JP2019053254A - Inspection apparatus of electrophotographic photoreceptor - Google Patents

Abstract

To provide an inspection apparatus of an electrophotographic photoreceptor configured to improve accuracy of measuring charging characteristics.SOLUTION: An inspection apparatus for inspecting an electrophotographic photoreceptor includes a corona charger for charging the electrophotographic photoreceptor. The corona charger includes a shield case having an opening formed on a surface facing the electrophotographic photoreceptor, a grid electrode arranged in the opening, and three discharge wires arranged at both ends and the center in the shield case. A distance between the central discharge wire of the three discharge wires and the grid electrode is larger than the distances between the grid electrode and the discharge wires arranged at both ends out of the three discharge wires.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inspection apparatus for an electrophotographic photosensitive member.

  An image forming apparatus using an electrophotographic system, that is, an electrophotographic apparatus, is widely used as a copying machine, a facsimile, and a printer. In an electrophotographic apparatus, the surface of an electrophotographic photosensitive member having a photoconductive layer is uniformly charged, and light (image exposure light) corresponding to image information is irradiated by a laser or an LED to thereby surface the electrophotographic photosensitive member. An electrostatic latent image is formed on the surface. The electrostatic latent image is developed with toner to form a toner image, and image formation is performed through a process of transferring the toner image to a recording medium such as paper.

  As an electrophotographic photoreceptor used in an electrophotographic apparatus, a photoconductive layer (hereinafter abbreviated as “a-Si photoconductive layer”) composed of hydrogenated amorphous silicon (hereinafter abbreviated as “a-Si”). An electrophotographic photoreceptor having the following (hereinafter abbreviated as “a-Si photoreceptor”) is known. As a layer structure of the a-Si photosensitive member, a layer structure in which an a-Si photoconductive layer and a surface layer composed of hydrogenated amorphous silicon carbide are stacked is well known. In addition, a layer structure in which an a-Si photoconductive layer and a surface layer made of hydrogenated amorphous carbon are stacked is also known.

  In manufacturing the a-Si photoconductor, a photoconductive layer, a surface layer, and the like are formed, and a manufacturing process for manufacturing the a-Si photoconductor is performed. Then, as the next process, an inspection process for inspecting whether various characteristics of the a-Si photoreceptor are within the allowable range is performed. And what was determined to pass in the inspection process is shipped as a product. In the inspection process, there is a role to prevent those whose characteristics are out of the allowable range (non-standard) from flowing into the market. Furthermore, it is very important for the inspection process to accurately measure the characteristics, feed back to the manufacturing process, and properly manage the manufacturing process in order to produce the characteristics stable at a suitable value. is there.

  An example of the characteristics of the a-Si photosensitive member is uniformity of charging characteristics. In particular, when a corona charger is used as the charging means to cause a negative discharge, unevenness is likely to occur in the discharge state. When a positive voltage is applied to the discharge wire, the supply of electrons to maintain the discharge is performed by the electrons accelerated toward the discharge wire by the electric field being ionized by the α action in the space near the discharge wire. Is called. On the other hand, when a negative voltage is applied to the discharge wire, electrons released by the collision of positive ions with the discharge wire are accelerated toward the counter electrode, causing an α action. That is, since the discharge is maintained by the electrons emitted from the surface of the discharge wire, if dirt is attached to the surface of the discharge wire, it becomes difficult for the electrons to be emitted from the discharge wire, and unevenness is likely to occur in the discharge state. .

  In order to improve such negative discharge unevenness, Patent Document 1 discloses a technique for forming a plurality of discharge wires. Japanese Patent Application Laid-Open No. H10-228561 describes that this technique can sufficiently and uniformly charge even if the peripheral speed of the electrophotographic photosensitive member is increased.

Japanese Patent Laid-Open No. 11-84817

  In recent years, the entry of electrophotographic devices into the light printing market is expected. In the light printing market, it is important to achieve high image quality, and there is an increasing demand for uniform characteristics over electrophotographic photoreceptors. For this reason, the inspection standard for the uniformity of characteristics has become stricter than before, and an increase in accuracy has been required for the measurement accuracy of an inspection apparatus for inspecting an electrophotographic photosensitive member.

