Electrostatic collection device

Abstract

An electrostatic collection device 10 has a rubbing member 1. The rubbing member 1 is in contact with the brush bristles 11p of a collection rotary body 11 at a tip section 1a1 which is one end in a second direction intersecting a first direction serving as the rotational axis direction of the collection rotary body 11, a base end section 1a2 which is the other end in the second direction is fixed to a fixing member 11b, and the tip section 1a1 is arranged in an inclined manner so as to be positioned downstream from the base end section 1a2 in the direction of rotation of the collection rotary body 11. The rubbing member 1 allows the brush bristles 11p to be restored following bending of the brush bristles 11p together with the rotation of the collection rotating body 11 and thereby enables collected objects P to fly from the brush bristles 11p toward a recovery member 12. In addition, the electrostatic collection device 10 is configured such that when the distance of movement of the tip section 1a1 due to bending of the rubbing member 1 is defined as the bending amount and the load received by the tip section 1a1 from the brush bristles 11p is defined as the contact pressure, the rate of change of the contact pressure when the bending amount changes by 1 mm is 20% or less.

Description

Electrostatic collection device

[0001] This invention relates to an electrostatic collection device for collecting objects from a cleaning target.

[0002] Conventionally, technologies have been proposed to collect fine particles using electrostatic adhesion in various manufacturing equipment, industrial products, and household vacuum cleaners. Here, "fine particles" refer to, for example, toner and paper dust in electrophotographic image forming apparatus, and dust in manufacturing equipment and homes.

[0003] For example, Patent Document 1 (Japanese Patent Publication No. 1-6989) discloses an electrostatic collection device (cleaning device) that collects toner from the surface of an electrostatic latent image carrier in an electrophotographic image forming apparatus using electrostatic adhesion force. Patent Document 2 (Japanese Patent Publication No. 4886097) discloses an electrostatic collection device (cleaning device) that collects dust from the surface of glass substrates, printed circuit boards (PCBs, PCBAs, etc.), films, sheets, plastic plates, etc., using electrostatic adhesion force.

[0004] These electrostatic collection devices first collect the material to be collected on the object to be cleaned by rubbing it against a collection rotating body, and then collect the material that has electrostatically adhered to the collection rotating body using a recovery rotating body or the like. As the collection rotating body, a brush roller with a brush section arranged around a core is used. Similarly, a recovery roller is used as the recovery rotating body. The material to be collected and the brush bristles (hairs of the brush) of the collection rotating body rub against each other, and they become triboelectrically charged in opposite polarities, causing the material to electrostatically adhere to the brush bristles. The material that has adhered to the brush bristles then electrostatically adheres to the recovery rotating body, which is charged to a potential greater than the absolute value of the brush bristles on the same polarity side relative to the material, and is recovered from the brush bristles.

[0005] In such electrostatic collection devices, the collection of materials attached to the brush bristles of the collection rotating body is primarily carried out by electrostatic force. Therefore, for example, if the particle size of the materials to be collected becomes small, and the non-electrostatic adhesion force of the materials to be collected to the brush bristles becomes relatively large, it may become difficult for the collection rotating body to electrostatically collect the materials from the collection rotating body.

[0006] Patent documents 3 (JP 2014-228849 A) ​​and 4 (JP 2007-310336 A) disclose a configuration in which a highly rigid abrasive member is positioned to bite into the brush bristles, and fine particles are removed from the brush bristles by a method other than electrostatic means (mechanically removed). In this configuration, the brush bristles are bent by the abrasive member as the brush roller rotates, and then quickly return to their original shape as they pass through the abrasive member. The acceleration at that time causes fine particles electrostatically attached to the brush bristles to fly away. [Means for solving the problem]

