JP5084225B2 - Image forming apparatus and image forming method - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus and an image forming method used for a copy, a printer, and the like, and in particular, corrects an image forming condition for preventing a ghost image from occurring due to a difference in surface potential of an image carrier and a difference in toner adhesion amount. The present invention relates to an image forming apparatus and an image forming method.

  Conventionally, an electrophotographic apparatus generally irradiates a uniformly charged photosensitive member with writing light modulated by image data to form an electrostatic latent image on the photosensitive member. The developing unit supplies toner to the formed photoreceptor, forms a toner image on the photoreceptor and develops it, and transfers the toner image on the photoreceptor to the transfer unit (recording paper or intermediate transfer member). The toner transferred onto the transfer paper at the fixing unit is fixed by heating and pressurizing, and the toner remaining on the surface of the photoreceptor is scraped off by a cleaning blade at the cleaning unit and collected and cleaned. . The image forming process as described above is taken.

  In order to maintain a stable image density, process control is performed in which an image forming condition is changed from a detection result using a sensor. The types of sensors include a potential sensor that detects the surface potential on the photoconductor, a photosensor (P sensor) that detects the toner adhesion amount on the photoconductor and the transfer belt, and a toner that detects the toner concentration of the developer in the developer. There is a density sensor (T sensor).

  In process control, surface potential, toner supply, γ characteristics, and the like necessary for image formation are controlled.

  Since current process control uses image density as the primary target, corrections for abnormal images are not actively performed, but there are cases where abnormal conditions can be prevented by selecting conditions that do not affect image density. There are many.

  A ghost image in a halftone image is an abnormal image caused by uneven surface potential of the photoreceptor. If a charge history remains in the next image forming position where the toner is developed on the photoreceptor, the remaining history appears as a density difference. This phenomenon is particularly seen in halftone images that are strongly influenced by the potential difference.

  As the types of afterimages, there are a positive afterimage in which the density of toner is first developed at a location where the toner is developed, and a negative afterimage in which the potential of the location where toner is first developed increases and the density becomes lower than that of the surrounding.

  Numerous methods have been proposed for removing the photoreceptor potential difference that causes ghost images (afterimages) in halftone.

  For example, Patent Document 1 proposes a method that has afterimage recognition means and outputs an image for removing afterimages when an afterimage is detected by repeating a large amount of image formation.

  Further, Patent Document 2 discloses the charging device grid voltage, developing voltage, discharge lamp light amount, etc. for each circumference of the photoconductor based on the photoconductor film thickness, image formation standby time, photoconductor temperature, photoconductor prescription, and production lot. In other words, a method for stabilizing the surface potential and making the image density constant has been proposed.

  Further, Patent Document 3 proposes a method of eliminating static electricity by irradiating light between transfer and cleaning.

In Patent Document 4, an electrode in contact with the surface of the photoconductor is installed between the transfer unit and the charger, and a voltage having the same polarity as the charging potential of the surface of the photoconductor is applied on the upstream side of the charger. A method for removing afterimages has been proposed.
JP 2005-165229 A Japanese Patent Laid-Open No. 5-289458 Japanese Patent No. 3331219 JP-A-5-173460

  However, in Patent Document 1, when an afterimage is detected, an image for removing the afterimage (solid image) is output. However, image formation stops during continuous output, and productivity is reduced. Further, when afterimages frequently occur, there is a problem such as an increase in toner consumption.

  In Patent Document 2, the image forming conditions are changed for each circumference in accordance with the creation conditions of the photoconductor and the standby state. However, the photoconductor conditions vary widely, and the afterimage may not be removed.

  In Patent Document 3, static elimination is performed by light irradiation between transfer and cleaning. However, in the case of reversal development using negatively charged toner, many positive charges are trapped at the time of transfer, and a negatively charged photoreceptor. In this case, since it is a negative charge that can be neutralized by light irradiation, in that case, there is a high possibility that the effect is not seen.

  In Patent Document 4, an electrode in contact with the photosensitive member is provided. However, there is a problem that it is impossible to deny the possibility that toner that could not be cleaned adheres to this portion and potential unevenness occurs.

  The present invention has been made in consideration of the above-described circumstances, and detects an occurrence of a ghost image in a halftone and corrects an image forming condition so that the ghost image in a halftone is hardly generated. It is another object of the present invention to provide an image forming method.

In order to solve the above problems, an image forming apparatus according to the present invention includes at least a charging unit that uniformly charges an image carrier and a latent image forming unit that forms a latent image on the uniformly charged image carrier. A developing unit that develops the latent image with toner, a transfer unit that transfers the toner on the image carrier to the transfer target, a detection unit that detects occurrence of a ghost image on the image carrier, and the detection result A surface potential meter capable of measuring the surface potential of the pattern formed on the image carrier, and a toner generated on the surface of the image carrier. It has a photosensor capable of measuring the difference in adhesion amount, and the correcting means is charged when either the value measured by the surface electrometer or the value measured by the photosensor is not within a predetermined specified value. The charging current value in the means is If it is within the plurality of first setting values as a result of the determination, the charging current is corrected to a predetermined value, while the plurality of first setting values are determined. If the value is not within the value, it is determined whether the value of the transfer current in the transfer unit is within a predetermined second set value. If the value is within the second set value as a result of the determination, the transfer current is set to a predetermined value. On the other hand, if the current value is not within the second set value, the charging current and the transfer current are not corrected. The charging current is corrected by dividing the charging current control area into a plurality of charging devices. It is characterized by being controlled by sharing.

