JP2006030849A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein filming, remaining toner, etc. stuck to an image carrier can be easily removed by a simple configuration. <P>SOLUTION: In the image forming apparatus provided with the image carrier for carrying a toner image formed on the basis of image data, a transfer roller for press-fitting a fed transfer material to the image carrier to transfer the toner image to the transfer material, and a cleaning means for cleaning away residual toner remaining on the image carrier, a roller which is disposed above the cleaning means in an upstream side in a rotation direction of the image carrier and is brought into contact with the image carrier and is rotated at a linear speed relatively different from that of the image carrier and a toner band forming means which forms a prescribed toner band on the image carrier facing a non-passage range on the outside of a passage range where transfer materials passes the transfer roller when consecutively feeding a plurality of transfer material of the same dimensions to transfer toner images are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic method such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, and more specifically, prevents filming of a photosensitive drum and an intermediate transfer belt and edge chipping of a cleaning blade. , Related to high durability technology.

  A configuration in which a toner image is formed on a photosensitive drum having charging, exposure, and development means around it, and the toner image is transferred to a transfer material (paper), or a toner image formed on a plurality of photosensitive drums is intermediate In an image forming apparatus configured to secondarily transfer a toner image on an intermediate transfer belt to a transfer material after primary transfer to a transfer belt, the image is transferred to a photosensitive drum or an intermediate transfer belt (also referred to as an image carrier) after transfer. In order to remove the residual toner remaining, a blade cleaning system is known in which an elastic cleaning blade made of urethane rubber or the like is brought into contact with the running direction of the image carrier in the counter direction.

  In recent years, high speed and high durability of image forming apparatuses have been demanded, and image defects such as image streaks and unevenness due to filming of the photosensitive drum and intermediate transfer belt, and cleaning defects due to wear and chipping of the edge of the cleaning blade have become problems. It has become. Filming is a lubricant that is added to the toner, such as calcium stearate (CaSt), zinc stearate (ZnSt), or wax contained in the toner, which adheres to the image carrier. Therefore, the transfer electric field is weakened. Further, since the adhesion force between the toner and the intermediate transfer belt is increased at the adhesion portion, the toner is difficult to be separated from the intermediate transfer belt. For these reasons, the transferability at the adhered portion is lowered, and streaks and unevenness occur in the image. In addition, the frictional resistance is increased at the portion where filming has occurred, and the edge of the cleaning blade is caught on the surface of the intermediate transfer belt to cause turning, and as a result, the edge of the cleaning blade is chipped.

  In the case of the intermediate transfer belt, filming and chipping of the edge of the cleaning blade tend to occur more frequently than the photosensitive drum. This is because the intermediate transfer belt has a harder surface than the photosensitive drum and is difficult to scrape. This is probably because adhesion of toner substances or the like is easily accumulated.

  Further, when a sheet is fed in the vertical direction such as A4R size or a small size sheet such as B5 size is fed, the side portion of the image carrier positioned outside the feeding range of these sheets is used. Therefore, filming and chipping of the edge of the cleaning blade tend to occur frequently. Note that there are few problems within the paper feeding range because the paper adsorbs and removes deposits such as toner, and the paper acts like an abrasive by polishing the intermediate transfer belt. Because.

  As a countermeasure against the above problems, a technique for removing filming by polishing an image carrier is known.

Also, during non-image formation, a toner band is formed in areas other than the image, and a large amount of toner is supplied to the edge of the cleaning blade, improving the lubricity and polishing effect between the image carrier and the cleaning blade, and reducing the frictional resistance. The technology to make it known is also known. As an example of this, there is an image forming apparatus that forms a toner band (toner layer, toner solid) outside the image area of the intermediate transfer belt and removes adhering matter attached to the intermediate transfer belt with a cleaning blade (for example, Patent Document 1). reference).
JP 2000-231274 A

  It is conceivable to polish a rotating image carrier by bringing a sandpaper, a nonwoven fabric containing abrasive particles, a wrapping film or the like into contact with the image carrier. However, sandpaper and non-woven fabric containing abrasive particles are liable to damage the image bearing member, and although fine wrapping films are effective, clogging occurs and the polishing power is not maintained.

