JP2009222789A - Electrophotographic photoreceptor and image forming apparatus including it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor, having excellent effect of preventing the occurrence of abnormal sound and uneven pitch in a formed image due to vibration of the electrophotographic photoreceptor in high temperature and high humidity condition, especially remarkably caused in continuous use. <P>SOLUTION: This electrophotographic photoreceptor 1 includes a hollow cylindrical substrate 2 having a photosensitive layer on the surface and fillers 3a, 3b built in the hollow cylindrical substrate, wherein the fillers have a stacking structure formed of two materials different in higher percentage of water absorption, and the distal side of the filler from the hollow cylindrical substrate inner wall surface is formed of material having a higher percentage of water absorption than that of the proximal side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus including the same.

  An electrophotographic photoreceptor is generally produced by applying a photosensitive layer, a protective layer, or the like to the surface of a metal hollow cylindrical substrate such as conductive aluminum. Such an electrophotographic photosensitive member is used in an image forming apparatus such as an electrophotographic multifunction peripheral, a laser printer, or a facsimile.

In recent years, with the reduction in size and weight of image forming apparatuses, electrophotographic photoreceptors are also required to have a substrate with a smaller diameter and a thinner wall.
Conventionally, in electrophotographic cleaning, a method in which a cleaning blade is pressed against the surface of an electrophotographic photosensitive member is frequently used. However, when blade cleaning is performed, resonance noise may occur.

In recent years, with the above-mentioned trend toward miniaturization and weight reduction, the frequency of occurrence of abnormal noise has increased and has come to be regarded as important year after year.
It is known that abnormal noise due to friction between the cleaning blade and the photosensitive member is generated mainly during continuous use under high temperature and high humidity.

In order to prevent abnormal noise in the photoconductor, some kind of filler is inserted and fixed inside the hollow of the electrophotographic electrophotographic photoconductor.
Moreover, as a shape of a filler, there are many cylindrical things.

  And as a material of a filling body, using a porous elastic body and a cotton-like body is known (for example, refer patent document 1).

  In terms of structure, a double structure in which a weight member having a specific JIS hardness is used is known (for example, see Patent Document 2).

  Furthermore, structurally, a vibration isolator is known that disperses a number of weight members having a specific gravity greater than that of an elastic member (see, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 63-60481 Japanese Patent Laid-Open No. 5-35166 JP-A-8-202206

  In general, when an image forming apparatus adopts a structure that fills the space of a hollow cylindrical substrate of an electrophotographic photosensitive member, the entire electrophotographic photosensitive member has an effect of preventing vibration because the weight increases.

  However, since the overall weight increases, it is necessary to use a drive motor having a large capacity in the drive system because the starting rotational torque becomes too large.

  Further, since no consideration has been given to the humidity environment, there has been a problem that the effect of preventing the occurrence of abnormal noise vibration and the occurrence of pitch unevenness in the formed image cannot be obtained sufficiently in a high temperature and high humidity environment.

  Therefore, in the present invention, it is excellent in the effect of preventing the occurrence of abnormal noise due to vibration of the electrophotographic photosensitive member during continuous use, which is particularly noticeable under high temperature and high humidity, and the occurrence of pitch unevenness in the formed image. The present invention provides an electrophotographic photosensitive member equipped with a filler, which is easy to produce, is easy to produce, has no deformation of a hollow cylindrical substrate, and can be easily removed during recycling, and an image forming apparatus using the same.

  The present invention comprises a hollow cylindrical substrate having a photosensitive layer on the surface and a filler incorporated in the hollow cylindrical substrate, and the filler has a laminated structure made of two types of materials having different water absorption rates. Further, the side farther from the inner wall surface of the hollow cylindrical substrate of the filling body provides an electrophotographic photosensitive member composed of a material having a higher water absorption than the near side.

