JP4111149B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, and a facsimile, and more particularly to a cleaning unit that removes toner remaining on an image carrier.

  A toner image is formed on a photosensitive member having charging, exposure, and developing means around it, and the toner images are directly transferred to a transfer material, or the toner images on a plurality of photosensitive members are temporarily transferred to an intermediate transfer member. In the image forming apparatus configured to secondarily transfer the toner image on the intermediate transfer member to the transfer material after the transfer, the residual toner on the photosensitive member or intermediate transfer member (typically referred to as an image carrier) after transfer is removed. In order to remove, a blade cleaning method is known in which an elastic blade made of urethane rubber or the like (hereinafter referred to as a cleaning blade) is brought into contact with the running direction of the image carrier in the counter direction to perform cleaning.

  In the blade cleaning method, in order to surely scrape the toner, it is necessary to press the cleaning blade against the image carrier with a force of a certain magnitude or more, so there is friction between the image carrier and the cleaning blade. Due to this friction, problems such as cleaning blade curling, cleaning blade edge damage, toner filming, or image pitch unevenness due to a change in driving force of the image carrier accompanying an increase in frictional force may occur.

  On the other hand, it is known that the toner has a function as a lubricant, and the following techniques for solving the above-described problems by effectively utilizing this function have been proposed.

  One is to detect the replenishment amount of toner replenished from the toner replenishment container to the developing device, and based on the detection result, forcibly attach the toner to the image carrier and send it to the cleaning unit. This is to prevent the occurrence (see, for example, Patent Document 1).

  This is based on the idea that the amount of toner consumed on the image carrier is proportional to the amount of toner replenished to the developing device. When a large amount of toner is consumed on the image carrier, the cleaning unit is forcibly used. The amount of toner to be sent is reduced, and conversely, if the amount of toner to be consumed is reduced, the amount of toner sent to the cleaning unit is increased.

  One is to detect the specularity of the surface of the photoconductor, which is an image carrier, and when the photoconductor surface is in a mirror state, a high density fog toner image is formed on the non-image portion of the photoconductor surface and sent to the cleaning unit. The frictional resistance between the photosensitive member and the cleaning blade is lowered to prevent the above-described problem from occurring (for example, see Patent Document 2).

One is that the cleaning blade is pressed in the counter direction with respect to the running direction of the image carrier, and the tip of the pressure contact surface that is in pressure contact with the image carrier is placed on both sides from the visible region where the toner image is formed. The toner gradually scraped off in the image carrier traveling direction as it reaches both ends of the image carrier over the non-image area near the edge, and the toner scraped off in the image area is non-image area on both sides. In this region, the friction between the cleaning blade and the image carrier is reduced by conveying and supplying the toner to the substrate (for example, see Patent Document 3).
JP-A-5-40438 JP-A-6-318019 Japanese Patent Laid-Open No. 7-104627

  However, in the method described in Patent Document 1, since information in the print width direction is not taken into account, when the print width is narrow and a high-concentration toner image is continuously formed, a large amount of toner is consumed. Therefore, the amount of toner to be forcibly supplied to the cleaning unit is reduced.

  For this reason, the toner as the lubricant is insufficient in the non-printing region, and the above-described problems, that is, the problem of the cleaning blade curling, cleaning blade edge damage, toner filming, image pitch unevenness, etc., occur. .

  In the method described in Patent Document 2, the mirror surface degree of the photosensitive member in the rotation axis direction is affected by the print width history. That is, the specularity of the surface of the photoconductor that is commonly printed (formation of a toner image) is increased regardless of the printing width, but there is a problem that the specularity of a surface that is not used much does not increase so much. For this reason, if toner is forcibly supplied to the cleaning unit based on the specularity of the surface of the photoreceptor that is not often used, the amount of toner is insufficient on the surface with the increased specularity, causing the above-described problems. On the other hand, if toner is forcibly supplied to the cleaning unit based on the specularity of the commonly used surface, unnecessary toner is supplied on the surface where the specularity has not increased so much, and the toner is wasted. End up.

  In the case of Patent Documents 1 and 2, image formation time is required to forcibly send toner to the cleaning unit, and productivity is reduced. Toners are wasted if image formation is frequently performed. It also has the problem of end up.

