JPS5848067A - Electrophotographic method - Google Patents

Abstract

PURPOSE:To prevent the change in image density according to a change in the potential of a photoreceptor by regulating the charging current for the photoreceptor separately in the initial period of copying cycles and succeeding period. CONSTITUTION:In the initial cycle of copying for the 1st sheet or the like, the charging current for a photoreceptor is kept at a constant value, and in the copying cycle for the 2nd and succeeding sheets, said current is regulated separately by which the charging current is changed exponential-functionally. By said regulation the potential of the photoreceptor after the rese is kept constant and the generation of the change in the image density according to the change in the potential of the photoreceptor is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an image fi! This is about how to prevent change.

When there is a rise (or fall) in a copy image at once, the following method is used.

■If the change in image exposure is weak at first and becomes more difficult as the number of copies increases, then the light intensity should be adjusted to a low level and more frequently depending on the number of copies. Conversely, if the change is from light to light, the exposure amount is changed from strong to weak.

■One-shoulder image of the amount of fireflies f#L If the equation is from light to rocky, change the amount of charge from strong to weak. Conversely, if the change is from carpet to light, the amount of charge is changed from weak to strong.

In any of the above methods, the amount of change is adjusted using charging and discharging using a capacitor or resistor so that it changes exponentially over an hour.

However, the following drawbacks were encountered in the preparation method using the above method.

1) Changes in image density during copying, that is, changes in the position of the photoreceptor, do not match the exponential decay curve, especially in the early stages of copying.

When a February function attenuation curve is used, the amount of attenuation becomes large especially in the early stages of copying, and a single difference appears between the leading edge and the trailing edge within the same copy.

The present invention eliminates the above-mentioned drawbacks, and at the same time efficiently suppresses changes in image quality during continuous copying.

The purpose is to reduce density differences within the same copy as much as possible.

FIG. 1 is a graph showing an embodiment of the present invention. The horizontal axis is the number of copies, and the vertical axis is the number of copies per image.
This shows an example of using changes in accent. In this embodiment, separate fA* means are used at the beginning of the copy cycle and thereafter.

The first copy is charged with a constant 'd current, and the second and subsequent copies are charged with an exponentially attenuated charging current.

When the image changes once, the next surface potential on the photoreceptor is
It changes over time as shown in the figure. In an attempt to correct this change, when the charging '1FG flow is adjusted as shown in FIG. 6 (0) or (b), the surface potential becomes as shown in FIG. 4 (() or ←). Looking at this, it can be seen that the potential on the second and subsequent sheets is almost constant, but the potential on the first sheet is not corrected. In the adjustment shown in Figure 6 0), the correction is too effective and the density of the first copy becomes too dark, as shown in the Figure 4 0) curve. Also, even within the same copy, the identity changes between the first half and the second half. In addition, if you try to prevent this by adjusting the correction in Figure 6 ←) to reduce the correction in the first image, the curve in Figure 4 (B)
The 911th image will be under-corrected as shown below. This is because the position '1' on the surface of the photoreceptor is not completely exponential, and the deviation from the exponential function is large, especially at the beginning of the copy cycle.

In the embodiment of the present invention shown in FIG. 1, in order to prevent this drawback, the charging current for the first sheet was adjusted to be a constant current independent of the exponential decay curves for the second and subsequent sheets. The sharpening of the narrow surface potential at this time is shown in the curve (・) in Figure 4,
Image fluctuations, which are a practical problem, are completely corrected.

Embodiment 2 Adjustment of the change in image quality was performed using −
This can be corrected by sharpening the image light.

FIG. 5 shows changes in the lighting pressure of the halogen lamp for exposure. In this case as well, the first sheet was a constant voltage, and the second and subsequent sheets were corrected by exponential changes. .

Similar to the 4-stream correction, the 9-image acidification had no practical problems.

In addition to the above-mentioned image density change prevention means, front light intensity, moderate image bias, etc. can also be used.

In the embodiment, the initial copy cycle is for the first copy, but it can also be used for the initial copy cycle for a plurality of copies. It is also possible to set the initial stage to be an exponential change having a time constant different from the subsequent exponential change instead of a constant current or constant voltage.

As described above, the present invention provides two independent means at the beginning of the copy cycle and at the end thereof.
There is an effect that the change in image density can be reduced to '4=A degree, which poses no problem in practice.

[Brief explanation of the drawing]

Figure 1 shows the correction curve of the present invention using band current. Figure 2 shows the potential fluctuation curve of the photoreceptor, Figure 3 (a) and (b).
4 is a corrected potential curve of the photoreceptor, and FIG. 5 is a correction curve of the present invention based on exposure amount. ”*w Yaretsu@baku Yayotei Yayaaki to Chise Reef

Claims (1)

[Claims] (1) In a method for preventing potential changes at the time of rising or falling of a photosensitive plate, the aI4 adjustment means in the initial copy cycle and the adjustment means after the initial copy cycle and after the initial copy cycle are independently provided. An electrophotographic method characterized by the following. (2. In claim 111, the initial adjustment is constant for each copy cycle over time,
An electrophotographic method characterized by an exponential change over time from the initial stage to the later stage. (3) An electrophotographic method characterized in that the adjustment means in claim ILL is a means for distorting the amount of charge applied to the photoreceptor. (4) An electrophotographic method characterized in that the first means in claim 11 is a means for adjusting the amount of exposure given to the photoreceptor.