  According to the electrophotographic photosensitive member of the present invention, the filler is incorporated in the hollow cylindrical substrate in a double structure, and the side of the filler far from the inner wall surface of the hollow cylindrical substrate has a higher water absorption than the closer side. Because it is made of a high material, it is caused by the cleaning blade due to the fact that the highly water-absorbing filler on the side far from the inner wall surface of the hollow cylindrical substrate absorbs moisture and increases its weight and volume under high temperature and high humidity. By preventing the generation of abnormal noise and providing a low water-absorbing filler on the side closer to the inner wall surface of the hollow cylindrical base body, even if the high water-absorbing filler on the far side absorbs moisture slightly unevenly, Since the filler is evenly inscribed on the inner wall surface of the cylindrical substrate, there is an effect that it is possible to prevent image defects such as pitch unevenness in image formation.

  An electrophotographic photoreceptor according to the present invention includes a hollow cylindrical substrate having a photosensitive layer on a surface thereof, and a filler incorporated in the hollow cylindrical substrate, and the filler is made of two types of materials having different water absorption rates. It has a laminated structure, and the side farther from the inner wall surface of the hollow cylindrical substrate of the filler is made of a material having a higher water absorption rate than the near side.

  The electrophotographic photosensitive member according to the present invention has, for example, a cylindrical shape, and is used by being rotationally driven by mounting flanges at both ends and a driving gear at one end.

  The photosensitive layer includes, for example, an undercoat layer on the hollow cylindrical substrate, and a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material thereon.

  The photosensitive layer may further be provided with a protective layer to protect the surface as necessary. For the protective layer, for example, a thermoplastic resin, a photocurable resin, a thermosetting resin, or the like is used.

  As the hollow cylindrical substrate, a conductive material can be used, and examples of the material include metals such as aluminum, nickel, copper, iron, and zinc, and alloys containing two or more of these metals. it can.

  Further, examples of the hollow cylindrical substrate include those having an outer diameter of 20 mm to 100 mm, a length of 240 mm to 400 mm, and a thickness of 0.5 mm to 4 mm.

The filler preferably has a high elastic modulus and excellent workability that can be cut and bent.
The filler may be provided on the inner wall surface of the hollow cylindrical base body either manually or by a machine.

  The laminated structure can be produced by stacking two kinds of materials having different water absorption rates without using an adhesive.

  In the electrophotographic photosensitive member according to the present invention, the far side can be formed of a foam.

  In the electrophotographic photosensitive member according to the present invention, the far side can be formed by hydrophilic urethane foam, and the near side can be formed by rubber sponge.

  In the electrophotographic photosensitive member according to the present invention, it is preferable that the filler has a donut shape having a space in the center.

  If it is a donut shape, it can prevent that the whole weight of a filling body becomes too heavy, Therefore It becomes possible to prevent that starting rotation torque of an electrophotographic photosensitive member becomes large too much. For this reason, it is possible to use a drive motor having a small capacity for the drive system of the electrophotographic photosensitive member.

  In the electrophotographic photosensitive member according to the present invention, the filler can be divided in the longitudinal direction of the hollow cylindrical substrate.

  In the electrophotographic photoreceptor according to the present invention, it is preferable that the hollow cylindrical substrate has a flange fitted to both ends, and at least one of the flanges has a vent hole.

  Since the flange includes the air holes, the filler can absorb moisture in the atmosphere. For this reason, the weight of the filling body is increased, and it is possible to prevent the occurrence of abnormal noise due to vibration and pitch unevenness of the formed image under high temperature and high humidity.

  In another aspect, the present invention provides an electrophotographic process cartridge provided with the electrophotographic photosensitive member.

  From another viewpoint, the present invention provides an image forming apparatus provided with the electrophotographic photosensitive member.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. The present invention is not limited to this, and various modifications are possible. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is common between different drawings.

<Image forming device>
FIG. 1 is a configuration explanatory view of an image forming apparatus (manufactured by Sharp Corporation, MX-2300 type) according to the present invention.
The image forming apparatus 100 according to the present embodiment forms multi-color and single-color images on a sheet based on read image data of a document or image data transmitted via a network or the like.

