JP2005301107A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of prolonging the life of a cleaning blade and stabilizing the cleaning performance for a long period by stabilizing behavior of a cleaning blade edge part. <P>SOLUTION: The image forming apparatus having a photoreceptor whose photosensitive layer contains a compound produced by polymerizing or bridging and curing a positive-hole transport compound with a compound having an unsaturated polymerizable functional group, a charging means of charging the surface of the photoreceptor, a latent image forming means of forming an electrostatic latent image on the charged surface of the photoreceptor, a developing means of developing the electrostatic latent image into a toner image with toner carried by a developing roller, a transfer means of transferring the toner image to a recording medium, and a cleaning means of cleaning untrasferred toner is characterized in that a sponge roller containing abrasives is made to abut against the photoreceptor surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and the same printer.

  In a well-known cleaning device for an image forming apparatus, it is difficult to transfer all the toner of a toner image formed on the surface of a photoconductor to a transfer material during transfer, and it is inevitable that some toner remains on the photoconductor. Further, transfer material powder or the like generated when the transfer material contacts the photoconductor also adheres to the photoconductor. For this reason, it is necessary to sufficiently clean toner and transfer material powder (hereinafter collectively referred to as transfer residual development toner) remaining on the photoreceptor after transfer.

  Various cleaning means have been proposed for this purpose, but there are those that scrape and remove the transfer residual toner by bringing the edge of a cleaning blade made of an elastic material such as rubber into contact with the photosensitive member. Since the structure is simple and low in cost, and the transfer residual toner removing function is excellent, it is well known that it is already widely used.

  FIG. 1 shows an example of a known cleaning device, which has an axis in a direction perpendicular to the paper surface, and a rotating cylinder (not shown in the figure) in which a charger, a developing device, a transfer means, and the like are arranged in the periphery. A cleaning device is disposed close to the photoconductor 2 in the form of a ring.

  The cleaning device has a casing 14 having an opening in one direction of the photosensitive member 2, and one end of a cleaning blade 15 made of urethane rubber or the like is attached to the opening. One edge of the edge of the blade is in contact with the photosensitive member 2, and when transfer residual toner generated at a transfer portion (not shown) reaches the edge portion of the cleaning blade 15, it is scraped off.

  In order to improve the cleaning efficiency, those using various auxiliary members upstream of the cleaning blade are known. A cleaning roller is disposed upstream of the cleaning unit and brought into contact therewith to promote the cleaning effect and prevent contamination of the photoreceptor surface (for example, Patent Document 1).

JP-A-8-328441

  In recent years, it has been known that it is effective to use a photoconductor having a photoconductor surface cured for the purpose of improving image quality, speeding up, and stabilizing the electrophotographic copying machine / printer. Specifically, the photosensitive member is composed of a photosensitive layer in which a compound having an unsaturated polymerizable functional group is polymerized or cross-linked with a hole transport compound and cured, or the photosensitive member surface layer is composed of amorphous silicon. .

  When charging these photoconductors with a charger, those using a corona discharger or those in which a charging member to which a voltage is applied is brought into contact with the photoconductor to charge the photoconductor (Japanese Patent Laid-Open No. 57-017826, Japanese Laid-Open Patent Publication No. 58-040566 has been proposed and has already been put into practical use.

In either case, however, the discharge phenomenon generates pollutants such as nitrogen oxide (NOx, NH ₃ NOx, etc.), silicon oxide (SiOx) or sulfide oxide (SOx) on the surface of the photoreceptor, and the photoreceptor. A phenomenon that adheres to the surface occurs. When the photosensitive member is very hard, these contaminants cause various problems caused by the contamination of the surface of the photosensitive member itself without being removed by a cleaning blade or the like. Specifically, since the contaminant is a low-resistance material, image flow caused by lowering the resistance value on the surface of the photoreceptor, and if the contaminant is highly hygroscopic and reacts with moisture, the surface of the photoreceptor and the cleaning edge are further increased. There is a concern that the frictional force of the portion may be increased, causing defective cleaning (blade squealing, chattering, dripping, etc.) and damage to the cleaning edge portion.

