JP2006251268A - Image carrier, electrifying device, and process cartridge and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image carrier and an electrifying device that can accurately predict a reduction amount of the film thickness in the image carrier by discharge and facilitate accurate designing of the film thickness, and to provide a process cartridge and an image forming apparatus equipped with them. <P>SOLUTION: The image carrier 2 is equipped with the electrifying device which includes an electrifying member 3 disposed in contact with or near the image carrier 2 and applies a voltage on the charging member 3 to induce discharge in the gap between the charging member 3 and the image carrier 2 surface to uniformly charge the image carrier 2, wherein the film thickness of the image carrier 2 is determined by characteristics of the light intensity of the light generating in the gap. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image carrier, a charging device, a process cartridge including these, and an image forming apparatus in an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

In recent years, due to the increasing interest in the environment, the charging means has been shifting from a corona charging system that generates a large amount of ozone to a charging roller system that suppresses the generation of ozone. The charging roller system includes a “contact type charging roller system” in which the charging roller is placed in contact with the image carrier, and a “non-contact type” in which the charging roller is placed in close proximity without contacting the image carrier. There is a “charging roller system”.
Compared to the corona charging method, the contact charging roller method has the advantage that the generation amount of discharge products such as ozone is extremely small, the applied voltage can be set low, the cost of the power supply is reduced, and the design of electrical insulation is easy. There is. However, the uniformity of charging is inferior to that of the corona charging method. In the contact roller charging method, the roller is in direct contact with the image carrier, so if a foreign object is caught between the charging roller and the image carrier, the charging roller is contaminated and charging failure occurs. In this case, there is a drawback that the image carrier is contaminated and image defects such as horizontal stripes occur. In order to improve the above-described charging uniformity failure, there is an example in which an AC voltage having a peak-to-peak voltage more than twice the charging start voltage when a DC voltage is applied is superimposed on the related art (see, for example, Patent Document 1). .)
The non-contact type charging roller method is a method in which a charging member is arranged in contact with the surface of the image carrier with a certain gap in order to improve the problem of contamination of the charging member due to contact charging. There is. Even in such a non-contact roller charging method, a method of applying a DC voltage is difficult in practical use due to problems such as variations in charging potential due to minute gap fluctuations and stability of discharge. For this reason, the AC voltage superposition type is considered to be a suitable method even in the case of non-contact.
In this way, by adopting the AC voltage superimposing type roller charging method, it is possible to realize a charging process with sufficient charging uniformity, low generation amount of ozone and nitrogen oxide, and low power consumption. On the other hand, in the AC voltage superimposing type roller charging method, it is known that the amount of decrease in the film thickness of the image carrier is larger than that of other charging methods (for example, see Patent Document 2). This is because the cleaning blade mechanically scrapes the surface layer each time it rotates during image formation, and the protective layer of the image carrier deteriorates and disappears due to discharge due to the application of an alternating voltage to the charging member. It is because it will wait.

As described above, when the image carrier is scraped by the mechanical contact of the cleaning blade or by a chemical reaction due to electric discharge, and the photosensitive layer has a certain thickness or less, an image defect occurs. For this reason, it is necessary to replace the image carrier when it reaches the end of its life. Here, in order to establish the image carrier as a component of the image forming apparatus, it is necessary to design the film thickness so as to guarantee the life of the image carrier specified as a product. The film thickness design of the image carrier needs to be performed based on the light attenuation sensitivity and gain, but at the same time, the film thickness reduction must be taken into consideration. If the film thickness is increased, the life is extended, but it is expensive to increase the film thickness more than necessary. In order to achieve high resolution of the image, it is inappropriate that the photosensitive layer is thicker than necessary. Therefore, it is necessary to grasp the amount of film thickness reduction that occurs with respect to usage conditions and to design the film thickness based on the amount of film thickness reduction. For that purpose, it is important to establish means for accurately grasping the film thickness reduction amount.
2. Description of the Related Art In recent years, functions of an image carrier have been improved, and a technique for reducing mechanical wear by providing a hard coat layer on a surface layer has been established. In addition, a technique for reducing mechanical wear by applying a lubricant such as a fatty acid metal salt to an image carrier has already been implemented. On the other hand, the reduction in the film thickness of the image bearing member due to the charging process is a problem that appears when an AC voltage is applied by roller charging, and has recently been highlighted. This problem cannot be addressed by changing the surface material, and no fundamental solution has been found. That is, in designing the thickness of the image carrier, the thickness reduction due to discharge in the charging process is more important than mechanical wear, and the amount of film thickness reduction due to discharge is accurately predicted. Technology is required.
In order to accurately predict the amount of film thickness reduction due to discharge, it is necessary to quantitatively evaluate the intensity of the generated discharge. As a method for evaluating the intensity of the discharge, there is a “method of detecting a current value”. In the prior art, in order to control the surface potential of the image carrier, there is an example using a method of detecting the discharge current of the charging member and the inflow current of the image carrier and controlling the applied voltage from these current ratios (for example, , See Patent Document 3). However, this method cannot accurately measure the current flowing in the discharge space between the image carrier and the charging member, and thus cannot accurately quantify the discharge intensity. That is, when an ammeter is set between the image carrier and the charging member, the current value flowing between the charging member and the image carrier directly related to the charging potential control and the charging member and the image not directly related to the charging potential control. The sum of the current value as the capacitor component that becomes the charge accumulated in each carrier is detected, and these current values cannot be measured separately. For this reason, the “method of detecting the current value” can approximately evaluate the degree of discharge, but cannot accurately evaluate it.

JP-A 63-149668 JP-A-11-305522 JP-A-63-80277

  The present invention has been made in view of the above-described problems, and accurately predicts the amount of decrease in the thickness of the image carrier due to discharge, and enables an accurate film thickness design, a charging device, and the like. It is an object of the present invention to provide a process cartridge and an image forming apparatus including the above.

In order to solve the above problems, the present invention has the following features.
In the present invention, the image carrier has a charging member disposed in contact with or close to the image carrier, and a voltage is applied to the charging member to discharge the gap between the charging member and the surface of the image carrier. An image carrier including a charging device that uniformly charges the image carrier to be generated is characterized in that the film thickness of the image carrier is set by characteristics of light intensity generated in the gap.
When the roller charging method is used, the decrease in the film thickness of the image carrier due to discharge is larger than the decrease in the film thickness of the image carrier due to mechanical contact with a cleaning blade or the like. For this reason, it is necessary to accurately predict the amount of film thickness reduction due to discharge in the charging process. Therefore, by measuring the characteristics of the light intensity generated in the gap, it is possible to accurately predict the amount of decrease in the thickness of the image carrier due to discharge, and to set the thickness of the image carrier according to the lifetime. did.

