JP4681891B2 - Cleaning device, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a cleaning device that cleans an image carrier after a transfer process, and to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that includes the cleaning device, and a process cartridge.

JP-A-8-62893 JP-A-8-95286 Japanese Patent Laid-Open No. 5-18836 JP-A-6-167912 Japanese Patent No. 3024125 Japanese Patent Laid-Open No. 10-240094 Japanese Utility Model Publication No. 63-78973

  In an electrophotographic image forming apparatus, a toner image formed on a latent image carrier (also an image carrier) such as a photoconductor in a developing process is transferred to an intermediate transfer member (also an image carrier) such as an intermediate transfer belt. Or directly on a transfer material such as transfer paper to form an image, but the residual toner is transferred to the surface of the latent image carrier and the intermediate transfer material after the toner image is transferred. Remains. For this reason, a cleaning device for removing residual toner from the latent image carrier and the intermediate transfer member is provided. Various cleaning devices are known, and a fur brush, a magnetic brush, or the like can be used in addition to a cleaning blade and a cleaning roller made of an elastic member. Among them, the cleaning blade is widely put into practical use because it has a simple configuration, can be easily downsized, and is advantageous in terms of cost. In recent years, however, toner particles have been made smaller and spherical to improve image quality. Polymerized toners such as suspension polymerization methods and emulsion polymerization methods, and toners that have undergone spherical treatment using hot air flow or fluidized granulation methods are now available. There is a problem that when this spherical or small particle size toner is used, image defects due to poor cleaning are likely to occur in an image forming apparatus equipped with various cleaning devices.

  As countermeasures, Patent Document 1, Patent Document 2, and the like have proposed a method in which spherical toner and irregular toner are mixed and used at a specific ratio. However, even with such a method, the spherical toner may pass through the gap between the irregular toners and advance to the blade edge portion, so that the cleaning defect for the spherical toner is not sufficiently improved.

  Therefore, many cleaning devices using a cleaning roller or a cleaning brush have been proposed. For example, in Patent Document 3, a predetermined voltage is applied to each of the cleaning brush and the collected cleaning roller to clean the residual toner on the surface of the photosensitive drum. In a cleaning device that collects on the surface of the recovery cleaning roller via a brush, the recovery cleaning roller is disposed at a predetermined distance from the inner peripheral surface of the recovery cleaning roller below the horizontal plane including the axis of the recovery cleaning roller. The tip of the magnetic material to be recovered or the surface of the recovery cleaning roller near the magnetic material is disposed so as to scrape the remaining toner recovered on the surface of the recovery cleaning roller as the recovery cleaning roller rotates. The magnetic blade to be dropped The configuration of Re or one magnet, to extend the life of the cleaning device has been proposed which prevents deterioration of print quality. Further, in Patent Document 4, in a cleaning device of an electrophotographic apparatus provided with a cleaning brush for cleaning a portion to be cleaned and a collection roll for removing and collecting dust attached to the cleaning brush, the cleaning brush is to be cleaned during a non-cleaning operation. The cleaning brush is rotated in the direction opposite to that during the cleaning operation to prevent the dust adhering to the cleaning brush from being scattered outside the cleaning device and extending the life of the cleaning brush. Etc. have been proposed. However, in a cleaning device that collects residual toner on the surface of the drum-shaped photoconductor on the surface of the recovery cleaning roller via a cleaning roller or a cleaning brush, it is used over time even if it exhibits good initial cleaning performance. As a result, the performance of the cleaning roller and the cleaning brush deteriorates with time. That is, as the transfer residual toner is removed, the toner gradually adheres to the cleaning roller and becomes difficult to collect, or is accumulated in the cleaning brush and clogged. In the cleaning roller and the cleaning brush in such a state, the performance of removing the transfer residual toner is lost, and the function as the cleaning member cannot be performed.

  In addition, an apparatus using a cleaning belt has been proposed. For example, Patent Document 5 proposes a cleaning device that includes a cleaning belt that rotates reversely to the moving direction of the image carrier and collects toner on the image carrier and a scraper that finally removes toner on the cleaning belt. . However, in such a configuration, when spherical toner is used, the rotational force of the spherical toner increases between the cleaning belt and the image carrier, so that the toner slips through, and good cleaning cannot be performed. Further, since the spherical toner slips through the scraper even after being collected by the cleaning belt, there is a problem that the cleaning belt becomes dirty and leads to image deterioration in the long term. Patent Documents 6 and 7 propose an apparatus that collects toner on an image carrier with a cleaning belt and finally removes toner on the cleaning belt with a cleaning blade. However, when the spherical toner is used, the spherical toner passes through the cleaning blade even after being collected by the cleaning belt, so that the cleaning belt becomes dirty in the long term, leading to image deterioration.

  As described above, the conventional cleaning device has a problem that it is difficult to clean the toner having a spherical shape or a small particle size because of high image quality, and the image deteriorates with time.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the object of the present invention is to provide a cleaning device capable of performing good cleaning with respect to toner having a spherical shape and a reduced particle size, and the cleaning device. An object of the present invention is to provide an image forming apparatus and a process cartridge capable of obtaining a high-quality image with few abnormal images by using the apparatus.