[0007] According to one aspect of the present invention, a rotatable brush-shaped collecting rotating body comprises a collecting rotating body having brush bristles that contact an object to be cleaned to form a collecting section, and which, by rotating, electrostatically collects objects from the object to be cleaned onto the brush bristles in the collecting section; a collection member that contacts the brush bristles to form a collection section, and which electrostatically collects the objects to be collected from the brush bristles in the collection section; a sliding member formed of a flexible plate-shaped member that contacts the brush bristles downstream of the collecting section and upstream of the collection section in the rotational direction of the collecting rotating body, and slides against the brush bristles as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed, wherein the sliding member is in the direction of the rotational axis of the collecting rotating body. An electrostatic collection device is provided in which the tip portion, which is one end in a second direction intersecting the first direction, contacts the brush bristles, the base portion, which is the other end in the second direction, is fixed to the fixing member, the tip portion is inclined to be located downstream of the base portion in the rotation direction of the collection rotating body, and the brush bristles are allowed to bend and then return to their original state as the collection rotating body rotates, thereby enabling the object to be collected to fly from the brush bristles toward the collection member, and when the distance the tip portion moves due to the bending of the sliding member is defined as the amount of bending, and the load the tip portion receives from the brush bristles is defined as the contact pressure, the rate of change of the contact pressure when the amount of bending changes by 1 mm is 20% or less.

[0008] According to another aspect of the present invention, a rotatable brush-shaped collecting rotating body comprises a brush bristle that contacts an object to be cleaned to form a collection section, and by rotating, electrostatically collects objects from the object to be cleaned onto the brush bristle in the collection section; a collection member that contacts the brush bristle to form a collection section, and electrostatically collects the objects from the brush bristle in the collection section; a sliding member formed of a flexible plate-shaped member that contacts the brush bristle downstream of the collection section and upstream of the collection section in the rotation direction of the collecting rotating body, and slides against the brush bristle as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed, wherein the sliding member contacts the brush bristle at a tip that is one end in a second direction intersecting the first direction which is the rotation axis direction of the collecting rotating body, and the other end in the second direction The base end of the brush is fixed to the fixing member, and the tip is positioned at an inclination such that it is located downstream of the base end in the rotational direction of the collecting rotating body, and the brush bristles are allowed to bend and then return to their original position as the collecting rotating body rotates, thereby allowing the collected object to be launched from the brush bristles toward the collection member. The provided electrostatic collecting device has a penetration amount where, assuming that the brush bristles are not bent by the abrasive member at the position in contact with the abrasive member, the distance from the top of the brush bristles to the end of the tip in the second direction on the side of the abrasive member facing the collecting rotating body is defined as the penetration amount, the ratio of the penetration amount to the free length of the brush bristles is defined as the penetration rate, and the distance the tip moves due to the bending of the abrasive member is defined as the deflection amount, wherein the rate of change of the penetration rate when the deflection amount changes by 1 mm is 20% or less.

[0009] Furthermore, according to another aspect of the present invention, a rotatable brush-shaped collecting rotating body comprises a brush bristle that contacts an object to be cleaned to form a collection section, and by rotating, electrostatically collects objects from the object to be cleaned onto the brush bristle in the collection section; a collection member that contacts the brush bristle to form a collection section, and electrostatically collects the objects to be collected from the brush bristle in the collection section; a sliding member formed of a flexible plate-shaped member that contacts the brush bristle downstream of the collection section and upstream of the collection section in the rotation direction of the collecting rotating body, and slides against the brush bristle as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed, wherein the sliding member contacts the brush bristle at one end in a second direction that intersects with a first direction which is the rotation axis direction of the collecting rotating body, and the other end in the second direction The provided electrostatic collection device has a base end fixed to the fixing member, and is positioned at an inclination such that the tip is located downstream of the base end in the rotational direction of the collecting rotating body, and allows the brush bristles to bend and then return to their original position as the collecting rotating body rotates, thereby enabling the collected material to be launched from the brush bristles toward the collection member, and when the distance from the top of the brush bristles at the position in contact with the abrasive member, assuming that the brush bristles are not bent by the abrasive member, to the end of the tip in the second direction on the side of the abrasive member's surface facing the collecting rotating body is defined as the penetration amount, and the ratio of the penetration amount to the free length of the brush bristles is defined as the penetration rate, the average value of the penetration rate during one rotation of the collecting rotating body is 20% or more and 50% or less, and the rate of change of the penetration rate during one rotation of the collecting rotating body is 20% or less.