In the method described in Patent Document 3, when a toner image having a narrow print width and a low printing rate is continuously formed, the toner removed by the cleaning blade is reduced, and the toner reaches both ends of the cleaning blade. There is a fear that it will not spread.
Further, the rigidity of both ends of the cleaning blade is lowered, and the toner may pass through the cleaning blade, which may cause cleaning failure.

  The present invention has been made in view of the above-described problems, and the object thereof is not affected by the print width or the print rate, but the cleaning blade is swung, the cleaning blade edge is damaged, the toner filming, or the image is printed. An object of the present invention is to provide an image forming apparatus that can solve problems such as pitch unevenness while preventing a decrease in productivity and wasteful toner consumption.

  The present inventors pay attention to the toner removed by the cleaning blade, do not collect the removed toner as it is, temporarily store it in the vicinity of the cleaning blade, and always keep the toner at the pressure contact portion between the cleaning blade and the image carrier. Therefore, the present invention is considered to be capable of imparting lubricity to the cleaning blade without being affected by the printing width and the printing rate.

  That is, the object of the present invention can be achieved by the following configuration.

(1) In an image forming apparatus having a cleaning means for removing toner remaining on an image carrier,
The cleaning means includes
A cleaning blade in pressure contact with the image carrier;
Viewed in the rotational direction of the image bearing member, and contact with the image bearing member on the upstream side of the pressure contact position of the cleaning blade, in the contact position between the image bearing member, the same as the rotational direction of said image bearing member A toner guide member rotating in a direction ;
A position abutting on said image bearing member of the toner guide member at a position opposite to said toner guide member abutting toner discharge regulating member,
Have
An image forming apparatus , wherein a space for storing toner is formed by the cleaning blade, the toner guide member, the toner discharge regulating member, and the image carrier .

(2) The above (1) is characterized in that the contact pressure of the toner discharge regulating member that contacts the toner guide member is stronger at both end portions than at the center portion in the rotation axis direction of the image carrier. The image forming apparatus described.

(3) The lengths of the cleaning blade, the toner guide member, and the toner discharge regulating member as viewed in the rotation axis direction of the image carrier are: cleaning blade> toner guide member ≧ toner discharge regulating member. The image forming apparatus according to (1) or (2).

(4) The toner guide member is a sponge roller, the peripheral speed of said sponge roller is equal to or faster than the peripheral speed of said image bearing member (1) of any crab wherein said (3) Image forming apparatus.

(5) The image forming apparatus according to any one of (1) to (4), wherein the toner discharge regulating member is an elastic member .

  According to the first aspect of the present invention, the space for storing the toner removed by the cleaning blade is formed by the image carrier, the cleaning blade, the toner guide member, and the toner discharge regulating member. The toner can always be supplied to the pressure contact portion with the image carrier, and lubricity can be imparted to the cleaning blade. As a result, it is possible to solve problems such as cleaning blade curling, cleaning blade edge damage, toner filming, and image pitch unevenness without being affected by the print width and print rate.

  At the same time, productivity reduction and wasteful toner consumption can be prevented.

  According to the second aspect of the invention, in addition to the effect of the first aspect, the toner discharge restricting member holds a certain amount of toner in the space, so that, for example, continuous image formation with a low printing rate is achieved. Even if it is carried out, the toner in the space does not run out and lubricity is imparted to the cleaning blade. Further, when image formation is continuously performed with a high printing rate, it is possible to prevent the toner held in the space from being in a packing state or slipping out of the cleaning blade.

  According to the third aspect of the invention, in addition to the effect of the first or second aspect, the contact pressure of the toner discharge regulating member that is in contact with the toner guide member is the center when viewed in the direction of the rotation axis of the image carrier. By strengthening both ends rather than the edges, even if less toner is removed at both ends due to continued image formation with a narrow print width, more toner is retained at both ends, resulting in damage over the entire length of the cleaning blade. Can be prevented.

According to the invention of claim 4, in addition to the effect of the invention of any one of claims 1 to 3,
The length of the cleaning blade, the toner guide member, and the toner discharge restricting member as viewed in the rotation axis direction of the image carrier is such that cleaning blade> toner guide member> toner discharge restricting member. In the vicinity of both ends of the body, the removed toner falls as it is, so that the toner does not leak to the outside from both ends and toner scattering and toner contamination can be prevented.