Of the above problems, the cleaning device has a belt-like toner holding member as a cleaning belt according to the present invention, and the belt-like toner holding member is brought into contact with or substantially in contact with the surface of the image carrier to transfer residual matter. A removal blade for removing the toner from the surface of the image carrier and scraping off the toner adhering to the belt-like toner holding member and a recovery box for collecting and discarding the scraped toner are further provided, facing the removal blade. And a belt at a position facing the image carrier so that the surface of the belt-like toner holder is in a substantially horizontal state and in contact with the removal blade. by configuring to attaching a voltage applying means for applying a voltage to the support rollers for supporting wound to Jo toner holding member, It is determined.

The belt-shaped toner holding member is wound around a plurality of support rollers, the removal blade is an elastic blade, and the removal blade that comes into contact with scraping off the toner attached to the belt-like toner holding member is a belt-like toner. tilted with respect to the opposite roller shaft holder surface abut, the larger of the displacement distance in the belt-shaped toner carrier both end portions of the contact position between the roller shaft the removal blade x, the counter roller A belt-like toner stretched between a support roller and a counter roller that stretches a belt-shaped toner holding member adjacent to the counter roller, and a tangent line at an ideal contact point of the counter roller with the removal blade. When the larger one of the two angles formed by the straight line that matches the holding body is φ, and the amount that the removal blade is pushed into the belt-like toner support is D,
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1−cosφ−tanφ × sinφ) ≦ D (I)
It is preferable that the above relationship is satisfied.

The removal blade is pivotally supported at the central portion in the width direction of the belt-shaped toner holding body, and the width of the belt-shaped toner holding body is L, and the toner adhering to the belt-shaped toner holding body is removed. scraping tilted the removing blade abutting upon Otosuru is relative to the counter roller shaft to the belt-shaped toner carrier on the surface abutting, the angle between the line of abutment of the roller shaft the removal blades and θ When
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1-cosφ−tanφ × sinφ) ≦ D
Where x = 1/2 × L × sinθ (II)
It is also more convenient to satisfy this relationship.

It is preferable that the adhesion force between the surface of the belt-shaped toner holding member and the toner is larger than the adhesion force between the surface of the image carrier and the toner . The belt-like toner holding member may be an intermediate transfer member for transferring an image on a photosensitive member as an image carrier to a recording material.

  Among the above problems, the image forming apparatus and the process cartridge are solved by providing the cleaning device. At that time, a spheroidized toner can be used in a manufacturing process or a process after manufacturing.

The toner particles used are
Shape factor = {(maximum particle size) ² × π / (projected area of particle × 4)} (III)
The shape factor expressed by the formula is 1.0 to 1.35, the volume average particle size of the toner used is adjusted to be 1 to 7 μm, and the toner particles used are toner base particles. It was composed of an external additive, and was prepared so that the coating area ratio of the external additive to the toner base particles was 10% to 90%. The external additive was silica (SiO ₂ ), titanium oxide (TiO ₂ ), It is more preferable to contain at least one or two of alumina (Al ₂ O ₃ ).

  According to the present invention, the residual toner on the image carrier is collected by the belt-like toner holder provided in the cleaning device, the positions of the support roller and the opposing roller of the removal blade are controlled, and the surface of the belt-like toner holder By substantially paralleling each other, the gap between the belt-shaped toner holding member and the removal blade is eliminated, and the toner on the belt-shaped toner holding member can be reliably removed and collected in the collection box. For this reason, even if the toner has been reduced in size and spheroidized for the purpose of obtaining a high-quality electrophotographic image, the transfer residual toner remaining on the surface of the image carrier can be surely damaged without damaging the surface of the image carrier. By removing it, it is possible to prevent the occurrence of image defects due to poor cleaning.

The details of the present invention will be described below based on the example shown in the drawings.
First, the cleaning device will be described. FIG. 1 shows a configuration of a toner scraping portion of a cleaning device according to the present invention. Cleaning of the image carrier is performed at a location not shown in FIG. 1 (shown in FIG. 9 ; for convenience of drawing, the voltage applying means is not shown in FIG. 1 or the like ). As shown in FIG. 1, the cleaning device is provided on the surface of a belt-like toner holder 1 that is wound around a plurality of support rollers (only a part is shown with reference numerals 2 and 3) and moves in the direction of the arrow. The removal blade 5 that comes into contact, and the roller that contacts the back surface of the belt-shaped toner holding body 1, the opposed roller 4 that faces the removal blade 5, and the toner scraped from the belt-like toner holding body 1 are collected. A recovery box 6 is provided, and the removal blade 5 is configured to scrape off toner from the surface of the belt-shaped toner holding member 1. Unnecessary toner scraped off is collected in a collection box 6, transported to a predetermined location of the apparatus as needed, and discarded or reused outside the apparatus.

