JP2012252157A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that uses a blade with ends thereof subjected to high hardness processing for both cleaning blades for a drum and an intermediate transfer body, and has width Q of an unprocessed area of the blade for the intermediate transfer body larger than width P of an unprocessed area of the blade for the drum.SOLUTION: When a cleaning blade has both ends thereof subjected to isocyanate processing to obtain high hardness in order to reliably prevent curling of the blade, there appears a level difference at a boundary between a processed part and an unprocessed part when the cleaning blade contacts a photoreceptor drum, and a trace amount of toner slips through the level difference. Such trance amount of toner slipped through between sheets or the blade on the photoreceptor drum during a test rotation accumulates on the intermediate transfer body, and is subsequently transferred onto a recording medium, which results in appearing as image failure.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a fax machine using an electrophotographic system or an electrostatic recording system, and more particularly to an image forming apparatus using a cleaning blade.

  Conventionally, a cleaning blade made of an elastic material such as urethane rubber has been widely put into practical use as a cleaning means for cleaning residual toner and the like.

  As rubber materials for cleaning blades, rubber materials such as urethane rubber, which have high hardness and high elasticity, and are excellent in wear resistance, mechanical strength, oil resistance and ozone resistance, are generally used. Yes.

  Although the slipperiness between the image carrier and the blade is mainly maintained by the toner and the external additive contained in the toner, the amount of toner reaching both ends of the image carrier is significantly smaller than that in the central portion. For this reason, the sliding property of the cleaning blade is not maintained, and a phenomenon that the cleaning blade is turned up starting from the end portion in the longitudinal direction (hereinafter referred to as blade turning) is likely to occur.

  In recent years, as a method for preventing the blade from turning up, a cleaning blade treated by impregnating an isocyanate compound throughout the longitudinal direction of the rubber material forming the cleaning blade, or by applying isocyanate to the longitudinal end of the cleaning blade in the longitudinal direction An invention has been proposed in which the rubber hardness at the end is increased, the coefficient of friction with the image carrier is lowered, and the blade turning from the end is reduced (Patent Document 1).

JP2009-63993A

  However, when a portion subjected to a treatment for increasing hardness is formed at both ends in the longitudinal direction of the cleaning blade, the hardness treatment is performed when the cleaning blade comes into contact with the image carrier due to swelling of the treated portion (hereinafter referred to as a hardness treatment portion). There may be a step at the inner end of the hardness processing portion, which is the boundary between the unprocessed portion and the unprocessed portion, and toner slip may occur from the step.

  Further, in an image forming apparatus using an intermediate transfer member, toner slipped from the cleaning blade on the image carrier may be transferred and accumulated on the intermediate transfer member, and then transferred onto a recording material, causing image defects. There is.

  Therefore, the present invention suppresses the occurrence of blade turning starting from the end in the longitudinal direction, and the toner that has passed through the cleaning blade on the image carrier accumulates on the intermediate transfer member and is transferred to the recording material. The object is to suppress image defects.

  The present invention is characterized by the following configuration, thereby solving the above-mentioned problems. That is, an image carrier on which an electrostatic latent image is formed, a developing unit that uses the electrostatic latent image on the image carrier as a toner image, and abuts on the image carrier and remains on the image carrier. A first blade member that is a first blade member that removes residual toner, and includes a first hardness processing portion that is processed to increase the hardness at an end in a longitudinal direction on the side in contact with the image carrier; An intermediate transfer member that transfers and carries a toner image from the image carrier, a primary transfer unit that primarily transfers a toner image on the image carrier to the intermediate transfer member in a primary transfer region, and an intermediate transfer member A second blade member that removes residual toner remaining on the intermediate transfer member by contacting the second hardness processing portion that has been processed to increase the hardness in the longitudinal direction on the side that contacts the intermediate transfer member A second blade member provided at the end of the In the longitudinal direction, in the longitudinal direction, the inner end of the first hardness processing section does not overlap with the inner end of the second hardness processing section, and the inner end of the second hardness processing section does not overlap. The part is located outside.

  Suppressing the occurrence of blade turning at the end in the longitudinal direction of the cleaning blade, and the toner that has passed through the high-hardness blade on the image carrier is deposited on the intermediate transfer member and further transferred to the recording material Therefore, it is possible to suppress image defects.