  According to the invention of claim 5, in addition to the effect of any one of claims 1 to 4, the toner guide member is constituted by a sponge roller, rotates in the same direction as the image carrier, and the sponge By making the peripheral speed of the roller faster than the peripheral speed of the image carrier, the frictional force with the image carrier can be set appropriately, so that the toner is applied to the space of the sponge roller without damaging the image carrier. While being held, the sponge roller has an effect of rubbing and polishing the surface of the image carrier using toner as a medium, so that toner fusion on the surface of the image carrier, that is, toner filming can be prevented.

  Hereinafter, an example of an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

  In addition, the assertive description in the following embodiment shows the best mode, and does not limit the meaning or technical scope of the term of the present invention.

  First, the schematic configuration of the image forming apparatus will be described with reference to FIG.

  FIG. 1 is a schematic configuration diagram of a tandem type color image forming apparatus.

  This image forming apparatus is called a tandem-type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7, and a paper feeding / conveying means (no symbol). ) And fixing means 24 and the like. A document image reading device B is arranged on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a photoreceptor 1Y as a first image carrier, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a primary transfer unit disposed around the photoreceptor 1Y. Primary transfer roller 5Y and cleaning means 6Y.

  The image forming unit 10M that forms a magenta image includes a photoconductor 1M as a first image carrier, a charging unit 2M disposed around the photoconductor 1M, an exposure unit 3M, a developing unit 4M, and a primary transfer unit. Primary transfer roller 5M and cleaning means 6M.

  An image forming unit 10C that forms a cyan image includes a photoconductor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer unit arranged around the photoconductor 1C. Primary transfer roller 5C and cleaning means 6C.

  An image forming unit 10K that forms a black image includes a photoconductor 1K as a first image carrier, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a primary transfer unit arranged around the photoconductor 1K. It comprises a primary transfer roller 5K, a cleaning means 6K, and the like.

  The developing means 4Y, 4M, 4C, and 4K are yellow (Y), magenta (M), cyan (C), or black (K) charged to the same polarity as the charged polarity of the photoreceptors 1Y, 1M, 1C, and 1K. Each component contains a two-component developer (may be a one-component developer) made of toner of each color, 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. Developing rollers 4Y1, 4M1, 4C1, and 4K1, which are developer carriers, are provided.

  The developing rollers 4Y1, 4M1, 4C1, and 4K1 are kept in contact with the photoreceptors 1Y, 1M, 1C, and 1K with a predetermined gap, for example, 100 to 1000 μm, by contact rollers (not shown). The rotation direction is 1M, 1C, 1K and the forward direction.

  During development, a DC bias voltage having the same polarity as the toner or a developing bias voltage that superimposes an AC voltage on the DC voltage is applied to the developing rollers 4Y1, 4M1, 4C1, and 4K1, thereby causing the photosensitive drums 1Y, 1M, 1C, and 1K to Non-contact 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 body unit 7 includes a plurality of rollers 71, 72, 73, 74, and 75, a semiconductive endless belt-like intermediate transfer body 70, and the like.

  The intermediate transfer body 70 is stretched so as to circumscribe the drive roller 73, support rollers 71 and 72, secondary transfer backup roller 74, and backup roller 75 coupled to a drive motor (not shown). Is arranged so that the rotation direction thereof is clockwise in FIG.

  The primary transfer rollers 5Y, 5M, 5C, and 5K for each color are provided through the intermediate transfer body 70 so as to face the photoreceptors 1Y, 1M, 1C, and 1K.

  Each color formed on the photoreceptors 1Y, 1M, 1C, and 1K is applied to the primary transfer rollers 5Y, 5M, 5C, and 5K by applying a DC voltage having a polarity opposite to that of the toner to form a transfer electric field in the transfer area. The toner image is primarily transferred onto the intermediate transfer member 70.

  A secondary transfer roller 5 </ b> A is provided opposite to the secondary transfer backup roller 74 via an intermediate transfer body 70.

  A DC voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 5A, and a transfer electric field is formed in the transfer region, whereby the superimposed toner image carried on the intermediate transfer body 70 is transferred onto the transfer material (paper) P. Secondary transfer to the surface of

  The paper P is fed from the paper feed cassette 20 by the paper feed means 21 and is conveyed to the secondary transfer position via the plurality of intermediate rollers 22A, 22B, 22C, 22D and the registration roller 23, and the color image is collectively transferred. The

  When the size of the paper P is changed, the length (paper width) in the direction perpendicular to the transport direction is configured to change with the center reference of the intermediate transfer body 70.