[0010] Figure 1 is a schematic cross-sectional view of the image forming apparatus in Example 1.

[0011] Figure 2 is a schematic cross-sectional view of the electrostatic collection device (paper dust collection device) in Example 1.

[0012] Figure 3 is a schematic enlarged cross-sectional view of the brush portion of the brush roller.

[0013] Figure 4 is a schematic enlarged cross-sectional view of the vicinity of the sliding member.

[0014] Figure 5 is a schematic enlarged cross-sectional view near the tip of the rubbing member.

[0015] Figure 6 is a schematic diagram for explaining the height difference (concavity and convexity) at the root of the brush bristles.

[0016] Figure 7 is a schematic diagram for explaining the method of measuring the contact pressure.

[0017] Figure 8 is a graph showing the relationship between the moving distance of the base of the contact pressure measuring device and the contact pressure.

[0018] Figure 9 is a schematic diagram for explaining the method of measuring the penetration amount.

[0019] Figure 10 is a graph showing the measurement results of the contact pressure for the examples and comparative examples.

[0020] Figure 11 is a schematic diagram for explaining the cantilever beam model of the rubbing member.

[0021] Figure 12 is a schematic diagram for explaining the cantilever beam model of the brush bristles.

[0022] Figure 13 is a schematic diagram for explaining the method of measuring the flying rate.

[0023] Figure 14 is a schematic external perspective view of the electrostatic dust collection device (cleaning device) in Example 3.

[0024] Figure 15 is a schematic cross-sectional view of the electrostatic dust collection device (cleaning device) in Example 3.

[0025] Hereinafter, a preferred embodiment of the electrostatic dust collection device according to the present invention will be described in detail with reference to the drawings. However, the scope of the present invention is not limited to the dimensions, materials, shapes, relative arrangements, etc. of the components in this embodiment.

[0026] In this embodiment, as an example of its embodiment, the electrostatic dust collection device according to the present invention is used as a paper dust collection device for collecting paper dust from a recording material in an image forming device that forms an image on the recording material. (1) Overall configuration of the image forming device

[0027] Figure 1 is a schematic cross-sectional view of the image forming apparatus 100 of this embodiment. The image forming apparatus 100 of this embodiment is a monochrome laser beam printer capable of forming a black monochrome image using an electrophotographic method.

[0028] The image forming apparatus 100 has a photosensitive drum 101, which is a rotatable drum-shaped (cylindrical) photoreceptor (electrophotographic photoreceptor) that serves as an image carrier. When the image output operation is started, the photosensitive drum 101 is driven to rotate in the direction of the arrow in the figure (clockwise direction). In this embodiment, the outer diameter of the photosensitive drum 101 is 30 mm, and the peripheral speed (surface movement speed) is 140 mm / sec.

[0029] The surface of the rotating photosensitive drum 101 is uniformly charged to a predetermined potential with a predetermined polarity (negative polarity in this embodiment) by a charging roller 102, which is a roller-type charging member acting as a charging means. The charging roller 102 contacts the surface of the photosensitive drum 101 and, as the photosensitive drum 101 rotates, it rotates in the direction of the arrow in the figure (counterclockwise), thereby charging the surface of the photosensitive drum 101.

[0030] The surface of the electrostatically charged photosensitive drum 101 is scanned and exposed by an exposure device (laser scanner device) 103, which serves as an exposure means, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 101. The exposure device 103 irradiates the surface of the photosensitive drum 101 with laser light B, which is modulated according to image data sent to the image forming apparatus 100 from an external device such as a personal computer.