The present invention is characterized in that the film thickness of the image carrier is set as D = D1 + D2 + d according to the characteristic of the light intensity generated in the gap between the image carrier and the charging member.
Here, D is the designed film thickness D [μm], D1 is the minimum film thickness D1 [μm] of the image carrier capable of maintaining a uniform charging potential, and D2 is the film thickness that decreases due to factors other than the charging action. D2 [μm]. d is a preliminary film thickness d [μm] set in preparation for the expected film thickness reduction due to electrification, and is expressed as follows.
2.0 · h · (1 / L) · k · I <d <2.5 · h · (1 / L) · k · I
Here, h is the running time, h [hour], L is the circumferential length L [mm] of the image carrier, and I is the light intensity I [optional] of the light generated in the gap between the image carrier and the charging member. Unit]. K is a correction coefficient for determining the light intensity I depending on the photodetector and the position of the detector, and is expressed as follows.
k = 1 / I '
However, I ′ is generated in the gap between the image carrier and the charging member when the peak-to-peak voltage Vpp of the AC voltage applied to the charging member is 2.2 [kV] and the frequency is 1.35 [kHz]. This is the light intensity [arbitrary unit].

The present invention is characterized in that the image carrier contains at least polycarbonate or polyarylate as a resin for forming a protective layer.
When an AC voltage is applied to the organic photoreceptor by a roller charging method, the film thickness is significantly reduced due to discharge. Polycarbonate and polyarylate are typical constituent materials of the organic photoreceptor, and it is necessary to design the life in consideration of the reduction in the film thickness due to discharge. Since the present invention can accurately predict the amount of decrease in the film thickness of the image carrier due to electric discharge, the film thickness of the image carrier can be set according to the lifetime even in the case of an organic photoconductor, and is effective.

The present invention is characterized in that the image carrier is composed of an organic photoreceptor having a protective layer in which a filler is dispersed.
When an organic photoreceptor having a protective layer in which a filler is dispersed is used, durability against mechanical abrasion such as blade scraping is improved, but thickness reduction due to discharge cannot be prevented. Since the present invention can accurately predict the amount of decrease in the thickness of the image carrier due to discharge, the thickness of the image carrier can be set according to the lifetime even when the protective layer is an organic photoreceptor in which filler is dispersed. Demonstrate.

In the present invention, the image carrier is characterized in that the protective layer is a cross-linked charge transport material.
By using a crosslinkable charge transport material for the protective layer, durability against mechanical abrasion such as blade shaving is improved, but it is not possible to prevent a decrease in film thickness due to discharge. Since the present invention can accurately predict the amount of decrease in the thickness of the image carrier due to discharge, the thickness of the image carrier corresponding to the lifetime can be reduced even in the case of an organic photoreceptor using a crosslinkable charge transport material for the protective layer. Can be set and is effective.

The present invention is characterized in that the image carrier has fluororesin particles dispersed in a protective layer.
Dispersing the fluororesin particles in the protective layer can reduce the friction coefficient of the surface and improve the durability stability against film scraping, but cannot prevent the film thickness decrease itself. Since the present invention can accurately predict the reduction in the thickness of the image carrier due to discharge, the thickness of the image carrier can be set according to the lifetime even in the case of an organic photoreceptor in which fluororesin particles are dispersed in a protective layer. Can be effective.

In the present invention, the charging device includes a charging member disposed in contact with or close to the image carrier, and a voltage is applied to the charging member by a voltage applying device disposed inside or outside the charging device. The charging device, wherein the voltage application device simultaneously applies a DC voltage and an AC voltage to the charging member, and sets the absolute value of the amplitude voltage of the AC voltage to be twice or more the absolute value of the discharge start voltage. It is characterized by.
In the roller charging method, the amount of decrease in the film thickness of the image carrier is greater when the DC voltage and the AC voltage are applied simultaneously than when only the DC voltage is applied. Therefore, it is more important to design the film thickness in consideration of the film thickness reduction amount due to charging when the DC voltage and the AC voltage are applied simultaneously. Since the present invention can accurately predict the amount of decrease in film thickness of the image carrier due to discharge, the film thickness of the image carrier can be set according to the life even when a DC voltage and an AC voltage are applied simultaneously, and this is effective. To do.

The present invention is characterized in that the process cartridge integrally supports at least the image carrier and the charging device, and has the image carrier described above and the charging device described above.
When replacing a member that contacts the image carrier, the image carrier must be touched. At this time, the gap between the charging member and the image carrier varies. When the gap varies, the intensity of the discharge varies, so even if the life of the image carrier is set with the intensity of the discharge light in the initial stage, the film thickness cannot be maintained as the lifetime is set. By integrating all the members that come into contact with the image carrier as a process cartridge, it becomes an integral replacement, and the gap does not fluctuate at the time of replacement and stable charging can be performed. The body can be used.

According to the present invention, the image forming apparatus includes at least an image carrier and a charging device or a process cartridge that integrally supports the image carrier and the charging device. It has the apparatus.
In particular, in the case of a color image forming apparatus, the charging uniformity of the image carrier is more important than a monochrome image forming apparatus. When the film thickness of the image carrier changes, the image quality deteriorates, so the film thickness design becomes important. According to the present invention, since the image forming apparatus includes the above-described image carrier and a charging device or a process cartridge, the uniformity of charging can be stably maintained, and high image quality can be maintained for a set lifetime. I made it.

According to the present invention, the image forming apparatus includes a lubricant supply device, and the lubricant is a fatty acid metal salt.
By applying a lubricant to the image carrier, mechanical abrasion due to a blade or the like can be prevented, but a reduction in the film thickness of the image carrier due to discharge cannot be prevented. The present invention is provided with a lubricant supply device, and by reducing the mechanical wear, it is possible to accurately grasp the amount of decrease in the film thickness of the image carrier due to electric discharge. Can do.

  The image forming apparatus according to the present invention is characterized in that the lubricant is zinc stearate.

  By means for solving the above problems, the present invention makes it possible to accurately predict the amount of decrease in the thickness of the image carrier due to discharge, and to set the thickness of the image carrier according to the lifetime accurately. . Further, by integrating all the members in contact with the image carrier as a process cartridge and providing the image forming apparatus, stable charging can be performed, and the image carrier can be used according to the initial lifetime setting. As a result, it was possible to reduce the frequency of maintenance, improve convenience, and reduce the cost for manufacturing the image carrier.

  The best mode for carrying out the present invention will be described below with reference to FIGS. However, these are merely embodiments and do not limit the scope of the claims of the present invention.

FIG. 1 is a schematic diagram of an image forming unit of the image forming apparatus.
The image forming apparatus 1 includes an image carrier 2, a charging member 3, an exposure unit 4, a development unit 5, a transfer unit 6, a cleaning unit 13, a charge removal unit 9, and a voltage application unit 16. The charging member 3 is a hard conductive roller. In the image formation, when the image carrier 2 is rotated clockwise and the surface of the image carrier 2 is uniformly charged by the charging member 3, the exposure unit 4 irradiates a laser modulated with image data to carry the image. An electrostatic latent image is formed on the surface of the body 2, and the electrostatic latent image is developed by attaching the toner of the developing unit 5 to the electrostatic latent image. The toner image on the surface of the image carrier 2 is transferred to the recording paper P by the transfer unit 6, and the recording paper P is conveyed to a fixing unit (not shown) to fix the toner image on the recording paper P and then onto the paper discharge tray. To be discharged. Then, the image carrier 2 is further rotated, and the toner remaining on the surface of the image carrier 2 is removed by the cleaning unit 13 with a cleaning blade, and then the surface of the image carrier 2 is neutralized by the charge eliminating unit 9. The image carrier 2 is uniformly charged again by the charging member 3 and forms the next image. The cleaning unit 13 is not limited to a cleaning blade, and may be a unit that removes residual toner on the surface of the image carrier 2 with a fur brush, for example.