  Further, when a toner band is formed outside the image area of the intermediate transfer belt, if the toner band is formed between sheets, there is a problem that the toner band adheres to the transfer roller and the back side of the sheet becomes dirty. In order to prevent this contamination, a configuration in which the transfer roller is retracted when the toner band passes can be considered. However, in the case of a high-speed machine, sufficient time for retracting cannot be taken, and a normal image is formed to form the toner band. Formation is sacrificed and the number of copies per unit time is reduced. Therefore, if the toner band is formed outside the sheet passing range, the sheet that has been passed through does not get dirty.

  However, even if the toner band is formed outside the paper range, there is a risk that the edge of the cleaning blade will be worn if a large amount of toner is supplied in the configuration as in Patent Document 1. A cleaning brush may be provided in place of the cleaning blade, particularly when durability is required or when a polymerized toner having a small particle size is used for the purpose of improving image quality. If it is formed, there is a problem that the toner slips through the cleaning brush, and it is difficult to put it to practical use.

  The present invention has been made in view of such problems, and is an image forming apparatus that can easily remove filming, residual toner, and the like adhering to an image carrier with a simple configuration. When a cleaning blade is used, an object is to provide an image forming apparatus capable of preventing edge chipping and realizing high durability.

[Claim 1] An image carrier for carrying a toner image formed on the basis of image data, and a transfer roller for pressing the fed transfer material onto the image carrier and transferring the toner image to the transfer material And a cleaning means for removing residual toner remaining on the image carrier. The image forming apparatus is located upstream of the cleaning means in the rotation direction of the image carrier. When a roller that contacts and rotates at a linear velocity relatively different from the linear velocity of the image carrier and a plurality of transfer materials of the same size are continuously fed and transferred, the transfer material An image forming apparatus comprising: a toner band forming unit that forms a predetermined toner band on the image carrier facing a non-passing range outside a passing range when passing a roller.
[2] The image forming apparatus according to [1], wherein the image carrier is an intermediate transfer belt.
[3] The image forming apparatus according to [1] or [2], wherein the cleaning means is a cleaning blade, and the roller is a brush roller.
[Claim 4] The image forming apparatus according to claim 1 or 2, wherein the cleaning means is a cleaning brush, and the roller is a sponge roller.

  According to the image forming apparatus of the present invention, by providing a brush roller or a sponge roller in contact with the image carrier and forming a toner band, the residual toner attached to the image carrier is surely removed and the image carrier is provided. The body can be polished to remove filming. Further, when a cleaning blade is used, edge chipping can be prevented and high durability can be realized.

  The image forming apparatus of the present invention will be described below with reference to the drawings.

  First, an example of an image forming apparatus for forming a color image will be described with reference to FIG. FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus. The present invention is not necessarily used only in an image forming apparatus that forms a color image, but is also used in an image forming apparatus that forms a monochrome image.

  The color image forming apparatus shown in FIG. 1 includes an image forming apparatus 100 and an image reading apparatus 200.

  The image forming apparatus 100 is referred to as a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer member 6, a sheet feeding / conveying unit 20, and a belt fixing device. It consists of 30 mag.

  An image reading device 200 including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the image forming apparatus 100.

  The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 202, and the line image sensor CCD is scanned. Is read.

  The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in the image processing unit 101, and then to the exposure means 3Y, 3M, 3C, 3K. Entered.

  The image forming unit 10Y that forms a yellow image includes a photosensitive drum 1Y as an image carrier, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a cleaning device 5Y, and a primary unit arranged around the photosensitive drum 1Y. It comprises a primary transfer roller 7Y as a transfer means.

  The image forming unit 10M that forms a magenta image includes a photosensitive drum 1M as an image carrier, a charging unit 2M arranged around the photosensitive drum 1M, an exposing unit 3M, a developing unit 4M, a cleaning device 5M, a primary unit. It comprises a primary transfer roller 7M as a transfer means.

  The image forming unit 10C for forming a cyan image includes a photosensitive drum 1C as an image carrier, a charging unit 2C disposed around the photosensitive drum 1C, an exposure unit 3C, a developing unit 4C, a cleaning device 5C, a primary unit. It comprises a primary transfer roller 7C as transfer means.

  The image forming unit 10K that forms a black image includes a photosensitive drum 1K as an image carrier, a charging unit 2K arranged around the photosensitive drum 1K, an exposure unit 3K, a developing unit 4K, a cleaning device 5K, a primary transfer unit. It comprises a primary transfer roller 7K as a means.