[0031] The electrostatic latent image formed on the photosensitive drum 101 is developed (visualized) by a developing device 104, which is a developing means, when toner T is supplied as a developer, and a toner image (toner image, developer image) is formed on the photosensitive drum 101. The developing device 104 has a developing roller 104a as a developer carrier (developing member) that contacts the photosensitive drum 101. During development, a predetermined developing voltage is applied to the developing roller 104a by a developing power supply (high voltage power supply), which is a developing voltage application means (not shown). As a result, at the opposing part (contact part) between the developing roller 104a and the photosensitive drum 101, the toner T conveyed by the developing roller 104a adheres to the electrostatic latent image on the photosensitive drum 101, and a toner image is formed on the photosensitive drum 101. In this embodiment, toner T charged with the same polarity as the charging polarity of the photosensitive drum 101 (negative polarity in this embodiment) adheres to the exposure area (image area) on the photosensitive drum 101, where the absolute value of the potential has decreased after uniform charging treatment and exposure (reverse development method).

[0032] A transfer roller 105, which is a roller-type transfer member serving as a transfer means, is positioned opposite the photosensitive drum 101. The transfer roller 105 contacts the photosensitive drum 101 to form an image transfer section (image transfer nip section) Nt. The toner image formed on the photosensitive drum 101 is transferred in the image transfer section Nt onto a sheet-like recording material S, such as paper, which is held and transported between the photosensitive drum 101 and the transfer roller 105. During transfer, a predetermined transfer voltage (positive polarity in this embodiment) is applied to the transfer roller 105 by a transfer power supply (high-voltage power supply), which is a transfer voltage application means (not shown), with a polarity opposite to the normal charging polarity of the toner (the main charging polarity of the toner during development).

[0033] The recording material (recording medium, transfer material, sheet) S is fed out from the cassette 106, which serves as the recording material storage section, by a feeding roller 107 or the like, which serves as a feeding means. The recording material S is then transported to the image transfer section Nt by a pair of transport rotating bodies 108 of the paper dust collection device 10, which also functions as a transport means, in time with the toner image on the photosensitive drum 101. In addition to the paper dust collection device 10, a separate transport means (such as a pair of transport rollers) may be provided to transport the recording material S to the image transfer section Nt.

[0034] The recording material S onto which the toner image has been transferred is sent to a fixing device 109, which acts as a fixing means. The fixing device 109 applies heat and pressure to the recording material S carrying the unfixed toner image to fix (melt and solidify) the toner image to the recording material S. The recording material S with the fixed toner image is discharged (output) to the outside of the image forming apparatus 100.

[0035] Furthermore, toner that remains on the photosensitive drum 101 without being transferred to the recording material S during transfer (transfer residue toner) is recovered by the developing device 104. In other words, the negatively charged toner adhering to the photosensitive drum 101 is transferred to the developing roller 104a due to the potential difference between the potential of the photosensitive drum 101 and the developing voltage (the potential of the developing roller 104a), and is recovered from the developing roller 104a into the developing device 104. The toner recovered in the developing device 104 is used again for image formation. Thus, in this embodiment, the image forming apparatus 100 has a cleanerless configuration and does not have a dedicated cleaning device for removing transfer residue toner from the photosensitive drum 101.

[0036] In the image forming apparatus 100 of this embodiment, the surface of the photosensitive drum 101 is in direct contact with paper, which is often used as the recording material S, so paper dust P (Figure 2) tends to adhere to the surface of the photosensitive drum 101. Paper dust P contains pulp fibers (cellulose extracted from hardwoods and softwoods), which are the main raw materials of paper. In addition to pulp fibers, paper dust P also contains fillers to make the paper opaque or white, internal sizing agents to prevent ink bleeding, and internal sizing fixatives to adsorb the internal sizing agents to the pulp fibers. Among these, the substances that are most likely to adversely affect the electrophotographic process are pulp fibers and fillers. For example, if paper dust P is collected in the developing apparatus 104 along with the toner T remaining on the photosensitive drum 101, it may cause image defects. In other words, if paper dust P is collected in the developing apparatus 104, it may reduce the charge level of the toner in the developing apparatus 104. Furthermore, if the image forming operation is repeated in this state, the amount of charge on the toner in the developing device 104 may become insufficient compared to the amount of charge required for the image forming operation. When the amount of charge on the toner is insufficient, a phenomenon called "fogging," in which a thin layer of toner adheres to areas on the photosensitive drum 101 where an image should not be formed (non-image areas), may occur beyond the acceptable range.