The image forming method of the present invention includes at least a charging step for uniformly charging the image carrier, a latent image forming step for forming a latent image on the uniformly charged image carrier, and the latent image as a toner. A development process for developing the toner, a transfer process for transferring the toner on the image carrier to the transfer target, a detection process for detecting occurrence of a ghost image on the image carrier, and an image forming condition based on the detection result In the detection step, the surface potential of the pattern formed on the image carrier is measured by a surface potential meter, and the difference in the amount of toner adhered to the surface of the image carrier is measured by a photosensor. In the measurement and correction step, the value of the charging current in the charging step is determined in advance when either the value measured by the surface electrometer or the value measured by the photosensor is not within a predetermined specified value. Multiple It is determined whether the current value is within one set value. If the result of the determination is that the current value is within a plurality of first set values, the charging current is corrected to a predetermined value. It is determined whether the value of the transfer current in the process is within a predetermined second set value, and if the result of the determination is within the second set value, the transfer current is corrected to a predetermined value, while the second If it is not within the set value, the charging current and transfer current are not corrected, and the charging current correction is controlled by dividing the charging current control area into a plurality of parts and sharing them with each charger in the charging process. It is characterized by that.

  According to the present invention, charging means for uniformly charging the image carrier, latent image forming means for forming a latent image, developing means for developing the latent image using toner, and toner on the carrier are provided. In an electrophotographic image forming apparatus having a transfer means for transferring to a transfer target, a means for detecting the occurrence of a ghost image in halftone based on a difference in surface potential of the image carrier and a difference in toner adhesion amount, and whether a ghost image is generated A potential difference detected by a potential sensor or a photosensor with respect to a ghost image in halftone by an image forming apparatus characterized by having a means for forming a pattern for confirming the image and correcting the image forming condition from the detection result It is possible to suppress the occurrence of abnormal images by correcting at least one of the charging current or the transfer current based on at least one of the toner adhesion amount differences detected in Step 1. That.

Hereinafter, an image forming apparatus of the present invention will be described in detail with reference to the drawings.
As a result of intensive investigations to solve the above-mentioned problems, the present inventor detects the occurrence of a ghost image in a halftone (so-called intermediate color), and changes the image forming conditions for charging and transfer using the detection result. As a result, generation of a ghost image in halftone can be suppressed, and the reliability of the electrophotographic apparatus has been dramatically improved, and the present invention has been completed. A ghost image is considered not to occur from the beginning, and is a phenomenon that occurs after the photoconductor repeats copying, for example, several tens of thousands of times.

  As a cause of the ghost image generation, in the transfer process in which a positive voltage is applied to move the toner to the transfer paper, a difference occurs in the amount of charge captured by the photoconductor at a location where the toner is not present on the photoconductor. In the image forming process, an unnecessary potential difference occurs. The potential difference that should not exist originally becomes a difference in toner adhesion amount during development, and appears as an image density difference. The image of the density difference that appears is a ghost image.

  FIG. 1 shows an example of a configuration of an electrophotographic image forming apparatus having a configuration in which a surface potentiometer for measuring the potential of a photoreceptor surface after exposure and after transfer is attached as an evaluation of a ghost image in halftone. As shown in FIG. 1, the image forming apparatus includes a charging device 1 that uniformly charges an image carrier, an image exposure system 2 that forms a latent image on the uniformly charged image carrier, and an image carrier. A surface potential meter 3 for measuring the surface potential, a developing device 4 for developing the latent image with toner, a transfer device 6 for transferring the toner on the image carrier to the transfer target, and removing the toner on the image carrier. It has a cleaning device 7 (consisting of a cleaning brush 7a, an elastic rubber cleaning blade 7b, etc.), a static elimination device 8 for neutralizing the image carrier, and a photoconductor 9 as an image carrier.

  Using such an image forming apparatus, for example, using an image forming apparatus after forming 10,000 images, the image shown in FIG. 2 is formed twice, and a ghost image in halftone is evaluated and formed in the present invention. Correct the image conditions. FIG. 3 shows the output result of each surface electrometer when the potential is measured using the image forming apparatus configured as shown in FIG. 1 when the image forming conditions are corrected using such an image forming apparatus. Show.

  As shown in FIG. 3, the change in the surface potential of the photoconductor is shown at the ghost image generation position in the halftone in the second cycle in the photoconductor 9. The surface potential was measured using a Trek surface potential meter Model344.

  As shown in FIG. 3, the history of the portion where the potential dropped in the pattern of the first round of the photoreceptor remains at the next image formation and appears as the surface potential difference, resulting in a ghost image. This is an example in which the appearance of such a ghost image can be grasped as a surface potential difference by the surface potential meter 3 of FIG.

  Further, FIG. 4 shows the amount of toner adhering on the photosensitive member 9 by measuring the amount of light reflected from the light emitting portion irradiated onto the photosensitive member on which the toner image is formed, as shown in FIG. The structure of the apparatus which provided the photo sensor 5 which can detect this is shown. The photo sensor is provided in order to measure the toner adhesion amount difference caused by the above-described potential difference.

  As a photosensor used here, an infrared light emitting diode such as GaAs is used as a light emitting element, and a light receiving element is an example employing a combination of a Si phototransistor or a Si photodiode. In the present invention, a photosensor including a light emitting element and a light receiving element is used as described above.