  The image forming apparatus 100 includes an exposure unit E, drum-type electrophotographic photosensitive members 101a to 101d, developing devices 102a to 102d, charging rollers 103a to 103d, and cleaning units 104a to 104d.

  The image forming apparatus 100 further includes an intermediate transfer belt 110, primary transfer rollers 130a to 130d, a secondary transfer roller 140, a fixing device 150, paper transport paths P1, P2, and P3, a paper feed cassette 160, A manual paper feed tray 170 and a paper discharge tray 180 are provided.

In the image forming apparatus 100 as described above, four colors of cyan (C), magenta (M), and yellow (Y), which are three subtractive primary colors obtained by color separation of black (B) and a color image, are used. It is done.
Then, image formation is performed in the image forming units Pa to Pd using image data corresponding to the four hues.

  The image forming units Pa to Pd have the same configuration. For example, the image forming unit Pa forms black and includes an electrophotographic photosensitive member 101a, a developing device 102a, a charging roller 103a, a primary transfer roller 130a, a cleaning unit 104a, and the like.

The image forming units Pa to Pd are arranged in a line in the moving direction (sub-scanning direction) of the intermediate transfer belt 110.
Here, the charging rollers 103a to 103d are contact-type chargers that uniformly charge the surfaces of the electrophotographic photosensitive members 101a to 101d to a predetermined potential, respectively.

  Further, instead of the charging rollers 103a to 103d, a contact type charger using a charging brush or a non-contact type charger using a charging wire can be used.

  The exposure unit E, which is an exposure apparatus, includes a semiconductor laser (not shown), a polygon mirror E1, a first reflection mirror E2, a second reflection mirror E3, and the like.

Further, the exposure unit E irradiates each of the electrophotographic photosensitive members 101a to 101d with a light beam such as a laser beam modulated by the image data of each of the four colors.
On each of the electrophotographic photoreceptors 101a to 101d, electrostatic latent images are formed based on the image data of the four colors.

  Further, each of the developing devices 102a to 102d stores the toner of each of the four colors. Each of the developing devices 102a to 102d visualizes the toner images of the four colors with the electrostatic latent images of the hues formed on the electrophotographic photosensitive members 101a to 101d.

  The cleaning units 104a to 104d remove and collect toner remaining on the surfaces of the electrophotographic photoreceptors 101a to 101d after development and image transfer.

  The intermediate transfer belt 110 disposed above the electrophotographic photosensitive members 101a to 101d is stretched between the driving roller 110a and the driven roller 110b to form a loop-shaped moving path.

  The outer peripheral surface of the intermediate transfer belt 110 is opposed to the electrophotographic photoreceptor 101d, the electrophotographic photoreceptor 101c, the electrophotographic photoreceptor 101b, and the electrophotographic photoreceptor 101a in this order.

Primary transfer rollers 130a to 130d are disposed at positions facing the electrophotographic photosensitive members 101a to 101d with the intermediate transfer belt 110 interposed therebetween.
Each of the positions facing the intermediate transfer belt 110 and the electrophotographic photosensitive members 101a to 101d is a primary transfer position.

The intermediate transfer belt 110 is formed of a film having a thickness of about 100 to 150 μm.
Then, the toner images carried on the surfaces of the electrophotographic photoreceptors 101a to 101d are transferred onto the intermediate transfer belt 110. At this time, a primary transfer bias having a polarity opposite to the toner charging polarity is applied to the primary transfer rollers 130a to 130d by constant voltage control.

  As a result, the toner images of the respective colors formed on the electrophotographic photosensitive members 101a to 101d are sequentially transferred onto the outer peripheral surface of the intermediate transfer belt 110. Then, a full color toner image is formed on the outer peripheral surface of the intermediate transfer belt 110.

  However, when image data of only a part of the hues of the four colors is input, the electrostatic latent image and the toner are only applied to some of the electrophotographic photosensitive members 101a to 101d corresponding to the hue of the input image data. An image is formed.

