JPH03129364A - Method for correcting deterioration of photosensitive body with time - Google Patents

Abstract

PURPOSE:To exactly correct the deterioration of the photosensitive body with time by measuring the accumulated revolving speed of the photosensitive body and correcting the conditions for forming images by the quantity which is preset with respect to the respective accumulated revolving speeds at every passage of the set specified revolving speed. CONSTITUTION:The accumulated revolving speed of the photosensitive body is measured and the conditions for forming images are corrected by the quantity which is preset with respect to the respective accumulated revolving speeds at every time when the accumulated revolving speed passes the preset specified revolving speed. Namely, the accumulated revolving speed of the photosensitive body is corrected by the preset quantity for each of the specified revolving speeds of the photosensitive body, by which the same correction of the image forming conditions is executed with the accumulated revolving speed of the same photosensitive body regardless of whether the continuous image formation is frequent or the image formation of a small number of sheets, such as one sheet or two sheets, is frequent in the form of the copying or printing to the attainment of the above-mentioned accumulated revolving speed. The exact correction is executed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the aging of a photoconductor of an image forming apparatus that records a toner image formed on a photoconductor by an electrostatic photographic process and transfers it to a transfer paper. This invention relates to a deterioration correction method.

In image forming apparatuses that use an electrophotographic process, such as electrophotographic copying machines, facsimile machines, and electrostatic printers, the toner image formed on the photoreceptor through the processes of charging, exposure, and development is transferred to a transfer paper. The image is transferred to and recorded. The toner remaining on the photoreceptor after transfer is cleaned in a cleaning process.
Residual charges are removed by the charge removal step in preparation for the next image formation.

As the photoreceptor undergoes the above image forming processes repeatedly, it suffers from various failures, such as electrostatic fatigue, wear, and adhesion of toner and other foreign matter to the surface, resulting in deterioration of the surface charging characteristics that the photoreceptor originally has. This occurs, resulting in a decrease in the density of the recorded image and background fogging (background staining).

Conventionally, as a means of correcting this, the surface potential of a charged photoreceptor is measured every time a certain number of images are formed, and the amount of deviation from the initial setting value is read, and the charging conditions, exposure conditions, and current conditions are determined. A method has been adopted in which the development potential is kept constant by changing image forming conditions such as bias.

The second method directly measures the surface potential of the photoreceptor, so if the potential is accurately measured, the accuracy of the correction is good, but on the other hand, the measurement area is very small. If toner or other foreign substances adhere to or are scratched, the surface WJ potential as a whole cannot be accurately captured, and there is a possibility that incorrect correction will be performed. In order to prevent this, it is possible to measure the potential at several locations and exclude abnormal values, but this would complicate the equipment and operation, increase costs, and is not suitable for so-called low-end machines (minimum machine H). Not suitable.

As an alternative to the above method, a method for correcting the deterioration of the photoreceptor over time is to detect the cumulative number of imaged sheets used on the photoreceptor, and change the charging condition, exposure condition, A method has been proposed in which one or a combination of two or more of image forming conditions such as image bias is corrected in accordance with a preset setting.

However, with this method, even if the cumulative number of sheets is the same, the cost of image formation is ¥! Mr. A: In other words, the cumulative rotation of the photoconductor depends on whether you have made many copies or prints in a row, or whether you have made a small number of copies or prints such as 1, 2, or 3 copies. There is a large difference in the number of rotations, and this cumulative number of rotations causes a difference in the fatigue of the photoconductor, so it is not possible to make a sufficiently appropriate correction.The reason is that fatigue of the photoconductor is caused by the rotation of the photoconductor This is because when you are there, you are suffering from a disability. This point is important for low-end machines, especially printers, because they are rarely used continuously and often print in small numbers of one to three sheets.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of conventionally implemented or proposed methods for correcting photoreceptor deterioration over time, the present invention provides a correction method capable of accurately correcting photoreceptor deterioration over time. The task is to provide a method.

In order to solve the above-mentioned problem, the photoconductor aging correction method of the present invention, which is described in t. The present invention is characterized in that the image forming conditions are corrected by a preset amount for each cumulative number of rotations each time.

As mentioned above, since the cumulative number of rotations is corrected by a preset amount every time the photoreceptor rotates a certain number of times, the number of copies or prints that have reached that cumulative number of rotations is consecutive. Regardless of whether many images were created or only one or two images were created, the same image forming conditions are corrected for the same cumulative number of rotations of the photoreceptor, so relatively accurate corrections are made. It turns out.