Similarly, FIG. 5 shows a photosensor output when an image is formed using the pattern shown in FIG.
Similar to the result of the surface electrometer, it can be seen that a ghost image in halftone can be detected by the difference in the toner adhesion amount in the photosensor output shown in FIG. 5 (see the portion Z in FIG. 5). As described above, in the present invention, it is considered that generation of a ghost image in a halftone can be suppressed by detecting at least one output of a surface electrometer or a photosensor and controlling an image forming condition. That is, as shown in the pattern of the first round in FIG. 3, the plateau portion (see A in FIG. 3) near 800V is a white portion of the typical pattern in FIG. → White → Black → White → Black → White → Black After the window-like pattern, it becomes white and then a halftone image. 3 is repeated from the vicinity of 800V to the vicinity of 200V → 800V... (See B to H in FIG. 3), and then the pattern of the vicinity of 800V is once obtained (FIG. 3). After that, the voltage drops to around 520 V (see J in FIG. 3), stays near this potential for a while, and the first week is over. At the beginning of the second week, the voltage drops from around 520 V to around 480 V, and then swings so that the upper potential oscillates at about 510 to 520 V and the lower potential about 480 to 490 (see “ (See “Ghost image location in halftone”). In order to correspond to this, in FIG. 5 showing the photosensor output, a plateau portion having a photosensor output of around 4 V is seen corresponding to the plateau portion around 800 V shown in FIG. 3 (see A in FIG. 5). In addition, with the surface potential of FIG. 3, after repeating from 800V near 200V → 800V... At once, corresponding to 800V once, 4V to 1V → 4V. In response to the pattern once in the vicinity of 800V in FIG. 3 after that (see B to H in FIG. 5), the plateau portion in the vicinity of 2V after the plateau portion in 4V (see I in FIG. 5) in FIG. (See J in FIG. 5) and it can be seen that they correspond to each other. Also in FIG. 5, the fluctuation of the photosensor output in the range of about 2 to 2.3 V similar to the fluctuation of the potential as in the “ghost image generation position in halftone” of FIG. 3 could be found. . This shake is a portion corresponding to a portion detected as a ghost image similar to the “ghost image generation position in halftone” in FIG.

  FIG. 6 is a diagram showing a configuration of an electrophotographic apparatus as an example of an image forming apparatus provided with a halftone ghost image detecting means. As shown in FIG. 6, the photosensitive member 9 is charged (uniformly) to (±) 600 to 1400 V by the charging device 1. A latent image is formed by the image exposure system 2 after a charge is imparted (charged) to the photoconductor by this charging. In the case of an analog copying machine, a document image irradiated by an exposure lamp is projected onto a photoconductor in the reverse image form, and in a digital copying machine, a document image read by a CCD (charge coupled device) is 400. It is converted into a digital signal by an LD or LED of ˜780 nm and imaged on the photoreceptor. Although the wavelength range of analog and digital is different, charge separation is performed in the photosensitive layer by image formation, and a latent image is formed on the photoreceptor. The photosensitive member 9 on which the latent image has been formed corresponding to the original is developed with a developer in the developing device 4 and the current draft image is developed (development with toner: toner image).

  Next, the toner image (development image) on the photosensitive member is transferred to the copy paper 10 by the transfer device 6 and sent to the fixing device 11 where it is fixed by being pressurized and heated to form a hard copy. On the other hand, after transfer of the developed image, the photoreceptor 9 is cleaned with the cleaning device 7 (consisting of a cleaning brush 7a, an elastic rubber cleaning blade 7b, etc.) and the toner image (residual toner) after being transferred to the copy paper 10 is cleaned. 9 is cleaned. Since the latent image (original image) after the toner image is formed is held on the photosensitive member 9 after the cleaning, the static eliminator is used to erase and make uniform the remaining image of the held latent image. Static electricity is removed at 8 (generally red light is used), and preparation for the next latent image formation is completed, and a series of copying processes is completed. As shown in FIG. 6, the surface electrometer 3 is positioned after the charging process, and the photosensor 5 is positioned after the developing process.

  Next, a method for detecting a ghost image in halftone in such an image forming apparatus will be described.

  At least one of a potential sensor or a photosensor is used as a sensor that is a detection unit that detects a ghost image in halftone. As for the sensor mounting position, the potential sensor 3 is provided between the rear of the exposure system 2 and the developing device 4, and the photosensor 5 is mounted from the developing device 4 to the transfer device 6.

  The measured value of the potential sensor 3 is obtained by using, for example, a sensor whose surface potential is measured from a change in capacitance between the electrode and the object generated by vibrating a diaphragm inside the sensor facing the object to be measured. The potential is measured. An electric signal of the photoreceptor surface potential obtained from the potential sensor is converted into a standardized value so that it can be easily handled. FIG. 7 is a diagram showing the relationship between the photoreceptor surface potential and the potential sensor output. However, a developing bias potential of 550 V is applied to the surface potential of the photoreceptor shown in FIG. 3, and the surface potentials of white (near 800 V) and black (near 200 V) vary. Since the difference in the toner adhesion amount due to development hardly occurs, the ghost phenomenon does not appear even if there is a potential difference. On the other hand, since the potential difference in the halftone image is highly sensitive to the toner adhesion amount, if a potential difference of 30 V is generated, a ghost image appears as a large density difference when developed.

  A photosensor used in the present invention as a sensor that is a detecting means for detecting a ghost image in halftone has a light emitting part and a light receiving part as shown in FIG. 8, for example, and is emitted from the light emitting part. A ghost image can be obtained as shown in FIG. 5 by irradiating the detected light onto the detection surface, and detecting and measuring the reflected light by the light receiving unit (see A in FIG. 5).

  Since the toner used this time is black, the greater the amount of adhesion to the photoreceptor, the less reflected light from the photoreceptor, and the tendency is as shown in FIG. Based on the output result of each sensor as shown in FIG. 9, a ghost image in halftone can be detected.

  Next, a ghost image suppression method (image forming method) by correcting the image forming conditions will be described.

  It has been confirmed that ghost images are generated due to differences in imaging conditions. The cause of the difference in image density is the photoreceptor potential difference, but the mechanism causing the potential difference is still unclear. For example, as shown in FIGS. 10 and 11, from the examination results so far, the current (transfer current) applied at the time of transfer is increased (FIG. 10), and the current (charge current) at the time of charging is increased (FIG. 10). 11) can be improved. In the exposed area where the potential has dropped, positive charges are more likely to enter the photoconductor during transfer than in unexposed areas, and the trapped positive charges remain completely unreleased during charging, resulting in a potential difference from the unexposed areas. It is considered that ghost images are generated. As a result of the investigation up to now, it has been confirmed that a ghost image is generated with a potential difference of 30V.