  The sheet P on which the color image has been transferred is subjected to fixing processing by the fixing unit 24, sandwiched between the sheet discharge rollers 25, and placed on the sheet discharge tray 26.

  A cleaning unit 60 for removing toner remaining on the intermediate transfer body 70 is provided on the downstream side of the secondary transfer position in the rotational direction of the intermediate transfer body 70.

  The details of the cleaning means 60 will be described later.

  Here, materials of the intermediate transfer belt, the transfer roller, and the like in the present embodiment will be described.

The intermediate transfer member 70 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 5Y, 5M, 5C, and 5K are, for example, conductive materials such as carbon, polyurethane, EPDM, silicone, and other rubber materials on a peripheral surface of a conductive metal core (not shown) such as stainless steel having an outer diameter of 8 mm. In a solid state or foamed sponge state with a volume resistance of about 10 ⁵ to 10 ⁹ Ω · cm by dispersing a filler or containing an ionic conductive material, the thickness is 5 mm and the rubber hardness is 20 to 70. It is formed by covering a semiconductive elastic rubber (not shown) with a degree of about (Asker hardness C).

The secondary transfer roller 5A is formed by dispersing a conductive filler such as carbon in a rubber material such as polyurethane, EPDM, or silicone on the peripheral surface of a conductive metal core (not shown) such as stainless steel having an outer diameter of 8 mm. In a solid state or foamed sponge state with a volume resistance of about 10 ⁵ to 10 ⁹ Ω · cm by including an ionic conductive material, the thickness is about 5 mm and the rubber hardness is about 20 to 70 ° (Asker- C) a semiconductive elastic rubber (not shown) is coated.

  Unlike the primary transfer rollers 5Y, 5M, 5C, and 5K, the secondary transfer roller 5A is in contact with toner, so that the surface may be coated with a material having good releasability such as semiconductive fluororesin or urethane resin. The secondary transfer backup roller 74 is formed by dispersing 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 bar (not shown) such as stainless steel, It is formed by coating a semiconductive material containing a conductive material with a thickness of about 0.05 to 0.5 mm.

  Next, the image forming process will be described with reference to FIG.

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

  After the photoconductor 1Y is applied with an electric potential, the exposure means 3Y starts to write an image using an electrical signal corresponding to the first color signal, that is, the Y image data. A corresponding electrostatic latent 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 photoreceptor 1Y according to the rotation of the photoreceptor 1Y.

  The Y toner image formed on the photoreceptor 1Y by the image forming process is transferred onto the intermediate transfer body 70 by the primary transfer roller 5Y.

  Subsequently, the Y toner image on the intermediate transfer body 70 is synchronized, and magenta (M), cyan (C), and black (K) toner images are sequentially superimposed to form a color toner image. can get.

  The transfer residual toner remaining on the peripheral surfaces of the photoreceptors 1Y, 1M, 1C, and 1K after the transfer is removed by the cleaning units 6Y, 6M, 6C, and 6K.

  In synchronism with the formation of the color toner image on the intermediate transfer body 70, the sheets P separated and conveyed one by one from the sheet feeding cassette 20 are conveyed through the registration rollers 23, and the intermediate transfer is performed by the secondary transfer roller 5A. The color toner images on the body 70 are collectively transferred onto the paper P.

  The sheet P on which the color toner image is transferred is neutralized by a separating means (not shown), conveyed to the fixing device 24, and after the toner image is fixed, the sheet P is discharged to a discharge tray 26 by a discharge roller 25. The

  On the other hand, the transfer residual toner remaining on the peripheral surface of the intermediate transfer body 70 after the transfer is removed by the cleaning unit 60.

  Next, the details of the cleaning means 60 will be described with reference to FIG.

  FIG. 2 is a cross-sectional view of the main part of the cleaning means 60.

  Reference numeral 601 denotes a casing, which has a housing portion to which the members constituting the cleaning means 60 are attached and the toner removed from the intermediate transfer body 70 is housed.

  Reference numeral 602 denotes a cleaning blade made of an elastic material such as urethane rubber, and is fixed to the blade holder 603 with an adhesive or the like.

  The blade holder 603 is rotatably attached to a support shaft 604 provided in the casing 601.

  A pressing spring 605 urges the blade holder 603 to rotate counterclockwise around the support shaft 604, and the tip of the cleaning blade 602 is in a direction opposite to the rotation direction of the intermediate transfer body 70 (counter direction). In this state, the intermediate transfer body 70 backed up by the backup roller 75 is disposed in pressure contact at the pressure contact position C.