  The developing means 4Y, 4M, 4C, 4K are yellow (Y), magenta (M), cyan (C), or black (K) charged to the same polarity as the charging polarity of the photosensitive drums 1Y, 1M, 1C, 1K. The two-component developer (which may be a one-component developer) made of each color toner is accommodated, and is formed of, for example, a cylindrical nonmagnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm. And developing rollers 4Y1, 4M1, 4C1, and 4K1, which are developer carriers.

  The developing rollers 4Y1, 4M1, 4C1, and 4K1 are maintained in a non-contact manner by providing a predetermined gap, for example, a gap of 100 to 1000 μm, with the photosensitive drums 1Y, 1M, 1C, and 1K by an abutting roller (not shown). The drums 1Y, 1M, 1C, 1K rotate in the forward and reverse directions.

  By applying a developing bias voltage that superimposes an AC voltage on the DC voltage or DC voltage having the same polarity as the toner to the developing rollers 4Y1, 4M1, 4C1, and 4K1 during development, the photosensitive drums 1Y, 1M, 1C, and 1K are Reversal development is performed on the electrostatic latent image.

  Generally, so-called external additives are added to toners for the purpose of improving fluidity and cleaning properties. Among these, as a lubricant related to the present invention, for example, zinc stearate is used. Salt of aluminum, copper, magnesium, calcium, zinc oleate, salt of manganese, iron, copper, magnesium, etc., zinc of palmitic acid, salt of copper, magnesium, calcium, etc., zinc of linoleic acid, calcium, etc. And salts of higher fatty acids such as salts, zinc of ricinoleic acid, salts of calcium, and the like.

  The amount of these external additives added is about 0.01 to 10% by mass with respect to the toner.

  The intermediate transfer belt 6 is a semiconductive endless belt, is wound around a plurality of backup rollers 61, 62, etc., and is driven by a motor (not shown) to rotate clockwise.

  Opposite to the photosensitive drums 1Y, 1M, 1C, and 1K, primary transfer rollers 7Y, 7M, 7C, and 7K for the respective colors are provided via the intermediate transfer belt 6.

  The primary transfer rollers 7Y, 7M, 7C, and 7K are formed on the photosensitive drums 1Y, 1M, 1C, and 1K by applying a DC voltage having a polarity opposite to that of the toner and forming a transfer electric field in the transfer area. The toner images of the respective colors are primarily transferred onto the intermediate transfer belt 6.

  A secondary transfer roller 9 is provided through the intermediate transfer belt 6 so as to face the backup roller 62 for secondary transfer.

  A DC voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 9 to form a transfer electric field in the transfer area, so that the superimposed toner image carried on the intermediate transfer belt 6 is transferred onto the transfer material (paper) P. Secondary transfer to the surface of

  The transfer material P is fed from the sheet feeding cassette 21 by the sheet feeding means 20, and is conveyed to the secondary transfer position via a plurality of intermediate rollers 23, 24, 25, and 26 and a registration roller 27, and the color image is collectively transferred. Is done.

  When the size of the transfer material P is changed, the length (paper width) in the direction orthogonal to the transport direction is configured to change based on the center of the intermediate transfer belt 6.

  The transfer material P onto which the color image has been transferred is fixed by the fixing unit 30, is sandwiched by the paper discharge roller 28, and is placed on the paper discharge tray 29.

  A cleaning device 8 for removing toner remaining on the intermediate transfer belt 6 is provided on the downstream side of the secondary transfer position in the rotational direction of the intermediate transfer belt 6. The details of the cleaning device 8 will be described later.

  Here, materials of the intermediate transfer belt 6, the primary transfer roller 7, the secondary transfer roller 9 and the like in the present embodiment will be described.

The intermediate transfer belt 6 is an endless belt having a volume resistance of 10 ⁶ to 10 ¹² Ω · cm. For example, polycarbonate (PC), polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), and etrafluoro A resin material such as ethylene-ethylene copolymer (ETFE) or a rubber material such as EPDM, NBR, CR, polyurethane, etc., in which a conductive filler such as carbon is dispersed or an ionic conductive material is contained. The thickness used is preferably about 50 to 200 μm in the case of a resin material and about 300 to 700 μm in the case of a rubber material.