  As a result of intensive studies by the present inventors, it is clear that corona charging discharge unevenness is one of the factors that can lower the measurement accuracy when measuring the uniformity of the charging characteristics of the electrophotographic photosensitive member. It has become. That is, it has been found that discharge unevenness remains in the corona charging, and if there is discharge unevenness, it causes variations in the measurement results caused by the measurement system as noise in the measurement system, and decreases the measurement accuracy. For this reason, in order to perform measurement with higher accuracy than before, there is room for further improvement with respect to discharge unevenness of corona charging.

  Patent Document 1 discloses a preferable range of the relationship between the distance from the discharge wire to the grid electrode and the distance from the discharge wire to the shield case in the case of a corona charger having two discharge wires in the shield case. Has been. Patent Document 1 describes that both charging efficiency and discharge unevenness can be achieved by setting the relationship between these distances within a suitable range.

  However, regarding the discharge unevenness, as described above, there is room for further improvement in the case where uniformity with higher accuracy is required. That is, in the case of improving the discharge unevenness by using a plurality of discharge wires, in order to obtain a greatly improved effect, the balance of the discharge current flowing from each discharge wire toward the electrophotographic photosensitive member is considered. Design was important and there was room for further improvement.

  An object of the present invention is to provide an electrophotographic photosensitive member inspection apparatus capable of improving the accuracy of measurement of charging characteristics.

The present invention relates to an inspection apparatus for inspecting an electrophotographic photosensitive member,
The inspection apparatus has a corona charger for charging the electrophotographic photosensitive member,
The corona charger is
A shield case having an opening on a surface facing the electrophotographic photoreceptor;
A grid electrode disposed in the opening;
Three discharge wires disposed at both ends and in the center of the shield case;
Have
The distance between the discharge wire arranged at the center of the three discharge wires and the grid electrode is larger than the distance between the discharge wire arranged at both ends of the three discharge wires and the grid electrode. An inspection apparatus for an electrophotographic photosensitive member.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member inspection apparatus capable of increasing the accuracy of measurement of charging characteristics.

FIG. 3 is a schematic diagram illustrating a configuration example of a corona charger that is preferably used in the electrophotographic photoreceptor inspection apparatus of the present invention. It is a schematic diagram which shows the structural example of the conventional corona charger. FIG. 3 is a vector diagram showing the electric field distribution in the corona charger when corona discharge is generated in the corona charger having the configuration shown in FIG. 2. FIG. 3 is a vector diagram showing the electric field distribution in the corona charger when corona discharge is generated in the corona charger having the configuration shown in FIG. 1. It is a figure showing the measurement result of potential nonuniformity.

  FIG. 1 is a schematic diagram showing a configuration example of a corona charger suitably used in the electrophotographic photoreceptor inspection apparatus of the present invention.

  In the configuration shown in FIG. 1, the shield case 102 has three discharge wires 101 arranged at both ends and in the center. The distance between the discharge wire arranged at the center and the grid electrode 103 is larger than the distance between the discharge wire arranged at both ends and the grid electrode. The shield case 102 has an opening on the surface facing the electrophotographic photosensitive member.

  FIG. 2 is a schematic diagram illustrating a configuration example of a conventional corona charger.

  Also in the configuration shown in FIG. 2, the shield case 202 has three discharge wires 201 arranged at both ends and in the center. However, unlike the configuration shown in FIG. 1, the distances between the three discharge wires 201 and the grid electrode 203 are substantially equal. The shield case 202 also has an opening on the surface facing the electrophotographic photosensitive member.

  FIG. 3 is a vector diagram showing the electric field distribution in the corona charger when corona discharge is generated in the corona charger having the configuration shown in FIG.