  A toner guide member 608 is a sponge roller. The intermediate transfer member 70 is located upstream of the pressure contact position C between the cleaning blade 602 and the intermediate transfer member 70 in the rotational direction indicated by the arrow in the drawing of the intermediate transfer member 70. It is arrange | positioned so that it may contact | abut.

  The sponge roller 608 is rotated in the same direction as the intermediate transfer body 70 at a contact position with the intermediate transfer body 70 by a rotating means (not shown), and the peripheral speed of the sponge roller 608 is higher than the peripheral speed of the intermediate transfer body 70. It is configured to be faster.

  Reference numeral 609 denotes a toner discharge regulating member made of a PET sheet, one end of which is in contact with the surface of the sponge roller 608 at a position opposite to the contact position between the sponge roller 608 and the intermediate transfer body 70 and the other end. The sheet holding member 610 provided above the sponge roller 608 is fixed with a double-sided tape or the like.

  The sheet holding member 610 is fixed to the protrusion 611 of the casing 601 with a screw or the like.

  With such a configuration, the intermediate transfer member 70, the cleaning blade 602, the sponge roller 608, and the toner discharge regulating member 609 form a space S.

  Reference numeral 612 denotes a collection screw provided at the bottom of the casing 601. The toner stored in the bottom of the casing 601 is transported in a direction perpendicular to the paper surface of the drawing and discharged outside the casing 601.

  As shown in the figure, reference numeral 613 denotes a toner receiving sheet made of PET having one end bonded to the bottom of the casing 601 facing the intermediate transfer body 70 and the other end lightly contacting the intermediate transfer body 70, and the toner inside the casing 601. Prevents falling down.

  The operation of the cleaning means 60 having the above-described configuration will be described.

  After the toner image on the intermediate transfer body 70 is transferred to the sheet at the secondary transfer position, the toner remaining on the intermediate transfer body 70 is stored in the space S described above.

  When the amount of toner stored in the space S exceeds a certain amount, the toner is discharged from the contact portion between the toner discharge regulating member 609 and the sponge roller 608, and the amount of stored toner is maintained to be constant.

  In other words, when the amount of toner stored in the space S increases, the toner discharge regulating member 609 is configured by an elastic PET sheet, and thus functions as a so-called pressure adjustment valve, and the toner in the space S Acts to maintain a certain amount.

  Therefore, by configuring the upper surface level of the stored toner to be always above the pressure contact position C, the tip of the cleaning blade 602 is used as a lubricant even when image formation with a low printing rate continues. Toner is supplied.

  Further, even if the image formation continues in a state where the sheet length (referred to as sheet width or print width) in the direction of the rotation axis of the intermediate transfer body, that is, the direction perpendicular to the sheet conveyance direction is short, the toner exhibits fluidity. Therefore, the toner spreads in the paper width direction and is uniformly stored in the space S due to the rotational movement of the sponge roller 608, slight vibration of the apparatus, etc. I will go around.

  Next, details of the materials, configurations, etc. of the cleaning blade, sponge roller, and toner discharge regulating member in the present embodiment will be described below.

(1) Cleaning blade-Material: Urethane rubber-Hardness: 74 ° (JIS, A rubber hardness)
・ Load: 0.16 N / cm
-Contact angle: 17 °
(2) Sponge roller ・ Material: NBR (acrylonitrile-butadiene rubber)
・ Hardness: 30 ° (Asker hardness C)
-Peripheral speed: 1.2 times the peripheral speed of the intermediate transfer member 70 (3) Toner discharge regulating member-Material: PET
・ Thickness: 50μm
Contact pressure: 0.014 N / cm
・ Free length: 9mm
Here, the load of the cleaning blade is generated by the action of the pressing spring 605 in the direction perpendicular to the line connecting the center SC of the support shaft 604 and the pressure contact position C at the pressure contact position C as shown in FIG. The force (load) P1 per unit length (cm) of the cleaning blade 602.

  The contact angle is an angle θ between the cleaning blade 602 and the tangent line of the outer circumference of the backup roller 75 at the pressure contact position C in FIG.