  FIG. 10 is an example showing the relationship between the transfer current value and the ghost image, and FIG. 11 is an example showing the relationship between the charging current value and the ghost image. These relationships vary with time depending on the frequency of use of the photoconductor, and the degree of change varies among the types of photoconductors, and there is a slight difference even with the same product type, so only an example of the tendency is shown. . Therefore, as described above, it can be said that there is a tendency that when the current (transfer current) applied at the time of transfer is increased, it is deteriorated, and it can be improved by increasing the current at the time of charging (charge current).

  Next, an image forming method by correcting a ghost image using the image forming apparatus of the present invention will be described with reference to a flowchart. FIG. 12 is a flowchart showing the flow of correction. In the following description, it is assumed that the ghost image is reduced using the patterns shown in FIGS. 13 and 14 as the ghost detection pattern.

  The pattern portion potential after these detection patterns are imaged is measured using, for example, a potential sensor. An allowable lower limit of a potential difference that generates a ghost image is set in advance, and correction is performed when a value exceeding the set value is detected.

  Further, even if the surface potential difference of the ghost image does not exceed the lower limit, the toner adhesion amount difference is detected by the photo sensor thereafter, and correction is performed when the lower limit value that similarly appears as the density difference is exceeded.

  As a correction method, first, the set value of the charging current is confirmed. If it is within the settable range, the value of the charging current is changed, and the ghost detection pattern is imaged and detected again. Further, when the charging current is in a non-settable range, the transfer current setting is confirmed, and when it is within the settable range, correction is performed. If both the charging current and the transfer current are outside the settable range, nothing is done and the execution ends.

  More specifically, for example, as shown in FIG. 12, at the time of starting the image formation of the ghost detection pattern, the pattern portion potential after the image formation of the detection pattern of the photosensitive member is first measured using a potential sensor. (Step S01). As a result, it is determined whether or not the surface potential difference is within a specified value (step S02). If it is within the specified value (Yes in step S02), it is then determined whether or not the difference in adhesion amount is within the specified value based on the value detected by the photosensor (step S03). Then, in the case of No in step S02 described above and in the case of No in step S03, it is determined whether or not the charging current value is within the set range (step S04). If it is within the settable range (Yes in step S04), the charging current is corrected (step S05).

  In the image forming method of the present invention, an example using both step S02 and step S03 has been shown. However, for example, a method using only the detection unit of step S02 or a method using only the detection unit of step S03 can be used. .

  In the present invention, it is determined in step S04 whether or not it is within the charging current set value. However, this set value may be provided as a plurality of threshold values and controlled.

  For example, the main charger 1 can control the charging current value up to 1000 μA as shown in FIG. 11, and up to 1600 μA can be controlled by the precharger when exceeding this value. In this way, for example, by controlling the charging current value by dividing the charging current control region into a plurality of parts and sharing them with each charger, the ghost image can be controlled to be reduced.

  In this charging current control, for example, as shown in FIG. 4, it is possible to control by changing the charging current value of the main charger 1, but the main charger 1 makes the photoconductor 9 substantially uniform. In many cases, the main charger 1 has a function of charging. Therefore, at least one of a precharger 12 or a postcharger (not shown) is provided in the front stage or the rear stage of the main charger 1, and the precharger 12 or the postcharger is provided. Can be executed to pre-charge or post-charge as a control system for controlling the ghost image. The number of prechargers 12 or postchargers for charging may be plural. As described above, the present invention includes a method of using a precharger or a postcharger other than the main charger for reducing ghost images and an invention of an image forming apparatus.

  In this example, there are two examples: the surface potential during charging and the toner adhesion amount during development, and two charging currents and transfer currents as control targets. However, either one may be used for each target. Good. If the transfer current is changed, an abnormal image tends to be generated due to a transfer failure or the like, so that only correction with the charging current can be performed. This control may be performed after a certain number of images are formed (for example, after about 10,000 images), but it is also possible to create a pattern between the images before the limited number of images and perform detection and correction.

  Next, the electrophotographic photoreceptor used in the present invention will be described. FIG. 15 is a schematic cross-sectional view of an electrophotographic photoreceptor used in the present invention, which is a functional separation constituted by laminating a charge generation layer 91 and a charge transport layer 92 containing inorganic fine particles on a conductive support 90. Having a photosensitive layer of the mold. In FIG. 16, an undercoat layer 93 is provided between a conductive support 90 and a photosensitive layer comprising a charge generation layer 91 and a charge transport layer 92 containing fine particles. In FIG. 17, a protective layer 94 containing fine particles is laminated on the charge transport layer 92.

Examples of the conductive support 90 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. The metal oxide of the above is coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel or the like and extruded by drawing or drawing. After pipe formation, surface treatment pipes such as cutting, superfinishing, and polishing can be used. Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 can also be used as the conductive support.

  In addition, a material obtained by dispersing conductive powder in an appropriate binder resin and coating it on the support can also be used as the conductive support 90 of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done. 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 of the present invention.

  The charge generation layer 91 is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. A known material can be used as the charge generating substance. 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 a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Jigoido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  Binder resins used as necessary for the charge generation layer 91 include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly- N-vinyl carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more. Moreover, you may add a low molecular charge transport material as needed.

  The charge transport materials that can be used together with the charge generation layer 91 include an electron transport material and a hole transport material.

  Examples of the electron transporting 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-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-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.

  The charge generation layer 91 includes a charge generation material, a solvent, and a binder resin as main components, and includes any additive such as a sensitizer, a dispersant, a surfactant, and silicone oil. Also good.

  Methods for forming the charge generation layer 91 include a vacuum thin film manufacturing method and a casting method from a solution dispersion system. As the former method, a vacuum 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 by a coating method such as casting, a ball mill using the above-described inorganic or organic charge generation material together with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone. It can be formed by dispersing with an attritor, sand mill, etc., and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

  The film thickness of the charge generation layer 91 provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

  The charge transport layer 92 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 thickness of the charge transport layer is suitably about 10 to 100 μm, and about 10 to 30 μm is appropriate when resolution is required.