FIG. 5 is a diagram illustrating a relationship between longitudinal widths of hardness processing portions of the drum blade and the intermediate transfer body blade according to the first embodiment. 1 is a schematic configuration diagram of an image forming apparatus according to Embodiment 1. FIG. 1 is a diagram of a blade subjected to hardness processing according to Example 1. FIG. FIG. 4 is a diagram of the blade according to the first embodiment when viewed from the Z direction in FIG. 3. FIG. 4 is a view of the blade according to the first embodiment when viewed from the X direction of FIG. 3. It is the figure which showed the relationship of the longitudinal width of the braid | blade which concerns on Example 1, and another component. FIG. 6 is a diagram illustrating toner that has passed through from an intermediate transfer body blade and a drum blade. FIG. 6 is a diagram illustrating a longitudinal relationship between a cleaning blade and an intermediate transfer body blade in each image forming unit according to Embodiment 2.

  The configuration according to the present invention will be described below with reference to the drawings.

  FIG. 2 is a diagram illustrating a schematic configuration of the image forming apparatus according to the present exemplary embodiment.

  When image formation is started, the moving optical system operates to optically scan the original surface of the recording material. As a result, the image information on the document surface is photoelectrically read as an electrical image signal by the image sensor (CCD) and input to the controller 100. A controller (CPU) 100 serving as a control unit decomposes an input image information signal into yellow, cyan, magenta, and black color components, and based on the input image information signal of each color, an image of each color. An image forming operation of an image forming unit (PY, PM, PC, PBk) having a forming process means is controlled according to a control program or a reference table.

  An image forming operation on the photosensitive drums (1Y, 1M, 1C, 1Bk) which are image carriers in the image forming units of the respective colors will be described using a yellow image forming unit PY. Hereinafter, since the configurations of the respective colors are substantially the same, the yellow image forming unit PY is collectively referred to as the image forming unit P, and the yellow photosensitive drum 1Y is collectively referred to as the photosensitive drum 1.

  The photosensitive drum 1, which is a rotatable image carrier on which a toner image is formed, is rotationally driven in the direction of the arrow at a predetermined rotational speed (process speed).

  The surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charging roller 2 which is a primary charging unit as a charging unit. The primary charging roller 2 is a contact type charging roller that rotates following the rotation of the photosensitive drum 1.

  A predetermined primary charging bias is applied to the primary charging roller 2 from a charging bias application power source (not shown). In this embodiment, the charging bias is a superimposed bias of an AC bias and a DC bias.

  The charged surface of the photosensitive drum 1 is exposed to an image by a laser scanner 3 as an exposure unit, and an electrostatic latent image is formed. The laser scanner 3 scans and exposes the surface of the photosensitive drum by outputting a laser beam modulated in accordance with the image information signal input from the controller 100.

  A direction (drum longitudinal direction) orthogonal to the rotation direction (sub-scanning direction) of the photosensitive drum 1 is the main scanning direction, and the rotation direction of the photosensitive drum 1 is the sub-scanning direction. By this scanning exposure, an electrostatic latent image (latent image pattern) corresponding to the read document image is formed on the photosensitive drum surface.

  The electrostatic latent image is developed as a toner image by a developing device 4 as developing means. The developing device 4 is a developing roller 5 (developing sleeve) as a developer carrying member that carries toner (developer), supplies the toner to the electrostatic latent image on the photosensitive drum 1 and develops it, and driving means (motor: (Not shown) is driven to rotate in the counterclockwise direction of the arrow. A predetermined developing bias is applied from a developing bias applying power source (not shown).

  The toner image formed on the photosensitive drum 1 is applied with a primary transfer bias at the primary transfer portion T1 which is a facing portion between the photosensitive drum 1 and the primary transfer roller 52 as a primary transfer unit, and is applied to the intermediate transfer body 54. It is transcribed. The toner image transferred to the intermediate transfer member 54 is conveyed toward the secondary transfer portion T2.

  On the other hand, residual toner remaining on the photosensitive drum 1 without being transferred after passing through the primary transfer portion T1 is scraped off from the surface of the photosensitive drum by the drum blade 8 provided in the drum cleaning means 7. The residual toner scraped off is collected in a toner container.

  The image forming operation described above is also performed on the magenta image forming unit PM, the cyan image forming unit PC, and the black image forming unit, and the color component toner images of the respective colors are sequentially superimposed on the intermediate transfer member 54.

  The toner image superimposed on the intermediate transfer member is given a predetermined charge from the post charger 55 and then conveyed to the secondary transfer portion T2.