Furthermore, the correction can be easily performed without the need to measure the surface potential of the photoreceptor or to perform difficult process control.

Embodiments of the present invention will now be described in detail based on the drawings.

Figure 1 is a diagram showing an example of the change in surface potential over time when a photoreceptor is actually used repeatedly. Figures (a) and (b) are for the case where V does not change over time and only VL changes, and when (a) figures are printed continuously, (b) figures are printed one at a time. This is the curve when printed. ] When printing one sheet at a time, the change in VL is larger with respect to the number of prints. (c)
In the case shown in the figure, both VD and VL change.

In this figure, the curve ■ is for continuous printing, and the curve ■ is for 1
In the case of printing one sheet at a time, the changes over time in VD and VL are larger in the case of printing one sheet at a time.

Figure 3 shows the relationship between the number of sheets used and the cumulative number of rotations of the photoconductor.
These are examples, where A represents a continuous print and B represents a single print. In addition, curves A and B
is V = 36 using equations (a) and (c) shown below.
m+a/m, D=40mm.

It was calculated as follows: T = 10 crowns, Tt = 22.2.

1) Linear speed of photoconductor: V (drum) 2) Diameter of photoconductor drum: D (shima) 3) Printing time per sheet When printing continuously: Ta (see) When printing 1 sheet: T1 (see) 4) Cumulative number of rotations of photoconductor
:n 5) Number of prints 2N When printing one sheet at a time When printing continuously When printing NA sheets continuously in one printing operation, and repeating this to print a total of N sheets FIG. 7 is a diagram showing the surface potential of a photoconductor when the potential of the photoconductor and/or the development bias are changed every fixed number of times with respect to the cumulative number of rotations to keep the development potential approximately constant.

Figure 2 (a>, (b) shows the case of so-called reversal development in which toner is attached to the exposed area of the photoreceptor.The toner adhesion to the photoreceptor in reversal development is Vi, Vs.
Since it is determined by the development potential expressed by , stabilizing the image (i density) consists in maintaining this development potential.

Figure 2 (a) shows the case where VB is changed so that the cumulative number of rotations of the photoconductor becomes IOK rotation (10,000 rotations) in response to a change in VL, and Figure 2 (b) shows the case where VB is The amount of light from the exposure light source is made variable in order to change the VL while keeping it fixed.

Figure 2 (c) shows the case where both VD and vL are corrected, VL is the same as above, ■ is a charger, and in this case a scorotron charger is used, so the grid voltage can be varied. Let's do it.

The amount of correction of the image forming conditions for the cumulative number of rotations of the photoreceptor according to the correction method of the present invention can be set from the countries shown in FIG. 2 described above.

As a means for detecting the cumulative number of rotations of the photoreceptor, a microswitch or an optical switching element can be used.

The image forming conditions to be changed for correction are not limited to those mentioned above, and the deterioration curve of the photoreceptor to be used should be checked in advance to determine variable conditions and cumulative rotation speed suitable for that photoreceptor. This enables appropriate correction.

As mentioned above, according to the correction method of the present invention, it does not matter whether the 0 image formation mode is continuous or a small number of prints such as one print, and there is no need for difficult process control. A relatively stable image, particularly an image that is appropriate in terms of image density and background smudge, can be maintained for a long time.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (c) are curve diagrams showing examples of changes in exposed area potential, non-exposed area potential, and development bias potential with respect to the cumulative number of prints of the photoreceptor; FIG. 2(a), (b),
(C) is a curve diagram showing an example of the image forming condition correction amount with respect to the cumulative number of rotations of the photoreceptor, and FIG. 3 is a curve diagram showing an example of the relationship between the cumulative number of prints and the cumulative number of rotations of the photoreceptor. ￥1 Figures not printed (lawn diagram)

Claims (1)

[Scope of Claim] A method for correcting aging deterioration of a photoconductor of an image forming apparatus in which a toner image formed on a photoconductor is transferred to a transfer paper through a series of image forming processes for recording, comprising: cumulative rotation of the photoconductor; A correction method comprising: measuring the number of rotations, and correcting the image forming conditions by a preset amount for each cumulative rotation number each time the cumulative rotation number passes a predetermined number of times.