  For example, when a monochrome image is formed, an electrostatic latent image and a toner image are formed only on the electrophotographic photosensitive member 101a corresponding to the black hue. At this time, only the black toner image is transferred to the outer peripheral surface of the intermediate transfer belt 110.

  Each of the primary transfer rollers 130a to 130d is configured by covering the surface of a shaft made of a metal (for example, stainless steel) having a diameter of 8 to 10 mm with a conductive elastic material (for example, EPDM, urethane foam, or the like). A high voltage is uniformly applied to the intermediate transfer belt 110 by the conductive elastic material.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 110 at each primary transfer position is conveyed to a secondary transfer position that is a position facing the secondary transfer roller 140 by the rotation of the intermediate transfer belt 110.

  Further, the secondary transfer roller 140 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 110 whose inner peripheral surface is in contact with the peripheral surface of the driving roller 110a at a predetermined nip pressure during image formation.

  A sheet fed from the sheet feeding cassette 160 or the manual sheet feeding tray 170 passes between the secondary transfer roller 140 and the intermediate transfer belt 110. At that time, a high voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 140.

As a result, the toner image is transferred from the outer peripheral surface of the intermediate transfer belt 110 to the surface of the sheet.
Of the toner adhering to the intermediate transfer belt 110 from the electrophotographic photosensitive members 101a to 101d, the toner remains on the intermediate transfer belt 110 without being transferred onto the paper. The toner is collected by the cleaning unit 120 in order to prevent color mixing in the next process.

  The sheet on which the toner image has been transferred is guided to the fixing device 150, and passes between the heating roller 150a and the pressure roller 150b and is heated and pressed.

  As a result, the toner image is firmly fixed on the surface of the paper. The sheet on which the toner image is fixed is discharged onto the discharge tray 180 by the discharge roller 180a.

  In the image forming apparatus 100, a substantially vertical direction for feeding the paper stored in the paper feed cassette 160 to the paper discharge tray 180 between the secondary transfer roller 140 and the intermediate transfer belt 110 and via the fixing device 150. Paper transport path P1 is provided.

  In the paper transport path P1, a pickup roller 160a that feeds the paper in the paper feed cassette 160 one by one into the paper transport path P1, and a transport roller r10 that transports the fed paper upward.

  The paper transport path P1 further includes a registration roller 190 that guides the transported paper between the secondary transfer roller 140 and the intermediate transfer belt 110 at a predetermined timing, and paper discharge that discharges the paper to the paper discharge tray 180. A roller 180a is disposed.

  Further, inside the image forming apparatus 100, a paper conveyance path P2 in which a pickup roller 170a and a conveyance roller r10 are arranged is formed between the manual paper feed tray 170 and the registration rollers 190.

  Further, a sheet conveyance path P3 is formed between the paper discharge roller 180a and the upstream side of the registration roller 190 in the sheet conveyance path P1.

  The paper discharge roller 180a is rotatable in both forward and reverse directions, and is driven in the forward rotation direction when a single-sided image is formed to form an image on one side of the paper, and discharges the paper to the paper discharge tray 180.

  Further, the paper discharge roller 180a is driven in the normal rotation direction to discharge the paper to the paper discharge tray 180 even when the second side image is formed in the double-sided image formation for forming images on both sides of the paper.

  At the time of image formation on the first side (sheet surface) in double-sided image formation, the discharge roller 180a is driven in the forward direction until the trailing edge of the sheet passes through the fixing device 150. Thereafter, the sheet is driven in the reverse direction with the trailing edge of the sheet held therebetween, and the sheet is guided into the sheet conveyance path P3.

  As a result, the paper on which the image is formed only on the first surface (front surface) when the double-sided image is formed is guided to the paper transport path P1 with the front and back surfaces and the front and rear ends reversed.

  Then, the sheet passes between the secondary transfer roller 140 and the intermediate transfer belt 110, and the toner image is transferred to the second surface (back surface) of the sheet. The sheet onto which the toner image has been transferred is fixed as described above and discharged onto the discharge tray 180.