  In order to cope with this problem, it is necessary to ensure the stability of the cleaning blade edge portion over a long period of time. Specifically, the frictional force generated between the cleaning blade and the surface of the photoconductor is reduced by preventing contamination of the surface of the photoconductor, and the lubricant is constantly supplied to the edge of the cleaning blade.

  Therefore, various proposals have been made as cleaning blade auxiliary members. For example, by providing a layer containing an abrasive on the cleaning blade in the vicinity of the edge portion to remove contaminants, the polishing effect can be promoted by adding an abrasive to the polishing roller or sponge roller. Are known (for example, Japanese Patent Laid-Open No. 1-018744).

  However, under circumstances where contaminants are difficult to adhere to the surface of the photoreceptor due to changes in the environment, etc., not only the contaminants but also the surface of the photoreceptor will be polished, reducing the soaking of the image and the life of the photoreceptor itself. There was a problem that. Furthermore, by polishing contaminants adhering to the surface of the photoconductor, the friction force between the photoconductor and the cleaning blade can be reduced, but no lubricant is supplied to the cleaning edge, which makes the behavior of the cleaning blade unstable. There has been a concern about the occurrence of image defect problems due to chattering, squeaking and turning of the cleaning blade.

  On the other hand, for the purpose of stability of the edge portion of the cleaning blade, a lubricant is provided near the edge portion of the cleaning blade to provide a lubrication function.

  However, on the surface of a hard photoconductor, contaminants due to the discharge phenomenon increase in proportion to the discharge time. There was concern about poor cleaning due to damage.

  The present invention has been made in view of the above problems, and the object of the process is to stabilize the behavior of the cleaning blade edge, thereby achieving a long life of the cleaning blade and long-term stabilization of the cleaning property. An image forming apparatus capable of performing

  In order to achieve the above object, the invention described in claim 1 is a photoconductor comprising a compound having an unsaturated polymerizable functional group obtained by polymerizing or cross-linking a hole transporting compound and curing the photosensitive layer, and the photosensitive layer. Charging means for charging the surface of the body, latent image forming means for forming an electrostatic latent image on the charging surface of the photoconductor, and developing means for developing the electrostatic development as a toner image by toner carried on the developing roller; An image forming apparatus having a transfer unit for transferring the toner image to a recording medium and a cleaning unit for cleaning the transfer residual toner is characterized in that a sponge roller containing an abrasive is brought into contact with the surface of the photoreceptor.

  According to a second aspect of the present invention, in the first aspect of the invention, the contact angle of water on the surface of the photosensitive member is always kept at 70 ° or more, and the transfer corresponding to a printing area of 8% or more is always provided on the cleaning blade edge portion. The sponge roller is brought into contact so that the remaining developer and lubricant are supplied.

  A third aspect of the invention is characterized in that, in the first aspect of the invention, the sponge roller contains abrasive particles having different particle sizes and shapes.

  The invention described in claim 4 is characterized in that in the invention described in claim 1, a sensor capable of sensing humidity is provided.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the environmental information detected by the environmental condition detection means comprising a humidity sensor is input to the control means, and the control means is driven based on the information. The contact pressure of the sponge roller is controlled through an energization circuit.

  According to the present invention, a large particle size abrasive having an effect of removing contaminants adhering to the surface of the photoconductor due to a discharge phenomenon, and a small particle size abrasive imparting lubrication characteristics to the cleaning blade edge portion. By using each sponge roller and controlling it by using a humidity sensor at the optimum contact pressure for the usage environment, the ability to scrape off contaminants on the photoreceptor is high and the cleaning ability is also high. In addition, it is important to contribute to maintaining the long life of both the cleaning blade and the sponge roller as well as achieving long life and stabilization of the photoreceptor.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The present invention relates to a cleaning auxiliary device for an image forming apparatus in which a transfer residual toner is scraped off from a photoreceptor by a cleaning blade, and two kinds of abrasive fine particles having different particle sizes and shapes are contained in a sponge roller. Thus, a polishing function for removing contaminants due to a discharge phenomenon and a function of supplying a lubricant to the edge of the cleaning blade are provided.