  The contact pressure of the toner discharge restricting member 609 is the contact position D, the toner discharge restricting member 609, and the contact position D between the toner discharge restricting member 609 and the sponge roller, similarly to the load of the cleaning blade. The force per unit length (cm) of the toner discharge regulating member 609 generated by the elasticity of the toner discharge regulating member 609 in the direction perpendicular to the line connecting the joining end portion HC with the sheet holding member 610 (contact) Pressure) P2.

  The free length of the toner discharge regulating member 609 is the length F of the toner discharge regulating member 609 from the joint end HC to the contact position D as shown in FIG.

  Further, as shown in FIG. 4, the width L1 of the intermediate transfer member 70 is 360 mm, the length L2 of the cleaning blade 602 is 340 mm, the length L3 of the sponge roller 608 is 330 mm, and the toner discharge restricting member 609 is viewed in the paper width direction. The length L4 is 330 mm, and the lengths of the respective lengths are configured such that L1> L2> L3 = L4.

  Note that the width L3 of the sponge roller 608 is configured to be larger than the maximum sheet width.

  Further, as shown in FIG. 4, the toner discharge regulating member 609 has a notch of 9 mm in length with a pitch of 2.5 mm between the width of 150 mm in the central portion in the paper width direction.

  By making such a cut, the contact pressure of the toner discharge regulating member 609 on the sponge roller 608 is stronger at both end portions than at the center portion in the paper width direction.

  In order to confirm the effect of the present embodiment described above (condition (A)), a comparative experiment was performed.

  Differences between the compared condition (B) and condition (A) are as follows.

-Toner guide roller: brush roller-Toner discharge regulating member: None In addition, the environmental conditions are set to a temperature of 30 ° C and a humidity of 80%, the paper is A4 size, and the long side of the paper is matched to the transport direction to continuously 5000 An image with a printing rate of 1% was formed on both sides of the sheet, and the result shown in FIG. 5 was obtained.

  FIG. 5A shows the damage ratio of the portion where the cleaning blade is pressed against the intermediate transfer belt (blade edge), that is, the blade edge is damaged with respect to the entire length in the longitudinal direction of the cleaning blade (paper width direction). It shows how much the total length of the locations is, and it was 2% in the condition (A) and 38% in the condition (B).

  In the condition (A), the damage ratio is low because a constant amount of toner is always stored in the space S, and toner as a lubricant is present at the blade edge to prevent damage.

  FIG. 5B shows the edge damage near the center and near both ends as viewed in the longitudinal direction of the cleaning blade, and the toner filming near the center and near both ends as viewed in the paper width direction of the intermediate transfer member. It has been evaluated.

  ○ indicates no problem at all, Δ × indicates a considerable problem in practical use, and xx indicates a problem in practical use.

  As is apparent from the figure, both the blade edge damage and the toner filming are at a level where there is no problem at all in the vicinity of the center and at both ends in the condition (A) compared to the condition (B).

  This is because a constant amount of toner is always stored in the space S with respect to damage to the blade edge. The blade edge is not damaged at both ends because the contact pressure of the toner discharge regulating member is This is because the toner is sufficiently stored in the space S at both ends regardless of the narrow paper width because it is larger at both ends than the center.

  As for toner filming, the toner is held on the surface of the sponge roller, and the surface of the intermediate transfer member is polished by the toner held on the surface due to the difference in the peripheral bundle between the sponge roller and the intermediate transfer belt, so that it is kept clean. Because it is.

  The occurrence of toner filming on the intermediate transfer belt was confirmed by the streak defect appearing in the image on the paper and the adhesion state of the toner on the surface of the intermediate transfer belt corresponding to the streak defect.

  In addition, since the width L1 of the intermediate transfer belt, the length L2 of the cleaning blade, the length L3 of the sponge roller, and the length L4 of the toner discharge regulating member are set to a relationship of L1> L2> L3 = L4, both ends of the casing There was no scattering or spillage of toner from the part.

  If L2> L3 ≧ L4, there will be no toner scattering or spillage from both ends of the casing.

  Further, the temperature around the cleaning means was 55 ° C. or less, and there was no aggregation of the toner stored in the space.

  Next, in this embodiment, when the environmental conditions are set to a temperature of 30 ° C. and a humidity of 80%, and the load of the cleaning blade and the contact pressure of the toner discharge regulating member are changed, the range in which the cleaning blade operates normally. We confirmed how much there was. The result is shown in FIG.

  The horizontal axis represents the load of the cleaning blade, and the vertical axis represents the contact pressure of the toner discharge regulating member.

