JPH09325169A - Low dielectric strength defect inspecting instrument, conductive roller for inspection and inspection method for electrophotographic photoreceptor body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspecting instrument and method for inspecting a low dielectric strength defect existing in a photosensitive layer of an electrophotographic photoreceptor body. SOLUTION: A low dielectric strength defect inspecting instrument of an electropotographic photosensitive body has a conductive roller 3 which has a conductive shaft piercing a cylindrical roller consisting of a ground layer comprising a foaming body made of ethylene-propylene based rubber or polyurethane based rubber containing a conductive application agent and a cover layer comprising ethylene-propylene based rubber or polyurethane based rubber containing a conductive application agent, drive means 5, 6 and 7 to drive and rotate an electrophotographic photoreceptor drum 4, a high voltage power source 8 to apply a voltage between the electrophotographic photoreceptor drum 4 and the conductive roller 3 and a measuring device 9 to monitor a current flowing between the electrphotographic photoreceptor drum 4 and the conductive roller 3. The instrument thus obtained is used to monitor the current flowing between the conductive roller 3 and the electrophotographic photoreceptor drum 4, thereby enabling detecting of a lower dielectric strength defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and an inspection method for inspecting a low withstand voltage defect existing in a photoconductor layer of an electrophotographic photoconductor.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic photosensitive member used in an electrophotographic apparatus such as a copying machine or a printer, an undercoat layer is formed on a conductive substrate, and a charge generating layer and a charge transporting layer are sequentially formed as photosensitive layers. Laminates are known, and these electrophotographic photoreceptors are coated with a coating solution for forming each layer, that is, a photosensitive layer is prepared by dissolving or dispersing an organic photoconductive material together with a binder resin. Make a body coating solution,
It is manufactured by sequentially coating the coating solution on a conductive substrate and drying. In such an electrophotographic photoreceptor,
There are various defects that cannot be avoided due to the manufacturing method. For example, substrate protrusions such as minute protrusions existing on the conductive substrate or adhered foreign substances when subjected to interference fringe prevention processing, foreign substances adhered during transportation during the coating process, and There are coating defects caused by foreign matters, and external surface defects such as scratches and dents generated during conveyance during the coating process.

On the other hand, it is known that such an electrophotographic photosensitive member is charged by a charger as one step for obtaining an image in an electrophotographic apparatus. As the charger, a non-contact charger such as a corotron or a scorotron, or a BCR (Bias Cha) that has been widely used in recent years
A common type is a contact type charger such as the Rge Roll). In an electrophotographic apparatus, an electrophotographic photosensitive member having defects on the base material or surface as described above is
As a problem that occurs when used in combination with such a contact type charger, there is a problem of charge leakage. This is a phenomenon that occurs when the insulation resistance is low at the defective portion of the electrophotographic photosensitive member, and spark discharge occurs due to the resistance change due to the defect, resulting in image quality defects. In addition, once this phenomenon occurs, damage to the surface of the electrophotographic photosensitive member and the surface of the contact type charger is continuously given,
The range of image quality defects expands, causing a serious problem in image quality. This phenomenon is called dielectric breakdown, and the defect that causes it is called a "low breakdown voltage defect" here. Therefore, in the manufacturing process of an electrophotographic photosensitive member used in combination with a contact type charger such as a BCR in an electrophotographic apparatus, it is indispensable to inspect all of these low dielectric strength defects.