  A schematic diagram of the present invention is shown in FIG. In addition, in order to optimize the efficiency of abrasiveness and lubricant supply capacity according to the specification environment, environmental information consisting of humidity detected by the environmental condition detection means consisting of humidity sensors is detected, and the control means detects the information. Based on the above, the contact pressure of the sponge roller is controlled through an energization circuit as drive means.

  The sponge roller according to the present invention is a polishing unit that contacts the photosensitive member on one or both of the upstream side and the downstream side of the cleaning unit that contacts the surface of the image carrier and rotates with a rotational speed difference with respect to the image carrier. It is.

  The material of the sponge roller is preferably a rubber material or a foam material. Suitable rubber materials include EPM, EPDM, norbornene rubber, NBR, chloroprene rubber, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chlorosulfonated polyethylene, hydrin rubber, urethane rubber, SBS and SEBS. As the foam material, polystyrene, polyolefin, polyester, urethane and the like are suitable, and a soft and low specific gravity foamed material is used. Air, nitrogen, argon gas, or the like can be enclosed in the bubble portion of the foam material.

  As the abrasive, two kinds of metal oxides having different particle sizes and shapes are used. The abrasive that promotes the polishing function is an irregular shape with a large particle size, and the spherical abrasive with a small particle size is used as a lubricity supply member. The average particle size of the large particle size abrasive is preferably 3 to 10 μm.

  Next, the shape of the abrasive particles will be described using the surface shape sphericity φ0. The surface area shape sphericity φ0 is defined as follows.

The actual measurement of the BET specific surface area is measured by using, for example, a specific surface area meter autosorb 1 manufactured by QUANTACHROME. In the present invention, the surface shape sphericity φ0 of the large abrasive that promotes the polishing function
Is preferably 0.3 to 0.5. In order to gradually remove the adhesion of the discharge product to the photoreceptor, it is considered that the spherical fine particles having a certain degree of unevenness are more effective (FIG. 4A). Conversely, as a small particle size abrasive for imparting a lubricating function, as shown in FIG. 4 (b), it is preferable that the surface of the abrasive particles has few irregularities, and φ ₀ exceeds 0.9. It is preferably close to 1.0.

  As for the amount contained in the sponge roller, taking into consideration that the content of the abrasive and the hardness of the sponge roller are inversely proportional, the amount of the abrasive is large and small in size with respect to the weight of the sponge roller. Each is preferably 1 to 5 wt%.

  Examples of the metal oxide include silica, alumina, titanium oxide, calcium titanate, strontium titanate, barium titanate, magnesium titanate, zinc oxide, zirconium oxide, chromium oxide, manganese oxide, iron oxide, ferrite and the like, or Two or more types can be used in combination.

  The image forming apparatus according to the present invention operates at an image forming speed, that is, a driving speed of the photosensitive member of 100 to 300 mm / sec, and a sponge roller containing an abrasive disposed in contact with the photosensitive member is a photosensitive member. The peripheral speed is preferably rotated through an external motor at a speed of 100% to 200% and brought into contact with a pressure of 30 to 300 gf / cm.

  The operation of the present invention will be described by paying attention to the influence on the photosensitive member or the cleaning blade when the abrasive is selectively contained. The usage environment was normal temperature and humidity. FIG. 5 shows the contact angle of the photosensitive member surface and the amount of distortion of the cleaning blade when the contact pressure is changed when a sponge roller containing a large particle size and irregular shaped abrasive is used. It is shown that the contact angle of the surface of the photoreceptor can be maintained by containing an abrasive in the sponge roller, and the adhesion of contaminants due to discharge is reduced. The effect tends to increase in proportion to the contact pressure.

  However, in the case of a sponge roller containing only an abrasive having a large particle diameter, when the contact pressure P> 100 gf / cm, a scar due to the abrasive is seen on the surface of the photoreceptor, indicating that the contact pressure is too large. . Regarding the distortion amount of the cleaning blade, the distortion amount was smaller when the abrasive was contained than when the abrasive was not used. This is due to a decrease in the frictional force with the cleaning blade due to a decrease in the contact angle on the surface of the photoreceptor, which is an effect of containing an abrasive.