  In the present invention, examples of the polymer compound that can be used as the binder component of the charge transport layer 92 include polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, and polyester. , Polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate (bisphenol A type, bisphenol Z type, etc.), cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl Examples include thermoplastic or thermosetting resins such as formal, polyvinyl toluene, acrylic resin, silicone resin, fluororesin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. But it is 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 and hole transport materials. The amount of the charge transport material used is 20 to 200 parts by weight, preferably about 50 to 100 parts by weight, based on 100 parts by weight of the polymer compound.

  Examples of the dispersion solvent that can be used when preparing the coating solution for the charge transport layer 92 include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve, toluene, and xylene. And aromatics such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate.

  For example, a method of adding a leveling agent to the charge transport layer 92 is effective as a method for reducing the unevenness of the film thickness. As the leveling agent, a known material can be used, but a silicone oil-based leveling agent that can impart a high level of smoothness in a small amount and has a small influence on electrostatic characteristics is particularly preferable. Examples of silicone oils include dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen polysiloxane, cyclic dimethyl polysiloxane, alkyl modified silicone oil, polyether modified silicone oil, alcohol modified silicone oil, fluorine modified silicone oil, amino modified. Examples include silicone oil, mercapto-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, higher fatty acid-modified silicone oil, and higher fatty acid-containing silicone oil. It is also possible to reduce the unevenness depending on the coating conditions. For example, in dip coating, when the surface of the coating film is still wet after it has been lifted, unevenness is reduced by covering it with a hood so that the surface is not disturbed by the flow of wind. The

  Further, when the charge transport layer 92 becomes the outermost surface layer of the photoreceptor, inorganic fine particles are contained in the surface portion of the charge transport layer. Inorganic fine particle materials include copper, tin, aluminum, indium and other metal powders, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide, Examples thereof include metal oxides such as indium oxide doped with tin, metal fluorides such as tin fluoride, calcium fluoride, and aluminum fluoride, and inorganic materials such as potassium titanate and boron nitride. Among these fine particles, the use of an inorganic material is advantageous for improving the wear resistance from the viewpoint of the hardness of the fine particles. In particular, silica, titanium oxide, and alumina can be used effectively. These fine particle materials are used alone or in combination of two or more.

  Further, together with the inorganic fine particles, fluorine resin powder such as polytetrafluoroethylene, silicon resin powder, a-carbon powder and the like may be contained.

  These fine particle materials can be dispersed together with a charge transport substance, a binder resin, a solvent and the like by using an appropriate disperser. The average primary particle diameter of the fine particles is preferably 0.01 to 1.0 μm, and more preferably 0.05 to 0.5 μm from the viewpoint of the transmittance and wear resistance of the charge transport layer.

  Although it is possible to contain these fine particles in the entire charge transport layer, since the exposed portion potential may be high, the outermost surface side of the charge transport layer has the highest fine particle content, and the support side is It is preferable to provide a structure in which a fine particle concentration gradient is provided so as to be lowered, or a plurality of charge transport layers are provided so that the fine particle concentration is gradually increased from the support side to the surface side.

  If necessary, an undercoat layer 93 may be provided between the conductive support and the photosensitive layer (see FIG. 16). The provided undercoat layer is provided for the purpose of improving adhesiveness, preventing moire, improving the coatability of the upper layer, and reducing residual potential. The undercoat layer generally contains a resin as a main component, but these resins are resins having a high resistance to dissolution in general organic solvents in consideration of applying a photosensitive layer thereon using a solvent. It is 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, alkyd-melamine resin, and epoxy resin. And a curable resin that forms a three-dimensional network structure. Further, fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be dispersed and contained. These undercoat layers can be formed using a suitable solvent and coating method.

  Furthermore, a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful as the undercoat layer 93 of the present invention.

In addition, the undercoat layer 93 of the present invention is formed by anodizing Al ₂ O ₃ , organic materials such as polyparaxylylene (parylene), 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. The thickness of the undercoat layer is suitably from 0.1 to 20 μm, preferably from 1 to 10 μm.

  In the photoreceptor of the present invention, the protective layer 94 may be provided on the photosensitive layer (see FIG. 17). Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, aryl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, polyarylate, AS (acryl-styrene) resin, butadiene-styrene copolymer And resins such as polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin.

  When a protective layer is used, a fine particle material may be added to the protective layer, and the fine particle material includes an organic fine particle material and an inorganic fine particle material. Examples of the organic fine particle material include fluororesin powder such as polytetrafluoroethylene, polyethylene wax, silicone resin powder, a-carbon powder, etc., and examples of the inorganic fine particle material include copper, tin, aluminum, and indium. Metal powder, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide, tin-doped indium oxide and other metal oxides, tin fluoride Metal fluorides such as calcium fluoride and aluminum fluoride, and inorganic materials such as potassium titanate and boron nitride.

Since the fine particles made of an inorganic pigment have higher hardness than the fine particles made of an organic material, the abrasion resistance of the outermost layer of the photoreceptor can be further improved. However, generally, when the wear resistance of the latent image carrier is improved, the surface portion of the latent image carrier is hardly worn, but the surface portion is caused by reactive gases such as ozone and NOx generated during charging. It is known that the resistance is lowered, the electrostatic charge on the surface portion is gradually not retained, and the electrostatic charge moves toward the surface. As a result, the electrostatic latent image is blurred and an abnormal image called image blur or image flow that occurs when the electrostatic latent image is developed with toner or the like occurs. The fine particles used in the present invention preferably have a high resistance of 10 ¹⁰ Ωcm or more. By using such fine particles, the resistance of the outermost layer of the latent image carrier can be reduced, and the occurrence of the abnormal image can be greatly suppressed.

  Among these fine particles, silica, titanium oxide, and alumina can be used effectively. In addition, since these fine particle materials are cheaper and easier to obtain than other metal oxide fine particles, the manufacturing cost of the latent image carrier can be reduced.