  Conventional cleaning devices mainly use a cleaning blade to scrape off the transfer residual toner even on the curved surface of the image carrier. However, the toner has been reduced in size and spheroidized due to the demand for higher image quality. In contrast, the toner rotates at the contact portion between the cleaning blade and the image carrier, and the so-called “cleaning failure” in which the toner passes through the cleaning blade increases. Although the cleaning failure can be reduced by setting the pressurizing force of the cleaning blade high, the torque on the image carrier is increased, so that the deterioration of the image carrier is promoted. When scraping off toner with a cleaning blade, if the object to be cleaned is a cylindrical body and the cleaning area is a curved surface, it is necessary to increase the parallelism between the rotation axis of the object to be cleaned and the straight line in the longitudinal direction of the cleaning blade. The blade is lifted at the part, and cleaning is liable to occur. In particular, the cleaning blade is more likely to float as the radius of curvature of the object to be cleaned is smaller. In recent years, the image forming apparatus has been miniaturized and the radius of curvature of the image carrier tends to be smaller. Therefore, a cleaning apparatus using a cleaning blade requires higher accuracy. Also, when a cleaning roller or cleaning belt is used, a cleaning blade is often used to finally collect toner from the cleaning roller, where scraping failure occurs and the cleaning roller becomes dirty over time. The image is disturbed by reattaching to the image carrier.

  In the cleaning device according to the present invention, the residual toner on the image carrier is once taken up by the belt-like toner holder, and the residual toner on the toner holder is collected. The carrier is not damaged, and even a toner having a small particle size and a spherical shape can be reliably recovered. Further, since the collecting means is a belt, it is possible to scrape off the toner adhering to the belt with a flat surface when removing the toner with a blade, or in a substantially flat state with little influence of curvature.

  FIG. 2 shows the relationship with the removal blade 5 at a location where a slight curvature is provided in the vicinity of the opposing roller 4 in the belt-shaped toner holding member 1 of the cleaning device. FIG. 3 is a straight line showing a position where the removal blade 5 is intended to contact on the belt-like toner holding member 1 parallel to the central axis of the opposing roller 4 (parallel to the vertical line with respect to the running direction of the belt-like toner holding member 1). It is a perspective view which shows the case where the straight line (beta) which shows an actual contact position has angle (theta) with respect to (alpha). FIG. 4 is an enlarged view of the vicinity of contact between the belt and the blade. As in FIG. 1, as shown in FIG. 2, the removal blade 5 of the cleaning device has its tip inclined so that the downstream side has an acute angle with respect to the running direction (arrow direction) of the belt-like toner holder 1. In this state, it is in contact with the opposing roller 4 via the belt-shaped toner holding member 1. In such a configuration, the angle formed by the tangent line at the contact point of the counter roller 4 with the removal blade 5 and the tangent line connecting the surface of the counter roller 4 and the surface of the support roller 2 is φ1, and the removal blade 5 of the counter roller 4 is When the angle formed by the tangent at the contact point and the tangent connecting the surface of the support roller 4 and the surface of the support roller 3 is φ2, the larger one is φ.

  As shown in FIG. 3, a straight line α indicating the target position of contact of the removal blade 5 parallel to the vertical axis in the driving direction of the belt-shaped toner holding member 1 and a straight line β indicating the actual contact position have an angle θ. In this case, as shown in FIG. 4, floating occurs due to the actual contact position deviating from the contact position of the removal blade 5 at the end portion. For this reason, the toner having a small particle size and a spherical shape is very easy to slip through. In FIG. 4, the tangential distance at the target contact position of the facing roller 4 between the target contact position and the actual contact position is x, and the belt-like toner holder 1 and the removal blade 5 at that time are It is also shown that the distance in the vertical direction with respect to the tangent at the position where the opposing roller 4 is aimed at is z and the radius of the opposing roller 4 is r.

FIG. 5 shows the contact state of the removal blade. When the removal blade 5a is pressed against the object to be cleaned (belt-shaped toner holding body) as shown in FIG. Is bent, but assuming that it is a virtually rigid body, it will bite into the object to be cleaned in a state like a virtual blade 5b shown by a broken line. The distance between the tip of the virtual blade 5b and the original surface of the object to be cleaned at this time is defined as the biting amount D. There are two methods for pressurizing the removal blade: a fixing method in which a blade support member (not shown) is fixed and pressed, and a constant load method in which the blade support member is pressed with a constant load by a spring. The biting amount D is calculated from the applied pressure and the Young's modulus of the elastic blade. If z> D at this time, a gap is formed between the removal blade 5 and the belt-shaped toner holding body 1, so that a defective removal occurs on the belt-shaped toner holding body. Therefore, when 0 ≦ z ≦ D, the removal blade 5 and the belt-like toner holding body 1 can be in contact with each other in the entire axial direction and can be removed. As shown in FIG. 2, the belt-like toner holding member 1 is on a tangent line connecting the surface of the support roller 4 and the surface of the support roller 3 or the support roller 2, so that the counter roller 4 satisfies the following formula (I). Can improve the removal failure on the belt-like toner holder:
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1−cosφ−tanφ × sinφ) ≦ D (I)

  This means that the smaller the radius of the opposing roller 4 is, the more φ needs to be close to 0 °. If the counter roller 4 is out of this range, the removal defects on the belt-shaped toner holding member abruptly increase. Cannot be recovered and reattachment to the image carrier occurs.

