JPS5971077A - Evaluation of light fatigue of photoreceptor for electronic photography - Google Patents

Abstract

PURPOSE:To evaluate light fatigue for dependence on a wavelength, dependence on the intensity of irradiated light and a light fatigue recovering characteristic simply and accurately by extracting a light component existing among fatigue at repetition by the difference of the charge potential between an unirradiated part and an irradiated part of light. CONSTITUTION:A cylindrical pootoreceptor 1 is rotated in the direction of the arrow 2. The positions of an electrostatic charger 3 and a potential measuring probe 5 are fixed to make an angle of 30 deg. but a light irradiating part 4 is variable. When the photoreceptor 1 is rotated, and an electrostatic charging 3 and light irradiation 4 are started simultaneously, a potential waveform is obtained by the probe 5. Out of this, an initial high potential part 31 is the potential of the unirradiated part positioned between the electrostatic charger 3 and the irradiated part 4 before starting operation, and low potential part 32 is potential of the irradiated part which was positioned at the position 7 in front of the irradiated part 4. The light fatigue is evaluated by the difference DELTAV between the two potentials. The larger is the DELTAV, the larger is the light fatigue.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for quantitatively evaluating the degree of optical fatigue that occurs when an electrophotographic photoreceptor undergoes repeated electrophotographic processes.

2. Description of the Related Art Electrophotographic photoreceptors used in copiers, printers, and the like have their surfaces charged by a charger in an electrophotographic process, and then a photoelectric effect caused by exposure forms surface charges in exposed areas to provide a latent image. Thereafter, a developing device performs development, and a transfer device transfers the developed image onto paper. Finally, the residual potential on the surface of the photoreceptor is neutralized to a level close to zero for the next process. This type of static elimination includes optical static elimination, AC corona static elimination, and DC corona static elimination.

If the above process is repeated, the photoreceptor tends to undergo fatigue phenomena such as a decrease in surface potential after charging and an increase in residual potential. One of the causes of this fatigue phenomenon is optical fatigue caused by light irradiation on the photoreceptor, such as exposure and photostatic discharge. Quantitative evaluation of such optical fatigue is necessary for property management technology or electrophotographic process control technology to improve the reliability of photoreceptors. Conventionally, the fatigue characteristics of a photoconductor have been determined by first measuring them using, for example, an electrophotographic copying machine.
Charging potential versus number of copying repetitions as shown in the figure (curve 1
1), Post-exposure potential (curve 12), residual potential (curve 13)
You can evaluate it by getting '#,,. However, in this case, repeated fatigue appears as a combination of the effects of the charging method and the static elimination method, so it is impossible to extract and analyze the fatigue component using only light, and there are also problems with measurement accuracy and reproducibility. There is.

In contrast, it is an object of the present invention to easily and accurately evaluate the fatigue component caused by light alone, and to utilize this method in techniques for managing characteristics of photoreceptors and in reducing fatigue in electrophotographic processes.

The purpose of this is to sequentially arrange a light source for light irradiation, a charger, and a potential measurement probe in the direction of movement facing the surface of the photoreceptor that moves in one direction, and to position the probe between the light source and the charger at the beginning of light irradiation. This is achieved by evaluating optical fatigue based on the difference in charging potential between the surface of the photoreceptor that is not irradiated and the surface of the photoreceptor that is located on the side opposite the charger of the light source and is irradiated with light.

The present invention is based on the recognition that the photo-fatigue phenomenon occurs when carriers freed by light irradiation are trapped, resulting in a decrease in surface potential or an increase in charged potential. It evaluates light fatigue based on the number.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, a cylindrical photoreceptor 1 is rotatable in the direction of the arrow 2, a corona charger 3 is disposed opposite to the surface thereof, and a light irradiation section from a light source (not shown) is placed in front of the photoreceptor in the rotational direction. 4. A potential measuring probe 5 is located at the front. Although the positions of the charger 3 and the globe 5 are fixed and form an angle of 30° with respect to the rotation axis of the photoreceptor 1 in the figure, the position of the light irradiation section 4 is variable. Using this device, photoreceptor 1
When the probe 5 rotates and simultaneously starts charging by the charger 3 and irradiating light by the light irradiator 4, a potential waveform shown in FIG. 3 is obtained by the probe 5. The first high-potential portion 31 of this waveform is the potential of the photoconductor surface portion irradiated with light, which was located at position 6 between the charger 3 and the light emitting unit 40 before the start of operation, and the low-potential portion 32 is the potential of the surface portion of the photoreceptor that is irradiated with light at a position 7 in front of the light emitting section 4. The difference ΔV between these potentials is used to evaluate optical fatigue. That is,
ΔV indicates the number of traps mentioned above, and the larger Δ■, the greater the optical fatigue. The value of △V depends on the wavelength when the intensity of light irradiation is constant, and on the distance of the light irradiation part 6 when the circumferential speed of the photoreceptor is constant, and generally depends on the distance of the light irradiation part 6. The smaller the value, the larger the value of Δ■. This means that carriers are released from the traps before reaching the charger 3 after irradiation with light. Therefore, by sequentially moving the position of the light irradiation unit 4 and changing the elapsed time after light irradiation to obtain the curve shown in FIG. 4, the recovery characteristics of optical fatigue can be determined.

As described above, the present invention allows the light-based component of the fatigue phenomenon during repeated electrophotographic processes to be easily extracted using only the difference in charging potential between the non-irradiated area and the irradiated area. be. This makes it possible to easily and accurately evaluate the wavelength dependence of photofatigue, the dependence of irradiation light intensity, and the photofatigue recovery characteristics. Therefore, Se-based I Zn0j Cas, op
c l Evaluate the optical fatigue of general electrophotographic photoreceptors such as amorphous silicon to manage and develop photoreceptor characteristics.
It can greatly contribute to the development of electrophotographic process control technology such as RPC copiers, laser printers, and intelligent copiers.

[Brief explanation of the drawing]

FIG. 1 is a potential change curve diagram showing an example of photoconductor fatigue measurement during repetition of the copying process by an electrophotographic copying machine;
FIG. 2 is a layout diagram showing an example of an apparatus for carrying out the present invention, and FIG. 3 is a potential waveform diagram obtained by the apparatus shown in FIG.
Figure 4 is a relationship diagram 1 between △V in Figure 3 and the elapsed time from light irradiation to charging. Measurement probe○

Claims (1)

[Claims] 1) A light source for light irradiation, a charger, and an i-position measurement probe are placed in sequence in the direction of movement facing the surface of a photoreceptor that moves in one direction, and when light irradiation starts, it is positioned between the light source and the charger to A photoreceptor for electrophotography, characterized in that optical fatigue is evaluated based on the difference in charging potential between the surface of the photoreceptor that is not irradiated and the surface of the photoreceptor that is located on the opposite side of the charger of the light source and is irradiated with light. photo fatigue evaluation method.