  Among these, α-type alumina, which has a hexagonal close-packed structure with high insulation, high thermal stability, and high wear resistance, is particularly useful in terms of suppressing image blur and improving wear resistance. . Such fine particle materials may be used alone or in admixture of two or more.

  These fine particle materials can be dispersed using a conventional method such as a ball mill, an attritor, a sand mill, or an ultrasonic wave together with a charge transport material, a binder resin, a solvent, and the like. The average primary particle diameter of the fine particles is preferably 0.1 to 1.0 μm from the viewpoint of the transmittance of the protective layer and the like and the wear resistance. In addition, the addition of the charge transport material mentioned in the charge transport layer to the protective layer is an effective means for improving the image quality.

  As a method for forming the protective layer 94, conventional methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, and ring coating can be used. The thickness of the protective layer is about 0.1 to 10 μm, preferably 2 to 5 μm.

  Here, when the protective layer 94 is formed on the charge transport layer 92, it is considered that the surface charge at the time of charging exists on the protective layer. It can be said that the film thickness difference is a combination of the layer and the protective layer. Therefore, the method of reducing the unevenness is applied in the formation of the protective layer as in the case of the charge transport layer described above.

  Further, providing the protective layer 94 and increasing the wear resistance in this way means that the history of irregularities of the layer containing the charge transport material during the formation of the photoreceptor is maintained over a long period of time. That is, in an electrophotographic photosensitive member having relatively low wear resistance, the surface is worn by outputting an image for a long period of time, but unevenness may occur due to a partial wear amount difference. Therefore, as in the present invention, the difference in film thickness of the unevenness is reduced before use and the wear resistance is increased by providing a protective layer, etc. Suppressing is a very effective means for obtaining a good image over a long period of time. The electrophotographic photosensitive member having high abrasion resistance includes those having a protective layer as described above, and those having a polymer charge transport material in the outermost layer and a low content of low molecular charge transport material. Can be mentioned.

  In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, oxidation is performed on each layer such as a charge generation layer, a charge transport layer, an undercoat layer, a protective layer, and an intermediate layer. Inhibitors, plasticizers, lubricants, ultraviolet absorbers, low molecular charge transport materials, and the like can be added. Representative materials of these compounds are described below.

Examples of the antioxidant that can be added to each layer include, but are not limited to, the following.
(A) Phenolic compounds 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4 '-Hydroxy-3', 5'-di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4- Ethyl-6-tert-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1 , 3-Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4 -Hydroxybenzyl) benzene, tetrakis -[Methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t- Butylphenyl) butyric acid] cricol ester, tocopherols and the like.
(B) Paraphenylenediamines N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylene Diamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
(C) Hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2 -(2-octadecenyl) -5-methylhydroquinone and the like.
(D) Organic sulfur compounds Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
(E) Organic phosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

Examples of the plasticizer that can be added to each layer include, but are not limited to, the following.
(A) Phosphate ester plasticizer Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, Examples include triphenyl phosphate.
(B) Phthalate ester plasticizers Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalate Dinonyl acid, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate and so on.
(C) Aromatic carboxylate plasticizers Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.
(D) Aliphatic dibasic ester plasticizer dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipic acid n-octyl-n-decyl , Diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2 sebacate -Ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.
(E) Fatty acid ester derivatives Examples include butyl oleate, glycerol monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, and tributyrin.
(F) Oxyacid ester plasticizers include methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.
(G) Epoxy plasticizer Epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. There is.
(H) Dihydric alcohol ester plasticizers include diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate.
(I) Chlorine-containing plasticizer There are chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl and the like.
(J) Polyester plasticizer Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, and the like.
(K) Sulfonic acid derivatives p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide, etc. is there.
(L) Citric acid derivatives Examples include triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and acetyl citrate-n-octyldecyl.
(M) Others Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.

Examples of the lubricant that can be added to each layer include, but are not limited to, the following.
(A) Hydrocarbon compounds There are liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene and the like.
(B) Fatty acid compounds There are lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and the like.
(C) Fatty acid amide compounds Stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide and the like.
(D) Ester compounds There are lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, fatty acid polyglycol esters, and the like.
(E) Alcohol compounds There are cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
(F) Metal soaps There are lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
(G) Natural wax Carnauba wax, candelilla wax, beeswax, whale wax, ibotarou, and montan wax.
(H) Others Examples include silicone compounds and fluorine compounds.

Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
(A) Benzophenone series 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4- There are methoxybenzophenone and the like.
(B) Salsylates There are phenyl salsylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, and the like.
(C) Benzotriazole series (2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3) '-Tertiarybutyl 5'-methylphenyl) 5-chlorobenzotriazole.
(D) Cyanoacrylate-based ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, and the like.
(E) Quencher (metal complex)
There are nickel (2,2′thiobis (4-t-octyl) phenolate) normalbutylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- There are 2,2,6,6-tetramethylpiperidine and the like.

Resin Synthesis Example for Charge Blocking Layer 6-Nylon 100 parts were dissolved in 160 parts of methanol, and 75 parts of formaldehyde and 2 parts of phosphoric acid were mixed and stirred therein, and the temperature was raised to 125 ° C. over 1 hour. After maintaining at 125 ° C. for 30 minutes, the mixture was cooled to room temperature over 45 minutes. The mixture was a translucent gel.
In order to neutralize phosphoric acid, the gel was dissolved in 95% ethanol containing excess ammonia. This solution was poured into water to precipitate polyamide.
The precipitated polyamide was filtered, washed with 1 L of tap water, and further dried to obtain N-methoxymethylated nylon.
(Coating solution for charge blocking layer)
N-methoxymethylated nylon (resin) 6.4 parts Methanol 70 parts n-butanol 30 parts Resin N-methoxymethylated nylon was dissolved in a solvent at the above composition ratio to prepare a coating solution for a charge blocking layer.