The primary transfer rollers 7Y, 7M, 7C, and 7K, for example, disperse a conductive filler such as carbon in a rubber material such as polyurethane, EPDM, or silicone on the peripheral surface of a conductive core such as stainless steel having an outer diameter of 8 mm. In addition, an ionic conductive material is contained, and the volume resistance is about 10 ⁵ to 10 ⁹ Ω · cm in a solid state or a foamed sponge state, the thickness is 5 mm, and the rubber hardness is about 20 to 70 ° (Asker hardness C) is formed by coating a semiconductive elastic rubber.

The secondary transfer roller 9 is formed by dispersing a conductive filler such as carbon in a rubber material such as polyurethane, EPDM, or silicone on a peripheral surface of a conductive metal core such as stainless steel having an outer diameter of 8 mm, for example. Semi-conducting material that contains a material and has a volume resistance of about 10 ⁵ to 10 ⁹ Ω · cm in a solid state or foamed sponge state, a thickness of 5 mm, and a rubber hardness of about 20 to 70 ° (Asker-C) It is formed by covering an elastic rubber.

  Unlike the primary transfer rollers 7Y, 7M, 7C, and 7K, the secondary transfer roller 9 may come in contact with toner and may cover the surface with a good releasability such as semiconductive fluorine resin or urethane resin. The secondary transfer backup roller 62 disperses a conductive filler such as carbon in a rubber or resin material such as polyurethane, EPDM, or silicone on the peripheral surface of a conductive core metal such as stainless steel or an ionic conductive material. It is formed by coating a semiconductive material that is contained or having a thickness of about 0.05 to 0.5 mm.

  Next, the image forming process will be described.

  When the image recording is started, a drive motor (not shown) of the photosensitive drum 1Y is started, and the photosensitive drum 1Y of the yellow (Y) image forming unit 10Y is rotated counterclockwise as indicated by an arrow in FIG. Application of a potential to the photosensitive drum 1Y is started by the charging action of the charging unit 2Y.

  After a potential is applied to the photosensitive drum 1Y, image writing is started by the exposure means 3Y using an electrical signal corresponding to the first color signal, that is, yellow (Y) image data, and a document is formed on the surface of the photosensitive drum 1Y. An electrostatic latent image corresponding to the yellow (Y) image of the image is formed. The electrostatic latent image is reversely developed in a contact or non-contact state by the developing roller 4Y1, and a yellow (Y) toner image is formed on the photosensitive drum 1Y according to the rotation of the photosensitive drum 1Y.

  The yellow (Y) toner image thus formed on the photosensitive drum 1Y is transferred onto the intermediate transfer belt 6 by the primary transfer roller 7Y.

  Subsequently, the yellow (Y) toner image on the intermediate transfer belt 6 is synchronized, and magenta (M), cyan (C), and black (K) toner images are sequentially superimposed to form a color. A toner image is obtained.

  Residual toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is removed by the cleaning devices 5Y, 5M, 5C, and 5K.

  In synchronization with the formation of the color toner image on the intermediate transfer belt 6, the transfer material P separated and conveyed one by one from the paper feed cassette 21 is fed with paper feed rollers 22, 23, 24, 25, 26 and a registration roller 27. The color toner images on the intermediate transfer belt 6 are collectively transferred onto the transfer material P by the secondary transfer roller 9.

  The transfer material P onto which the color toner image has been transferred is neutralized by a separating means (not shown), conveyed to the fixing device 30, fixed and fixed by heat and pressure, and then discharged by a paper discharge roller 28. It is discharged to the paper tray 29.

  On the other hand, residual toner remaining on the peripheral surface of the intermediate transfer belt 6 after the transfer is removed by the cleaning device 8.

  When the recording material P that has been subjected to the fixing process is reversed and discharged, the recording material P passes through the conveyance path on the right side of the branch plate 28A disposed between the belt fixing device 30 and the discharge roller 28, and the lower side. After being transported to the first transport path <1>, it is transported in reverse, passes through the second transport path <2> on the left side of the branch plate 28A, and is discharged out of the apparatus by the paper discharge roller 28.