FIG. 2 is a schematic diagram of a tandem type color image forming apparatus.
The tandem type color image forming apparatus includes an image carrier 2 and color developing units 5C, 5M, 5Y, and 5K in a horizontal direction, and includes an intermediate transfer unit 7 and a paper transfer unit 8. The color toner image formed on the image carrier 2 is primarily transferred to the intermediate transfer belt by the intermediate transfer unit 7 and secondarily transferred to the recording paper P conveyed to the paper transfer unit 8. The recording paper P is conveyed to a fixing unit (not shown), and after fixing the toner image on the recording paper P, it is discharged onto a paper discharge tray.

FIG. 3 is a schematic view of a revolver type color image forming apparatus.
In the revolver type color image forming apparatus, color developing units 5C, 5M, 5Y, and 5K are installed in the rotation direction of the image carrier 2, and a plurality of images are sequentially formed on the surface of one image carrier 2 by switching the operation of the developing unit. The color toner is developed. The color toner image formed on the image carrier 2 is primarily transferred to the intermediate transfer belt by the intermediate transfer unit 7 and secondarily transferred to the recording paper P conveyed to the paper transfer unit 8. The recording paper P is conveyed to a fixing unit (not shown), and after fixing the toner image on the recording paper P, it is discharged onto a paper discharge tray.

FIG. 4 is a configuration diagram of the charging member.
The charging member 3 includes a conductive base 201 and a resistance layer 202 and a protective layer 203 around the conductive base 201. The conductive substrate 201 is a stainless steel cylindrical member having a diameter of 8 to 20 [mm]. However, the conductive substrate 201 is made of aluminum or a conductive resin of 10 ² Ω · cm or less instead of stainless steel to reduce the weight. May be. The resistance layer 202 is made of a polymer material obtained by kneading a conductive material into ABS resin or the like. As the conductive material, a metal ion complex, carbon black, ionic molecule, or other material that can be uniformly charged may be used. The protective layer 203 is made of a fluorine resin.
A charging power source is connected to the charging member 3. As a result, a discharge is generated in the gap H between the surface to be charged on the surface of the image carrier 2 and the surface to be charged on the surface of the charging member 3, and the surface to be charged is uniformly charged. The applied voltage bias uses a voltage waveform in which an AC voltage is superimposed on a DC voltage, and the peak-to-peak voltage of the AC voltage is preferably at least twice the charging start voltage. Further, if necessary, a DC voltage, preferably a constant current voltage may be used.

FIG. 5 shows an example in which a gap is provided between the image carrier and the charging member.
The charging member 3 may move in the same direction as the image carrier 2 or may be stationary. The longitudinal dimension of the conductive roller shaft as the charging member 3 is set slightly longer than the length 297 [mm] of the A4 paper size which is the maximum image width.
The charging member 3 is provided with spacers 302 by winding a film around both ends in the longitudinal direction, and the spacers 302 are brought into contact with non-image forming regions at both ends of the image carrier 2 so that the surface of the image carrier 2 is charged. A slight gap is held as a gap H between the surface and the charging surface of the charging member 3 surface. Although the minimum value of the gap H is held to be 5 to 100 [μm], the optimum value of the gap H is 30 to 65 [μm]. In this embodiment, it is held at 55 [μm]. Furthermore, by pressing the conductive roller shaft with the spring 303 or the like, a slight gap can be accurately maintained.
The spacer member may be integrally formed with the charging member 3, and there is a method of winding and fixing two spacer members made of tape around the entire longitudinal direction of the charging member 3. At this time, at least the surface of the gap portion of the spacer member is preferably an insulator. When reaction products (hereinafter referred to as “discharge products”) generated during discharge, such as nitrogen oxides, are deposited in the gap portion, the electrical resistance of the surface of the image carrier 2 is lowered and the charging member 3 itself is contaminated. This is because it may cause insulation failure and charging failure.
Further, a heat shrinkable tube may be used as the spacer member, and this method is optimal at present. When a heat-shrinkable tube is used, the tube shrinks due to heat. Therefore, the charging member 3 needs to be cut in consideration of the shrinkage of the heat-shrinkable tube. For example, a Sumitube for 105 ° C. is used as the heat shrinkable tube. When the Sumitube is used, its thickness is 300 [μm], and depending on the diameter of the charging member 3 to be mounted, the Sumitube exhibits a shrinkage rate of about 50 to 60% and is about 0 to 200 [μm] due to heat. Shrink. For example, when the Sumitube is mounted on the charging member 3 having a diameter of 12 [mm], a Sumitube having a cutting depth of 350 [μm] and an inner diameter of about 15 [mm] may be used. After the Sumitube is attached to the cutting portion at the end of the charging member 3, the charging member 3 is rotated and uniformly contracted while being heated by a heat source at 120 to 130 ° C. inward from the end surface, thereby forming the charging member 3 and the image. The gap with the carrier 2 can be set to about 50 [μm]. Although the heat-shrinked and fixed Sumitube does not come off during use, for prevention, a small amount of liquid adhesive such as cyanoacrylate resin may be poured and fixed to the end.
Further, the spacer member may be a roller member by inserting a member having a diameter larger than that of the charging member 3 later.

FIG. 6 shows an example in which a step is provided at the end of the resistance layer of the charging member.
FIG. 7 shows an example in which a groove is formed while leaving a part of the end of the resistance layer of the charging member.
FIG. 8 shows an example in which a groove is formed in an arc shape while leaving a part of the end of the resistance layer of the charging member.
When a heat-shrinkable tube is used as the spacer member, the heat-shrinkable tube has a thickness. Therefore, it is desirable to cut the end portion of the charging member 3 so that the heat-shrinkable tube can be easily inserted. In FIG. 6, a step is provided at the end of the charging member 3 to facilitate insertion of the heat shrinkable tube. In FIG. 7, a groove is provided at the end of the charging member 3, and a square ring-shaped heat-shrinkable tube having endless stretchability is easily attached to the groove. In FIG. 8, an arc-shaped groove is provided at the end of the charging member 3 so that a round ring-shaped (usually referred to as an O-ring) heat-shrinkable tube can be easily attached.
In the case where the spacer member is mounted and fixed to a portion where a cut portion or a groove is formed, it is desirable to use an adhesive such as a two-component epoxy resin in addition to the cyanoacrylate resin. It is also possible to completely cut the end of the charging member 3 and fix it with an adhesive.

  FIG. 9 is a configuration diagram of an apparatus for measuring the intensity of the discharge light generated in the gap between the image carrier and the charging member 3. The image carrier 2 and the charging member 3 are rotated by a motor (not shown). For the light measuring device 31 for measuring the intensity of the discharge light, it is necessary to use a device having a high sensitivity to the wavelength of the discharge light. A CCD image sensor, an image intensifier, or a combination of these may be used. Discharge light generated in the gap between the image carrier 2 and the charging member 3 is introduced into the light measurement device 31 through the optical fiber 30. The optical fiber 30 is installed so that its light receiving axis is aligned with the contact surface between the image carrier 2 and the charging member 3. It needs to be close. Furthermore, when receiving light, it is desirable to surround the entire apparatus with a black curtain sheet or a light-shielding curtain so as not to detect indoor lighting.