  Next, the same effect was examined when a sponge roller having a small particle diameter and a spherical shape was used as the abrasive. The results are shown in FIG.

  The contact angle on the surface of the photoreceptor showed a further decreasing tendency, and an increase in polishing power was confirmed. This is considered not only to increase the polishing power by further mixing the polishing agent, but also to work the polishing agent having a small particle diameter over the details of the uneven portions on the surface of the photoreceptor. When the strain amount of the cleaning blade was compared, the effect of reducing the strain amount was slightly seen when P <80 gf / cm, but the effect was large when P> 80 gf / cm. At this time, when the vicinity of the cleaning blade edge portion was observed, the presence of an abrasive having a small particle diameter was confirmed together with the developer. This is because, as a result of the surface of the sponge roller containing a small particle size being brought into contact with a pressure of 80 gf / cm or more, shaving powder was generated and supplied to the cleaning blade edge as a lubricant, and the amount of distortion was reduced. Conceivable. When P> 80 gf / cm, scratches on the surface of the photoreceptor were observed, and no scratches due to the abrasive contained in the sponge roller were observed. Similar to the edge portion of the cleaning blade, it can be presumed that this is a result of a small particle size abrasive acting on the sponge roller as a lubricant.

  The sponge roller according to the present invention can exhibit its original characteristics by being brought into contact with the surface of the photosensitive member with a strong pressure, but the abrasive particles contained by scraping the sponge roller are supplied to the cleaning blade edge portion. In terms of configuration, the life of the sponge roller itself cannot be denied.

  Therefore, by arranging an environmental detection sensor around the photoconductor, the humidity sensor detects an environment in which moisture is easily adsorbed due to adhesion of discharge products to the surface of the photoconductor, and the sponge roller is applied via an energization circuit. The contact pressure is controlled, and the sponge roller is brought into contact in an appropriate environmental state. In order to optimize the contact pressure of the sponge roller that is most appropriate for the usage environment, the environment is changed between a low temperature / low humidity environment (15 ° C, 10%) and a high temperature / high humidity environment (30 ° C, 80%). The distortion amount of the cleaning blade and the life of the sponge roller were examined. The result is shown in FIG.

  The contact pressure of 80 gf / cm is an appropriate pressure for maintaining lubricity and polishing in a room temperature / humidity environment, and 90 gf / cm in order to achieve the same amount of strain at this time in a high temperature / high humidity environment. It has been found that a contact pressure of 70 gf / cm is necessary when the contact pressure is realized in a low temperature and low humidity environment. Therefore, when the humidity in the apparatus is detected using the humidity sensor, the contact pressure is increased if the humidity is about 80%, and the contact pressure is decreased if the humidity is about 15%. By providing and controlling the circuit, it is possible to optimize the contact state of the sponge roller, and it is possible to reduce the occurrence of scratches and the increase in the amount of photoconductor scraping. That is, it is possible to extend the life and high stability of the photoreceptor. As a contact pressure method of the sponge roller, it is preferable to adopt a structure in which pressure is applied from both ends with a spring from the viewpoint of contact unevenness of the sponge roller length and behavior stability.

  Next, the photoconductor used in the present invention will be described.

  In the structure of the photoreceptor of the present invention, a photosensitive layer and a protective layer are laminated in this order on a conductive support, and the protective layer contains at least a curable resin and conductive particles.

  In the present invention, examples of the conductive particles used in the protective layer include metals, metal oxides, and carbon black. These can be used alone or in combination of two or more.

  The average particle diameter of the conductive particles used in the present invention is preferably 0.3 μm or less, particularly preferably 0.1 μm or less, from the viewpoint of the transparency of the protective layer.

  Moreover, in this invention, it is especially preferable to use a metal oxide from the point of transparency among the electroconductive particle mentioned above.

  Furthermore, fluorine atom-containing resin particles can be dispersed in order to improve the slipperiness of the photoreceptor surface. The molecular weight of the resin particles and the particle size of the particles can be appropriately selected and are not particularly limited.

