charging roll rotates and charges the surface layer of the image carrier, and the current leak state determining unit determines the current leak state on the basis of the current that the detector has detected in a period of time equal to or greater than any one period of the charging roll or the image carrier whose rotational period is relatively long.

6. The image forming apparatus of claim 3, wherein the current leak state determining unit sets the threshold in accordance with the amount of time during which the leak current flows.

7. The image forming apparatus of claim 3, wherein the detector can detect a combined value of a maximum value of a periodic leak current that is reproducible and a current supplied to the image carrier.

8. The image forming apparatus of claim 3, wherein the current leak state determining unit sets the threshold in accordance with an integrated value of the leak current.

9. The image forming apparatus of claim 3, further comprising a counter that counts the number of rotations of the image carrier, wherein the current leak state determining unit determines the current leak state on the basis of the counting result of the counter.

10. The image forming apparatus of claim 3, further comprising a saturation determining unit that determines whether or not the charge amount of the surface layer is saturated, wherein the current leak state determining unit determines the current leak state on the basis of the determination result of the saturation determining unit.

11. The image forming apparatus of claim 10, wherein the current leak state determining unit determines the current leak state on the basis of the leak current after the charge amount of the surface layer has become saturated.

12. The image forming apparatus of claim 10, wherein the current leak state determining unit determines the current leak state on the basis of the leak current after the charge amount of the surface layer has exceeded 90% of a saturated state.

13. The image forming apparatus of claim 10, wherein when the current leak state determining unit has determined that the layer thickness calculating unit should calculate the numerical value, the layer thickness calculating unit calculates the numerical value relating to the thickness of the surface layer on the basis of the current that the detector has detected until the saturation determining unit determines that the charge amount of the surface layer is saturated, and the leak current that the leak current detector has detected in a period of time of the same length as the period of time when the detector has detected the current after the saturation determining unit has determined that the charge amount of the surface layer is saturated.

14. The image forming apparatus of claim 2, further comprising an information output unit which, when the current leak state determining unit has determined that the layer thickness calculating unit should not calculate the numerical value, outputs information indicating that the detector has detected an abnormal value or that at least any of the image carrier or the charging roll has reached the end of its lifespan.

15. An image forming apparatus comprising: rotatable image carrying means for carrying a toner image by a surface layer disposed on a surface thereof;charging means for charging the surface layer of the image carrying means while the image carrying means completes one or more rotations;a power supply that supplies a current to the charging means;detecting means for detecting the current that the power supply outputs;leak current detecting means for detecting a leak current included in the current that the detecting means has detected;layer thickness calculating means for calculating a numerical value relating to the thickness of the surface layer of the image carrying means on the basis of the current that the detecting means has detected; andcurrent leak state determining means for determining a current leak state on the basis of the current that the detecting means has detected and the leak current that the leak current detecting means has detected.

16. A layer thickness calculating method comprising: while an image carrier that rotates and carries a toner image by a surface layer disposed on its surface completes one or more rotations, charging the surface layer while detecting a current that is supplied in order to charge the surface layer;detecting a leak current included in the detected current;determining a current leak state on the basis of the detected current and the leak current; andcalculating a numerical value relating to the thickness of the surface layer in accordance with the determined current leak state.