There are roughly three types of causes of low withstand voltage defects. That is, coating film pinhole defects,
There are three types of foreign matter defects in the layer and substrate defects. Diagrams schematically showing these defects are shown in FIGS. 6, 7, and 8. FIG.
The coating film pinhole defect as shown in (1) is that there is a pinhole 12 penetrating to the conductive base material 13 for some reason in the coating film 11, and the conduction resistance with the contact type charger 14 is low. The phenomenon is likely to occur. Further, the foreign matter defect in the layer as shown in FIG. 7 is a defect in which the foreign matter 15 is buried in the coating film 11, and when the foreign matter 15 is a metal, the occurrence of dielectric breakdown remarkably appears. That is, the contact type charger 14-
Electrical polarization between the coating films 11 and the coating film 11 to the conductive substrate 1
Since the foreign matter 15 exists during the electrical polarization between the three,
Between the coating film 11 and the foreign material 15 and between the foreign material 15 and the conductive base material 13
Polarization also occurs between them. As described above, in the electrophotographic process, the charged electrophotographic photosensitive member surface is always electrically neutralized every cycle. Therefore, the foreign matter 15 repeats the cycle of polarization to static elimination for each process. Due to the electrical energy stress at the time of polarization, formation of a conductive path progresses, and dielectric breakdown may occur even in an electrophotographic photosensitive member that initially obtains an image quality with no problem. In addition, the base material defects as shown in FIG. 8 are such that the conductive base material 13 has sharp points due to scratches or the like in the base material manufacturing process and protrusions 16 such as metallic foreign matters, which are buried in the coating film 11. It was done. In this way, when there is a defect having electrical continuity with the conductive base material 13 itself, the electrostatic field due to the discharge energy applied from the contact type charger 14 concentrates on the protrusion. For example, if the shape of the protrusion is approximated to a semi-spheroid and its size is assumed to have a radius of 5 μm and a height of 10 μm, it is known that the electric field strength is about twice that of the parallel portion. When such a strong electric field is applied to the above-mentioned substrate defect, the intensity of stress increases, the dielectric strength of the coating film 11 is exceeded, and dielectric breakdown occurs. That is, the coating film pinhole defect is a defect in which a conduction path is formed in advance, whereas the foreign matter defect in the layer and the base material defect are not formed in advance and the formation of a conduction path due to electrical stress is promoted. It can be said that it is a defect.

In many cases, the position of occurrence of these defects on the photosensitive member changes depending on the relationship with the equipment in the manufacturing process. For example, various forms are conceivable for the work holding mechanism and the conveyance mechanism during the coating process, and the case where the drum is held and conveyed from above, the case where the drum is held and conveyed from below, and the like are conceivable. In these holding / conveying mechanisms, mechanical contact and wear of, for example, a device such as a conveyor is unavoidable and often becomes a source of foreign matter. When these foreign matters adhere to the electrophotographic photosensitive drum base material before coating, they generally adhere to the vicinity of the source. In the electrophotographic photosensitive member layer thus coated with the foreign matter, such defects may cause a low withstand voltage defect. At this time, when the drum is held and conveyed from above, the low withstand voltage defects are concentrated on the upper side of the shaft of the electrophotographic photosensitive drum, and when the drum is held and conveyed from below,
It often occurs in the lower part of the axis. That is, it can be said that the low withstand voltage defect of the electrophotographic photosensitive drum as described above occurs at a position related to an abnormal portion in the manufacturing process. In the manufacturing process of electrophotographic photosensitive drums, especially small electrophotographic photosensitive drums used in electrophotographic printers, etc., when considering the speed of production, frequent occurrence of the above defects has a fatal result. Therefore, early detection of abnormal parts and urgent process improvement are essential.

It has been considered that the presence or absence and the position of these defects can be detected by the coating film pinhole defect detection method as described in, for example, Japanese Patent Publication No. 2-43134. That is, as shown in FIG.
A conductive roller 23 charged by being applied with a voltage from a high-voltage transformer 22 provided inside the electrophotographic photosensitive drum 2
4 is a method in which the surface is pressed against the surface of the electrophotographic photosensitive member 24 by the drive motor 26 while being pressed against the surface by the adjusting screw 25, and the excessive current in the defective portion on the electrophotographic photosensitive member 24 is detected by the ammeter 27. A suitable material for the conductive roller 23 in this method is silicone rubber, which is said to have a JIS hardness of preferably 15 to 23 degrees. The applied voltage is preferably about -0.7 to -1 kV. In addition, the position of the defect is determined by the conductive roller 2
It is said that this can be detected by moving 3 along the drum surface.

However, the above method has problems and is not very practical. For example, Japanese Patent Publication 2-43
In the case of the method described in Japanese Patent Publication No. 134, although the coating film pinhole defect can be detected, the applied voltage is too low and the dielectric breakdown caused by the foreign matter defect in the layer or the base material defect promotes a low dielectric breakdown. Dielectric strength defect cannot be detected. In order to detect this, a method of increasing the applied voltage can be considered. The reason for increasing the applied voltage is to replace the electrical stress that is constantly received and added in the electrophotographic apparatus with a temporary excessive electrical stress. However, the conductive roller made of silicone rubber having a JIS hardness of 15 to 23 degrees as described above has insufficient strength against overcurrent due to discharge, and carbonization and melting phenomena occur. Even if the detection control circuit is equipped with a current breaker, the instantaneous interruption of the current is limited, and the carbonization and melting phenomena are unavoidable.