  It is also possible to surface-treat the surface of the conductive particles with a fluorine atom-containing compound or the like so that the fluorine atom-containing resin and the conductive particles do not aggregate the particles in the resin solution. By performing the surface treatment, it is possible to improve the dispersibility of the conductive particles and fluorine atom-containing resin particles in the resin solution, and there is no formation of secondary particles that occur over time, and dispersion stability is also improved. Can be improved.

  In the present invention, as described above, as the binder resin for the protective layer, a curable resin is used from the viewpoint of the surface hardness, abrasion resistance, and scratch resistance of the protective layer, and it is cured by electron beam irradiation. . This curable resin refers to a monomer or oligomer having a functional group that undergoes a polymerization reaction with the energy of an electron beam. Is defined as

  Examples of the functional group causing a polymerization reaction include a group having a carbon-carbon double bond, a group causing ring-opening polymerization, and a group causing two or more types of molecules to react to cause polymerization.

In particular, in the present invention, among those described above, the curable resin may be an acryloyloxy group having a carbon-carbon double bond (CH ₂ ═CHCOO—) or a methacryloyloxy group (CH ₂ ═C (CH _3). It is preferable to use a resin containing) COO-).

  In the present invention, as described above, the curable resin of the photoreceptor is cured by electron beam irradiation. In the case of electron beam irradiation, any type of accelerator such as a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type can be used. When irradiating with an electron beam, the irradiation conditions are very important in the photoreceptor of the present invention in order to develop electric characteristics and durability. In the present invention, the acceleration voltage is preferably 250 kV or less, and optimally 150 kV or less. The dose is preferably in the range of 1 Mrad to 100 Mrad, more preferably in the range of 3 Mrad to 50 Mrad. When the acceleration voltage is higher than the above value, the electron beam irradiation damage to the photosensitive member characteristics becomes remarkable. Further, when the dose is less than the above range, curing is insufficient, and when the dose is too large, the photoreceptor characteristics are deteriorated.

  There is no clear reason why the protective layer formed of a curable resin containing conductive particles exhibits good abrasion resistance and scratch resistance when cured by electron beam irradiation. However, compared with heat or ultraviolet rays, the following is considered from the merits of electron beams.

  In the case of thermosetting, the amount of heat for completely curing the protective layer becomes considerably large, and the heat deteriorates the photosensitive layer itself existing under the protective layer. Since the protective layer was formed as it was, the protective layer hardness was insufficient.

  When ultraviolet rays are used, it is considered that the conductive particles absorb the ultraviolet rays and inhibit the curing of the resin near the conductive particles. For this reason, conventionally, in a system of a protective layer in which conductive particles are dispersed, a large number of uncured parts in the micro part in the protective layer are generated, and the three-dimensional crosslinking reaction in the protective layer is stopped. It is believed that the macroscopic surface hardness of the entire protective layer will also decrease.

  In the ultraviolet curing system, as described above, in order to cure, it is necessary to use a polymerization initiator in combination with the resin. Further, in a system in which conductive particles are mixed, a large amount of It has been clarified by the present inventors that the hardness cannot be increased without adding a polymerization initiator. On the contrary, it is known that the surface hardness of a system in which a large amount of polymerization initiator is mixed in a resin without conductive particles is reduced, and the protective layer of the conductive particle dispersion system is polymerized. Even if the amount of the initiator is optimized, a high hardness cannot be obtained, and the photoconductor produced by the above method is considered to have poor abrasion resistance and scratch resistance.

  On the other hand, the protective layer that is cured by electron beam irradiation is advantageous because it is not necessary to add a polymerization initiator. In addition, the irradiation energy is much larger than that of ultraviolet rays, and the penetration depth of the electron beam to the sample is also very deep, so the curing of the resin in the vicinity of the conductive particles has progressed, and the high surface hardness of the protective layer can be achieved. The protective layer is considered to have good abrasion resistance and scratch resistance. Taber abrasion was 0.4 to 0.5 (mg / 1000 rotations). The Taber abrasion test method is to mount the sample on the sample table of the Taber abrasion tester (YSS Taber: Yasuda Seisakusho) and attach the wrapping tape (Fuji Photo Film product name: C2000) to the two surfaces. Each rubber wear wheel (CS-0) was subjected to a load of 500 g, and the weight loss of the sample after 1000 revolutions was measured with a precision balance.