  FIG. 10 is a configuration diagram of an apparatus for measuring the intensity of discharge light generated in the gap between the image carrier and the charging member in the process cartridge. Even when a process cartridge that integrally supports at least the image carrier 2 and the charging member 3 is detachably installed from the main body of the image forming apparatus 1, the intensity of the discharge light can be sufficiently measured. By allowing the process cartridge itself to be installed in this way, the intensity of the discharge light generated in the gap between the image carrier 2 and the charging member 3 can be measured in a state close to actual use conditions. The film thickness reduction amount of the image carrier can be accurately predicted.

FIG. 11 is a graph showing the spectrum of the light of the discharge light.
FIG. 11 shows the results obtained by the following experiment. As an experimental condition, the charging member 3 is a hard type conductive roller that is not in contact with the image carrier 2. The optical fiber 30 is installed at a position of about 1 cm from the gap between the image carrier 2 and the charging member 3. The light measuring device 31 uses a spectroscope having a photomultiplier tube as a detector. The spectroscope is a device for obtaining a spectrum of light of electromagnetic waves generated by discharge, and uses FP6500 manufactured by JASCO Corporation. The voltage application condition to the charging member 3 is as follows: the applied bias is AC voltage component: AC peak-to-peak voltage Vpp = 2.2 [kV], frequency f = 1.35 [kHz], DC voltage component: DC voltage = − 600 [V].
A voltage is applied to the charging member 3 to cause the charging member 3 to approach the image carrier 2 and rotate to generate a discharge, thereby charging the image carrier 2. When the image carrier 2 is exposed to discharge by the charging member 3, a light wave as an electromagnetic wave is generated in the gap between the image carrier 2 and the charging member 3. The discharge light generated in the gap is introduced into the spectroscope by the optical fiber 30 and the spectrum of the discharge light is measured.
FIG. 11 is a result obtained from the above-described experiment, and shows a light spectrum from the relationship between the wavelength of the discharge light and the light intensity. Since the light intensity is a relative value, an arbitrary unit (arbitrary.unit) is used. From this graph, it can be seen that the discharge light has a wavelength ranging from the ultraviolet region to the visible region. The ultraviolet region is a short region with a wavelength of about 10 to 400 [nm], and the visible region is a region with a wavelength of about 400 to 700 [nm] that can be sensed by the naked eye.

  FIG. 12 is a graph showing the relationship between the peak voltage Vpp of the AC voltage and the light intensity of the discharge light. As experimental conditions, the voltage application condition to the charging member 3 is an applied bias, an alternating voltage component: an alternating peak voltage is applied from Vpp = 1.4 to 3.0 [kV], and a frequency f = 1.35 [ kHz] and DC voltage component: DC voltage = −600 [V]. From FIG. 12, it can be seen that increasing Vpp increases the intensity of the discharge light. From this, it is known that the intensity of the discharge light changes depending on the voltage application condition. Since Vpp can be uniquely determined from the intensity of the discharge light, it is considered that Vpp can be controlled based on the correlation between the intensity of the discharge light and Vpp.

FIG. 13 is a graph showing the relationship between the light intensity of the discharge light and the amount of film thickness reduction of the image carrier. As experimental conditions, polycarbonate is used as the resin constituting the image carrier, the diameter of the image carrier 2 is 30 [mm], the film thickness of the photosensitive layer is 30 [μm], the relative dielectric constant is about 3, and the film thickness. The amount of decrease is a value at a usage time of 100 hours. The gap between the image carrier 2 and the charging member 3 is set to about 50 [μm], and the light receiving surface of the optical fiber 30 that receives the discharge light generated in the gap is set to a position about 30 mm away from the gap. Yes. From FIG. 13, it can be seen that the light intensity and the film thickness reduction amount of the image carrier 2 are in a proportional relationship and have a strong correlation. The relationship of FIG. 13 is constant, and is always established if the constituent material of the image carrier 2 is the same material, and the light intensity changes depending on the voltage application condition applied to the charging member 3. Therefore, once the relationship of FIG. 13 can be obtained, the amount of film thickness reduction due to discharge can be easily predicted even when the voltage application conditions are changed.
This will be described in detail below. The film thickness reduction amount d ′ [μm] of the image carrier 2 is expressed by the following formula (1) with respect to the running time h [hour] of the image forming apparatus and the circumferential length L [mm] of the image carrier 2. There is a relationship.
d ′ ∝ h · (1 / L) (1)
The preliminary film thickness d [μm] of the image carrier 2 to be set is assumed that the light intensity is I [arbitrary unit], considering that the film thickness reduction amount of the image carrier 2 is proportional to the light intensity. The following formula (2) is obtained.
d ∝ h · (1 / L) · I Equation (2)
Further, if the design margin of the image carrier thickness is 10%, the preliminary film thickness d [μm] of the image carrier 2 to be set is in the range of the following formula (3).
2.0 · h · (1 / L) · I <d <2.5 · h · (1 / L) · I
Formula (3)
On the other hand, the light intensity I depends on the optical fiber 30 and the set position of the light receiving surface of the optical fiber 30 from the gap between the image carrier 2 and the charging member 3. Therefore, when these various conditions change, it is necessary to correct the above equation (3) as the following equation (4).
2.0 · h · (1 / L) · k · I <d <2.5 · h · (1 / L) · k · I
... Formula (4)
Here, k is a correction coefficient in which the light intensity I is determined by the type of the optical fiber 30 and the set position of the light receiving surface of the optical fiber 30, and is expressed by the following equation (5).
k = 1 / I ′ (5)
However, I ′ is the gap between the image carrier 2 and the charging member 3 when the peak-to-peak voltage Vpp of the AC voltage applied to the charging member is 2.2 [kV] and the frequency is 1.35 [kHz]. This is the light intensity of the generated discharge light. If the correction coefficient k of the above equation (5) is used, the preliminary film thickness d of the image carrier 2 is accurately designed even when the type of the optical fiber 30 and the setting position of the light receiving surface of the optical fiber 30 are changed. be able to.
Finally, the designed film thickness D [μm] to be set is the minimum film thickness D1 of the image carrier 2 that can maintain a uniform charging potential to the preliminary film thickness d [μm] of the image carrier 2. Considering [μm] and the film thickness D2 [μm] that decreases due to factors other than the charging action such as mechanical wear, the following equation (6) is obtained.
D = D1 + D2 + d Formula (6)

表１中には、光強度Ｉ、設定寿命から求めた像担持体膜厚と、実際にランニングを行った際の像担持体膜厚減少量（実測値）、ブレードによる像担持体膜厚減少量Ｄ２が示されている。このとき異常画像を発生させない最低膜厚量Ｄ１は、１８［μｍ］とした。この値は予め膜厚を数種類設定して所定の一定印加電圧に対する異常画像発生の有無から決定したものである。また、Ｄ２は、帯電、現像、転写のプロセスを省き、像担持体２とクリーニングブレードのみをセットできる試験機により実測して求めた値である。また、表１における検討条件においては、そのプロセス速度からランニング時間１時間あたりプリント枚数１５００枚と換算できる。
本発明を利用して像担持体２の膜厚設定をおこなった条件１、３、４、５は画像不良を起こすことなく、設定寿命まで像担持体２を使用することができた。一方、本発明を利用しなかった条件２においては、使用寿命前に部分的に５［μｍ］以上の磨耗が発生し、その部位に対応して帯電電位が高すぎることによる白抜けや画像濃度不足といった画像不良を起こすに至った。また、本発明を利用しなかった条件６においては、不具合を起こすことなく、像担持体２を使用できたが、寿命後も膜厚に余裕がありすぎ、非効率的である。これらの結果は、本発明が像担持体２の設計方法として、信頼性の高いものであることを示している。 Table 1 shows an example of designing the film thickness of the image carrier.