Further, in the positional relationship of the removal blade 5 on the belt-shaped toner holding body 1 shown in FIG. 3, if the removal blade 5 is pivotally supported so as to be rotatable at the center in the width direction of the belt-shaped toner holding body 1, This is preferable because fluctuations in the amount of biting due to entrainment are averaged. At this time, as shown in FIG. 3, assuming that the width of the belt-like toner holding member is L at an angle θ formed by the contact target position α and the actual contact position β, x = 1/2 × L in FIG. × sinθ. For this reason, by installing the facing roller 4 so as to satisfy the following formula (II), the removal failure on the belt-like toner holding member is improved:
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1-cosφ−tanφ × sinφ) ≦ D
Where x = 1/2 × L × sinθ (II)

  As described above, this cleaning device can improve the removal failure on the belt-shaped toner holding member by making φ close to 0 ° even when the radius of curvature of the facing roller facing the removing roller is small, and in particular φ = 0. More preferably.

FIG. 6 shows a contact state between the image carrier and the cleaning device B , which is not within the scope of the present invention, but has the same configuration as that of FIG. As shown in FIG. 6, the cleaning device B uses a cleaning belt 1 ′ as a belt-like toner holder, and the cleaning belt 1 ′ is wound around the image carrier 8 by being wound around a plurality of support rollers 2 and 3. While in contact, the image carrier 8 is rotationally driven at the contact position in the same direction as the moving direction of the image carrier 8 (arrow R1). In order to collect the removal blade 5 in contact with the surface of the cleaning belt 1, the roller in contact with the rear surface of the cleaning belt, the opposing roller 4 located at the position opposite to the removal blade, and the toner scraped from the cleaning belt by the removal blade The recovery box 6 is provided with a cleaning device. After the residual toner on the image carrier 8 is attached to the cleaning belt 1 ′, it is scraped off from the surface of the cleaning belt 1 ′ with the removal blade 5. Unnecessary toner that has been scraped off is collected in a collection box 6, transported to a predetermined place in the apparatus as needed, and discarded outside the apparatus.

  FIG. 7 shows the relationship between the cleaning belt and the removal blade of the cleaning device B (however, the cleaning belt 1 ′ has a curvature in the vicinity of the opposing roller 4). As in FIG. 1 and FIG. 2, as shown in FIG. 7, the removal blade 5 of the cleaning device B has its tip inclined to the acute angle on the downstream side with respect to the running direction (arrow direction) of the cleaning belt 1 ′. In this state, it is in contact with the opposing roller 4 via the cleaning belt 1 '. In the above configuration, φ1, φ2, and the larger one as φ are the same as in FIG. Also, the contact relationship between the cleaning belt and the removal blade can be shown in FIG. 3, and the end portion in the vicinity of the contact between the belt and the blade can be shown in FIG. 4 (however, the up and down directions are reversed). ) After all, in order to improve the toner removal failure on the cleaning blade, it is necessary to satisfy the above formula (I) or the above formula (II). The cleaning device B can also improve the removal failure on the cleaning belt by making φ close to 0 ° when the radius of curvature of the facing roller facing the removal blade is small. At this time, the state of φ = 0 ° is most preferable, and the cleaning device B can be easily set by equalizing the diameters of the support roller and the counter roller of the cleaning belt as shown in FIG.

The material of the removal blade 5 is not particularly limited as long as it has elasticity, and can be appropriately selected according to the purpose. Preferred examples include natural rubber and polyurethane rubber. In the cleaning device B, when the toner on the image carrier 8 is mechanically transferred to the cleaning belt 1 ′, the adhesion between the cleaning belt surface and the toner is larger than the adhesion between the image carrier surface and the toner. As a result, good cleaning properties are exhibited. As a method for measuring the adhesion force of toner, it is common to estimate the force required to separate the toner from the object to which the toner is adhered. As a method for separating the toner, a method using centrifugal force, vibration, impact, air pressure, electric field, magnetic field or the like is known. Among these, the method using centrifugal force is easy to quantify and has high measurement accuracy. Therefore, in this example, the centrifugation method described in IS & T NIP7th page 200 (1991) or the like was used. The adhesion force between the toner and the image carrier surface and between the toner and the cleaning belt surface depends on various factors such as constituent materials and conditions, but as a method of making a difference in adhesion force between the toner and the image carrier, and the toner and the cleaning belt. A method of making a difference in the contact area can be considered. For example, if an elastic layer is formed on the surface of the cleaning belt and the contact area between the cleaning belt and the toner is larger than the contact area between the image carrier and the toner, the adhesion on the cleaning belt is larger than the adhesion on the image carrier. can do. Another method is to reduce the contact area between the toner and the image carrier by applying fine particles to the surface of the image carrier. There is another method for differentiating the surface energy. When the image carrier is an organic substance such as a resin, the cleaning belt surface is made of metal or metal coating so that the surface energy of the cleaning belt surface is the surface of the image carrier. The energy becomes higher than the energy, and the adhesion force between the toner and the cleaning belt becomes larger than the adhesion force between the toner and the image carrier. At this time, in order to press the cleaning belt against the surface of the image carrier, it is possible to assist the control of the adhesion force by providing means for applying a tension force to the support rollers at the opposing positions. Furthermore, in the present invention, in order to effectively remove the toner on the image carrier, a potential gradient is formed between the cleaning belt and the image carrier, and the toner is removed from the image carrier based on the potential gradient. It is configured to make an electrical transition to. In this case, in the cleaning apparatus A, as shown in FIG. 9, a voltage applying means 9 for applying a voltage to the support roller 2 is arranged, and a bias opposite to that of the residual toner on the image carrier 8 is applied, thereby residual toner. Recover. In general, the residual toner includes a positive polarity toner having the original charged polarity and a reverse polarity toner whose polarity is reversed by discharge or the like when passing through the transfer electric field. For this reason, when collecting both positive polarity and reverse polarity residual toner, the toner is charged by the charging means 7 arranged in order to charge the toner to one polarity before entering the nip portion. However, when the spherical toner is used, the transfer efficiency is very good and the positive residual toner is extremely small. Therefore, the voltage application unit 9 is not provided with the charging unit 7 and the voltage application unit 9 collects only the reverse polarity toner. Cleaning can also be established simply by applying.

