JPH0238852A - Deterioration measuring apparatus for photosensitive body - Google Patents

Abstract

PURPOSE:To achieve an accurate replacement of a photosensitive drum by arranging a means for measuring a surface potential of a photosensitive body by a XTOF method comprising an exposure means and a surface potential detection means, a means of analyzing the results thereof and a means of storing the results of analysis. CONSTITUTION:A photosensitive drum 1 is charged with -several hundred V by a corotron 24, rotated and fixed in such a manner that a charging with -several hundred V occurs at the position of a surface potential probe 14. Then, from above the transparent probe 14, the drum is irradiated with a beam light from a semiconductor laser 20 as expanded with a beam expander 21. Attenuation of a surface potential following the laser irradiation is measured with the probe 14 and a surface potential meter 15. Here, a response speed of the potential meter 15 is set to be shorter sufficiently than a running time of a light carrier. A signal from the potential meter 15 is applied to a degree of deterioration calculator 17 to calculate a valve of an attenuation of the surface potential, thereby enabling the learning of a timing of changing the photosensitive drum.

Description

[Detailed Description of the Invention] [(Summary)] Regarding the deterioration measuring device for a functionally separated organic photoreceptor, the degree of deterioration of the photoreceptor can be measured using Xerographic Time-o.
By the f-Flight (abbreviated as X T OF) method,
The purpose is to provide a photoreceptor deterioration measurement device that constantly monitors and accurately determines when to replace the photoreceptor.
The apparatus includes means for measuring the surface potential of the photoreceptor by the RAPHIC Time-Of-Flight method, an analysis means for analyzing the results, and means for accumulating the results of the analysis by the analysis means.

[Industrial application field]

The present invention relates to a deterioration measuring device for a functionally separated organic photoreceptor.

Organic photoreceptors have recently come to be widely used in copying machines and printers. However, as organic photoreceptors are used repeatedly, their photosensitive characteristics deteriorate and print quality deteriorates, so it is necessary to replace the organic photoreceptor. Therefore,
In order to know when to replace the organic photoreceptor, it is necessary to measure photoreceptor deterioration.

[Conventional technology]

A conventional electrophotographic recording device is shown in FIG. The electrophotographic recording device rotates a photosensitive drum 1, charges it with a front charger 2, exposes it with an exposure device 3 to form a latent image, visualizes it with a developer 4, and then transfers the visible image. The transferred image is transferred to a paper 6 by a device 5, and the transferred image is fixed by a fixing device 7 and transferred to a paper tray 8.
to be accommodated.

Further, residual toner on the photosensitive drum 1 is cleaned by a cleaner 9, and static electricity is removed by a static eliminator 10, returning it to the initial state.
repeated again. 11 is a hopper in which paper 6 is set.

[Problem to be solved by the invention]

As the photosensitive drum 1 is repeatedly used, its photosensitive characteristics deteriorate. This occurs because the molecules responsible for charge transport in the organic photoreceptor (abbreviated as OPC) are destroyed by light and the like, resulting in poor charge transport properties.

For this reason, conventional printers and copiers using OPC adopt a method of replacing the OPC after a fixed number of sheets or a method of replacing the OPC when the print quality deteriorates.

However, with the method of replacing the OPC after a fixed number of sheets, there is a problem in determining the number of sheets to be replaced because the OPC deteriorates differently depending on the usage conditions (frequency of use, usage environment, etc.) of the printer or copier.

In addition, replacing the OPC when the print quality deteriorates is a method that eliminates the cause of the print quality deterioration, since the deterioration of the print quality may occur due to conditions other than the OPC, such as development.
It had the disadvantage that it could not be specified only to PCs.

Therefore, in the present invention, the degree of deterioration of the photoreceptor is determined by Xer.

graphic Time-of-Flight(X
It is an object of the present invention to provide a photoreceptor deterioration measuring device that constantly monitors the photoreceptor and accurately determines when to replace the photoreceptor using the TOF method.