In Table 1, the image carrier film thickness obtained from the light intensity I and the set life, the amount of decrease in the image carrier film thickness when actually running (actual measurement), and the image carrier film thickness reduction by the blade The quantity D2 is shown. At this time, the minimum film thickness D1 that does not generate an abnormal image was 18 [μm]. This value is determined from the presence or absence of occurrence of an abnormal image with respect to a predetermined constant applied voltage by setting several types of film thicknesses in advance. D2 is a value obtained by actual measurement with a testing machine that can set only the image carrier 2 and the cleaning blade, omitting the processes of charging, development, and transfer. Further, under the study conditions in Table 1, the number of printed sheets can be converted to 1500 sheets per hour of running time from the process speed.
Under the conditions 1, 3, 4, and 5 in which the film thickness of the image carrier 2 was set using the present invention, the image carrier 2 could be used until the set lifetime without causing image defects. On the other hand, under the condition 2 where the present invention was not used, wear of 5 [μm] or more partially occurred before the service life, and white spots and image density due to the charged potential being too high corresponding to the site. It led to image defects such as lack. Further, in condition 6 in which the present invention was not used, the image carrier 2 could be used without causing problems, but the film thickness was too large even after the service life, which is inefficient. These results indicate that the present invention is a highly reliable method for designing the image carrier 2.

FIG. 14 is a cross-sectional view of the image carrier of the present invention. A single photosensitive layer mainly composed of a charge generation material and a charge transport material is provided on a conductive support.
FIG. 15 shows a structure in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated on a conductive support.

As the conductive support 401, a conductive support having a volume resistance of 10 ¹⁰ Ω · cm or less is used. For example, metal, such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxide such as tin oxide, indium oxide, etc. coated on film or cylindrical plastic or paper by vapor deposition or sputtering Alternatively, it is possible to use a plate made of aluminum, aluminum alloy, nickel, stainless steel or the like, and a tube subjected to surface treatment such as cutting, superfinishing, or polishing after forming them into a raw tube by a method such as extrusion and drawing. An endless nickel belt or an endless stainless steel belt can also be used as the conductive support 401.
In addition, a conductive support obtained by dispersing conductive powder in an appropriate binder resin and coating the conductive support can be used as the conductive support 401 of the present invention. Examples of the conductive powder include metal powder such as carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support 401 of the present invention.

The photosensitive layer in the present invention may be a single layer type in which a charge generation material is dispersed in a charge transport layer 407, or a stacked type in which a charge generation layer 405 and a charge transport layer 407 are sequentially stacked.
First, a stacked type photoreceptor in which a charge generation layer 405 and a charge transport layer 407 are sequentially stacked will be described.
The charge generation layer 405 is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. As the charge generation material, inorganic materials and organic materials can be used.
Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, amorphous silicon, and the like. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.
On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.
The binder resin used as necessary for the charge generation layer 405 includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene. Poly-N-vinylcarbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more. In addition, a polymer charge transport material can be used as the binder resin of the charge generation layer 405. Furthermore, you may add a low molecular charge transport material as needed.
The charge transport materials that can be used in combination with the charge generation layer 405 include an electron transport material and a hole transport material, and these include a low molecular charge transport material and a high molecular charge transport material. Hereinafter, the polymer type charge transport material is referred to as a polymer charge transport material in the present invention.
Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7- Examples thereof include electron accepting substances such as trinitrodibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more.
Examples of the hole transporting material include the electron donating materials shown below and are used favorably. For example, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline , Phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials can be used alone or as a mixture of two or more.
Moreover, the polymeric charge transport material represented below can be used. Examples thereof include a polymer having a carbazole ring such as poly-N-vinylcarbazole, a polymer having a hydrazone structure, a polysilylene polymer, and a polymer having a triarylamine structure. These polymer charge transport materials can be used alone or as a mixture of two or more.
The charge generation layer 405 includes a charge generation material, a solvent, and a binder resin as main components, and may include additives such as a sensitizer, a dispersant, a surfactant, and silicone oil. Good.
Typical methods for forming the charge generation layer 405 include a vacuum thin film manufacturing method and a casting method from a solution dispersion system. As the former method, a vacuum vapor deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed. In addition, in order to provide the charge generation layer 405 by a casting method, a ball mill, an attritor or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone together with a binder resin, if necessary, the inorganic or organic charge generation material described above. It can be formed by dispersing with a sand mill or the like, and applying the solution after diluting the dispersion appropriately. For the application, a dip coating method, a spray coating method, a bead coating method, or the like can be used.
The film thickness of the charge generation layer 405 provided as described above is suitably about 0.01 to 5 [μm], preferably 0.05 to 2 [μm].

Next, the charge transport layer 407 will be described.
The charge transport layer 407 can be formed by dissolving or dispersing a mixture or copolymer mainly composed of a charge transport component and a binder component in an appropriate solvent, and applying and drying the mixture. The film thickness of the charge transport layer 407 is suitably about 10 to 100 [μm], and about 10 to 30 [μm] is appropriate when higher resolution is required.
In the present invention, examples of the polymer compound that can be used as the binder component include polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester, polyvinyl chloride, Vinyl chloride / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin , Thermoplastic or thermosetting resins such as melamine resin, urethane resin, phenol resin, alkyd resin, etc., but are not limited thereto. These polymer compounds can be used singly or as a mixture of two or more kinds, or copolymerized with a charge transport material.
Examples of the material that can be used as the charge transport material include the above-described low molecular weight electron transport materials, hole transport materials, and polymer charge transport materials. When a low molecular charge transport material is used, the amount used is 20 to 200 parts by weight, preferably about 50 to 100 parts by weight, per 100 parts by weight of the polymer compound. When a polymer charge transport material is used, a material in which the resin component is copolymerized at a ratio of about 0 to 500 parts by weight with respect to 100 parts by weight of the charge transport component is preferably used.
Examples of the dispersion solvent that can be used in preparing the charge transport layer coating solution include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve, toluene, xylene, and the like. Examples include aromatics, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate.
When the charge transport layer 407 is not provided with a filler reinforced charge transport layer 409, which will be described later, it is necessary to add a filler material at least to the surface portion of the charge transport layer 407 for the purpose of improving wear resistance. Examples of organic filler materials include fluororesin powders such as polytetrafluoroethylene, silicone resin powders, and a-carbon powders. Examples of inorganic filler materials include metal powders such as copper, tin, aluminum, and indium. , Silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, tin oxide doped with antimony, tin-doped indium oxide, etc., tin fluoride, fluorine Examples thereof include metal fluorides such as calcium fluoride and aluminum fluoride, and inorganic materials such as potassium titanate and boron nitride. Among these fillers, it is advantageous to use an inorganic material from the viewpoint of the hardness of the filler to improve the wear resistance. In particular, silica, titanium oxide, and alumina can be used effectively. Moreover, these filler materials are used individually or in mixture of 2 or more types. These fillers may be subjected to modification of the filler surface with a surface treatment agent for the purpose of improving dispersibility in the coating liquid and coating film.
These filler materials can be dispersed by using an appropriate disperser together with a charge transport material, a binder resin, a solvent and the like. The average primary particle diameter of the filler is preferably 0.01 to 0.8 [μm] from the viewpoint of the transmittance and wear resistance of the charge transport layer.
In addition, these fillers can be contained in the entire charge transport layer. However, since the exposed portion potential may be increased, the outermost surface side of the charge transport layer has the highest filler concentration and the support side has a lower value. It is preferable to provide a configuration in which the filler concentration gradient is provided, or the charge transport layer 407 is formed in a plurality of layers, and the filler concentration is sequentially increased from the support side to the surface side.
The film thickness (depth from the surface) of the inorganic filler layer contained on the surface side of the charge transport layer 407 is preferably 0.5 [μm] or more, more preferably 2 [μm] or more.