  The image forming apparatus provided with the cleaning device based on the above description will be described below. The image forming apparatus includes an image carrier that carries a toner image, a transfer unit that transfers the toner image carried on the image carrier to a transfer material, and the image carrier after the toner image is transferred to the transfer material. And a cleaning device that removes transfer residual toner remaining on the body surface, and further includes other configurations appropriately selected as necessary. Note that the concept of the “image carrier” is that the latent image is formed and an image carrier as a photoconductor capable of carrying a toner image and a toner image carried by the image carrier as the photoconductor are intermediate transferred. And an image carrier as an intermediate transfer medium.

  The image carrier is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a photoconductive organic semiconductor (OPC) as a photosensitive layer is provided on the circumferential surface of a cylindrical body made of metal. A structure formed by coating is preferred. The intermediate transfer medium is not particularly limited as long as it can carry a toner image, and can be appropriately selected according to the purpose. Examples thereof include a drum-like and belt-like transfer member.

  FIG. 10 shows an image forming apparatus according to the first structure of the present invention. As shown in FIG. 10, the image forming apparatus C is disposed above the image carrier 8, which is rotationally driven in the direction of arrow R <b> 1, and is in contact with the surface of the image carrier 8. A charging device 11 that is driven to rotate and charges the surface of the image carrier 8, an image writing unit 12 that writes light according to image information on the surface of the charged image carrier 8 to write an electrostatic latent image, and an image carrier A developing device 10 for developing the electrostatic latent image written on the body 8 is disposed below the image carrier 8 and is brought into contact with the image carrier 8 with a predetermined nip pressure and formed on the image carrier 8. Transfer means 13 for transferring the toner image to a recording medium P as a transfer material, a cleaning device B for removing residual toner remaining on the surface of the image carrier 8 after the toner image is transferred to the recording medium P, and a supply device (not shown). A paper device, a fixing device (not shown), and the like are also provided.

  FIG. 11 shows the structure of the process cartridge according to the present invention. However, in the present application, when referred to as a process cartridge, an image carrier that can form a latent image on which a toner image can be carried, a developing unit that develops the latent image formed on the image carrier with toner, and the developing unit After the developed toner image is transferred, it is configured to include the above-described cleaning device that removes transfer residual toner remaining on the surface of the image carrier, and is detachably attached to the image forming apparatus. Furthermore, it is possible to provide a charging device, a transfer unit, a paper conveying device, and a static eliminator that are appropriately selected as necessary, and various variations may exist.

  As shown in FIG. 11, the present process cartridge D is disposed above the image carrier 8 and is in contact with the surface of the image carrier 8 and is driven in the direction of arrow R1. The charging device 11 that rotates following the rotation and charges the surface of the image carrier 8, the developing means 10 that develops the electrostatic latent image written on the image carrier 8, and the surface of the image carrier 8 after transferring the toner image And a cleaning device B (described above) that removes transfer residual toner remaining on the toner.

The toner used in the image forming apparatus of the present invention is not particularly limited and can be appropriately selected according to the purpose, but a spherical toner can be preferably mentioned. By using the spherical toner, the cleaning device exhibits a cleaning effect particularly effectively. Examples of the spherical toner include a toner obtained by spheroidizing a pulverized toner prepared by melting and kneading, mixing, stirring, pulverizing and classifying a resin, a colorant, and the like, which are constituent materials of the toner. Examples thereof include a toner prepared by a polymerization method such as a combination method, a suspension polymerization method, and an emulsion polymerization method. Among these, a toner prepared by a polymerization method is preferable. The spherical toner preferably has a shape factor represented by the following formula (III) of 1.0 to 1.35 (the shape factor approaches 1 as it approaches a true sphere).
Shape factor = {(maximum particle size) ² × π / (projected area of particle × 4)} (III)
However, the maximum particle diameter indicates the maximum particle diameter passing through the center of gravity in the two-dimensional projection image of toner particles.

  When the shape factor exceeds 1.35, dot formation of the image becomes non-uniform and the graininess of the image may deteriorate. The spherical coefficient is obtained by, for example, randomly sampling 100 toner images magnified 1000 times using FE-SEM (S-4500) manufactured by Hitachi, Ltd., and image information thereof, for example, image processing software (Media Cybernetics) It is possible to measure by analyzing and calculating using Image-Pro Plus).