  As shown in FIG. 3, from the discharge wires at both ends, there are three directions: a direction toward the grid electrode 203, a direction toward the vertical portion 202 (a) of the shield case 202, and a direction toward the horizontal portion 202 (b). Current flows in the direction. On the other hand, from the central discharge wire, current does not flow in the direction toward the vertical portion 202 (a), but current flows in two directions, the direction toward the grid electrode 203 and the direction toward the horizontal portion 202 (b). Further, the central discharge wire has a symmetric electric field distribution in the direction of FIG. Of the current flowing from the central discharge wire, the current flowing in the horizontal portion 202 (b) direction and the current flowing in the grid electrode 203 direction are substantially equal. On the other hand, since the current flowing from the discharge wires at both ends is directed toward the vertical portion 202 (a), the ratio of the current flowing in the direction of the grid electrode 203 is less than half. For this reason, paying attention to the current flowing into the grid electrode, the current from the center discharge wire is larger than the current from the discharge wires at both ends. Therefore, the influence of the discharge state unevenness caused by the contamination of the discharge wire is most strongly affected by the discharge wire of the central discharge wire.

  FIG. 4 is a vector diagram showing the electric field distribution in the corona charger when corona discharge is generated in the corona charger having the configuration shown in FIG.

  As shown in FIG. 4, the electric field distribution around the central discharge wire is not the vertical target in the direction of FIG. 4. The current flowing from the central discharge wire has a large ratio of flowing in the horizontal portion 102 (b) direction and a small ratio of flowing in the grid electrode 103 direction. For this reason, when attention is paid to the current flowing into the grid electrode, the current flows from each discharge wire more evenly than the electric field distribution shown in FIG. As a result, the influence of the discharge state unevenness caused by the contamination of the discharge wires is almost uniform in the three discharge wires.

  In addition, when four or more discharge wires are arranged, it is possible to obtain a vector diagram of the electric field distribution as described above and adjust the distance of the discharge wires so that the currents flowing from the discharge wires to the grid electrodes are equal. it can. In the present invention, when the number of discharge wires (three or more) is an odd number, a total of two discharge wires located at both ends correspond to the discharge wires disposed at both ends, and 1 located at the center. A single discharge wire corresponds to the discharge wire arranged in the center. In the case of an even number, a total of two discharge wires located at both ends correspond to the discharge wires arranged at both ends, and a total of two discharge wires located at the center are arranged at the center. It corresponds to a discharge wire.

  An electrophotographic photosensitive member inspection apparatus using a corona charger having the configuration shown in FIG. 1 was prepared.

  As for the size of the shield case of the corona charger, the circumferential width of the electrophotographic photosensitive member is 32 mm, and the vertical height of the electrophotographic photosensitive member is 24 mm. Three discharge wires were placed in the shield case. Four corona chargers were prepared in which the distance between the discharge wire and the grid electrode at both ends was 12 mm, and the distance between the center discharge wire and the grid electrode was 12 mm, 13 mm, 14 mm, and 15 mm. The corona charger having a distance of 12 mm between the central discharge wire and the grid electrode is equivalent to the corona charger having the configuration shown in FIG. 2 with the same distance between the three discharge wires and the grid electrode, and is prepared as a comparative example. It is.

  A cylindrical a-Si photosensitive member (an electrophotographic photosensitive member having a photoconductive layer made of hydrogenated amorphous silicon) is arranged as an electrophotographic photosensitive member in the prepared inspection apparatus, and the peripheral speed becomes 500 mm / second. Rotated as follows. The voltage condition of the corona charger was determined so that the surface potential was approximately 500 V, and thereafter the voltage condition of the corona charger was fixed.

  In order to obtain the measurement accuracy when using the four prepared corona chargers, the surface potential of the electrophotographic photosensitive member is measured 10 times on the same day at intervals of 30 minutes or more while replacing the corona charger. did. Furthermore, such measurement was repeated for 5 days, and the measurement was performed 50 times in total.

  The surface potential was sampled with a recorder, and the average value of the rotation cycle time of the electrophotographic photosensitive member was adopted. The standard deviation σ was calculated from the measured surface potential data, and 3σ was taken as the measurement accuracy. The results are shown in Table 1.