  In the present invention, when the Taber wear is 0.1 or less, the cleaning property is deteriorated due to the surface property of the photoreceptor, and when it is 1.0 or more, the fluctuation of the discharge current due to the change in the film thickness is increased. Therefore, the charging property is deteriorated. Therefore, the Taber abrasion value of the photoreceptor is limited to a range of 0.1 to 1.0. In this photoreceptor, the conventional OPC drum can cut about 10 to 40% of the total film thickness per 50,000 sheets, but by having the above material as a surface layer, it was possible to suppress the cutting to 1 to 5%.

  Hereinafter, the structure below the photosensitive layer of the photoreceptor used in the present invention will be described.

  The structure below the photosensitive layer according to the present invention has a structure in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order on the conductive support, or vice versa. Further, it is possible to adopt any configuration of a single layer in which the charge generation material and the charge transport material are mixed and dispersed in the same layer.

The photosensitive layer may be an inorganic photoconductive material instead of an organic photoconductive material. For example, Se, As ₂ Se ₃ , a-Si, CdS, ZnO ₂ or the like may be used.

  However, in view of characteristics such as residual potential, which are characteristics as an electrophotographic photoreceptor, a function-separated type photoreceptor structure in which a charge generation layer and a charge transport layer of an organic photoconductive material are laminated is particularly preferable.

  When the electrophotographic photosensitive member of the present invention is produced, a metal or alloy such as aluminum or stainless steel, paper, plastic, or the like is used as the conductive support, and the shape is applied to a cylindrical cylinder or film. It can be arbitrary depending on the photographic apparatus. Moreover, you may use as a conductive support body by providing a conductive layer separately by a vapor deposition method or another method on a nonconductive support body.

  In the present invention, an undercoat layer having a barrier function and an adhesive function can be provided on the conductive support.

  The undercoat layer is used to improve the adhesion of the photosensitive layer, improve the coating property, protect the support, cover defects on the substrate, improve the charge injection from the support, and protect the photosensitive layer from electrical breakdown. It is formed. This is dissolved in a suitable solvent and coated on the support. The film thickness at that time is preferably about 0.1 to 2 μm.

  Examples of the charge generation material used in the charge generation layer of the present invention include selenium-tellurium, pyrylium, thiapyrylium dyes, various central metals and crystal systems, or amorphous silicones described in JP-A No. 54-143645. It is done.

  The charge generation layer is formed by dispersing the charge generation material in a 0.3 to 4 times amount of a binder resin and a solvent, applying a dispersion and drying, or depositing the charge generation material. It is formed as a single composition film such as a film. The film thickness is preferably 5 μm or less, particularly preferably in the range of 0.1 to 2 μm.

  The charge transport layer formed on the charge generation layer is preferably formed by applying a solution obtained by dissolving the above-described charge transport material and an appropriate resin in a solvent and drying. The resin can be selected from a wide range of binder resins, and commercially available resins such as polycarbonate resins, polyarylate resins, polystyrene resins, and the like can be used, but are not limited thereto. You may use these individually or in mixture of 2 or more types as a copolymer polymer.

  FIG. 1 is a schematic sectional view of an image forming apparatus according to the present invention, FIG. 2 is a side sectional view of a cleaning apparatus according to the present embodiment, and FIG. 3 is a schematic diagram of a sponge roller of the present invention.

(Image forming device)
An image forming apparatus 1 shown in FIG. 1 is an electrophotographic copying machine, and forms an image on a recording medium in accordance with an image signal sent from a computer or the like (not shown). The photosensitive member 2 of the image forming apparatus 1 is uniformly charged by the charging unit 3, and the laser oscillator 4 irradiates the light beam according to the image signal in accordance with the image signal. An electrostatic latent image is formed on the portion of the photoreceptor 2 irradiated with the light beam, and is developed with a toner as a developer by the developing device 5 to be visualized.