  There is no restriction | limiting in particular as a volume average particle diameter of the said spherical toner, Although it can select suitably according to the objective, It is preferable that it is 1-7 micrometers. When the volume average particle diameter is less than 1 μm of the toner, an image defect may occur. When the volume average particle diameter exceeds 7 μm, it may be difficult to meet the high resolution requirement of the electrophotographic image. The volume average particle size can be measured by Coulter Multisizer measurement manufactured by Coulter Electric.

  Furthermore, as the toner used in the image forming apparatus, a toner whose surface is coated with an external additive can be preferably exemplified. By coating the surface of the toner with an external additive, it is possible to reduce the adhesion between the toner and the photoconductor and enhance the cleaning effect of the cleaning device. The shape, particle size, external additive coverage, and material of the external additive are not particularly limited and can be appropriately selected according to the purpose. The shape of the external additive is different from that of other members. A spherical shape is preferable from the viewpoint of uniform contact area. Moreover, as a particle size of the said external additive, it is suitable that the average value of a primary particle diameter is 5 nm-150 nm. In addition, the external additive coverage of the external additive is preferably 10 to 90%. If the external additive coverage is less than 10%, it may be difficult to make the adhesive force between the toner and the photoreceptor appropriate, and this may cause an increase in the residual toner. When the external additive coverage is more than 90%, the external additive is extremely easily separated from the toner, and the constituent members of the image forming apparatus such as the photoreceptor may be easily damaged. The external additive coverage can be measured by image analysis of an electron microscope image of the toner surface to determine the ratio of the external additive coverage to the surface area of one toner particle.

  The external additive is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include organic fine particles and inorganic fine particles. There is no restriction | limiting in particular as said inorganic fine particle, Although it can select suitably according to the objective, For example, the thing etc. which used 1 or more types together from silica, titanium, an alumina, etc. are mentioned suitably. A combination of two of these is particularly preferred. As the inorganic fine particles, for example, in the case of inorganic fine particles having hygroscopicity, those subjected to a hydrophobizing treatment are preferable in consideration of environmental stability and the like. There is no restriction | limiting in particular as the method of hydrophobization processing, According to the objective, it can select suitably, For example, the method etc. which make a hydrophobization processing agent and the said fine powder react at high temperature etc. are mentioned. There is no restriction | limiting in particular as a hydrophobization processing agent, According to the objective, it can select suitably, For example, a silane coupling agent, silicone oil, etc. can be mentioned. There is no restriction | limiting in particular as the external addition method of the said external additive, According to the objective, it can select suitably, For example, the method of using various mixing apparatuses, such as a V-type blender, a Henschel mixer, a mechano-fusion, is mentioned suitably. It is done.

  Next, the operation of the image forming apparatus C will be described. As shown in FIG. 10, the surface of the image carrier 8 that is rotationally driven in the direction of the arrow R <b> 1 is charged to a predetermined polarity, for example, a negative polarity, by the charging device 11. Next, the charged surface of the image carrier 8 is irradiated with light-modulated laser light L emitted from the image writing means 12, thereby forming an electrostatic latent image on the surface of the image carrier 8. That is, the portion where the absolute value of the potential on the surface of the image carrier is lowered by the laser beam is an electrostatic latent image (image portion), and the portion where the absolute value of the potential is kept high without being irradiated with the laser beam is the background. Part. Next, the electrostatic latent image is developed with the toner T stored in the developing device 10 and charged to a predetermined polarity, and visualized as a toner image. On the other hand, the recording paper P is conveyed from an unillustrated paper feeding device between the image carrier 8 and the transfer device 13 from the direction of arrow F at a predetermined timing. At this time, the toner image formed on the image carrier 8 by the transfer device 13 is electrostatically transferred onto the recording paper P. The recording paper P to which the toner image has been transferred is heated and pressurized by a fixing device (not shown) to fix the toner image on the recording paper. Thereafter, the recording paper fixed by a fixing device (not shown) is discharged from a paper discharge unit (not shown).

  The transfer residual toner remaining on the image carrier 8 without being transferred to the recording paper P is adhered to the image carrier 8 by the cleaning belt 1 ′ pressed against the image carrier 8 by the support roller 2. The transfer residual toner collected and attached on the cleaning belt 1 ′ is removed by the removal blade 5. At this time, since the support roller 4 is installed so that x, r, φ, and D in FIGS. 4 and 5 satisfy the above formula (I), the removal failure can be improved. Then, the toner scraped off by the removing blade 5 is dropped and stored in the collecting device 6. The toner removed from the image carrier 8 can be transported to the developing device 10 by a toner recycling device (not shown) to recycle the toner.