Therefore, according to the method described in Japanese Patent Publication No. 2-43134, the mechanical strength against overcurrent due to discharge is low, and it is difficult to perform 100% inspection for low withstand voltage defects of the electrophotographic photosensitive member. Inevitably, the defect occurrence position or area cannot be detected, and the abnormal portion in the process cannot be identified promptly. For this reason, when an increase in low withstand voltage defects is observed due to some abnormality in the process, the position of the low withstand voltage defects is checked by visually observing the electrophotographic photosensitive drum determined to be unacceptable as a result of the inspection. There is a need. However, even in such a method, it is difficult to distinguish a low withstand voltage defect from other defects on the electrophotographic photosensitive drum, so that it is not very practical and inefficient.

When a material such as silicone rubber, which is suitable in Japanese Patent Publication No. 2-43134, is used for the conductive roller, the siloxane oligomer contained in the material causes depolymerization. The depolymerized product that is deposited by depolymerization can be removed by heat treatment or the like when the silicone rubber is formed, but it also has the property of being deposited over time. This component (bleed component) deposited from the conductive roller causes a transition due to contact with the electrophotographic photosensitive member, but may erode the coating film of the electrophotographic photosensitive member made of an organic material. This is due to the fact that the above-mentioned precipitation-depolymerization polymer and the polymer of the coating film of the electrophotographic photoreceptor are compatible substances, and such erosion of the coating film is called bleed erosion. . The electrophotographic photosensitive member in which such bleeding erosion occurs is likely to cause a serious defect in image quality, and is not suitable.

As a measure for preventing the occurrence of bleeding erosion, it has been proposed to use a rubber material containing no bleeding component, for example, a rubber material such as ethylene-propylene-diene rubber (EPDM rubber) or urethane rubber in terms of compounding the rubber. It By the way, in general, the rubber material itself has no conductivity, and therefore the conductivity imparting agent is dispersed in the matrix of the rubber material to obtain the conductivity. Typical examples of the conductivity-imparting agent include carbon and quaternary ammonium salts.
These conductivity-imparting agents have a problem of causing the action of curing the rubber material, and therefore, the conductive rubber has
A plasticizer is often used to soften the material. However, such a plasticizer also often causes bleed erosion, and when a plasticizer such as paraffin oil is used, bleed erosion occurs. Therefore, it is conceivable to form the conductive roller without compounding the plasticizer into the rubber material, but in that case, Japanese Patent Publication No. 43134/1990.
JI, which is the hardness of rubber that is preferred in Japanese Patent Publication
Since it is difficult to maintain the S hardness at 15 to 23 degrees, there is a problem that poor contact with the electrophotographic photosensitive member is caused.

On the other hand, it is conceivable to form a conductive roller with foamed rubber in order to reduce the hardness of the rubber. However, since such foamed rubber has many foamed cells exposed on the surface, Alternatively, foreign substances are easily mixed between the foam cells. In such a foamed rubber, it is extremely difficult to remove the above-mentioned adhering foreign matter, and when used as a charging member, dust in the air is likely to adhere due to the action of static electricity. Such a foamed rubber is used as a conductive roller in FIG.
When used in a device such as that shown in Fig. 6, foreign matter is transferred / adhered to the surface of the electrophotographic photosensitive member due to the action of static electricity, and is electrostatically attached, so it is difficult to remove it without contact such as air blow. There's a problem. Therefore, Japanese Patent Fair 2-
In the method as described in Japanese Patent No. 43134, the mechanical strength against an overcurrent due to discharge is low, and there is a risk of causing bleed erosion of the electrophotographic photosensitive member. It is considered difficult to carry out the inspection without giving a problem to the quality of the electrophotographic photosensitive member.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the prior art. That is, an object of the present invention is to provide an inspection device for inspecting a low withstand voltage defect existing in a photoconductor layer of an electrophotographic photoconductor. Another object of the present invention is to provide a method for inspecting a low withstand voltage defect existing in a photoreceptor layer of an electrophotographic photoreceptor.

[0013]

A low dielectric strength defect inspection apparatus for an electrophotographic photosensitive member according to the present invention contains a conductivity-imparting agent,
A cylindrical roller made of a base layer made of a foam of ethylene-propylene rubber or polyurethane rubber and a coating layer made of ethylene-propylene rubber or polyurethane rubber containing a conductivity-imparting agent is attached to a cylindrical roller. A conductive roller that penetrates the electrophotographic photosensitive drum, a driving unit that rotationally drives the electrophotographic photosensitive drum, a high-voltage power supply that applies a voltage between the electrophotographic photosensitive drum and the conductive roller, and the electrophotographic photosensitive drum. And a measuring device for monitoring a current flowing between the conductive rollers.