Next, the case where a filler dispersion layer is provided will be described.
FIG. 14 is a cross-sectional view of the image carrier of the present invention, in which a single-layer photosensitive layer mainly composed of a charge generation material and a charge transport material is provided on a conductive support. In this case, at least the photosensitive layer surface contains a filler.
FIG. 15 shows a structure in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated on a conductive support. In this case, at least the surface of the charge transport layer 407 contains a filler.
In FIG. 16, a single layer photosensitive layer mainly composed of a charge generation material and a charge transport material is provided on a conductive support, and a filler reinforced charge transport layer containing a filler is provided on the surface of the single layer photosensitive layer. ing.
FIG. 17 shows a structure in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated on a conductive support. A filler-reinforced charge transport layer containing a filler is provided.
When the filler-reinforced charge transport layer 409 is provided, the charge transport layer 407 is obtained by dissolving or dispersing a mixture or copolymer mainly composed of a charge transport component and a binder in an appropriate solvent, and applying and drying the mixture. Can be formed. The thickness of the charge transport layer 407 is suitably about 10 to 100 [μm], and about 10 to 30 [μm] is appropriate when resolution is required.
Examples of the binder component that can be used for the charge transport layer 407 in this case include the above-described thermoplastic or thermosetting resin. These polymer compounds can be used singly or as a mixture of two or more kinds, or copolymerized with a charge transport material.
Examples of the material that can be used as the charge transport material include the above-described low molecular weight electron transport materials, hole transport materials, and polymer charge transport materials.
If necessary, a low-molecular compound such as an appropriate antioxidant, plasticizer, lubricant, ultraviolet absorber, and low-molecular charge transport material and a leveling agent can also be added. These compounds can be used alone or as a mixture of two or more. The amount of the low molecular compound used is 0.1 to 200 parts by weight, preferably 0.1 to 30 parts by weight, and the amount of the leveling agent used is 100 parts by weight of the polymer compound. On the other hand, about 0.001 to 5 parts by weight is appropriate.

Next, the filler reinforced charge transport layer 409 will be described.
The filler-reinforced charge transport layer 409 in the present invention refers to a functional layer that includes at least a charge transport component, a binder resin component, and a filler, and has both charge transport properties and mechanical resistance. The filler-reinforced charge transport layer is characterized by exhibiting a high charge mobility comparable to the conventional charge transport layer 407, which is distinguished from the surface protective layer. The filler-reinforced charge transport layer 409 is used as a surface layer obtained by functionally separating the charge transport layer 407 in the multilayer photoconductor into two or more layers. That is, this layer is used in a laminate with the charge transport layer 407 not containing a filler, and is not used alone. For this reason, it is distinguished from the single layer of the charge transport layer 407 when the filler is dispersed in the charge transport layer as an additive.
As the filler material used for the filler-reinforced charge transport layer 409, as mentioned in the description of the charge transport layer 407, inorganic materials, particularly silica, titanium oxide, and alumina can be used effectively. Moreover, these filler materials are used individually or in mixture of 2 or more types.
For the purpose of improving the dispersibility in the coating liquid and coating film, these fillers may be subjected to modification of the filler surface with a surface treatment agent as described above. These filler materials can be dispersed by using an appropriate disperser together with a charge transport material, a binder resin, a solvent, and the like. The average primary particle diameter of the filler is preferably 0.01 to 0.8 [μm] from the viewpoint of the transmittance and wear resistance of the charge transport layer.
As the coating method, a dipping method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, a screen printing method, or the like is employed.
The film thickness of the filler-reinforced charge transport layer 409 is preferably 0.5 [μm] or more, more preferably 2 [μm] or more.

Moreover, the protective layer which consists of a crosslinked structure is also used effectively as a binder structure of a protective layer. Regarding the formation of a cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used to cause a cross-linking reaction using light or heat energy to form a three-dimensional network structure. is there. This network structure functions as a binder resin and exhibits high wear resistance.
From the viewpoint of electrical stability, printing durability, and life, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transporting site is formed in the network structure, and the function as a protective layer can be sufficiently expressed.
The reactive monomer having charge transporting ability includes a compound containing at least one charge transporting component and a silicon atom having a hydrolyzable substituent in the same molecule, and a charge transporting component in the same molecule. A compound containing a hydroxyl group, a compound containing a charge transporting component and a carboxyl group in the same molecule, a compound containing a charge transporting component and an epoxy group in the same molecule, a charge transporting component in the same molecule And a compound containing an isocyanate group. These charge transport materials having a reactive group may be used alone or in combination of two or more.
More preferably, a reactive monomer having a triarylamine structure is effectively used as the monomer having a charge transporting ability because of its high electrical and chemical stability and high carrier transfer speed.
In addition to this, monofunctional and bifunctional polymerizable monomers and polymerizable oligomers are used in combination for the purpose of viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, low surface energy, and reduction of friction coefficient. be able to. As these polymerizable monomers and oligomers, known ones can be used.
In the present invention, the hole transporting compound is polymerized or crosslinked by using heat or light. When the polymerization reaction is carried out by heat, the polymerization reaction proceeds with only the thermal energy and the polymerization initiator. However, it is preferable to add an initiator in order to advance the reaction efficiently at a lower temperature.
In the case of polymerization by light, it is preferable to use ultraviolet light as light, but the reaction rarely proceeds only by light energy, and a photopolymerization initiator is generally used in combination.
The polymerization initiator in this case mainly absorbs ultraviolet rays having a wavelength of 400 [nm] or less, generates active species such as radicals and ions, and initiates polymerization. In the present invention, the above-described heat and photopolymerization initiators can be used in combination.
The charge transport layer 407 having a network structure formed in this way has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it becomes too thick, cracks may occur. In such a case, the protective layer may be a laminated structure, a low molecular dispersion polymer protective layer may be used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure may be formed on the upper layer (surface side). Good.