  FIG. 12 shows an image forming apparatus according to the second structure of the present invention. The image forming apparatus E is a tandem type full color printer. As shown in FIG. 12, the image forming apparatus E is arranged in series and forms process toner cartridges D1 to D4 that form toner images of yellow (Y), magenta (M), cyan (C), and black (BK). The photosensitive drums disposed in the process cartridges D1 to D4, wound around a plurality of rollers 15a, 15b, 15c, 15d, and 16 and rotated in the direction of the arrows, are provided in the process cartridges D1 to D4. The intermediate transfer medium 14 to which the toner images carried on the image carriers 8a to 8d as a body are transferred and the roller 15b are arranged to face each other via the intermediate transfer medium 14, and the intermediate transfer medium 14 has a predetermined nip pressure. The transfer means 13 that contacts the toner image formed on the intermediate transfer medium 14 to the recording medium P that is a transfer material, and the intermediate transfer medium from the transfer means 13 14, a cleaning device A, which is disposed on the downstream side in the rotational direction of 14 and is opposed to a roller 16 that removes transfer residual toner remaining on the surface of the intermediate transfer medium 14 after the toner image is transferred to the recording medium P. A sheet feeding device, a fixing device (not shown), and the like are provided. Other configurations in each of the process cartridges D1 to D4, in particular, the configurations of the cleaning devices B1 to B4 and A, toners used for image formation, etc. are yellow (Y), magenta (M), cyan (C), black ( The process cartridge D is the same as the process cartridge D except that the toner of each color (BK) is used.

  Examples of the intermediate transfer medium 14 include those in which at least one elastic coating layer is formed on the surface of an endless belt base material. Examples of the endless belt base material include resin, rubber, and a metal thin plate. Examples of the elastic coating layer include resin, rubber, and elastomer. The intermediate transfer medium 14 is not particularly limited and may be appropriately selected depending on the purpose. At least one elastic coating layer is formed on the outer periphery of a drum-shaped core body made of a metal such as stainless steel or aluminum. It is also possible to make it a drum type. In this case, however, a cleaning device B having a belt-like toner holding member is provided instead of the cleaning device A.

  Next, the operation of the image forming apparatus E will be described. As shown in FIG. 12, the intermediate transfer medium 14 is driven to rotate in the direction of a white arrow. At this time, the yellow toner image, the magenta toner image, the cyan toner image, and the black toner image respectively formed on the image carriers 8a to 8d provided in the process cartridges D1 to D4 are sequentially superimposed on the intermediate transfer medium 14. Is transcribed. On the other hand, the recording paper P is conveyed from an unillustrated paper feeding device between the intermediate transfer medium 14 and the transfer device 13 at a predetermined timing from the direction of the arrow F. At this time, the toner images of the respective colors formed on the intermediate transfer medium 14 by the transfer device 13 are electrostatically collectively transferred onto the recording paper P. The recording paper P on which the toner images of the respective colors are transferred is heated and pressurized by a fixing device (not shown), and the toner image is fixed on the recording paper P. Thereafter, the recording paper fixed by a fixing device (not shown) is discharged from a paper discharge unit (not shown). Untransferred toner remaining on the image carriers 8a to 8d without being transferred onto the intermediate transfer medium 14 is removed by the cleaning devices B1 to B4. Further, the transfer residual toner remaining on the intermediate transfer medium 14 without being transferred from the intermediate transfer medium 14 onto the recording paper P is removed by the cleaning device A.

It is a figure which shows the structure of the toner scraping part of a cleaning apparatus. It is a figure which shows the relationship with the removal blade in the location which provided the slight curvature in the vicinity of the opposing roller 4 in the belt-shaped toner holding body of a cleaning apparatus. The perspective view which shows the case where the straight line (beta) which shows an actual contact position has angle (theta) with respect to the straight line (alpha) which shows the contact aim position of the removal blade 5 parallel to the perpendicular axis of the drive direction of the belt-shaped toner holding body 1. It is. It is a figure which expands and shows the contact vicinity of the belt and a braid | blade. It is a figure which shows a mode that a removal blade bites into a to-be-cleaned body. FIG. 2 is a diagram illustrating a contact state between the image bearing member and the cleaning device B having the same configuration of the belt-like toner holding member toner scraping unit as in FIG. 1. It is a figure showing the relationship between the cleaning belt of the cleaning apparatus B and a removal blade. It is a block diagram of the cleaning apparatus which made each diameter of the support roller and counter roller of a cleaning belt equal. FIG. 3 is a diagram illustrating a relationship between a cleaning device and an image carrier when a potential gradient is formed between the cleaning belt and the image carrier. 1 is a configuration diagram illustrating an image forming apparatus according to a first structure of the present invention. It is a block diagram of the process cartridge which concerns on this invention. It is a block diagram which shows the image forming apparatus which concerns on the 2nd structure of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Belt-shaped toner holding body 2, 3 Support roller 4 Opposed roller 5 Removal blade 6 Collection box 8 Image carrier

Claims (19)