  The registration roller 190 guides the paper fed from the paper feed cassette 160 or the manual paper feed tray 170 between the secondary transfer roller 140 and the intermediate transfer belt 110 at a timing synchronized with the rotation of the intermediate transfer belt 110. .

  Similarly, the registration roller 190 guides the sheet conveyed via the sheet conveying path P3 between the secondary transfer roller 140 and the intermediate transfer belt 110 at a timing synchronized with the rotation of the intermediate transfer belt 110.

  Accordingly, the registration roller 190 stops rotating when the electrophotographic photoreceptors 101a to 101d and the intermediate transfer belt 110 start to operate. Then, the sheet fed or conveyed prior to the rotation of the intermediate transfer belt 110 stops moving in the sheet conveyance path P1 with the front end in contact with the registration roller 190.

  Thereafter, the registration roller 190 is a position where the secondary transfer roller 140 and the intermediate transfer belt 110 are in pressure contact with each other, at a timing when the front end portion of the sheet and the front end portion of the toner image formed on the intermediate transfer belt 110 face each other. Start spinning.

  At the time of full color image formation in which image formation is performed in all of the image forming portions Pa to Pd, the primary transfer rollers 130a to 130d press the intermediate transfer belt 110 against all of the electrophotographic photoreceptors 101a to 101d.

  On the other hand, at the time of monochrome image formation in which image formation is performed only in the image forming portion Pa, only the primary transfer roller 130a presses the intermediate transfer belt 110 against the electrophotographic photosensitive member 101a.

<Configuration of electrophotographic photoreceptor>
FIG. 2 is a perspective view of the electrophotographic photosensitive member 1 used for each of the electrophotographic photosensitive members 101a to 101d shown in FIG. FIG. 3 is a longitudinal sectional view of FIG.

  As shown in FIGS. 2 and 3, the electrophotographic photoreceptor 1 includes a hollow cylindrical substrate 2 having a photosensitive layer 5 on the surface, and fillers 3a and 3b incorporated in the hollow cylindrical substrate 2.

  The electrophotographic photosensitive member 1 includes disk-like flanges 6a and 6b at both ends thereof. The disc-shaped flanges 6a and 6b have support shafts 40a and 40b and vent holes 50a, 51a, 50b and 51b, respectively.

The electrophotographic photosensitive member 1 includes a driving gear 7 that is coaxially fixed to the flange 6b. The driving gear 7 includes vent holes 50c and 51c that communicate with the vent holes 50b and 51b, respectively.
The photosensitive layer 5 includes an undercoat layer, a charge generation layer, and a charge transport layer that are sequentially laminated on the surface of the hollow cylindrical substrate 2.

The filler 3a is composed of a first member 4a and a second member 4b having different water absorption rates, and the filler 3b is also composed of a first member 4c and a second member 4d having mutually different water absorption rates, each having a two-layer structure. is doing.
The first members 4a and 4c have a higher water absorption rate than the second members 4b and 4d.

<Method for producing electrophotographic photoreceptor>
4 is a cross-sectional view of the hollow cylindrical substrate 2 of FIG. FIG. 5 is a perspective view of the fillers 3a and 3b.

  As shown in FIG. 4, a photosensitive layer 5 is formed by sequentially laminating an undercoat layer, a charge transport layer, and a charge transport layer on the surface of the hollow cylindrical substrate 2 by a general dip coating method. Next, the photosensitive layer 5 is heated and dried.

    Next, the members to be the first members 4a and 4c (FIG. 3) are cut into blocks. Similarly, the members to be the second members 4b and 4d (FIG. 3) are cut into blocks.

Next, the member cut into a block shape is bent into a cylindrical shape as shown in FIG. 5 to form a first member 4a and a second member 4b. Similarly, the first member 4c and the second member 4d are formed.
As a result, doughnut-shaped fillers 3a and 3b are formed, and have a space 8 at the center.