Next, the case where the photosensitive layer has a single layer structure will be described.
The single-layer photosensitive layer 403 can be formed by dissolving or dispersing a charge generation material, a charge transport material, and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
As the binder resin, in addition to the binder resin previously mentioned in the charge transport layer 407, the binder resin mentioned in the charge generation layer 405 may be mixed and used. Of course, the polymer charge transport materials listed above can also be used effectively. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight. The single-layer photosensitive layer 403 is a coating solution in which a charge generation material and a binder resin are dispersed together with a charge transport material using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane by a disperser or the like. It can be formed by coating with a bead coat. The film thickness of the single photosensitive layer 403 is suitably about 5 to 25 [μm].
In a configuration in which the photosensitive layer is the outermost surface layer, it is necessary to contain a filler at least on the surface of the photosensitive layer. In this case as well, as in the case of the charge transport layer, the entire photosensitive layer can contain a filler. However, a filler concentration gradient is provided, or a configuration in which a plurality of photosensitive layers are configured, and the filler concentration is sequentially changed. It is an effective means.
In the image carrier 2 of the present invention, an undercoat layer can be provided between the conductive support 401 and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.
These undercoat layers can be formed using an appropriate solvent and coating method as in the above-described photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 20 [μm], preferably from 1 to 10 [μm].

In the present invention, in order to improve environmental resistance, in particular, each layer such as a charge generation layer 405, a charge transport layer 407, an undercoat layer, a protective layer, and an intermediate layer is used for the purpose of preventing a decrease in sensitivity and an increase in residual potential. Antioxidants, plasticizers, lubricants, ultraviolet absorbers, low molecular charge transport materials and leveling agents can be added to the above. Typical materials for these compounds include phenolic compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, and organic phosphorus compounds.
Examples of plasticizers that can be added to each layer include phosphate ester plasticizers, phthalate ester plasticizers, aromatic carboxylic ester plasticizers, aliphatic dibasic ester plasticizers, fatty acid ester derivatives, and oxyacids. Examples include ester plasticizers, epoxy plasticizers, dihydric alcohol ester plasticizers, chlorine-containing plasticizers, polyester plasticizers, sulfonic acid derivatives, and citric acid derivatives.
Examples of the lubricant that can be added to each layer include hydrocarbon compounds, fatty acid compounds, fatty acid amide compounds, ester compounds, alcohol compounds, metal soaps, and natural waxes.
Examples of the ultraviolet absorber that can be added to each layer include benzophenone, salicylate, benzotriazole, cyanoacrylate, quencher (metal complex), and HALS (hindered amine).

FIG. 18 is a schematic configuration diagram when an amorphous silicon photoconductor layer is used. In the image carrier 2 shown in FIG. 18A, a photoconductive layer 502 made of a-Si: H, X and having photoconductivity is provided on a conductive support 401. The image carrier 2 shown in FIG. 18B includes a photoconductive layer 502 made of a-Si: H, X and having photoconductivity on an electroconductive support 401, and an amorphous silicon surface layer 503. It is configured. An image carrier 2 shown in FIG. 18C has a photoconductive layer 502 made of a-Si: H, X and having photoconductivity on an electroconductive support 401, an amorphous silicon-based surface layer 503, And an amorphous silicon based charge injection blocking layer 504. In the image carrier 2 shown in FIG. 18D, a photoconductive layer 502 is provided on a conductive support 401. The photoconductive layer 502 includes a charge generation layer 405 and a charge transport layer 407 made of a-Si: H, X, and an amorphous silicon surface layer 503 is provided thereon.
The present invention is effective even when a resin in which a filler is dispersed, a cross-linked resin, amorphous silicon, or the like is used for the surface layer of the image carrier 2. That is, even in such an image carrier 2, a decrease in the film thickness of the image carrier 2 due to the friction of the blade can be substantially suppressed, and the design considering the reduction in the film thickness can be made only by using the present invention.

Next, the present invention will be described in more detail with reference to an example of manufacturing the image carrier 2.
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution on a φ30 [mm] aluminum drum in order, 3.5 [μm] An undercoat layer, a 0.2 [μm] charge generation layer 405, and a 28 [μm] charge transport layer 407 were formed. On top of that, zirconia beads were used and ground with a paint shaker for 2 hours, and the following inorganic filler coating solution was used as the coating solution. This liquid was applied by spraying to provide a filler reinforced charge transport layer 409 having a thickness of 1.5 [μm] to obtain an image carrier 2 of the present invention.
[Coating liquid for undercoat layer]
Alkyd resin (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
6 parts by weight Melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
4 parts by weight Titanium oxide (CR-EL manufactured by Ishihara Sangyo Co., Ltd.) 40 parts by weight Methyl ethyl ketone 200 parts by weight [Coating liquid for charge generation layer]
Oxotitanium phthalocyanine pigment 2 parts by weight Polyvinyl butyral (UCC: XYHL) 0.2 part by weight Tetrahydrofuran 50 parts by weight [Coating liquid for charge transport layer]
Polycarbonate resin (Z polycarbonate, viscosity average molecular weight; 50,000, manufactured by Teijin Chemicals Ltd.)
12 parts by weight Low molecular charge transport material having the chemical structural formula of FIG. 19 10 parts by weight Tetrahydrofuran 100 parts by weight 1% silicone oil (KF50-100CS Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran solution 1 part by weight [for filler reinforced charge transport layer (Coating fluid)
Polycarbonate resin (Z polycarbonate, viscosity average molecular weight; 50,000, manufactured by Teijin Chemicals Ltd.) 4 parts by weight Low molecular charge transport material having the chemical structural formula of FIG. 19 3 parts by weight a-alumina (Sumicorundum AA-03, Sumitomo Chemical) 0.7 parts by weight Cyclohexanone 280 parts by weight Tetrahydrofuran 80 parts by weight

FIG. 20 shows an example of the configuration of the lubricant supply device. A solid lubricant 601 is applied to the image carrier 2 through a rotating fur brush 602. The fur brush 602 rotates in contact with the solid lubricant 601 and scrapes a part of the solid lubricant 601. The solid lubricant 601 thus scraped off adheres to the fur brush 602 and rotates and is applied to the image carrier 2. The lubricant applied to the image carrier is made uniform by the elastic blade 603. At this time, the fur brush 602 can also serve as a cleaning fur brush, and the blade 603 can also serve as a cleaning blade.
As the solid lubricant 601, for example, a higher fatty acid metal salt such as zinc stearate can be used. Zinc stearate is a typical lamellar crystal powder, but it is preferred to use such materials as lubricants. A lamellar crystal has a layered structure in which amphiphilic molecules are self-organized, and when a shearing force is applied, the crystal is broken and slips easily along the layer. This action is effective in reducing the coefficient of friction, and the characteristics of the lamellar crystal that uniformly covers the surface of the photoreceptor upon receiving a shearing force can effectively cover the surface of the photoreceptor with a small amount of lubricant.
The inventor has clarified that the zinc stearate can be sufficiently lubricated when the film thickness is about 10 [nm]. At this time, considering that the molecular chain length of zinc stearate is about 5 [nm], the optimum coating condition is that the lubricating layer thickness is about 10 [nm] on the image carrier 2. This shows that the molecule has a sufficient effect when two molecules are oriented. That is, the results of this study indicate that zinc stearate exhibits sufficient lubricity due to the displacement between the two molecular layers. Other fatty acid metal salts such as magnesium stearate, calcium stearate, etc. also exhibit the same properties as zinc stearate and have almost the same molecular chain length, so that zinc stearate is always in the range of 10 nm in thickness. It is considered that a sufficient lubricating effect is exhibited by forming a film.