  In the secondary transfer portion T2, the toner image on the intermediate transfer member is transferred to a recording material that is a recording medium fed from the paper feeding portion 9. In this embodiment, the nip portion between the intermediate transfer member 54 and the secondary transfer roller 53 is the secondary transfer portion T2. A transfer bias having a predetermined potential is applied to the secondary transfer roller 53 from a transfer bias applying power source (not shown) having a polarity opposite to the charging polarity of the toner. As a result, the toner image on the intermediate transfer member is transferred to the surface of the recording material that is nipped and conveyed by the secondary transfer portion T2.

  The recording material is stacked and accommodated in the paper feed cassette 9, and is separated and fed by a paper feed roller 61 driven at a predetermined control timing, and reaches the registration roller 62 through the recording material conveyance path.

  The recording material that has passed through the secondary transfer portion T2 is then nipped and conveyed by the fixing nip portion of the fixing device 70 serving as fixing means through the recording material conveyance path 63. As a result, the unfixed toner image on the recording material is fixed on the recording material surface as a fixed image. Then, the recording material exits the fixing device 70 and is discharged to the paper discharge tray 10 by the paper discharge roller 64.

  Further, residual toner and paper dust on the intermediate transfer member are cleaned by the intermediate transfer member cleaning device 56. The intermediate transfer body cleaning device 56 includes an intermediate transfer body blade 57 that contacts the intermediate transfer body 54 and removes residual toner, paper dust, and the like on the intermediate transfer body.

  Here, the drum blade 8 as the first blade member and the intermediate transfer member blade 57 as the second blade member are elastic blades made of a rubber material such as urethane rubber. The intermediate transfer body blade 57 will be described as an example. The intermediate transfer body blade 57 is provided along the longitudinal direction of the intermediate transfer body 54 and in the counter direction with respect to the rotation direction of the intermediate transfer body 54, and the edge of the intermediate transfer body blade 57 on the side in contact with the intermediate transfer body In this portion, a nip portion (cleaning portion) that is in contact with the intermediate transfer member 54 in a predetermined area is formed. The surface of the intermediate transfer member is cleaned by an intermediate transfer member blade 57 to remove residues such as residual toner and paper powder. The removed residual toner and the like are then collected into the cleaning container 56.

(Blade molding)
Here, a manufacturing method of the blade constituting the drum blade 8 as the first blade member and the intermediate transfer body blade 57 as the second blade member of the present embodiment will be described by taking the drum blade 8 as an example. The drum blade 8 in the present embodiment is made of a rubber member and is manufactured from a polyisocyanate compound and a polyfunctional active hydrogen compound.

  As the polyisocyanate compound used in this example, it is preferable to use a prepolymer or semi-prepolymer obtained by reacting a normal polyisocyanate and a polymer polyol which is a polyfunctional active hydrogen compound.

  The isocyanate group content (NCO%) of the prepolymer or semi-prepolymer is preferably 5 to 20% by mass in order to realize good elastic properties. In addition, isocyanate group content (NCO%) is the mass% of the isocyanate functional group (NCO, molecular weight is calculated as 42) contained in the prepolymer or semi prepolymer which is a raw material of a polyurethane resin.

  Specific examples of the polyisocyanate usually used for preparing a prepolymer, a semiprepolymer, etc. include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), and the like. be able to. Specific examples of the polymer polyol which is an active hydrogen compound for preparing a prepolymer or a semi-prepolymer include polyester polyol, polyether polyol, caprolactone ester polyol, polycarbonate ester polyol, and silicone polyol. it can. And these weight average molecular weights have preferable 500-5000 normally.

  Specific examples of the crosslinking agent include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, trimethylolpropane and the like.

  In addition, when making the said polyisocyanate compound, polymer polyol, polyisocyanate, and a crosslinking agent react, the normal catalyst used for formation of a polyurethane resin may be added. Specific examples of such a catalyst include triethylenediamine.

  As a method for forming the drum blade 88 formed of the polyurethane resin in the present embodiment, polymer polyol, polyisocyanate, cross-linking agent, catalyst and the like are mixed at a time, and then cast into a mold. At that time, the drum blade 8 made of polyurethane resin is directly formed on the support member 20 and the contact portion with the photosensitive drum 1 is accurately manufactured. Produced.

  As another drum blade 8 molding method, a method may be used in which a sheet-like rubber material is molded, then cut to a size to be used, and a part of the rubber material is attached to the support member 20 with an adhesive.