[Means to solve the problem]

The above-mentioned problem is caused by the X
OF (Xerographic Time-Of-F
The photosensitive device of the present invention is equipped with a means for measuring the surface potential of the photoreceptor 1 by means of light), an analyzing means 17.18 for analyzing the result, and an accumulating means 19 for accumulating the analysis result by the analyzing means 17.18. The problem is solved by a body deterioration measurement device.

[Effect]

That is, the XTOF method is known as a method for measuring the drift mobility of electrons (or holes) in a high-resistance semiconductor material such as a photoreceptor. Figure 1 shows the principle of the XTOF method. 1 is a photoreceptor, 13 is a light source for an exposure device, 14 is a surface potential probe, and 15 is a surface potential meter.

The photoreceptor 1 whose surface has been negatively (or positively) charged by a corotron is irradiated with light by an exposure light source 13,
Electron-hole pairs are generated in the photoreceptor 1. The generated holes (or electrons) move in the photoreceptor at a speed V (referred to as drift velocity, ■=μE, where μ: drift mobility, E: electric field in the photoreceptor) depending on the material. This movement of holes (or electrons) reduces the surface potential of the photoreceptor. The manner in which the surface potential decreases is measured using the surface potential probe 14 and the surface electrometer 15. At this time, the response speed of the surface potential probe 14 and the surface potential meter 15 must be made sufficiently shorter than the time tr (referred to as traveling time) required for the generated genuine tag (or electrons) to move through the photoreceptor 1. .

When the surface potential is measured under these conditions, a waveform as shown in FIG. 2 is obtained. Initial surface potential ν. is linearly reduced to a potential Vl/□, which is half of vo, by light irradiation, and then begins to decay slowly.

Slope when surface potential attenuates linearly dν/dt 3
It can be expressed as the following equation.

dv / dt = Vo/2tr -----(
1) Here, tr is the hole (or electron) photoreceptor la
At the medium running time, t r = L ”/IJVo --- (2)
(L: film thickness of photoreceptor (m) μ: positive hole or electron) can be expressed as drift mobility (m2/V S )l.

Deterioration of the organic photoreceptor occurs when the charge transport material in the photoreceptor 1 is destroyed by light or the like.

When the charge transport material is damaged, the charge transport properties of the photoreceptor 1 are destroyed, causing a decrease in drift mobility. (1)
, (2) shows that the slope d v / d L of surface potential attenuation by the XTOF method is proportional to the drift mobility μ. Therefore, by measuring dv/dt, the degree of deterioration of the photoreceptor 1 can be determined.

This is the principle of measuring photoreceptor deterioration using the XTOF method. The measurement conditions regarding the response speed of the surface potential probe 14 and surface potential meter 15 in the XTOF method have already been described, but the light source used during measurement must also be set so as to satisfy the following conditions. The exposure light source 13 may be continuous light or pulsed light, but the light power P
(W) is QX)7Pt, /hv≧CV, ---
(3) t is the time it takes for the photocarriers generated by exposure to become equal to the surface charge 1cv0 of the photoreceptor, and this time is set to be sufficiently smaller than the transit time tr of the photocarriers, that is, tp<<t, =L2 /μ■. It is necessary to set it so that ...--(4). These conditions are such that the surface potential decay after exposure becomes a straight line in FIG.

By setting the surface electrometer and the exposure light source as described above, it becomes possible to select the deterioration of the photoreceptor using the XTOF method.

(Example〕 FIG. 3 is a diagram illustrating an embodiment of the present invention.

In FIG. 3, 1 is a photosensitive drum, 14 is a surface potential probe, 15 is a surface electrometer, 17 is a deterioration level calculator, 18 is a comparator, 19 is a memory, 20 is a semiconductor laser, 21 is a beam expander, 23 is an alarm circuit, and 24 is a corotron.