  FIG. 21 is a graph showing the difference in the film thickness reduction amount of the image carrier that occurs with respect to use conditions. The decrease in the film thickness of the image carrier 2 is mainly divided into that due to electric discharge and that due to blade friction. From FIG. 21, when zinc stearate is applied as a lubricant, image bearing due to blade friction is carried out. It can be seen that the decrease in body film thickness is almost suppressed. That is, regarding the reduction in film thickness, only the effect due to discharge needs to be considered. Therefore, the image carrier 2 used in the image forming apparatus 1 provided with the lubricant coating device can be designed in consideration of the reduction in film thickness only by using the present invention.

2 is a schematic diagram of an image forming unit of the image forming apparatus. FIG. 1 is a schematic view of a tandem type color image forming apparatus. 1 is a schematic view of a revolver type color image forming apparatus. It is a block diagram of a charging member. This is an example in which a gap is provided between the image carrier and the charging member. This is an example in which a step is provided at the end of the resistance layer of the charging member. This is an example in which a groove is formed while leaving a part of the end portion of the resistance layer of the charging member. This is an example in which a groove is formed in an arc shape while leaving part of the end portion of the resistance layer of the charging member. FIG. 3 is a configuration diagram of an apparatus for measuring the intensity of discharge light generated in a gap between an image carrier and a charging member. FIG. 3 is a configuration diagram of an apparatus for measuring the intensity of discharge light generated in a gap between an image carrier and a charging member in a process cartridge. It is the graph which showed the spectrum of the light of discharge light. It is the graph which showed the relationship between the peak voltage Vpp of alternating voltage, and the light intensity of discharge light. 3 is a graph showing the relationship between the light intensity of discharge light and the amount of film thickness reduction of the image carrier. FIG. 2 is a cross-sectional view of an image carrier in which a single-layer photosensitive layer mainly composed of a charge generation material and a charge transport material is provided on a conductive support. FIG. 2 is a cross-sectional view of an image carrier in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated on a conductive support. An image carrier in which a single-layer photosensitive layer mainly composed of a charge generation material and a charge transport material is provided on a conductive support, and a filler-reinforced charge transport layer containing a filler is provided on the surface of the single-layer photosensitive layer. FIG. It has a structure in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material are laminated on a conductive support, and further contains a filler on the charge transport layer. It is sectional drawing of the image carrier provided with the filler reinforcement | strengthening charge transport layer. It is a typical block diagram at the time of using an amorphous silicon photoreceptor layer. It is the figure which showed the chemical structural formula which a low molecular charge transport material has. It is an example of a lubricant supply device configuration It is the graph which showed the difference in the film thickness reduction amount of the image carrier generate | occur | produced with respect to use conditions.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image carrier 3 Charging member 4 Exposure part 5 Development part 5C, 5M, 5Y, 5K Color development part 6 Transfer part 7 Intermediate transfer part 8 Paper transfer part 9 Static elimination part 13 Cleaning part 16 Voltage application part 20 Process Cartridge 30 Optical fiber 31 Optical measuring device 32 Fixing jig 201 Conductive substrate 202 Resistive layer 203 Protective layer 302 Spacer 303 Spring 401 Conductive support 403 Single layer photosensitive layer 405 Charge generation layer 407 Charge transport layer 409 Filler reinforced charge transport layer 502 Photoconductive layer 503 Amorphous silicon-based surface layer 504 Amorphous silicon-based charge injection blocking layer 600 Solid lubricant 602 Far brush 603 Blade

Claims (11)

  The image carrier has a charging member disposed in contact with or close to the image carrier, and a voltage is applied to the charging member to generate a discharge in the gap between the charging member and the surface of the image carrier, thereby generating an image. An image carrier comprising a charging device for uniformly charging the carrier, wherein the film thickness of the image carrier is set according to the characteristics of light intensity of light generated in the gap. The film thickness of the image carrier is set to D = D1 + D2 + d according to the characteristic of light intensity generated in the gap between the image carrier and the charging member. Item 2. The image bearing member according to Item 1.
Here, D is the designed film thickness D [μm], D1 is the minimum film thickness D1 [μm] of the image carrier capable of maintaining a uniform charging potential, and D2 is the film thickness that decreases due to factors other than the charging action. D2 [μm]. d is a preliminary film thickness d [μm] set in preparation for the expected film thickness reduction due to electrification, and is expressed as follows.
2.0 · h · (1 / L) · k · I <d <2.5 · h · (1 / L) · k · I
Here, h is the running time, h [hours], L is the circumferential length L [mm] of the image carrier, and I is the light intensity I [arbitrary] generated in the gap between the image carrier and the charging member. Unit]. K is a correction coefficient for determining the light intensity I depending on the photodetector and the position of the detector, and is expressed as follows.
k = 1 / I '
However, I ′ is generated in the gap between the image carrier and the charging member when the peak-to-peak voltage Vpp of the AC voltage applied to the charging member is 2.2 [kV] and the frequency is 1.35 [kHz]. This is the light intensity [arbitrary unit].   The image carrier according to claim 1, wherein the image carrier contains at least polycarbonate or polyarylate as a resin for forming a protective layer.   4. The image carrier according to claim 1, wherein the image carrier comprises an organic photoreceptor having a protective layer in which a filler is dispersed.   5. The image carrier according to claim 1, wherein the protective layer of the image carrier is a cross-linked charge transport material.   6. The image carrier according to claim 1, wherein the image carrier has fluorine resin particles dispersed in a protective layer.   The charging device includes a charging member disposed in contact with or close to the image carrier, and applies a voltage to the charging member by a voltage applying device disposed inside or outside the charging device. The voltage application device applies a DC voltage and an AC voltage simultaneously to the charging member, and sets the absolute value of the amplitude voltage of the AC voltage to be twice or more the absolute value of the discharge start voltage. The charging device according to claim 1.   8. A process cartridge comprising: an image carrier according to claim 1; and a charging device according to claim 7, wherein the process cartridge integrally supports at least the image carrier and the charging device. Cartridge.   The image forming apparatus includes at least an image carrier and a charging device or a process cartridge that integrally supports the image carrier and the charging device, and the image carrier according to any one of claims 1 to 6 and claim 7. An image forming apparatus comprising the charging device.   The image forming apparatus according to claim 9, wherein the image forming apparatus includes a lubricant supply device, and the lubricant is a fatty acid metal salt. 11. The image forming apparatus according to claim 9, wherein the lubricant is zinc stearate.

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