(Coating liquid for moire prevention layer)
Titanium oxide (purity: 99.8%) 70 parts Alkyd resin 14 parts (Beckolite M6401-50-S (solid content 50%) manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 10 parts
(Super Becamine G-821-60 (solid content 60%), manufactured by Dainippon Ink & Chemicals, Inc.)
2-butanone 100 parts A mixture having the above composition ratio was dispersed for 72 hours by a ball mill to prepare a coating solution for a moire prevention layer.

(Charge transport layer coating solution)
Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula 1 7 parts

  80 parts of tetrahydrofuran

(Preparation of photoconductor 1)
The above charge blocking layer coating liquid, moire prevention layer coating liquid, charge generation layer coating liquid 2, and charge transport layer coating liquid are sequentially applied to a 100 mm diameter aluminum cylinder (JIS1050) and dried. A 0.0 μm charge blocking layer, a 3.5 μm moire prevention layer, a 0.3 μm charge generation layer, and a 30 μm charge transport layer were formed to produce an electrophotographic photoreceptor. Subsequently, the obtained electrophotographic photoreceptor was heat-treated at 100 ° C. for 10 hours to obtain the electrophotographic photoreceptor of Example 1.

(Preparation of photoconductor 2)
A 5% methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) was applied on an aluminum cylinder (JIS 1050) having a diameter of 100 mm by an immersion method to provide an undercoat layer having a thickness of 0.3 μm. The aluminum cylinder was subjected to a cutting process so that moire was not generated.
Next, 10 parts of an oxytitanium phthalocyanine pigment having strong peaks at 9.0 °, 14.2 °, 23.9 °, and 27.1 ° at diffraction angles 2θ ± 0.2 ° in X-ray diffraction of CuKα, 10 parts of polycarbonate Z resin (weight average molecular weight 28,000) and 60 parts of cyclohexane were dispersed in a sand mill apparatus using 1φ glass beads for 20 hours. A solution obtained by adding 100 parts of methyl ethyl ketone to this dispersion was applied onto the undercoat layer and dried to form a charge generation layer. The film thickness was 0.12 μm.

次に上図構造式２に示すトリアリールアミン化合物７部と下図構造式３で示されるスチリル化合物３部をポリカーボネートＺ樹脂（重量平均分子量８０，０００）１０部及びモノクロルベンゼン６０部に溶解した。この溶液を上記電荷発生層上に塗布し、乾燥することによって電荷輸送層を形成した。乾燥後の膜厚は２０μｍであった。

Next, 7 parts of the triarylamine compound shown in the upper structural formula 2 and 3 parts of the styryl compound shown in the lower structural formula 3 were dissolved in 10 parts of the polycarbonate Z resin (weight average molecular weight 80,000) and 60 parts of monochlorobenzene. This solution was applied onto the charge generation layer and dried to form a charge transport layer. The film thickness after drying was 20 μm.

Further, a coating solution for a crosslinkable charge transport layer having the following composition was spray-coated on this charge transport layer, and after naturally drying for 20 minutes, a metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 500 mW / cm. ^2. Irradiation time: Light irradiation was performed under conditions of 60 seconds to cure the coating film. Furthermore, drying was performed at 130 ° C. for 20 minutes to provide a cross-linked charge transport layer having a thickness of 5.3 μm to obtain an electrophotographic photoreceptor of the present invention.

[Coating liquid for cross-linked charge transport layer]
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts [Trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku Co., Ltd.) Molecular weight: 296, functional group number: trifunctional, molecular weight / functional group number = 99]
10 parts of the following radical polymerizable compound having a monofunctional charge transporting structure

Photopolymerization initiator 1 part [1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)]
Tetrahydrofuran 100 parts (Preparation of pulverized toner)
Styrene-nbutyl acrylate copolymer (Mw 70,000, Mn 20,000) 200 parts by weight Carbon black 14 parts by weight Polar resin [saturated polyester (terephthalic acid-propylene oxide modified bisphenol A, acid value 15, peak molecular weight 60000)] 10 parts by weight Negative charge control agent (dialkyl salicylic acid metal compound) 2 parts by weight Low softening point substance (ester wax compound) 15 parts by weight After melt-kneading using the above composition extruder, the cooled kneaded material is mechanically crushed and coarsened. The pulverized product was made to collide with a collision plate using a jet stream and pulverized, and the pulverized product was further classified with an airflow classifier to obtain a pulverized toner having a volume average particle size of 8.6 μm and a circularity of 0.914. . The results are shown in Table 1.

(Lubricating substance supplied to the photoreceptor surface)
Table 2 shows the lubricating substances to be supplied to the photoreceptor surface.

  In the image forming apparatus of FIG. 6, the photoreceptors shown in Table 3 were used. Three ghost image detection patterns shown in FIG. 13 are formed, and detection is performed after a preset elapsed time from the pattern detection to the photosensitive member circumferential length [mm] / machine linear velocity [mm / sec.], And the average potential difference is detected. The toner adhesion amount difference was measured and used for control. Note that the charging charger, the photosensitive member, and the cleaning unit are integrally configured to be a detachable process cartridge.

  The potential sensor and the photosensor, which are detection means in the control diagram of FIG. 12, can be set to detect / not detect the occurrence of ghost. It is also possible to set whether or not to correct the charging current and the transfer current. For evaluation, this control was set to be performed when the machine power was turned on every day. An image forming apparatus as described above was produced.

<Comparative Examples 1 and 2>
In Comparative Examples 1 and 2, the control means of the present invention is not used.
Evaluation was performed using the photoreceptor 1 and the photoreceptor 2 in Table 3.

  A mode in which a ghost image is detected by a potential sensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 1 were used.

  A mode in which a ghost image is detected by a photosensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 1 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 1 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor and a transfer current is corrected is set. Otherwise, the same settings as in Comparative Example 1 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor to correct a charging current and a transfer current is set. Otherwise, the same settings as in Comparative Example 1 were used.

  A mode in which a ghost image is detected by a potential sensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 2 were used.