In this case, it is preferable to use two or more conductive rubber rollers, particularly 2 to 4 conductive rubber rollers, and arrange them at positions corresponding to a plurality of different areas of the electrophotographic photosensitive drum.

Further, the method for inspecting a low dielectric strength defect of an electrophotographic photosensitive member of the present invention contains an electroconductivity-imparting agent, ethylene-
A conductive roller is pierced through a cylindrical roller made of a propylene rubber or polyurethane rubber foam and a coating layer containing a conductivity-imparting agent and made of ethylene-propylene rubber or polyurethane rubber. It is characterized in that a voltage is applied to the thus-formed conductive roller so that the conductive roller is brought into pressure contact with the rotating electrophotographic photosensitive drum, and a current flowing between the conductive roller and the electrophotographic photosensitive drum is measured.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail. In the present invention, the conductive roller used for the low withstand voltage defect inspection device of the electrophotographic photosensitive member contains a conductivity-imparting agent, an underlayer made of a foam of ethylene-propylene rubber or polyurethane rubber, and a conductive material. A cylindrical roller containing an imparting agent and comprising a coating layer made of ethylene-propylene rubber or polyurethane rubber,
It is configured by penetrating a conductive shaft. FIG. 4 is a cross-sectional view of a conductive roller for low withstand voltage defect inspection of the present invention, in which the conductive roller 3 has a coating layer 3 on a base layer 31.
2 has a structure in which the conductive shaft 33 penetrates and is attached to the cylindrical roller provided.

FIG. 5 is another example of a conductive roller using the cylindrical roller having the above-mentioned structure, in which the conductive shaft 33 is passed through the cylindrical rollers 34, 35, 36 having the above-mentioned structure. It is configured. Cylindrical roller 3
The positions of 4, 35, and 36 are determined by the conductive shafts 33a, 33
When penetrating b, it is arranged at a position corresponding to a predetermined axial area of the electrophotographic photosensitive drum 4. For example, in FIG. 5, the cylindrical roller 34
Is the inspection area 41 of the electrophotographic photosensitive drum 4, and the cylindrical roller 35 is the inspection area 4 of the electrophotographic photosensitive drum 4.
2, the cylindrical roller 36 is arranged to inspect the inspection area 43 of the electrophotographic photosensitive drum 4. Further, the inspection area of the electrophotographic photosensitive drum 4 is divided into three in FIG. 5, but the number of divisions can be arbitrarily changed, and is preferably divided into 2 to 10. At that time, among the cylindrical rollers, the cylindrical rollers arranged on the same conductive shaft must be electrically separated from each other, and the portion of the conductive shaft 33a where the rubber is not press-fitted is insulated. It is necessary to form the flexible shaft 37 in advance. The number of conductive rollers is 2 or more, especially 2
4 to 4 are preferable.

In the present invention, examples of the conductivity-imparting agent that can be used include metals such as copper, silver, iron and stainless steel, and carbon black. Those having an average particle size of 10 to 20 μm are preferably used. The conductivity-imparting agent can be added to the underlayer and the coating layer in an amount of 5 to 20% by weight, preferably 8 to 12% by weight.

As the ethylene-propylene rubber, for example, an ethylene-propylene copolymer (copolymerization ratio 60:
40-70: 30), ethylene, propylene and third
As a component, a terpolymer (EPDM) composed of a diene compound such as 1,4-hexadiene, dicyclopentadiene and ethylidene norbornene is preferably used. Particularly preferable ethylene-propylene rubbers include those having a molecular structure represented by the following formula (1). As the polyurethane rubber, toluylene diisocyanate, aromatic diisocyanate compounds such as naphthalene diisocyanate, those obtained by reacting a chain polyester or polyether having a terminal OH group, or, Those obtained by reacting with a crosslinking agent such as water, diamine, glycol, diisocyanate, and sulfur can be used. A particularly preferred polyurethane rubber is polyurethane having a structural unit represented by the following formula (2).