In a cleaning device for removing residual toner remaining on the surface of an image carrier , a belt-like toner holder is provided as a cleaning belt , and the belt-like toner holder is brought into contact with or substantially in contact with the surface of the image carrier. The transfer residual toner is removed from the surface of the image carrier, and a removal blade for scraping off the toner adhering to the belt-shaped toner holding member and a recovery box for recovering and discarding the scraped toner are further provided. The belt-like toner holding body is provided with a counter roller on the peripheral surface side of the belt-like toner holding body, the surface of the belt-like toner holding body is in contact with the removal blade in a substantially horizontal state , and the position facing the image carrier in characterized by attaching a voltage applying means for applying a voltage to the support rollers for supporting wound the belt-shaped toner carrier Cleaning device that. The belt-shaped toner holder is wound around a plurality of support rollers, the removal blade is an elastic blade, and the removal blade that comes into contact with scraping off the toner adhering to the belt-shaped toner holder is a belt-like the toner holding member on the surface, abuts inclined with respect to the counter roller axis, the larger of the displacement distance in the belt-shaped toner carrier both end portions of the contact position of the removal blade and the roller shaft x, the counter A radius of the roller r, a tangent line at an ideal contact point of the counter roller with the removal blade, and a belt shape stretched between a support roller and a counter roller that stretches a belt-shaped toner holding member adjacent to the counter roller. When the larger of the two angles formed by the straight line matching the toner holding member is φ, and the amount of pushing the removal blade toward the belt-like toner support is D
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1−cosφ−tanφ × sinφ) ≦ D (I)
The cleaning apparatus according to claim 1, wherein the relationship is satisfied. The belt-shaped toner holding body is wound around a plurality of support rollers, and the removal blade is an elastic blade pivotally supported at the center in the width direction of the belt-shaped toner holding body. the removal blade abutting when scraping off the toner adhering to the toner carrier is a belt-shaped toner carrier surface, abuts inclined with respect to the counter roller axis, the contact position of the removal blade and the roller shaft X is the larger of the deviation distances at both ends of the belt-like toner holding member, r is the radius of the counter roller, the tangent at the ideal contact point of the counter roller with the removal blade, and adjacent to the counter roller. The larger of the two angles formed by the support roller that stretches the belt-shaped toner holding member and the straight line that coincides with the belt-like toner holding member that is stretched by the opposing roller is φ. The amount of pushing the removing blade toward the belt-like toner support is D, the width of the belt-like toner holding member is L, and the removing blade is brought into contact when scraping off the toner adhering to the belt-like toner holding member. When the angle formed by the roller shaft and the contact line of the removal blade when θ is in contact with the surface of the belt-shaped toner holding member inclined with respect to the opposing roller shaft is θ,
When 0 ≦ x <r × sinφ,
0 ≦ r−√ (r ² −x ² ) ≦ D
When r ≧ x ≧ r × sinφ,
0 ≦ tanφ × x + r (1-cosφ−tanφ × sinφ) ≦ D
Where x = 1/2 × L × sinθ (II)
The cleaning apparatus according to claim 1, wherein the relationship is satisfied. The cleaning device according to claim 1, wherein the adhesion force between the surface of the belt-shaped toner holding member and the toner is larger than the adhesion force between the surface of the image carrier and the toner.   2. The cleaning apparatus according to claim 1, wherein the belt-shaped toner holding member is an intermediate transfer member for transferring an image on a photosensitive member as an image carrier to a recording material. An image forming apparatus having a cleaning apparatus according to any one of claims 1-5. The image forming apparatus according to claim 6 , wherein a spherical toner is used in a manufacturing process or a process after manufacturing. The toner particles used are
Shape factor = {(maximum particle size) ² × π / (projected area of particle × 4)} (III)
The image forming apparatus according to claim 7 , wherein the shape factor is 1.0 to 1.35. The image forming apparatus according to any one of claims 6 to 8 , wherein the toner used has a volume average particle diameter of 1 to 7 µm. Toner particles used may consist toner base particles and the external additive, the coating area ratio of the external additive to the toner base particles characterized by being prepared so as to be 10% to 90% claims 6 to claim Item 10. The image forming apparatus according to any one of Items 9 to 9 . The external additive is silica (SiO _2), titanium oxide (TiO _2), any one of claims 6 to claim 10, characterized in that it contains at least one one of alumina (Al ₂ O ₃₎ The image forming apparatus according to one item. The external additive contains two kinds of silica (SiO ₂ ), titanium oxide (TiO ₂ ), and alumina (Al ₂ O ₃ ), according to any one of claims 6 to 11. The image forming apparatus described in the item. A process cartridge having a cleaning device according to any one of claims 1-5. The process cartridge according to claim 13 , wherein the toner formed into a spherical shape is used in a manufacturing process or a process after manufacturing. The toner particles used are
Shape factor = {(maximum particle size) ² × π / (projected area of particle × 4)} (III)
The process cartridge according to claim 14 , wherein the shape factor is 1.0 to 1.35. The process cartridge according to any one of claims 13 to 15 , wherein the toner used has a volume average particle diameter of 1 to 7 µm. Toner particles used may consist toner base particles and the external additive, the coating area ratio of the external additive to the toner base particles characterized by being prepared so as to be 10% to 90% claims 13 to claim Item 17. The process cartridge according to any one of Items 16 . The external additive is silica (SiO _2), titanium oxide (TiO _2), any one of claims 13 to claim 17, characterized in that it contains at least one one of alumina (Al ₂ O ₃₎ The process cartridge according to one item. The external additive contains two kinds of silica (SiO ₂ ), titanium oxide (TiO ₂ ), and alumina (Al ₂ O ₃ ), according to any one of claims 13 to 18. The process cartridge according to the item.

Images