(Formation of hardness processing part)
Next, a method for forming the first hardness treatment portion on the drum blade 8 formed of the polyurethane resin obtained as described above will be described. The second hardness processing portion of the intermediate transfer body blade is also formed in the same manner.

As a formation method of a 1st hardness process part, the method which has the following process can be mentioned, for example.
(1) a step of bringing an isocyanate compound into contact with both ends in the longitudinal direction of the photosensitive drum contact portion of the drum blade 8 formed of polyurethane resin;
(2) Next, the process of impregnating the drum blade 8 with the isocyanate compound by leaving the isocyanate compound in contact with the drum blade surface;
(3) a step of removing the isocyanate compound remaining on the surface of the drum blade 8 after impregnation; and
(4) A step of forming a hardness treatment part by reacting an isocyanate compound impregnated in a drum blade.

  That is, in steps (1) and (2), an isocyanate compound is impregnated at both ends in the longitudinal direction of the tip of the drum blade made of polyurethane resin that comes into contact with the photosensitive drum. Thereafter, in step (3), excess isocyanate compound is removed from the surface of the blade, and in step (4), the isocyanate compound is reacted to form a hardness treatment portion.

  In the step (4), it is considered that the polyurethane resin forming the blade 8 and the isocyanate compound react to form an allophanate bond, thereby forming a hardness-treated portion with high hardness. The hardness processing unit is provided at one end and the other end of the blade 8 in the longitudinal direction.

  In the polyurethane resin forming the blade 8, a urethane bond having active hydrogen is present. And it is thought that the hardness processing part of high hardness is formed when this urethane bond and the isocyanate compound impregnated react at step (4), and an allophanate bond is formed.

  In addition, it is considered that a multimerization reaction (for example, carbodiimidization reaction, isocyanurate reaction, etc.) by reaction between isocyanate compounds proceeds at the same time, and contributes to the formation of the hardness treated portion. As a result, it is considered that the hardness of the hardness processing portion is improved, the coefficient of friction with the photosensitive drum is lowered, the durability of the drum blade 8 is improved, and the blade turning can be reduced. In particular, the slidability between the image carrier and the blade is mainly maintained by the toner and the external additive contained in the toner, but the amount of toner reaching both ends of the image carrier is significantly smaller than that in the central portion. For this reason, the sliding property of the cleaning blade is not maintained, and a phenomenon that the cleaning blade is turned up starting from the end portion in the longitudinal direction (hereinafter referred to as blade turning) is likely to occur.

  As the isocyanate compound impregnated in the drum blade 8, an isocyanate compound having one isocyanate group in the molecule and an isocyanate compound having two or more isocyanate groups in the molecule can be used. Examples of the isocyanate compound having one isocyanate group in the molecule include aliphatic monoisocyanates such as octadecyl isocyanate (ODI), aromatic monoisocyanates, and the like.

  Further, as an isocyanate compound having two isocyanate groups in the molecule impregnated in the blade 8, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), m- Phenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate and the like can be used.

  In this embodiment, in order to accelerate the reaction of the isocyanate compound, the polyurethane resin may be impregnated with a catalyst in addition to the isocyanate compound.

  The impregnation of the isocyanate compound into the blade can be performed by, for example, impregnating a fibrous member or a porous member with the isocyanate compound and applying it to the blade, or applying by spraying.

  As described above, the blade is impregnated with the isocyanate compound for a predetermined time. The processing time can be changed depending on the image forming apparatus and the abutting member, and the optimum processing time and processing width may be set separately for the drum blade and the intermediate transfer member blade.

  In order to make the range of the treatment area of the blade in this embodiment, the contact time between the isocyanate compound and the blade formed of the polyurethane resin is preferably 5 minutes or more, and more preferably 10 minutes or more.

  Next, in step (3), the isocyanate compound remaining on the blade surface is wiped off using a solvent capable of dissolving the isocyanate compound.

  After passing through the above steps, in the step (4), the impregnated isocyanate compound reacts to form an allophanate bond, or is almost consumed by reaction with moisture in the air, and is white and opaque and has a high hardness. A layer is formed.

  And the drum blade 8 by which the predetermined | prescribed area | region of both ends shown in FIG. 3 was hardness-processed can be obtained. In the drum blade, as shown in FIG. 4, the portion impregnated with the isocyanate compound swells in the Y direction, which is the thickness direction of the blade.

