JPH0447813B2 - - Google Patents

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.

BACKGROUND 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 photoreceptor have been determined by measuring the charging potential (curve 11), post-exposure potential (curve 12), and residual potential (curve 13) with respect to the number of copying repetitions, as shown in FIG. 1 using, for example, an electrophotographic copying machine. It has been evaluated by obtaining. However, in this case, repetitive fatigue appears as a combination of the effects of the charging method and the static elimination method, making it impossible to extract and analyze fatigue components using only light, and 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 use a photoconductor that can be rotated in one direction, a light source that irradiates light from the front in the direction of rotation of the photoconductor, and a A charger placed in front of the
Using a device equipped with a potential measuring probe placed further ahead at an angle of 30° in this order, while rotating the photoreceptor, charging by the charger, light irradiation by the light irradiation light source, and body measurement by the probe are performed. The potential measurement is started at the same time, and the charged potential of the photoreceptor surface area that has not been irradiated with light and the charged potential of the photoreceptor surface area that has been irradiated with light is measured at the position of the probe, and the difference between these potentials is determined. This can be achieved by using a photofatigue evaluation method for electrophotographic photoreceptors.

The present invention is based on the recognition that the photo-fatigue phenomenon is caused by a decrease in surface potential or an increase in charged potential due to the trapping of carriers that have become free due to light irradiation. 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. Potential measurement probe 5 is located at the front. Although the positions of the charger 3 and the probe 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, when the photoreceptor 1 is rotated and charging by the charger 3 and light irradiation by the light irradiation unit 4 are started simultaneously, 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 surface portion of the photoreceptor that is not irradiated with light and is located at position 6 between the charger 3 and the light irradiation unit 4 before the start of operation, and the low potential portion Reference numeral 32 indicates the potential of the surface portion of the photoreceptor irradiated with the light that has arrived at the position 7 in front of the light emitting section 4 . The difference ΔV between both potentials is used to evaluate optical fatigue. That is, ΔV indicates the number of traps mentioned above, and the larger ΔV is, the greater the optical fatigue is. △
The value of V is determined by the wavelength when the intensity of light irradiation is constant, and by the value of the unirradiated area 6 when the circumferential speed of the photoreceptor is constant.
In general, the smaller the distance of the unirradiated area 6, the larger the value of ΔV. This means that the carrier is released from the trap before it reaches 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, the optical fatigue of general electrophotographic photoreceptors such as Se-based, ZnO, CaS, OPC, amorphous silicon, etc. has been evaluated to improve the property management and development of photoreceptors, PPC copiers,
This can greatly contribute to the development of electrophotographic process control technology such as laser printers and intelligent copying machines.

[Brief explanation of drawings]

FIG. 1 is a potential change curve diagram showing an example of photoconductor fatigue measurement during repeated copying processes using an electrophotographic copying machine, FIG. 2 is a layout diagram showing an example of an apparatus for carrying out the present invention, and FIG. 2 is a potential waveform diagram obtained by the apparatus shown in FIG. 2, and FIG. 4 is a relationship diagram between ΔV shown in FIG. 3 and the elapsed time from light irradiation to charging. 1... Photoreceptor, 3... Charger, 4... Light irradiation section, 5... Potential measurement probe.

Claims (1)

[Claims] 1. A photoreceptor that can be rotated in one direction, a light source that irradiates light from the front in the direction of rotation of the photoreceptor facing the surface of the photoreceptor, a charger placed in front of this light source, and a photoreceptor that emits light from this body electric device. Using a device equipped with, in this order, a potential measuring probe placed further ahead at an angle of 30° with respect to the axis of rotation of the body, charging by the charger and by the light source for light irradiation are performed while rotating the photoreceptor. Light irradiation and charging potential measurement using the probe are started at the same time, and the charging potential of a surface portion of the photoreceptor that has not been irradiated with light and the charging potential of a surface portion of the photosensitive belt that has been irradiated with light is measured at the position of the probe, respectively; A method for evaluating optical fatigue of an electrophotographic photoreceptor, the method comprising determining the difference in potential between them.