  Sheets as recording media are stacked on the cassette 6, separated and fed one by one by the feeding roller pair 7, and after the skew is corrected by the registration roller pair 8, the sheet reaches the photoreceptor 2. The toner image carried on the photosensitive member 2 is transferred to a sheet by the transfer unit 9, sent to the fixing unit 11 by the conveying belt 10, and after fixing the image by applying heat and pressure, the toner image is transferred by the discharge roller pair 12. Discharged outside. The toner remaining on the photoreceptor 2 after the toner image is transferred to the sheet is removed by the cleaning device 13, and the photoreceptor 2 is again used for image formation.

(Cleaning device)
As shown in FIG. 2, the cleaning device 13 includes a casing 14 having an opening on the photosensitive member 2 side, and a cleaning blade 15 made of urethane rubber or the like is attached to the opening by a support member. The cleaning blade 15 is in contact with the photosensitive member 2 at the edge, and when the residual toner that cannot be completely transferred by the transfer means 9 reaches the edge, it is scraped off. A scooping sheet 17 is attached to the lower part of the casing 14 to drop the scraped toner into the casing 14 and to prevent a large amount of the toner from flowing back to the photoreceptor 2.

  A screw is disposed in the casing 14 as a conveying means 18 for discharging the residual toner, and the residual toner dropped in the casing 14 is conveyed in a direction perpendicular to the paper surface of the figure and discharged from the cleaning device 13. Yes. With this configuration, the inside of the casing 14 is not clogged with residual toner due to residual toner.

Here, the setting of the cleaning blade 15 with respect to the photosensitive member 2 is a major factor that determines the cleaning performance. As shown in FIG. 3, the setting conditions for bringing the cleaning blade 15 into contact with the photosensitive member 2 include the contact pressure, the contact angle β, the free length L, and the thickness t of the cleaning blade 15.
Is mentioned. This time, the cleaning blade 15 was brought into contact with the photosensitive member 2 with a contact pressure of 25 gf / cm. The thickness of the cleaning blade 15 was 1.6 mm, and the free length was 5 mm.

  When the photoconductor of claim 1 was used, the contact angle of water on the surface of the photoconductor to maintain the cleaning property and the amount of developer and lubricant supplied in the vicinity of the edge portion were examined. The use environment was a high-temperature and high-humidity environment, and a paper-passing test was performed by changing the ratio of the printing area to the paper area. Under the condition where the sponge roller is not in contact, the contact angle of water decreases in proportion to the number of durable sheets, and the initial contact angle was 90 degrees, whereas it was 70 degrees after the 10,000 sheet passing test. Image flow was observed after the device had been allowed to stand overnight and left to stand overnight. The amount of distortion of the cleaning blade at this time also increased in proportion to the number of durable sheets, and “turning” was observed in which the cleaning blade was reversed with respect to the contact direction when 10,000 sheets were durable. FIG. 8 shows the results when the same examination was performed by changing the print area.

  The contact angle of water on the surface of the photoconductor surface tended to decrease in the same way, but the distortion amount of the cleaning blade was changed, and when the print area was 8% or more, there was a chipping near the edge of the cleaning blade. However, no turning occurred. Therefore, as a cleaning condition for the photosensitive member according to claim 1, if the amount of the residual transfer developer supplied in the vicinity of the cleaning edge portion is a print area of 8% or more, the behavior of the edge portion can be stabilized. Suggests.

  From the above examination, when using the photosensitive member according to claim 1, in order to maintain the cleaning property, the amount of residual transfer developer supplied to the cleaning edge portion with a water contact angle of 70 degrees or more in the paper passing test is provided. Is required to have a frictional force with the photoconductor and a behavior stability of the cleaning blade.

  Next, regarding the effect of the sponge roller in the present invention and the effect on the durability life of the variable contact pressure type sponge roller by providing an environment detection sensor, a copying machine using two sponges containing abrasives is used. Product name: CP660 (manufactured by Canon Inc.) ", normal temperature and normal humidity (24 ° C, relative humidity 55%), high temperature and high humidity (30 ° C, relative humidity 80%), low temperature and low humidity environment (15 ° C, relative humidity 15%) The endurance test was conducted on 10,000 sheets.