Measuring element 1+[Jt will be described. The photosensitive drum 1 is charged to several hundred square centimeters by the corotron 24, and the photosensitive drum 1 is rotated and fixed so that the position of the surface potential probe # is uniformly charged to a hundred square centimeters.

After that, the beam expander 21 increases the diameter of several mmφ.
The photosensitive drum 1 is irradiated with a beam of light from a semiconductor laser 20 that has been enlarged to a size of 200 mm from above the transparent surface potential probe 14. Attenuation of the surface potential after laser irradiation is measured by a surface potential probe 14 and a surface potentiometer 15. At this time, the response speed of the surface electrometer 15 is set to be sufficiently shorter than the transit time of the optical carrier, and the semiconductor laser light is
(Calculate the attenuation dv/dtO value.

An example of the results measured in this manner is shown in FIG. The figure shows the attenuation of the surface potential in the initial state and the attenuation of the surface potential after printing 20,000 sheets.

It can be seen that the attenuation characteristics of the surface potential are degraded by repeated printing. d determined by the deterioration degree calculator 17
The values of v/dt were 2.5 xlO' 1 xlO' (V/S) at the initial stage and after printing 20,000 sheets, respectively.

Due to the deterioration of the surface potential attenuation of the photosensitive drum 1, the time from exposure to latent image formation becomes longer. If the deterioration progresses, a latent image will not be sufficiently formed during development, resulting in a decrease in print quality. The extent to which the surface potential attenuation characteristics can be allowed to deteriorate is determined by the circumferential speed of the photosensitive drum 1 (that is, the process speed) and the device configuration. When the deterioration progresses beyond the allowable range of deterioration determined by this device,
The slope of the potential decay obtained from the result of the method d v / d
Based on the value of t, a comparator 18 compares the values, and an alarm circuit 23 generates an alarm indicating deterioration of the photoreceptor. Thereby, the photoreceptor 1 can be replaced accurately, and stable printing quality can be maintained.

〔Effect of the invention〕

As described above, according to the present invention, by monitoring the deterioration of the characteristics of the organic photoreceptor drum, it is possible to know when to replace the photoreceptor drum, which was previously impossible to know. Therefore, the photosensitive drum can be replaced accurately, and good printing quality can be maintained.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the XTOF method of the present invention, Fig. 2 is a diagram of measured waveforms of Fig. 1, Fig. 3 is a diagram illustrating an embodiment of the present invention, and Fig. 4 is a diagram of a measurement example of the present invention. , FIG. 5 is a diagram of an electrophotographic recording apparatus to which the present invention is applied, and FIG. 6 is an explanatory diagram of a conventional electrophotographic recording apparatus. In the figure, 1=# is a photoreceptor (photoreceptor drum), 13 is an exposure light source (exposure means), I4 is a surface potential probe, 15 is a surface potential meter, I7 is a deterioration degree calculator, 18 is a comparator, 19 is the memory, 20 is the semiconductor laser, 21 is the beam expander, 23 is the alarm circuit, 7≦Ichihahi row of 7≦Ichihahi row of Torakari Jroa Fujsori Tsuki no %TQF Gakufu Norikuchimine 12 Thousand and one evil 9° 1 Menhama Moguchi Sen 2 T Do (Yago 9

Claims (2)

[Claims] (1) Exposure means (13) and surface potential detection means (14, 1
5) XTOF (Xerographic Ti
Photoreceptor (1a) by me-Of-Flight) method
photoreceptor deterioration measurement comprising means for measuring the surface potential of a photoreceptor, analysis means (17, 18) for analyzing the results, and storage means (19) for accumulating the analysis results by the analysis means (17, 18). Device. (2) Claim (2) characterized in that the photoconductor deterioration measuring device is incorporated into an electrophotographic recording device, and an alarm is generated in response to deterioration of the photoconductor (1) to notify replacement of the photoconductor (1). 1) The photoreceptor deterioration measuring device described in item 1).