  FIG. 4 is a schematic view in which the end of the drum blade 8 of the present embodiment is enlarged and viewed from vertically upward in the longitudinal direction (Z direction shown in FIG. 3). FIG. 5 is a schematic view in which the end portion of the drum blade 8 of this embodiment is enlarged and viewed from the longitudinal direction (X direction shown in FIG. 3).

  When the drum blade formed from the polyurethane resin is impregnated with the isocyanate compound, swelling occurs in the width direction (Y direction) of the blade. The swelling width H is the distance in the blade width direction (Y direction) between the edge portion E that contacts the drum of the unprocessed portion of the drum blade and the edge portion E that contacts the photosensitive drum of the hardness processing portion.

  The processing width L of the drum blade 8 is the distance from one end in the longitudinal direction of the drum blade to the boundary between the hardness processing portion of the edge E that contacts the drum and the unprocessed portion that has not been subjected to the hardness processing.

  Moreover, when the isocyanate compound is impregnated to form the hardness processing portion, the inner end portion 100 of the hardness processing portion becomes as shown in FIG. That is, there is a region where the swelling width gradually decreases from the region where the swelling width becomes maximum toward the inner side in the longitudinal direction. Here, in particular, a region where the swelling width changes from 90% to 10% with respect to the swelling width of the region where the swelling width is maximum is defined as a boundary between the hardness-treated portion and the untreated portion, and in the longitudinal direction of the hardness-treated portion. The inner end 100 is assumed. The toner slips mainly from the region of the inner end portion 100.

(Positional relationship of hardness processing part)
Next, the positional relationship between the inner end portions 100 and 101 of the first and second hardness treated portions impregnated with the isocyanate compound of the drum blade 8 and the intermediate transfer member blade 57 will be described. FIG. 1 is a diagram showing the positional relationship between the inner end portions 100 and 101 of the first and second hardness processing portions of the drum blade 8 and the intermediate transfer member blade 57. FIG. 6 is a diagram showing the longitudinal relationship of components such as the drum blade 8, the intermediate transfer member blade 57, the primary transfer roller 52, and the like.

  First, there is an image forming area A that is an area where an image can be formed on the surface of the photosensitive drum. Further, in order to make the image forming area A developable in the longitudinal direction, a developer carrying area (hereinafter referred to as a developer carrying area) that can carry a developer (toner) on the surface of the developing sleeve 5Y in the area covering the image forming area A. There is a toner coat area) B. In order to prevent toner from adhering to the photosensitive drum 1 outside the toner coat area B in the longitudinal direction, there is a charging area C that is wider than the toner coat area B and can be charged by the charging unit 2.

  However, since a small amount of toner may adhere to the charging region C wider than the toner coating region B, the drum blade 8 is provided to the outside in the longitudinal direction in a wider range than the charging region C. . Here, the end portions of the image forming area A, the toner coat area B, and the charging area C are defined as an end a, an end b, and an end c.

  And the hardness processing part M impregnated with the isocyanate compound is formed in the both ends of the longitudinal direction of the drum blade 8. The primary transfer roller 5 for transferring an image to the surface of the intermediate transfer member is provided with a length that covers the developer coating width. The primary transfer area formed by the primary transfer roller is formed outside the inner end of the first hardness processing section so that the toner that has passed through the drum blade can be transferred to the intermediate transfer belt. The secondary transfer roller 53 for transferring the image on the intermediate transfer member to the recording material is provided with a length that covers the maximum sheet passing width of the recording material.

  The intermediate transfer body blade 57 that removes residual toner remaining on the intermediate transfer body is provided with a length that covers the width of the secondary transfer roller 53. Both ends of the blade 57 in the longitudinal direction are provided with an impregnated hardness processing portion M using an isocyanate compound. Further, the respective end portions of the primary transfer region, the maximum sheet passing region, the secondary transfer region, and the blade 57 are defined as an end portion e, an end portion f, an end portion g, and an end portion h.

  In the initial stage of use of the drum blade 8 and the intermediate transfer member blade 57, there is a possibility that the blade is turned up due to an increase in the frictional force between the unprocessed portion of the blade and the image carrier. In order to prevent this, a lubricant is applied in advance over the entire length of the blade.