  Then, the fillers 3a and 3b are inserted from both ends of the hollow cylindrical base 2 shown in FIG. Then, as shown in FIG. 3, the fillers 3a and 3b are in contact with the inner wall surface of the hollow cylindrical substrate 2. At this time, the fillers 3a and 3b are provided so as to have a predetermined interval in the longitudinal direction of the hollow cylindrical substrate 2.

  Next, as shown in FIG. 3, the electrophotographic photosensitive member 1 is obtained by fitting the flanges 6a and 6b to both ends of the hollow cylindrical base 2, and then press-fitting the driving gear 7 into the support shaft 40b of the flange 6b. Complete.

  Hereinafter, the present invention will be described in further detail using examples and comparative examples.

  As the hollow cylindrical substrate 2, an aluminum hollow cylinder having an outer diameter D = 30 mm, an inner diameter d = 28.4 mm, a length L1 = 357 mm as shown in FIG. 3 was used.

  A rubber sponge (E4070, manufactured by Inoac Corporation) having a water absorption rate of 4% and a volume swelling rate of 2.1 vol% at 25 ° C. was used for the second members 4b and 4d of the fillers 3a and 3b.

  Here, the size of the second members 4b and 4d, that is, the width, the length, and the thickness are 88 mm, the length L2 = 100 mm, and the thickness t2 = 2 mm, respectively, so as to be in contact with the inner wall surface of the hollow cylindrical base body 2 (FIG. 5).

  Also, hydrophilic urethane foam (Cosmion MI-1, manufactured by Inoac Corporation) having a water absorption rate of 1610% and a volume swelling rate of 99.8 vol% at 25 ° C. in the first members 4a and 4c of the fillers 3a and 3b ) Was used.

Here, the first members 4a and 4c have a width of 75 mm, a length L2 = 100 mm, and a thickness t1 = 5 mm (FIG. 5).
Such an electrophotographic photosensitive member 1 is loaded into the image forming apparatus 100 shown in FIG. 1 as each of the electrophotographic photosensitive members 101a to 101d, and image formation is performed in a high temperature / high humidity environment where the temperature is 35 ° C. and the humidity is 85%. went.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. Further, there was no occurrence of pitch unevenness in the formed image.

  After printing 30,000 sheets, the electrophotographic photosensitive member 1 was taken out from the main body of the image forming apparatus, the flanges 6a and 6b and the driving gear 7 were further removed from the electrophotographic photosensitive member 1, and the inside of the electrophotographic photosensitive member 1 was observed. As a result, the positions of the fillers 3a and 3b were not changed from the initial positions (before starting printing).

The water absorption rates of the first members 4a and 4c and the second members 4b and 4d are determined as follows in accordance with the American Society for Testing and Materials (ASTM) standard D1056.
A sample having a thickness of about 12.5 mm and an area of about 2500 mm ² is used.
First, the weight of the sample is measured.
Next, the sample is immersed in a position 50 mm below the surface of distilled water placed in a desiccator at a room temperature of 18 ° C. to 35 ° C.

  Then, the pressure in the desiccator is reduced to 170 hpa, and the sample is left for 3 minutes. Then, return the inside of the desiccator to atmospheric pressure and leave the sample in water for 3 minutes.

Next, the sample is taken out, wiped off with a filter paper to remove moisture, and the weight of the sample is measured. And a water absorption is calculated | required by following Formula.
Water absorption (%) = (W ₂ -W ₁ / W ₁ ) × 100 (1)
Here, W ₁ is the weight of the sample before immersion, and W ₂ is the weight of the sample after immersion.

In electrophotographic photosensitive member 1, hydrophilic urethane foam (Cosmion NS-1, Inoac Corporation) was used.
The other configuration of the electrophotographic photosensitive member 1 is the same as that of the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. Further, there was no occurrence of pitch unevenness in the formed image.

In the electrophotographic photoreceptor 1, only the thickness t1 (FIG. 5) of the first members 4a and 4c of the fillers 3a and 3b is set to 3 mm.
The other configuration of the electrophotographic photosensitive member 1 is the same as that of the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. Further, there was no occurrence of pitch unevenness in the formed image.