  As is apparent from Table 1, the inspection apparatus using the corona charger of the example in which the distance between the center discharge wire and the grid electrode is larger than the distance between the discharge wire and the grid electrode at both ends is the corona charge of the comparative example. The measurement accuracy is higher than the inspection equipment that uses the tester. This is because, by increasing the distance between the central discharge wire and the grid electrode, the ratio of flowing from the central discharge wire toward the grid electrode is reduced, and the current flowing from the three discharge wires into the grid electrode phrase is more even. This is probably because of In other words, it is considered that the influence of the discharge state unevenness caused by the contamination of the discharge wires is almost uniform from the three discharge wires.

  Further, as is clear from Table 1, the distance between the discharge wire arranged at the center and the grid electrode is preferably 1 to 3 mm larger than the distance between the discharge wire arranged at both ends and the grid electrode.

  In order to show the influence of the effect of increasing the measurement accuracy in the actual inspection process, an embodiment for inspecting the uniformity of the charging characteristics, that is, the potential unevenness will be described below.

  FIG. 5 is a diagram illustrating measurement results of potential unevenness.

  As shown in FIG. 5, the potential unevenness is defined by (maximum value−minimum value) in the measured data obtained by measuring the surface potential at a desired position in the axial direction of the electrophotographic photosensitive member. Whether or not the measured potential unevenness is within the allowable range is greatly related to the measurement accuracy.

  For example, when the allowable range is X [V] or less and the measurement accuracy is ± Y [V], if the measured value is (X−2Y) or less, it can be determined as acceptable. Moreover, if it is more than (X + 2Y), it can determine with disqualification.

  However, when the measured value falls within the range of (X−2Y) to (X + 2Y), it is difficult to determine pass / fail only with the measured potential unevenness when considering the measurement accuracy of the inspection device. It becomes necessary to conduct a more precise re-inspection. If the number that requires this re-inspection process becomes too large, it will be a burden on the inspection process in terms of time and man-hours. For this reason, it is preferable that the pass / fail judgment can be made by the first potential unevenness inspection without requiring a re-inspection step as much as possible. Therefore, for 300 a-Si photoconductors produced under the same manufacturing conditions, potential unevenness is inspected using the same inspection apparatus as in the above embodiment, and the pass / fail judgment cannot be made based on the measured potential unevenness data. Table 2 shows the ratios that required the re-inspection process.

  As apparent from Table 2, the inspection apparatus using the corona charger according to the embodiment in which the distance between the center discharge wire and the grid electrode is larger than the distance between the discharge wire and the grid electrode at both ends is as follows. , The rate of requiring a re-inspection process is low. This is presumably because the range required for re-inspection became narrow due to the improvement in measurement accuracy of the first inspection, and the result of the potential measurement itself was stabilized. Thus, if the ratio which requires a re-inspection process can be reduced, the load in an inspection process can be reduced and it leads to big efficiency improvement.

DESCRIPTION OF SYMBOLS 101 Discharge wire 102 Shield case 103 Grid electrode 201 Discharge wire 202 Shield case 203 Grid electrode

Claims (4)

In an inspection apparatus for inspecting an electrophotographic photoreceptor,
The inspection apparatus has a corona charger for charging the electrophotographic photosensitive member,
The corona charger is
A shield case having an opening on a surface facing the electrophotographic photoreceptor;
A grid electrode disposed in the opening;
Three discharge wires disposed at both ends and in the center of the shield case;
Have
The distance between the discharge wire disposed at the center of the three discharge wires and the grid electrode is greater than the distance between the discharge wire disposed at both ends of the three discharge wires and the grid electrode. An inspection apparatus for an electrophotographic photosensitive member.   2. The inspection apparatus for an electrophotographic photosensitive member according to claim 1, wherein the discharge wires disposed in the shield case are only three discharge wires disposed at both ends and the center.   3. The electrophotographic photosensitive member inspection apparatus according to claim 1, wherein the electrophotographic photosensitive member is an electrophotographic photosensitive member having a photoconductive layer made of hydrogenated amorphous silicon.   The distance between the discharge wire arranged at the center and the grid electrode is 1 to 3 mm larger than the distance between the discharge wire arranged at both ends and the grid electrode. Inspection apparatus for electrophotographic photoreceptors.

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