In this embodiment, the end of the blade is treated with isocyanate. However, the end of the blade may be coated with a fluorine compound or the like as the high hardness treated portion. However, an impregnation treatment such as an isocyanate treatment is more desirable because it is easier to peel off in the case of coating than the isocyanate treatment.
(Evaluation of cleaning blade)
For the evaluation of this blade, a Canon multifunction machine was used. Since the evaluation was performed in a relatively harsh environment, blade turning was evaluated in a high temperature and high humidity environment (32.5 ° C., 80%), and the cleaning property was evaluated in a low temperature and low humidity environment (15 ° C., 10%). Table 1 shows the results of the examples and comparative examples.

  In this embodiment, the intermediate transfer member blade 57 is also prepared in the same manner as the drum blade 8, and an isocyanate treatment time of 40 minutes is used to ensure the hardness necessary for preventing the blade from turning up. A cleaning blade having a swelling width H of 35 μm and a processing width L of 8 mm was used. Further, the width of the unprocessed area of the intermediate transfer body blade 57 not subjected to the isocyanate treatment is made longer than the width of the unprocessed area of the drum blade 8 and is intermediate to the inner end of the first hardness processing portion of the drum blade. The inner end portion of the second hardness processing portion of the transfer body blade is formed more outward in the longitudinal direction.

  In the blade of this embodiment under this condition, a slight toner slip occurred in the drum blade 8 and the intermediate transfer body blade 57, but the toner slipped out of the drum blade 8 as shown in FIG. Since it is removed every time it passes through the unprocessed area of the blade 57, even when the durability is 150,000 sheets, it does not become manifest as an image defect on the recording material. Further, neither the drum blade 8 nor the intermediate transfer member blade 57 turned up from the end portion, and good results were shown.

  Further, since the intermediate transfer member reciprocates in the longitudinal direction while rotating, a small amount of toner slipped from the processing boundary portion of the intermediate transfer member blade 57 rotates several times and passes through the intermediate transfer member blade. In most cases, the intermediate transfer body blade 57 is removed by a region other than the processing boundary portion. Therefore, no toner streak on the intermediate transfer member was observed. A similar experiment was performed in comparative examples under the following three conditions by changing the processing width and processing time of the first and second hardness processing sections. The results are shown in Table 1 below. This also shows that the swelling width of the blade end is desirably 35 μm or more.

[Comparative Example 1]
In Comparative Example 1, the widths of the unprocessed areas of the drum blade 8 and the intermediate transfer member blade 57 were the same. That is, the inner end portions 100 and 101 of the first and second hardness processing portions of the drum blade 8 and the intermediate transfer member blade 57 are overlapped in the longitudinal direction. The other isocyanate treatment time, swelling width H, and treatment width L were the same as in Example 1, and the same experiment was conducted with respect to the experimental conditions.

  Under these conditions, the drum blade 8 and the intermediate transfer member blade 57 did not turn over, but the toner slightly slipped from the drum blade 8 accumulates on the intermediate transfer member to form a toner streak. The image was transferred to the material and a defective image occurred.

[Comparative Example 2]
In Comparative Example 2, the width of the unprocessed area of the drum blade 8 was made longer than the width of the unprocessed area of the intermediate transfer body blade 57. That is, the inner end portion 100 of the first hardness processing portion of the drum blade 8 was formed on the outer side in the longitudinal direction from the inner end portion 101 of the second hardness processing portion of the intermediate transfer body blade 57. The other isocyanate treatment time, swelling width H, and treatment width L were the same as in Example 1, and the same experiment was conducted with respect to the experimental conditions.

  Under these conditions, neither the drum blade 8 nor the intermediate transfer member blade 57 turned up, but a chatter noise due to blade vibration, which was a precursor to blade turning up, occurred. This is probably because the amount of toner that has passed through the drum blade 8 exceeding the recovery capability has come to the area of the second hardness processing section.

  Further, in the latter half of the endurance, the toner that has slightly slipped from the drum blade 8 cannot be collected in the region of the second hardness processing portion of the intermediate transfer body blade 57, and a toner streak is formed on the intermediate transfer body, so that it is formed on the recording material. The image was transferred and defective.

[Comparative Example 3]
In Comparative Example 3, the width of the unprocessed area of the intermediate transfer body blade 57 was made the same as the width of the unprocessed area of the drum blade 8, and the swelling width was reduced by reducing the degree of impregnation treatment with the isocyanate compound of the intermediate transfer body blade. . Others are the same as Example 1, and the same experiment was conducted also about experimental conditions.