[0020]

Embedded image (In the formula, R represents a polyether or polyester chain, and R'represents a phenyl group or a naphthyl group.)
In the present invention, the ethylene-propylene rubber or the polyurethane rubber in the underlayer is required to be a foam, but the foam may have a foaming agent added at the synthesis stage of the rubber or after the synthesis. Can be manufactured. As the foaming agent, for example, benzene-m-disulfonylhydrazide, 4,4'-oxybis (benzenesulfonylhydrazide), p-toluenesulfonylazide, etc. can be used. The average diameter of foaming in the underlayer is 50 to 1000 μm, preferably 100 to 50.
It is preferably in the range of 0 μm.

The underlayer in the conductive roller of the present invention has a thickness in the range of 1 to 10 mm, preferably 2 to 8 mm.
It is set to the range of. Further, the coating layer has a thickness of 0.1 to
It is set to 2.0 mm, preferably 0.5 to 1.5 mm. Further, the resistance value of the conductive roller of the present invention,
10 ² to 10 ⁸ Ωcm, preferably 10 ⁴ to 10 ⁷ Ωc
The range of m and the rubber hardness in JIS hardness may be set to 70 degrees or less, preferably 60 degrees or less.

Stainless steel is preferably used as the conductive shaft which is inserted into the center of the cylindrical roller composed of the underlayer and the coating layer and penetrates through the roller, but copper, brass or the like having a good conductivity is also used. Any material can be used as long as it can be used as a support for the roller. As the insulating shaft for connecting the conductive shafts, resins such as Teflon, polyacetal, polyvinyl chloride can be preferably used, but any resin having a resistance value of 10 ¹⁰ Ω · cm or more can be used. Anything can be used.

Next, a specific example of the low withstand voltage defect inspection apparatus of the present invention using the above conductive roller will be described with reference to the drawings. FIG. 1 shows an embodiment of a low withstand voltage defect inspection apparatus of the present invention, in which a conductive roller supporting block 2 is provided inside a housing 1,
On top of that, two conductive rollers 3 are rotatably supported. The electrophotographic photosensitive drum 4, which is the object to be inspected, is arranged on the conductive roller 3. A rotary drive motor 5 for driving the electrophotographic photosensitive drum to rotate and a drive friction roller 6 are arranged in the upper part of the housing 1, and they are connected by a timing belt 7 for drive transmission. . Further, a high-voltage power supply 8 with a current interruption function is provided outside the housing 1, and its voltage output terminal and the ammeter 9 and one of the two conductive rollers 3 are connected in series by an electric wire. In addition, the inner surface of the electrophotographic photosensitive drum 4 is connected to the ground terminal of the high-voltage power supply 8 with a current interruption function, whereby a voltage is applied between the electrophotographic photosensitive drum and the conductive roller. It is supposed to be done.

When inspecting the electrophotographic photosensitive drum, the electrophotographic photosensitive drum 4 is placed on the conductive roller 3 supported by the conductive roller supporting block 2, and the driving friction roller 6 is placed. Is pressed against the electrophotographic photosensitive drum 4 from above and the electrophotographic photosensitive drum 4 is pressed.
Is driven to rotate. A voltage is applied between the conductive roller and the electrophotographic photosensitive drum from the high-voltage power supply 8 having a current interruption function, so that the fluctuation of the voltage is monitored by the ammeter 9 to detect the low withstand voltage defect. .

FIG. 2 shows another embodiment of the low withstand voltage defect inspection apparatus according to the present invention, in which a conductive roller supporting block 2 is provided inside a casing 1, and further on top of that. In addition, as shown in FIG. 5, two conductive rollers 3a and 3b formed by arranging cylindrical rollers at positions corresponding to predetermined axial areas of the electrophotographic photosensitive drum 4 are rotatable. Supported by. Then, the electrophotographic photosensitive drum 4 as the inspection object is the conductive roller 3
It is arranged on a and 3b. As in the case of FIG. 1, a rotary drive motor 5 and a drive friction roller 6 are arranged in the upper part of the housing 1, and they are connected by a drive transmission timing belt 7. Further, a high-voltage power supply 8 with a current interruption function is provided outside the housing 1, and is connected to each ammeter 27, 28, 29 as a measuring device for monitoring the current flowing through each conductive roller. The equivalent circuit shown is formed. That is, the DC output terminal of the high-voltage power supply 8 with a current interruption function is connected to the conductive rollers 3a, 3a, 3b through the ammeters 27, 28, 29.
b connected to each of the cylindrical rollers 34, 35, 36 on the b, and each of the cylindrical rollers 34, 35, 36 and the ammeter 2
7, 28 and 29 are connected in series to form a parallel circuit. During inspection, each cylindrical roller 34, 35, 36
And the electrophotographic photosensitive drum 4 are pressed against each other, so that the cylindrical rollers 34, 35, 36 and the ammeters 27, 28, 2 are respectively pressed.
The parallel circuit composed of 9 and the electrophotographic photosensitive drum 4 are connected in series.