  When copying on both surfaces of the recording material P, after fixing the image formed on the first surface of the recording material P, the recording material P is moved to the first conveyance path <1>, and further to the fourth below the branch plate 28B. After being introduced into the transport path <4>, it is transported in the reverse direction, passed through the transport path on the right side of the branch plate 28B, transported to the third transport path <3>, and then detoured upward and transported by the paper feed roller 26. . The recording material P is formed with images of the respective colors on the second surface by the image forming means 10Y, 10M, 10C, and 10K, heated and fixed by the belt fixing device 30, and discharged to the outside by the paper discharge roller 28.

Next, two types of forms and experimental results relating to the cleaning device 8 according to the present invention will be described in detail.
[First embodiment]
FIG. 2 is a cross-sectional view of a main part of a cleaning device having a cleaning blade.

  Reference numeral 811 denotes a casing on which members constituting the cleaning device are mounted.

  Reference numeral 812 denotes a cleaning blade (cleaning means) made of an elastic body such as polyurethane rubber, which is fixed to the blade holder 813 with an adhesive or the like. The blade holder 813 is rotatably attached to a support shaft 811A provided in the casing 811 and is urged counterclockwise by a spring (not shown). Accordingly, the edge 812A of the cleaning blade 812 is in pressure contact with the intermediate transfer belt 6 supported by the backup roller 61 in a state in which the edge 812A faces in the direction opposite to the rotation direction of the intermediate transfer belt 6 (counter direction).

  Reference numeral 814 denotes a brush roller having a brush on its surface, which contacts the intermediate transfer belt 6 at a position upstream of the contact position between the edge 812A of the cleaning blade 812 and the intermediate transfer belt 6 in the rotation direction of the intermediate transfer belt 6. . The brush roller 814 is rotated by a rotation unit (not shown), and the rotation direction of the brush roller 814 rotates in the direction opposite to the traveling direction of the intermediate transfer belt 6 at the contact position A with the intermediate transfer belt 6. That is, it rotates clockwise in FIG. Accordingly, the linear velocity of the brush roller 814 is different in direction from the linear velocity of the intermediate transfer belt 6, and the relative linear velocity is different even if the absolute values of both linear velocity are the same.

  Reference numerals 815 and 816 denote flickers made of a resin plate, a stainless plate or the like, one end of which is fixed to the casing 811 and the other end is in contact with the brush roller 814.

  A discharge screw 817 is provided at the bottom of the casing 811 and is rotated by a drive source (not shown).

  A seal plate 818 is fixed to the casing 811 and contacts the intermediate transfer belt 6 to prevent waste toner from leaking.

  In the cleaning device configured as described above, residual toner remaining after the toner image is transferred onto the recording material P by the transfer roller 9 adheres to the intermediate transfer belt 6 and moves together with the intermediate transfer belt 6. The residual toner is scraped off and removed from the intermediate transfer belt 6 by the rotation, and adheres to the brush roller 814. Part of the residual toner adhering to the brush roller 814 is scraped off by the flicker 816 and falls downward, is conveyed in the direction perpendicular to the paper surface by the rotation of the discharge screw 817, is discharged out of the cleaning device, and is discharged into a predetermined container. Accumulated. Further, residual toner interposed between the brush roller 814 and the intermediate transfer belt 6 serves as an abrasive to polish the intermediate transfer belt 6 and remove filming.

  Further, the residual toner which has not been completely removed by the brush roller 814 and has adhered to the intermediate transfer belt 6 is removed by the cleaning blade 812.

  If the residual toner is excessively removed from the intermediate transfer belt 6 by the rotation of the brush roller 814, the residual toner located at the edge 812A of the cleaning blade 812 is depleted and the frictional force increases, and the edge 812A is chipped or squeezed. . For this purpose, the residual toner adhering to the brush roller 814 is caused to fly by the flicker 815, adhere to the intermediate transfer belt 6, and supplied to the edge 812A.

  Further, when a sheet is passed in the vertical direction such as A4R size or a small size sheet such as B5 size is passed, the side portion of the image carrier positioned outside the sheet passing range of these sheets is used. That is, filming and the like tend to occur frequently in the non-sheet passing range. Therefore, a toner band is formed in the non-sheet passing range of the intermediate transfer belt 6 and a large amount of toner is supplied to increase the polishing force of the brush roller 814 and remove filming and the like.

  The position of the toner band will be described with reference to FIG.