  A mode in which a ghost image is detected by a photosensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 2 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor and a charging current is corrected is set. Otherwise, the same settings as in Comparative Example 2 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor and a transfer current is corrected is set. Otherwise, the same settings as in Comparative Example 2 were used.

  A mode in which a ghost image is detected by a potential sensor and a photo sensor to correct a charging current and a transfer current is set. Otherwise, the same settings as in Comparative Example 2 were used.

(Evaluation method)
Each image forming apparatus was evaluated for a half-tone ghost image and other abnormalities after outputting 1 million original images each with an initial image area ratio of 6%. The results are shown in Table 3.

The evaluation result stage is
◎ ・ ・ ・ Not generated at all ○ ・ ・ ・ Generated but slight (allowable range)
Δ: Occurrence, limit of allowable range ×: Evaluated in four stages, clearly generated and unacceptable.

  It can be seen from the detection results of the potential sensor and the photosensor that the generation of a ghost image in halftone can be suppressed by correcting the charging current and the transfer current. Further, when Examples 1, 2, 6, and 7 are compared with other examples, it is understood that ghost images can be further suppressed by using both the potential sensor and the photosensor.

It is sectional drawing of the example of the image forming apparatus which installed the surface electrometer after the exposure of this invention, and after transfer. It is a ghost image evaluation pattern used in the present invention. It is explanatory drawing of the output change of the surface electrometer at the time of image formation by the ghost image evaluation pattern of this invention. 1 is a cross-sectional view of an image forming apparatus provided with a photosensor after development according to the present invention. It is explanatory drawing of the photosensor output change at the time of image formation by the ghost image evaluation pattern of this invention. 1 is a cross-sectional configuration diagram of an image forming apparatus having a detection unit for ghost image evaluation according to the present invention. FIG. 5 is an explanatory diagram of a relationship between a photoreceptor surface potential used in the present invention and a potential sensor output. It is sectional drawing of the photosensor for toner density | concentration detection used by this invention. FIG. 6 is an explanatory diagram of a relationship between a toner adhesion amount and a photosensor output in the present invention. FIG. 5 is an explanatory diagram of a relationship between a transfer current and a ghost image in the present invention. FIG. 6 is an explanatory diagram of a relationship between a charging current and a ghost image in the present invention. 3 is a flowchart of charging current or transfer current correction according to the present invention. It is an example of the pattern for the ghost image detection of this invention. FIG. 6 is a schematic diagram showing a position at which the ghost image detection pattern of the present invention is measured on a circumference of the photoreceptor. It is sectional drawing which illustrates the layer structure of the electrophotographic photoreceptor of this invention. It is sectional drawing which illustrates another layer structure of the electrophotographic photoreceptor of this invention. It is sectional drawing which illustrates another layer structure of the electrophotographic photosensitive member of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging device 2 Image exposure system 3 Surface potential meter 4 Developing device 5 Photo sensor 6 Transfer device 7 Cleaning device 7a Cleaning brush 7a
7b Elastic rubber cleaning blade 8 Static elimination device 9 Photoconductor 10 Copy paper 11 Fixing device 12 Precharger 90 Conductive support 91 Charge generation layer 92 Charge transport layer 93 Undercoat layer 94 Protective layer

Claims (4)

At least charging means for uniformly charging the image carrier, latent image forming means for forming a latent image on the uniformly charged image carrier, and developing means for developing the latent image using toner. A transfer unit that transfers the toner on the image carrier to a transfer target, a detection unit that detects occurrence of a ghost image on the image carrier, and a correction unit that corrects an image forming condition based on the detection result; Have
As the detection means, a surface potential meter capable of measuring a surface potential of a pattern formed on the image carrier, and a photosensor capable of measuring a toner adhesion amount difference generated on the surface of the image carrier,
The correction means includes
When either the value measured by the surface electrometer or the value measured by the photosensor is not within a predetermined specified value, the charging current value in the charging means is determined by a plurality of predetermined first values. Determine if it is within one set value,
As a result of the determination, the charging current is corrected to a predetermined value when it is within the plurality of first setting values, while the value of the transfer current in the transfer unit is corrected when it is not within the plurality of first setting values. Determine whether it is within a predetermined second set value,
As a result of the determination, when the value is within the second set value, the transfer current is corrected to a predetermined value, while when the value is not within the second set value, the charging current and the transfer current are not corrected. West,
The correction of the charging current is as follows:
An image forming apparatus characterized in that it is controlled by causing shared by each charger of the charging unit is divided into a plurality of control areas of the charging current. The correction of the charging current is at least one of precharge by a precharger preceding the main charger other than the main charger of the charging means or postcharge by a postcharger subsequent to the main charger. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the measurement by the detection unit and the correction of the image forming condition by the correction unit are periodically performed. At least a charging step for uniformly charging the image carrier, a latent image forming step for forming a latent image on the uniformly charged image carrier, and a developing step for developing the latent image using toner. A transfer step of transferring the toner on the image carrier to the transfer target, a detection step of detecting occurrence of a ghost image on the image carrier, and a correction step of correcting the image forming condition based on the detection result; Consists of
In the detection step, a surface potential of a pattern formed on the image carrier is measured by a surface potential meter, and a toner adhesion amount difference generated on the surface of the image carrier is measured by a photosensor.
In the correction step,
When either the value measured by the surface electrometer or the value measured by the photosensor is not within a predetermined specified value, the charging current value in the charging step is a plurality of predetermined first values. Determine if it is within one set value,
As a result of the determination, the charging current is corrected to a predetermined value when it is within the plurality of first setting values, while the value of the transfer current in the transfer process is corrected when it is not within the plurality of first setting values. Determine whether it is within a predetermined second set value,
As a result of the determination, when the value is within the second set value, the transfer current is corrected to a predetermined value, while when the value is not within the second set value, the charging current and the transfer current are not corrected. West,
The correction of the charging current is as follows:
The image forming method according to claim 1, wherein the charging current is controlled by dividing a control region into a plurality of parts and sharing them with each charger in the charging step .

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