When the electrophotographic photosensitive drum is inspected, the electrophotographic photosensitive drum 4 is placed on the conductive rollers 3a and 3b supported by the conductive roller supporting block 2, and the driving friction is applied. The roller 6 is pressed against the electrophotographic photosensitive drum 4 from above to rotate the electrophotographic photosensitive drum 4. Since a voltage is applied between the conductive roller and the electrophotographic photosensitive drum from the high-voltage power supply 8 with a current interruption function, a low withstand voltage defect can be detected by monitoring the voltage fluctuation with an ammeter. At this time, of the ammeters 27, 28, 29 connected in series to each cylindrical roller on the conductive roller,
Information on which area on the electrophotographic photosensitive drum the defect exists can be obtained by which ammeter detected the current value corresponding to the defect. Furthermore, by using an ammeter with a measurement data output function and connecting to a data processing device such as a personal computer, it is possible to quickly collect defect position information and provide feedback to the process.

[0027]

【Example】

Example 1 Next, an example of the present invention will be described. The conductive roller 3 having the structure shown in FIG. 4 was produced as follows. E as a rubber material
The PDM rubber (EPDM rubber having the molecular structure represented by the above formula (1)) was used, and conductive Ketjen black was used as the conductivity-imparting agent, and both were mixed. In that case, E
The blending ratio of PDM rubber and conductive Ketjen Black is
It was set to 10: 1 (weight ratio). A foaming agent (4,4'-oxybis (benzenesulfonyl hydrazide)) was added to the obtained composition in an amount of 3 parts by weight based on 100 parts by weight of a rubber material, and extrusion molding was performed to obtain a cylindrical molded body, followed by vulcanization. 13 in the can
Vulcanization and foaming were performed at 0 ° C. to form a cylindrical foam having an average foam diameter of 300 μm. Then, the shape was adjusted by polishing to obtain a cylindrical foam having a thickness of 6 mm and a diameter of 17 mm. The cylindrical foam thus obtained was used as a base layer 31, and the EPDM rubber and the conductive Ketjen black described above were mixed in a ratio of 10: 1.
Thickness composed of a composition blended in a blending ratio of (weight ratio) 1
After covering with a rubber tube of mm as the coating layer 32, the coating layer 32 was heated to 130 ° C. in a vulcanizer to be welded to the base layer. A conductive shaft 33 made of SUS and having a diameter of 6 mm was press-fit into this to obtain a conductive roller 3. The electric resistance value of the conductive roller was 10 ⁶ Ω, and the rubber hardness was 55 degrees (JIS A).

Using the conductive roller formed as described above, the low withstand voltage defect inspection apparatus of FIG. 1 was manufactured. That is, two conductive rollers were prepared and supported by the conductive roller supporting block 2. The electrophotographic photosensitive drum 4, which is the object to be inspected, is arranged on the conductive roller 3. Further, a rotary drive motor 5 for rotationally driving the electrophotographic photosensitive drum 4 and a drive friction roller 6 are arranged and connected by a timing belt 7 for drive transmission.
Further, the driving friction roller 6 was pressed against the electrophotographic photosensitive drum 4 from above. The driving friction roller 6 has a weight of about 1 kg in order to increase the pressure contact area between the electrophotographic photosensitive drum 4 and the conductive roller 3. Furthermore, prepare a high-voltage power supply 8 with a current interruption function,
The voltage output terminal and the ammeter 9 and one of the two conductive rollers were connected in series by an electric wire. Further, the ground terminal of the high-voltage power supply 8 with a current interruption function was connected from the inner surface of the electrophotographic photosensitive drum 4. Further, each of the above device members was housed in the housing 1.