  As shown in the figure, when the contact pressure of the toner discharge regulating member is equal to or less than a straight line L5 (0.06 N / cm) connecting the square, the blade edge is damaged near both ends of the cleaning blade, and toner filming occurs.

  This is because the contact pressure of the toner discharge regulating member on the sponge roller is too small, and the toner removed by the cleaning blade is discharged as the sponge roller rotates, and a predetermined amount of toner is not stored in the space. is there.

  Further, above the straight line L6 connecting ◆, a cleaning failure that causes the toner to pass through the cleaning blade occurs.

  This is because the toner discharge regulation member presses the sponge roller too much, and the toner stored in the space increases without being smoothly discharged, and passes through the cleaning blade.

  Therefore, the range between the straight lines L5 and L6 is a range in which damage to the edge of the cleaning blade, filming of the intermediate transfer member, and cleaning failure do not occur.

  This range is sufficiently wide, and the load of the cleaning blade and the pressing force of the toner discharge regulating member can be appropriately set, and a stable cleaning operation can be performed.

  In this embodiment, the cleaning unit is applied to the intermediate transfer member. However, regardless of this, the photosensitive member that transfers the toner image to the intermediate transfer member or the photosensitive member that transfers the toner image directly to the transfer material is used. It may be applied to the body.

  In this embodiment, the toner guide member is a sponge roller, but any toner guide member may be used as long as it can hold the toner removed by the cleaning blade without dropping downward. For example, a toner guide roller such as a rubber roller or a resin roller. Or you may comprise by a sheet | seat member etc.

  In this embodiment, the toner discharge regulating member is a PET sheet. However, any member can be used as long as it can form the above-described space and has a function of discharging when the toner exceeds a certain amount. As shown, the toner discharge regulating member 609 may be formed of a thin metal plate or the like, and the toner discharge regulating member 609 may be rotatably held by the sheet holding member 610 and pressed by the pressing spring 620. .

1 is a schematic configuration diagram of a tandem color image forming apparatus. The principal part sectional drawing of a cleaning means. Sectional drawing of the cleaning blade vicinity for demonstrating the load of a cleaning blade, and the contact pressure of a toner discharge | emission control member. FIG. 4 is an explanatory diagram relating to the lengths of an intermediate transfer member, a cleaning blade, a sponge roller, and a toner discharge regulating member. The comparison experiment result of this Embodiment (condition (A)) and comparison conditions (B). The figure which shows the appropriate cleaning range when changing the cleaning blade load and the toner discharge regulating member contact pressure. FIG. 6 is a schematic configuration diagram illustrating another embodiment of a toner discharge regulating member.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductor 7 Intermediate transfer unit 60 Cleaning means 70 Intermediate transfer body 601 Casing 602 Cleaning blade 603 Blade holder 604 Support shaft 605 Pressing spring 608 Sponge roller 609 Toner discharge regulating member 610 Sheet holding member 612 Recovery screw 613 Toner receiving sheet C Pressure position D Contact position P1 Load P2 Contact pressure S Space

Claims (5)

In an image forming apparatus having a cleaning means for removing toner remaining on an image carrier,
The cleaning means includes
A cleaning blade in pressure contact with the image carrier;
Viewed in the rotational direction of the image bearing member, and contact with the image bearing member on the upstream side of the pressure contact position of the cleaning blade, in the contact position between the image bearing member, the same as the rotational direction of said image bearing member A toner guide member rotating in a direction ;
A toner discharge regulating member that contacts the toner guide member at a position opposite to the position where the toner guide member contacts the image carrier;
Have
An image forming apparatus , wherein a space for storing toner is formed by the cleaning blade, the toner guide member, the toner discharge regulating member, and the image carrier . 2. The image forming apparatus according to claim 1 , wherein the contact pressure of the toner discharge regulating member that contacts the toner guide member is stronger at both end portions than at the center portion in the rotation axis direction of the image carrier. apparatus. The length of the cleaning blade, the toner guide member, and the toner discharge regulating member as viewed in the rotation axis direction of the image carrier is: cleaning blade> toner guide member ≧ toner discharge regulating member. The image forming apparatus according to claim 1 or 2. The image forming apparatus according to claim 1, wherein the toner guide member is a sponge roller, and the peripheral speed of the sponge roller is faster than the peripheral speed of the image carrier. . The image forming apparatus according to claim 1 , wherein the toner discharge regulating member is an elastic member .

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