  Under this condition, a slight toner slip occurred from the drum blade 8, but the toner slipped from the drum blade 8 was removed by the intermediate transfer body blade 57, and no image defect due to the slip toner occurred. This is probably because the impregnation treatment of the intermediate transfer member blade was weakened, so that almost no toner slip occurred in the second hardness treatment portion. However, since the intermediate transfer member blade 57 was turned over at the initial stage of durability, the experiment was terminated there.

  In this embodiment, in an image forming apparatus having a plurality of image forming units and a plurality of image forming units arranged side by side on the intermediate transfer member, the width of the isocyanate treatment of the photosensitive drum cleaning blades for each color is different, and as a result, the cleaning blade The unprocessed areas have different widths. That is, the inner end portion of the first hardness processing portion of each image forming unit is formed on the outer side in the longitudinal direction as it goes downstream in the rotation direction of the intermediate transfer member.

  Here, the image forming unit includes at least a photosensitive drum that is an image carrier and a cleaning blade that is in contact with the photosensitive drum, and is a unit that can form a toner image.

  In this embodiment, the drum blades 8Y, 8M, 8C, and 8K of the image forming units of yellow, magenta, cyan, and black that are image forming units, and the width of the unprocessed area of the intermediate transfer member blade 57 in the longitudinal direction. It is the figure which showed the relationship. As can be seen from the figure, in this embodiment, the boundary portions of the drum blades of the respective colors are shifted so that the toner slipped from the boundary portions of the drum blades does not overlap on the intermediate transfer member. .

  Further, in this embodiment, the width of the unprocessed area of the blade is increased as the downstream image forming unit is formed. This is because the toner slipped from the upstream image forming unit is further removed from the intermediate transfer body onto the photosensitive drum of the image forming unit when it is further transferred to the unprocessed area of the intermediate transfer body blade. This is to further improve the effect.

  When shifting the width of the unprocessed area between the image forming units, the effect of the present invention can be easily obtained by shifting by 0.5 mm or more, preferably 1.0 mm or more.

  By using this embodiment, even if a small amount of toner slips out in each image forming unit, the slipping position shifts, so when transferring from the intermediate transfer member to the photosensitive drum of the image forming unit downstream, It can be removed in the unprocessed area of the intermediate transfer member blade.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Primary charging device 4 Developer 5 Development sleeve 8 Drum blade 20 Support member 52 Primary transfer roller 53 Secondary transfer roller 54 Intermediate transfer body 56 Intermediate transfer body cleaning device 57 Intermediate transfer body blade T1 Primary transfer part T2 Secondary Transcription part

Claims (5)

An image carrier on which an electrostatic latent image is formed, a developing unit that uses the electrostatic latent image on the image carrier as a toner image, and residual toner that contacts the image carrier and remains on the image carrier A first blade member that is provided with a first hardness processing portion that is processed so as to increase the hardness at a longitudinal end portion on a side in contact with the image carrier; An intermediate transfer member that transfers and carries a toner image from an image carrier; a primary transfer means that primarily transfers a toner image on the image carrier to the intermediate transfer member in a primary transfer region; and an abutting contact with the intermediate transfer member. A second blade member for removing residual toner remaining on the intermediate transfer member, and a second hardness processing portion processed so as to increase the hardness in a longitudinal end on the side in contact with the intermediate transfer member A second blade member provided in the section, There is,
In the longitudinal direction, the inner end portions of the first hardness processing portion do not overlap with each other, and the inner end portion of the second hardness processing portion is located outside the inner end portion of the first hardness processing portion. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein in the longitudinal direction, an inner end portion of the first hardness processing portion is located inside the primary transfer region and outside the image forming region.   The image forming apparatus according to claim 1, wherein the blade member is made of a rubber member, and the first and second hardness processing portions are processed by impregnating the rubber member with an isocyanate compound. .   A plurality of image forming units each including at least the image carrier and the first blade member in contact with the image carrier, and each of the first blade members in the plurality of first blade members in the longitudinal direction; The image forming apparatus according to claim 1, wherein an inner end portion of the hardness processing portion does not overlap. A plurality of the image forming units are arranged side by side on the intermediate transfer member, and inner end portions of the first hardness processing portions of the plurality of first blade members go downstream in the rotation direction of the intermediate transfer member. 5. The image forming apparatus according to claim 4, wherein the image forming apparatus is formed on an outer side in a longitudinal direction.

Images