  In FIG. 3, when a plurality of sheets P of the same size are continuously fed and a toner image TI corresponding to the sheet P is formed on the intermediate transfer belt 6, an area width W2 other than the area width W1 of the toner image TI. A toner band TP is formed on the surface. In other words, when transferring, the toner band TP is formed on the intermediate transfer belt 6 facing the non-passing range outside the passing range when the paper P passes the transfer roller 9.

  In the toner band TP, the image forming units 10Y, 10M, 10C, and 10K shown in FIG. 1 use a predetermined screen structure such as a line screen or a dot screen to form a toner image having a predetermined density on the photosensitive drums 1Y, 1M, and 1C. , 1K and formed by primary transfer at a predetermined position corresponding to the area width W2 (non-passage range) of the intermediate transfer belt 6 (toner band forming means).

  During normal image formation, the transfer roller 9 is pressure-bonded to the intermediate transfer belt 6, so a part of the toner in the toner band TP adheres to the transfer roller 9, but when changing the size of the paper P or normal image If the transfer roller 9 is cleaned before and after the formation, the back surface of the paper P will not be stained. In this cleaning, the toner attached to the transfer roller 9 is transferred to the intermediate transfer belt 6 by alternately applying a plus / minus electric field to the transfer roller 9 in a state where the transfer roller 9 is pressure-bonded to the intermediate transfer belt 6. .

Further, it is desirable that the toner band TP has an adhesion amount to the intermediate transfer belt 6 of 0.3 mg / cm ² and the length in the traveling direction is 1/10 or more of one turn of the intermediate transfer belt 6. In the case of full color, it is desirable that Y, M, C, and K have the same amount.

  Further, the brush roller 814 may be rotated in the forward direction with respect to the intermediate transfer belt 6 at the contact position A, that is, counterclockwise in FIG. 2, but in this case, the brush roller 814 at the contact position A is rotated. It is necessary to vary the linear velocity with respect to the linear velocity of the intermediate transfer belt 6 so that the residual toner on the intermediate transfer belt 6 can be scraped off by the brush roller 814. However, in this case, the residual toner cannot be ejected by the flicker 815 and adhered to the intermediate transfer belt 6. However, the amount of toner scraped off by the brush roller 814 is smaller than when the brush roller 814 is rotated clockwise. Therefore, the flicker 815 is unnecessary.

Next, an experiment in which the filming due to the presence / absence of the brush roller 814 and the presence / absence of the toner band and the state of the chipping of the edge 812A of the cleaning blade 812 are described.
(1) Experimental apparatus / experimental machine: Tandem full-color copying machine shown in FIG. 1 and cleaning device configured as shown in FIG. 2. Photosensitive drum: 60 mm outer diameter, coated with phthalocyanine pigment dispersed in polycarbonate as an organic semiconductor layer The film thickness of the photoreceptor layer including the charge transport layer is 25 μm.
Photoconductor non-image part potential: Detected by a potential sensor and feedback controlled, controllable range is -500V to -900V
-Total exposure potential: -50V to 0V
・ Exposure: Laser scanning method, power of semiconductor laser is 300μW
・ Development: Two-component development method ・ Intermediate transfer member: Seamless semiconductive resin belt, material polyimide, rotation speed 220 mm / s, surface resistivity 1 × 10 ¹¹ Ω / □, volume resistivity 1 × 10 ⁸ Ω · cm, tension 50N
・ Intermediate transfer member drive roller: 30 mm
Primary transfer means: A foaming roller (outer diameter 20 mm, resistance value 1 × 10 ⁶ Ω) is installed on the back of the intermediate transfer member, and a predetermined current value is selected from a current value table in which a matrix is formed by temperature and humidity and a counter. Applied / primary transfer conductive member: Roller pressure 5N with conductive roller
Secondary transfer means: The intermediate transfer member is sandwiched between the backup roller and the secondary transfer roller, the resistance value is 1 × 10 ⁷ , and a predetermined current value is selected from a current value table in which a matrix is formed by temperature and humidity and a counter. Application / toner: emulsion polymerization toner, particle size 6.5 μm, lubricant addition amount (% by mass) Y: 0.15, M: 0, C: 0, BK: 0.05
-Cleaning blade Material: Polyurethane rubber (thickness 2mm, free length 9mm)
Counter contact: Contact angle 17 degrees Spring load method: Weight 16N / m
・ Brush roller Material: Conductive acrylic Wire diameter: 10d
(D means denier, a unit representing linear density, which is a measure of fiber thickness, and a fiber having a length of 9,000 m and a mass of 1 g is defined as 1 denier.)
Density: 80,000 / inch ²
Hair length (loop height): 4.25 mm (core metal 10 mm, outer diameter 17.5 mm)
Outer diameter: 18.5mm
Belt biting amount: 0.7mm
(2) Experimental conditions and paper type: Konica 55kg
-Paper size: A4R
・ Mode: Double-sided continuous full color ・ Image pattern: Character pattern (printing rate 3%)
・ Environment: 30 ℃, 80% RH
・ Total number of copies: 10,000 sheets ・ Comparison: The presence or absence of brush rollers and toner bands confirmed the occurrence of filming and the lack of cleaning edges.
(2) Experimental results Table 1 shows.

