Image forming apparatus and method

1. An image forming apparatus comprising:

a rotatable latent image bearer to bear a latent image on its surface;

a charging device to electrically charge the surface of the latent image bearer;

a latent image writing device to write the latent image on the electrically charge surface of the latent image bearer after a charging process of the charging device;

a developing device to develop the latent image borne on the surface of the latent image bearer;

a surface potential detector to detect a potential of the surface of the latent image bearer;

a deterioration determining device to determine a deterioration degree of the latent image bearer based on a potential detected by the surface potential detector;

a counter to count and aggregate the number of pixels output after the latent image bearer is newly used to each of virtually divided regions of the latent image bearer, the virtually divided regions of the latent image bearer defined by virtually dividing the surface of the latent image bearer into multiple regions in a direction perpendicular to a rotating direction of the latent image bearer;

a time value determining device to determine a time value in accordance with a time at which a pixel is output to the virtually divided region, in which the pixel is determined to be outputted recently or outputted relative to a predetermined number of sheets that have been printed; and

an alarm to transmit a message that expiration of the latent image bearer is reached when the deterioration degree of any one of the virtually divided regions reaches or exceeds a prescribed threshold,

wherein the surface potential detector detects a potential of a detecting target region of the virtually divided region,

wherein the deterioration determining device calculates a relative value based on the aggregated number of pixels and the time value per virtually divided region,

the deterioration determining device determining a deterioration degree of the detecting target region of the virtually divided region based on the potential detected by the surface potential detector, and

the deterioration determining device further determining the deterioration degrees of non-detecting target respective regions of the virtually divided regions other than the detecting target region based on the relative values of the non-detecting-target respective regions, the relative value of the detecting target region, and the deterioration degree of the detecting target region.

2. An image forming apparatus comprising:

a rotatable latent image bearer to bear a latent image on its surface;

a charging device to electrically charge the surface of the latent image bearer;

a latent image writing device to write the latent image on the electrically charge surface of the latent image bearer after a charging process of the charging device;

a developing device to develop the latent image borne on the surface of the latent image bearer;

a surface potential detector to detect a potential of the surface of the latent image bearer;

a deterioration determining device to determine a deterioration degree of the latent image bearer based on a potential detected by the surface potential detector;

a counter to count and aggregate the number of pixels output after the latent image bearer is newly used to each of virtually divided regions of the latent image bearer, the virtually divided regions of the latent image bearer defined by virtually dividing the surface of the latent image bearer into multiple regions in a direction perpendicular to a rotating direction of the latent image bearer; and

a time value determining device to determine a time value in accordance with a time at which a pixel is output to the virtually divided region, in which the pixel is determined to be outputted recently or outputted relative to a predetermined number of sheets that have been printed;

an equalizing orientation determining device to determine whether or not the deterioration degrees of the virtually divided respective regions can be substantially equalized by changing an orientation of the next image after counting the numbers of pixels of the next image output to the virtually divided respective regions when the next image is formed on the surface of the latent image bearer in a normal orientation based on image information; and

an alarm to transmit a message that expiration of the latent image bearer is reached when the deterioration degree of any one of the virtually divided regions reaches or exceeds a prescribed threshold,

wherein the surface potential detector detects a potential of a detecting target region of the virtually divided region,

wherein the deterioration determining device calculates a relative value based on the aggregated number of pixels and the time value per virtually divided region,

the deterioration determining device determining a deterioration degree of the detecting target region of the virtually divided region based on the potential detected by the surface potential detector,

the deterioration determining device further determining the deterioration degrees of non-detecting target respective regions of the virtually divided regions other than the detecting target region based on the relative values of the non-detecting-target respective regions, the relative value of the detecting target region, and the deterioration degree of the detecting target region,

wherein the latent image writing device writes a latent image onto the image bearer with its orientation being changed when the equalizing orientation determining device has determined that the deterioration degrees of the virtually divided respective regions can be substantially equalized by changing the orientation of the next image, and

wherein the counter counts the numbers of pixels of the orientation changed next image output to the virtually divided respective regions when the orientation of the latent image is changed.

3. A method of forming an image comprising the steps of:

bearing a latent image on a surface of a rotatable latent image bearer;

electrically charging the surface of the latent image bearer;

writing the latent image on the electrically charge surface of the latent image bearer after charging thereof;

developing the latent image borne on the surface of the latent image bearer;

detecting a potential of the surface of the latent image bearer;

determining a deterioration degree of the latent image bearer based on a detected potential;

counting and aggregating the number of pixels output after the latent image bearer is newly used to each of virtually divided regions, the virtually divided regions of the latent image bearer defined by virtually dividing the surface of the latent image bearer into multiple regions in a direction perpendicular to a rotating direction of the latent image bearer;

determining a time value in accordance with a time at which a pixel is output to the virtually divided region, in which the pixel is determined to be outputted recently or outputted relative to a predetermined number of sheets that have been printed;

detecting a potential of a detecting target region;

calculating a relative value based on the aggregated number of pixels and the time value per virtually divided region;

determining a deterioration degree of the detecting target region based on the potential detected by the surface potential detector;

determining deterioration degrees of non-detecting-target respective regions other than the detecting target region based on the relative values of the non-detecting-target respective regions, the relative value of the detecting target region, and the deterioration degree of the detecting target region; and

transmitting a message that expiration of the latent image bearer is reached when the deterioration degree of any one of the virtually divided regions reaches or exceeds a prescribed threshold.

4. A method of forming an image comprising the steps of:

bearing a latent image on a surface of a rotatable latent image bearer;

electrically charging the surface of the latent image bearer;

writing the latent image on the electrically charge surface of the latent image bearer after charging thereof;

developing the latent image borne on the surface of the latent image bearer;

detecting a potential of the surface of the latent image bearer;

determining a deterioration degree of the latent image bearer based on a detected potential;

counting and aggregating the number of pixels output after the latent image bearer is newly used to each of virtually divided regions, the virtually divided regions of the latent image bearer defined by virtually dividing the surface of the latent image bearer into multiple regions in a direction perpendicular to a rotating direction of the latent image bearer;

determining a time value in accordance with a time at which a pixel is output to the virtually divided region, in which the pixel is determined to be outputted recently or outputted relative to a predetermined number of sheets that have been printed;

detecting a potential of a detecting target region;

calculating a relative value based on the aggregated number of pixels and the time value per virtually divided region;

determining a deterioration degree of the detecting target region based on the potential detected by the surface potential detector; and

determining deterioration degrees of non-detecting-target respective regions other than the detecting target region based on the relative values of the non-detecting-target respective regions, the relative value of the detecting target region, and the deterioration degree of the detecting target region;

determining whether or not the deterioration degrees of the virtually divided respective regions can be substantially equalized by changing an orientation of the next image after counting the numbers of pixels of the next image output to the virtually divided respective regions when the next image is formed on the surface of the latent image bearer in a normal orientation based on image information;

writing a latent image onto the image bearer with its orientation being changed when it is determined that the deterioration degrees of the virtually divided respective regions can be substantially equalized by changing the orientation of the next mage;

counting the numbers of pixels of the orientation changed image output to the virtually divided respective regions when the orientation of the latent image is changed; and

transmitting a message that expiration of the latent image bearer is reached when the deterioration degree of any one of the virtually divided regions reaches or exceeds a prescribed threshold.