  A sponge roller using this embodiment is shown in FIG. The outer diameter was 16 mm, and the thickness of the core for winding the sponge roller was 10 mm. The sponge roller was made of polyurethane rubber and used as a self-foaming type. As an abrasive, alumina powder was used in a sponge roller. For the particle size, a large particle size that promotes the polishing function is 0.1 to 0.5 μm in diameter, and a small particle size that imparts polishing and lubricity is in the range of 3 to 10 μm in diameter. 3% by weight with respect to the sponge roller. The physical properties measured according to the JIS vulcanized rubber test method were 40 ° in Asker C hardness. The sponge roller was contacted at a pressure of 100 gf / cm and rotated at 150% with respect to the photosensitive member rotation speed.

  Sample images with a 5% printing area are used, and there is no sponge roller, a sponge roller containing a large particle size abrasive, and a sponge roller containing large and small particle size abrasives. A test was conducted. The usage environment is set to be a high temperature / high humidity environment and a low temperature / low humidity environment every 1000 sheets, and the life of the roller when the contact pressure variable sponge roller and the normal sponge roller by the humidity sensor of the present invention are used is examined. did. As shown in FIG. 9, the pressure of the sponge roller during the durability test shows that the contact pressure changes according to the change of the use environment by the humidity sensor. Although the pressure of the cleaning blade was variable, the cleaning blade was stable and no cleaning failure such as blade squealing or chattering was observed. At this time, the decrease in the film thickness of the photoreceptor was measured. In the variable pressure type, the decrease in the outer diameter was 0.5 μm, whereas at a constant contact pressure, the decrease was 1 μm, confirming a double effect. In addition, scars due to rubbing of the sponge roller were confirmed in the drum circumferential direction under a constant pressure, but no drum scratches were observed under the variable pressure type.

  By controlling the sponge roller according to the present invention with an environmental sensor, the photoconductor itself is maintained while maintaining the original function (abrasiveness / lubricity) of the sponge roller by rubbing with the contact pressure optimum for the use environment. It has been found that long life and high stability can be realized.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. It is explanatory drawing of the cleaning member in the Example of this invention. It is a sponge roller schematic diagram. It is an abrasive particle schematic diagram. It is a schematic diagram for demonstrating the effect | action of this invention. It is a figure which shows the experimental result for demonstrating the effect | action of this invention. It is a figure which shows the experimental result for demonstrating the effect | action of this invention. It is a figure which shows the experimental result for demonstrating the effect | action of this invention. It is a figure which shows the experimental result for demonstrating the effect | action of this invention.

Explanation of symbols

2 Photoconductor 13 Cleaning device 14 Casing 15 Cleaning blade 15a Support portion 15b Abrasive layer 15c Lubricant layer
16 Rake sheet 17 Core 18 Sponge 19 Abrasive 20 Pressure variable device 21 Humidity sensor 22 Developer

Claims (5)

A compound having an unsaturated polymerizable functional group that polymerizes or crosslinks a hole transport compound, and a cured compound in the photosensitive layer, a charging means for charging the surface of the photoreceptor, a charging surface of the photoreceptor A latent image forming unit that forms an electrostatic latent image on the toner, a developing unit that develops the electrostatic development as a toner image with toner carried on a developing roller, a transfer unit that transfers the toner image to a recording medium, and a transfer unit In an image forming apparatus having a cleaning unit for cleaning residual toner,
An image forming apparatus, wherein a sponge roller containing an abrasive is brought into contact with the surface of a photoreceptor.   The sponge roller is used so that the contact angle of water on the surface of the photoreceptor is always kept at 70 ° or more, and the transfer residual developer and lubricant corresponding to the print area of 8% or more are always supplied to the cleaning blade edge. The image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with the image forming apparatus.   The image forming apparatus according to claim 1, wherein the sponge roller contains abrasive particles having different particle sizes and shapes.   The image forming apparatus according to claim 1, further comprising a sensor capable of sensing humidity.   The environmental information detected by the environmental condition detection means composed of the humidity sensor is input to the control means, and the control means controls the contact pressure of the sponge roller through the energization circuit as the drive means based on the information. The image forming apparatus according to claim 1.

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