  In Table 1, “◯”, “Δ”, and “x” of filming indicate the following degrees.

  ○: No streaks of filming are observed.

  Δ: Minor, but streaks of filming are observed.

  X: Clear filming streaks are observed.

  Further, the edge chip ratio is the chip ratio of the edge of the cleaning blade, and is calculated by the following formula.

Edge chip ratio = chip width × 100 / measurement length of cleaning blade Further, the chip width is as shown in FIG.

According to Table 1, a brush roller 814 that removes residual toner adhering to the intermediate transfer belt 6 and polishes the intermediate transfer belt 6 is provided, and when vertical feed or small size paper is continuously fed. Filming occurs most in the case where a toner band is provided in the non-sheet passing area of the intermediate transfer belt 6 in order to prevent the occurrence of filming in a range where the sheet does not pass and to prevent the edge of the cleaning blade from being chipped. And the edge chip ratio was the smallest.
[Second form]
FIG. 5 is a sectional view of an essential part of a cleaning device having a cleaning brush.

  Reference numeral 821 denotes a casing on which various members constituting the cleaning device are mounted.

  Reference numeral 822 denotes a cleaning brush (cleaning means) made of conductive acrylic, which is in pressure contact with the intermediate transfer belt 6. The cleaning brush 822 is rotated by a rotating means (not shown). The rotation direction of the cleaning brush 822 rotates in the opposite direction with respect to the intermediate transfer belt 6 at the contact position B with the intermediate transfer belt 6. That is, it rotates clockwise in FIG. A cleaning roller 823 formed of stainless steel or the like that rotates in the forward direction is pressed against the cleaning brush 822, and a scraper 824 formed of PET or the like is further in pressure contact with the cleaning roller 823.

  Reference numeral 825 denotes a sponge roller made of urethane or the like, which contacts the intermediate transfer belt 6 at a position upstream of the contact position B between the cleaning brush 822 and the intermediate transfer belt 6 in the rotation direction of the intermediate transfer belt 6. The sponge roller 825 is rotated by a rotating means (not shown), and the rotation direction of the sponge roller 825 rotates in the opposite direction to the traveling direction of the intermediate transfer belt 6 at the contact position C with the intermediate transfer belt 6. That is, it rotates clockwise in FIG. Therefore, the linear velocity of the sponge roller 825 is different in direction from the linear velocity of the intermediate transfer belt 6, and the relative linear velocity is different even if the absolute values of both linear velocity are the same.

  Reference numeral 826 denotes a flicker made of a resin plate, a stainless plate or the like, one end of which is fixed to the casing 821 and the other end is in contact with the sponge roller 825.

  827 is a discharge screw provided at the bottom of the casing 821, and is rotated by a drive source (not shown).

  Reference numeral 828 denotes a seal plate fixed to the casing 821, which contacts the intermediate transfer belt 6 to prevent waste toner from leaking.

  In the cleaning device configured as described above, the residual toner remaining after the toner image is transferred to the recording material P by the transfer roller 9 adheres to the intermediate transfer belt 6 and moves together with the intermediate transfer belt 6. The residual toner is removed from the intermediate transfer belt 6 by the rotation and adheres to the sponge roller 825. Part of the residual toner adhering to the sponge roller 825 is scraped off by the flicker 826 and falls downward, and is conveyed in the direction perpendicular to the paper surface by the rotation of the discharge screw 827, and is discharged out of the cleaning device and discharged into a predetermined container. Accumulated. Further, residual toner interposed between the sponge roller 825 and the intermediate transfer belt 6 serves as an abrasive to polish the intermediate transfer belt 6 and remove filming.