In the electrophotographic photoreceptor 1, only the thickness t1 (FIG. 5) of the first members 4a and 4c of the fillers 3a and 3b was set to 8 mm.
Other configurations of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. Further, there was no occurrence of pitch unevenness in the formed image.

In the electrophotographic photoreceptor 1, only the thickness t1 (FIG. 5) of the first members 4a and 4c of the fillers 3a and 3b is set to 2 mm.
Other configurations of the fillers 3a and 3b of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 did not generate abnormal noise at the start of its rotation.

  However, the electrophotographic photosensitive member 1 sometimes generates a small noise that causes no problem in use as it is repeatedly used. Further, there was no occurrence of pitch unevenness in the formed image.

In the electrophotographic photoreceptor 1, only the thickness t1 (FIG. 5) of the first members 4a and 4c of the fillers 3a and 3b was set to 12 mm.
Other configurations of the fillers 3a and 3b of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets.

  However, minute streaks such as pitch unevenness occurred in full-surface halftone printing. This is probably because the weight balance of the fillers 3a and 3b has changed.

In the electrophotographic photoreceptor 1, the filler 3b was not used and only one filler 3a was used. Here, the length L2 (FIG. 5) of the material of the first member and the second members 4a and 4b of the filler 3a was set to 200 mm, and the filler 3a was provided in the vicinity of the center in the hollow cylindrical substrate 2.
The other configuration of the electrophotographic photosensitive member 1 is the same as that of the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. Further, there was no occurrence of pitch unevenness in the formed image.

  However, it was difficult to insert the filler 3a into the hollow cylindrical substrate 2. Further, the movement of the electrophotographic photosensitive member 1 during rotational driving was somewhat unstable.

[Comparative Example 1]
In the electrophotographic photoreceptor 1, the first members 4a and 4c were made of rubber sponge (E4070, manufactured by Inoac Corporation). The second members 4b and 4d were made of hydrophilic urethane foam (Cosmion MI-1, manufactured by Inoac Corporation).
Other configurations of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 did not generate abnormal noise at the start of its rotation.

However, an abnormal noise occurred more than 10,000 prints. This is presumably because the second members 4b and 4d having a high water absorption rate were affected by the first members 4a and 4c and could not sufficiently absorb moisture from the outside air.
Further, there was no occurrence of pitch unevenness in the formed image.

[Comparative Example 2]
In the electrophotographic photosensitive member 1, only the second members 4b and 4d of the polyethylene foam (cross-linked foamed polyethylene “Hiethylene S”, manufactured by Hitachi Chemical Co., Ltd.) having a water absorption rate of 0% are used for the fillers 3a and 3b. Formed. Other configurations of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. Since the fillers 3a and 3b moved in the hollow cylindrical substrate 2 during the repetition of printing, the electrophotographic photosensitive member 1 generated noise from the start of rotation to the end of the experiment. Further, there was no occurrence of pitch unevenness in the formed image.

[Comparative Example 3]
In the electrophotographic photosensitive member 1, the fillers 3a and 3b were formed using only the second members 4b and 4d of hydrophilic urethane foam (Cosmion MI-1, manufactured by Inoac Corporation) to form an image. In addition, the dimensions of the second members 4b and 4d were 76 mm in width, length L2 = 100 mm, and thickness t2 = 7 mm (FIG. 5).
Other configurations of the electrophotographic photosensitive member 1 are the same as those in the first embodiment.

  Such an electrophotographic photosensitive member 1 was loaded into the image forming apparatus 100 as described above, and image formation was performed under the same high temperature and high humidity environment as in Example 1.

  Then, abnormal noise during image formation and the occurrence of pitch unevenness in the formed image were observed. The electrophotographic photosensitive member 1 was quiet without generating abnormal noise from the start of rotation to the end of printing of 30,000 sheets. However, streaks such as pitch unevenness occurred after the printing of about 15,000 sheets.