Using the inspection apparatus shown in FIG. 1, the electrophotographic photosensitive member was inspected for low insulation resistance defects. For comparison,
The same inspection was carried out using the apparatus shown in FIG. 9 which is conventionally known to be used for the method for detecting the surface defect of the electrophotographic photosensitive member, and the two were compared. As the electrophotographic photosensitive member, one whose presence or absence of the above-mentioned coating film pinhole defect, in-layer foreign matter defect, substrate defect, etc. was previously confirmed by visual surface inspection was used. The applied voltage is -1 kV in the device of FIG. 9 and -4 kV in the device of FIG.
And The population of each electrophotographic photosensitive member to be inspected was 200, and the detection rates of various defects were determined. The obtained results are shown in Table 1 (invention) and Table 2 (comparative example).

[0030]

[Table 1]

[Table 2] As is clear from the comparison of these tables, according to the present invention, it is possible to detect, for example, a foreign matter defect in the layer or a substrate defect in the layer, which has a poor detection rate or cannot be detected by the conventional method. there were.

Example 2 In the same manner as in Example 1 above, a cylindrical foam having a thickness of 6 mm and a diameter of 17 mm was formed, the obtained cylindrical foam was used as an underlayer, and the same composition as in Example 1 was formed thereon. 1m thick consisting of objects
After covering with a rubber tube of m as a coating layer, the coating was heated to 130 ° C. in a vulcanizer to be welded to the base layer. A conductive shaft made of SUS having a diameter of 6 mm was press-fit into this to obtain a conductive roller having a structure shown in FIG. One of the conductive rollers was manufactured by connecting the conductive rollers with an insulating shaft made of polyacetal. Two obtained conductive rollers are prepared, and the arrangement of the cylindrical rollers is such that the first cylindrical roller 34 is in the range of 10 mm to 100 mm from the upper end of the photosensitive drum, and the second cylindrical roller 35 is the upper end of the photosensitive drum. In the range of 100 mm to 200 mm, the third cylindrical roller 36 is 200 m from the upper end of the photosensitive drum.
It was arranged to inspect a range from m to 290 mm. The electric resistance value of these conductive rollers was 10 ⁶ Ω, and the rubber hardness was 55 degrees (JIS A).

Using the conductive roller formed as described above, the low withstand voltage defect inspection apparatus of FIG. 2 was manufactured. That is, two conductive rollers were prepared (3a, 3b) and supported by the conductive roller supporting block. The electrophotographic photosensitive drum 4, which is the object to be inspected, is a conductive roller 3a,
Placed on 3b. Further, a rotary drive motor for driving the electrophotographic photosensitive drum and a friction roller for driving were arranged, and they were connected by a timing belt for driving transmission. Further, the driving friction roller was pressed against the electrophotographic photosensitive drum from above. The driving friction roller has a weight of about 1 kg in order to increase the pressure contact area between the electrophotographic photosensitive drum and the conductive roller. Further, a high-voltage power supply 8 with a current interruption function is prepared, and its voltage output terminal is connected via an ammeter so that each cylindrical roller 34, 35, 36 on the conductive roller is in parallel, and each The cylindrical roller and the ammeters 27, 28 and 29 were connected in series. Further, a ground terminal of a high-voltage power supply with a current interruption function was connected from the inner surface of the electrophotographic photosensitive drum. Further, each of the above device members was housed in the housing 1.

Using this inspection device, the electrophotographic photosensitive drum was inspected for low withstand voltage defects. For comparison, the same inspection was performed using the apparatus shown in FIG. 9 which is conventionally known to be used in the method for detecting the surface defect of the electrophotographic photosensitive member, and the two were compared. As the electrophotographic photosensitive drum, the one whose presence and position of the above-mentioned coating film pinhole defect, foreign matter defect in the layer, substrate defect, etc. is known in advance by visual surface inspection is used, and the applied voltage is , -1 kV in the device of FIG. 9, and -4 in the device of FIG.
kV. The results obtained are shown in Table 3 (invention) and Table 4.
(Comparative Example)

[0034]

[Table 3]

[Table 4] As is clear from the comparison of these tables, according to the present invention, it was possible to detect the presence and position of a low withstand voltage defect that could not be detected by the conventional method.

[0035]

EFFECT OF THE INVENTION Since the low dielectric strength defect inspection apparatus for an electrophotographic photosensitive member according to the present invention uses the conductive roller having the above-mentioned structure, it has high mechanical strength against an overcurrent due to discharge and is compatible with the electrophotographic photosensitive member. It has an effect that the contact property is high and the bleeding corrosion of the electrophotographic photosensitive member does not occur. Therefore, according to the present invention, it is possible to perform 100% inspection of low dielectric strength defects of an electrophotographic photosensitive member without giving a problem to the quality of the electrophotographic photosensitive member. Further, by disposing a plurality of conductive rollers at positions corresponding to a plurality of areas of the photoconductor, it is possible to identify the presence and position of the low withstand voltage defect existing in the photoconductor layer.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a low withstand voltage defect inspection apparatus of the present invention.