  Further, residual toner that has not been completely removed by the sponge roller 825 and has adhered to the intermediate transfer belt 6 is removed by the cleaning brush 822 and adhered to the cleaning brush 822. The toner adhering to the cleaning brush 822 adheres to the cleaning roller 823, is scraped off by the scraper 824, falls, and is discharged by the discharge screw 827.

  Further, when a sheet is passed in the vertical direction such as A4R size or a small size sheet such as B5 size is passed, the side portion of the image carrier positioned outside the sheet passing range of these sheets is used. That is, there is a tendency that filming and the like frequently occur in the non-sheet passing area. Therefore, a toner band similar to that described in the first embodiment is formed in the non-sheet passing range of the intermediate transfer belt 6 and a large amount of toner is supplied, so that the polishing force of the sponge roller 825 is increased, filming, etc. Remove.

Next, an experiment in which the occurrence of filming depending on the presence / absence of the sponge roller 825 and the presence / absence of the toner band is examined will be described.
(1) Experimental apparatus The same as the experimental apparatus described in the first embodiment. However, since the cleaning device is not provided with the cleaning blade 812 or the brush roller 814 but is provided with the cleaning brush 822 or the sponge roller 825 shown in FIG. 5, these specifications will be described.
Cleaning brush Material: Conductive acrylic Wire diameter: 6.25d
Density: 100,000 / inch ²
Hair length (loop height): 4.25 mm (core metal 10 mm, outer diameter 17.5 mm)
Outer diameter: 18.5mm
Belt biting amount: 1.0mm
・ Sponge roller Material: Urethane Core: 9mm
Outer diameter: 17.5mm
Belt biting amount: 0.7mm
(2) Experimental conditions The filming occurrence state was confirmed with the presence of the sponge roller 825 and the toner band as in the first embodiment. In this embodiment, if the toner band is provided without providing the sponge roller 825, there is a high risk that the toner in the toner band will slip through the cleaning brush 822. Therefore, this combination experiment was not performed.
(3) Experimental results Table 2 shows.

  According to Table 2, when a sponge roller 825 for removing residual toner adhering to the intermediate transfer belt 6 and polishing the intermediate transfer belt 6 is provided, and longitudinal feeding or small-size paper is continuously fed, In order to prevent the occurrence of filming in a portion where the sheet does not pass, it has been demonstrated that the filming does not occur most when the toner band is provided in the non-sheet passing area of the intermediate transfer belt 6.

1 is a cross-sectional configuration diagram of an image forming apparatus. It is principal part sectional drawing of the cleaning apparatus which has a cleaning blade. It is a figure which shows a toner belt. It is a figure which shows the edge notch width of a cleaning blade. It is principal part sectional drawing of the cleaning apparatus which has a cleaning brush.

Explanation of symbols

1Y, 1M, 1C, 1K Photosensitive drum 6 Intermediate transfer belt 8 Cleaning device 812 Cleaning blade 812A Edge 814 Brush roller 822 Cleaning brush 825 Sponge roller 9 Secondary transfer roller P Transfer material TP Toner belt

Claims (4)

An image carrier that carries a toner image formed based on image data;
A transfer roller for pressing the fed transfer material to the image carrier and transferring the toner image to the transfer material;
Cleaning means for removing residual toner remaining on the image carrier;
In an image forming apparatus comprising:
A roller that is positioned on the upstream side in the rotation direction of the image carrier with respect to the cleaning unit, abuts on the image carrier, and rotates at a linear velocity relatively different from the linear velocity of the image carrier;
When a plurality of transfer materials of the same size are continuously fed and transferred, a predetermined toner is applied to the image carrier facing the non-passage range outside the pass range when the transfer material passes through the transfer roller. An image forming apparatus comprising: a toner band forming unit that forms a band. The image forming apparatus according to claim 1, wherein the image carrier is an intermediate transfer belt. The image forming apparatus according to claim 1, wherein the cleaning unit is a cleaning blade, and the roller is a brush roller. The image forming apparatus according to claim 1, wherein the cleaning unit is a cleaning brush, and the roller is a sponge roller.

Images