  Table 1 shows the conditions in Examples 1 to 7 and Comparative Examples 1 to 3 described above. Table 2 shows the results obtained under these conditions.

  Examples 1 to 5 and 7 in Table 1 and Table 2 are compared with Example 6. In Examples 1 to 5 and 7, the fillers 3a and 3b (doughnut shape) have a wide space at the center. And in Examples 1-5, it turns out that pitch nonuniformity does not occur.

  Furthermore, Examples 1 to 6 and Table 7 in Table 1 and Table 2 are compared. In Examples 1 to 6, the fillers 3a and 3b (FIG. 3) are divided in the longitudinal direction of the hollow cylindrical substrate 2. In Examples 1 to 6, it can be seen that it is easy to insert the fillers 3a and 3b into the hollow cylindrical substrate 2, and the stability of the electrophotographic photosensitive member 1 during rotation driving is increased.

  Further, Examples 1 to 7 in Table 1 and Table 2 are compared with Comparative Example 1. In Examples 1 to 7, the first members 4a and 4c have a higher water absorption rate than the second members 4b and 4d. In Examples 1 to 7, it can be seen that the electrophotographic photosensitive member 1 does not generate abnormal noise due to the use of the cleaning blade even under high temperature and high humidity.

1 is a configuration explanatory diagram of an image forming apparatus according to the present invention. FIG. FIG. 2 is an explanatory diagram of a configuration of an electrophotographic photosensitive member according to the present invention. FIG. 3 is a longitudinal sectional view of the electrophotographic photosensitive member shown in FIG. FIG. 3 is a cross-sectional view of a hollow cylindrical substrate of the electrophotographic photosensitive member shown in FIG. FIG. 3 is a perspective view of a filling body of the electrophotographic photosensitive member shown in FIG.

Explanation of symbols

1,101a, 101b, 101c, 101d Electrophotographic photoreceptor
2 Hollow cylindrical substrate
3a, 3b filler
4a, 4c 1st member
4b, 4d Second member
5 Photosensitive layer
6a, 6b flange
7 Drive gear
8 space
40a, 40b Spindle
50a, 51a, 50b, 51b, 50c, 51c Vent
100 Image forming device
102a, 102b, 102c, 102d Developing device
103a, 103b, 103c, 103d Charging roller
104a, 104b, 104c, 104d Cleaning unit
110 Intermediate transfer belt
110a Drive roller
110b driven roller
120 Cleaning unit
130a, 130b, 130c, 130d Primary transfer roller
140 Secondary transfer roller
150 Fixing device
150a heating roller
150b pressure roller
160 Paper cassette
170 Manual feed tray
160a, 170a Pickup roller
180a paper discharge roller
190 Registration roller
E Exposure unit
E1 polygon mirror
E2 First reflection mirror
E2 Second reflection mirror
Pa, Pb, Pc, Pd Image forming part
P1, P2, P3 Paper transport path
r10 Transport roller

Claims (7)

A hollow cylindrical substrate having a photosensitive layer on a surface thereof, and a filler incorporated in the hollow cylindrical substrate, wherein the filler has a laminated structure made of two kinds of materials having different water absorption rates, An electrophotographic photoreceptor composed of a material having a higher water absorption rate on the side farther from the inner wall surface of the hollow cylindrical substrate than the near side. 2. The electrophotographic photosensitive member according to claim 1, wherein the far side is formed of a foam. 3. The electrophotographic photosensitive member according to claim 1, wherein the far side is formed of a hydrophilic urethane foam and the near side is formed of a rubber sponge. 4. The electrophotographic photosensitive member according to claim 1, wherein the filler has a donut shape having a space in a central portion. 5. The electrophotographic photosensitive member according to claim 1, wherein the filler is divided in a longitudinal direction of the hollow cylindrical substrate. 6. The electrophotographic photosensitive member according to claim 1, wherein the hollow cylindrical substrate has flanges fitted at both ends, and at least one of the flanges includes a vent hole. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1.

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