FIG. 2 is a diagram showing a schematic configuration of another embodiment of the low withstand voltage defect inspection apparatus of the present invention.

FIG. 3 is a schematic diagram of a connection circuit used in the present invention.

FIG. 4 is a cross-sectional view of a conductive roller for low withstand voltage defect inspection of the present invention.

FIG. 5 is a diagram showing a correspondence relationship between an example of a conductive roller for low withstand voltage defect inspection of the present invention and an electrophotographic photosensitive drum.

FIG. 6 is a diagram schematically showing a coating film pinhole defect.

FIG. 7 is a diagram schematically showing a foreign matter defect in a layer.

FIG. 8 is a diagram schematically showing a substrate defect.

FIG. 9 is a schematic configuration diagram of an example of a conventional coating film pinhole defect detection device for an electrophotographic photosensitive member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Block for electroconductive roller support, 3 ... Electroconductive roller, 4 ... Electrophotographic photosensitive drum, 5 ... Rotation drive motor, 6 ... Friction roller for drive, 7 ... Timing belt for drive transmission, 8 ... High-voltage power supply with current interruption function, 9 ... Ammeter, 11 ... Coating film, 12 ... Pinhole,
13 ... Conductive substrate, 14 ... Contact type charger, 15 ... Foreign matter,
16 ... Projection part, 21 ... Housing, 22 ... High voltage transformer, 23
... conductive roller, 24 ... electrophotographic photosensitive drum, 25
... Adjusting screw, 26 ... Drive motor, 27,28,29 ...
Ammeter, 31 ... Base layer, 32 ... Covering layer, 33, 33a,
33b ... Conductive shaft, 34, 35, 36 ... Cylindrical roller, 37 ... Insulating shaft, 41, 42, 43 ... Inspection area.

Claims (7)

[Claims] 1. An undercoat layer containing a conductivity-imparting agent and made of a foam of ethylene-propylene rubber or polyurethane rubber; and an underlayer containing a conductivity-imparting agent, made of ethylene-propylene rubber or polyurethane rubber. A cylindrical roller composed of a coating layer, a conductive roller formed by penetrating a conductive shaft, a driving means for rotationally driving the electrophotographic photosensitive drum, and a voltage between the electrophotographic photosensitive drum and the conductive roller. And a measuring device for monitoring a current flowing between the electrophotographic photosensitive drum and the conductive roller, and a low withstand voltage defect inspection apparatus for the electrophotographic photosensitive member. 2. The low dielectric strength defect inspection apparatus for an electrophotographic photosensitive member according to claim 1, further comprising a plurality of conductive rollers, and a measuring device for monitoring a current flowing through each conductive roller. 3. A low withstand voltage defect inspection of an electrophotographic photosensitive member according to claim 1, wherein a plurality of conductive rollers are arranged at positions corresponding to a plurality of different areas of the electrophotographic photosensitive drum. apparatus. 4. An underlayer containing a conductivity-imparting agent and made of a foam of ethylene-propylene rubber or polyurethane-based rubber, and an electroconductivity-imparting agent and made of ethylene-propylene rubber or polyurethane-based rubber. A conductive roller for low dielectric strength defect inspection, which is obtained by penetrating a conductive shaft into a cylindrical roller composed of a coating layer. 5. An undercoat layer containing a conductivity-imparting agent and made of a foam of ethylene-propylene rubber or polyurethane-based rubber, and an ethylene-propylene rubber or polyurethane rubber containing a conductivity-imparting agent. Between the conductive roller and the electrophotographic photosensitive drum, the cylindrical roller composed of the coating layer is pressed against the rotating electrophotographic photosensitive drum by applying a voltage to the conductive roller formed by penetrating the conductive shaft. A method for inspecting a low withstand voltage defect of an electrophotographic photosensitive member, which comprises measuring a current flowing through the film. 6. The method of inspecting a low dielectric strength defect of an electrophotographic photosensitive member according to claim 5, wherein a plurality of conductive rollers are used. 7. The method for inspecting a low dielectric strength defect of an electrophotographic photosensitive member according to claim 6, wherein a plurality of conductive rollers and a plurality of measuring devices for monitoring the current are operated in parallel.