[0037] Therefore, the image forming apparatus 100 of this embodiment has a paper dust collection device 10, which is an example of an embodiment of the electrostatic collection device according to the present invention, that collects paper dust P as the object to be collected from the surface of the recording material S as the object to be cleaned (object to be cleaned). As described above, in this embodiment, the paper dust collection device 10 has the function of a means for transporting the recording material S. In this embodiment, the paper dust collection device 10 is located downstream of the cassette 106 and upstream of the image transfer unit Nt in the transport direction of the recording material S. The paper dust collection device (hereinafter also referred to as the "electrostatic collection device") 10 collects positively charged paper dust P from the surface of the recording material S. This makes it possible to suppress the occurrence of fogging as described above. (2) Overall configuration of the electrostatic collection device

[0038] Next, the electrostatic collection device 10 of this embodiment will be described. Figure 2 is a schematic cross-sectional view of the electrostatic collection device 10 of this embodiment (showing a cross-section substantially perpendicular to the rotation axis direction of the brush roller 11, which will be described later). Figure 3 is a schematic enlarged cross-sectional view illustrating the configuration of the brush portion 11a of the brush roller 11, which will be described later, that constitutes the electrostatic collection device 10 of this embodiment.

[0039] The electrostatic collection device 10 of this embodiment includes a brush roller (rotating brush) 11 and a recovery roller 12. The brush roller 11 is an example of a collection rotating body, which is a rotatable collection member that constitutes the collection means. The recovery roller 12 is also an example of a recovery rotating body, which is a rotatable recovery member that constitutes the collection means. Furthermore, the electrostatic collection device 10 of this embodiment includes a cleaning blade 13 as a removal member (scraping member), a storage section (storage container) 14 for storing paper dust P, and an opposing roller 16 for transporting the recording material S together with the brush roller 11. Moreover, the electrostatic collection device 10 of this embodiment has a sliding mechanism 1 equipped with a sliding member 1a that slides against the brush bristles 11p of the brush roller 11, which will be described later. In this embodiment, the brush roller 11 and the opposing roller 16 constitute a transport rotating body pair 108 for transporting the recording material S. The brush roller 11 is positioned to contact the surface of the recording material S that comes into contact with the photosensitive drum 101 immediately after passing through the transport rotating body pair 108. The opposing roller 16 is positioned to contact the surface of the recording material S opposite to the surface that comes into contact with the photosensitive drum 101 immediately after passing through the transport rotating body pair 108.

[0040] The brush roller 11 rotates in the direction of arrow K1 (clockwise) in the figure, driven by a drive transmission member (not shown) that constitutes a drive transmission means, with driving force transmitted from a motor (not shown) that constitutes a drive source that constitutes a drive means. In other words, the brush roller 11 rotates in the direction of arrow K1 (clockwise) in the figure, such that the direction of movement of the brush portion 11a and the direction of movement (conveying direction) S1 of the recording material S are in the forward direction at the first transfer portion (collection portion) R1 (dotted line portion), which is the contact portion between the brush portion 11a of the brush roller 11 and the recording material S. The recovery roller 12 rotates in the direction of arrow K2 (clockwise) in the figure, driven by a drive transmission member (not shown) that constitutes a drive transmission means, with driving force transmitted from a motor (not shown) that constitutes a drive source that constitutes a drive means. In other words, the recovery roller 12 rotates in the direction of arrow K2 (clockwise) in the figure, such that the direction of movement of the brush portion 11a and the direction of movement of the surface of the recovery roller 12 are in opposite directions at the second transfer portion (recovery portion) R2 (dotted line portion), which is the contact portion between the brush portion 11a of the brush roller 11 and the recovery roller 12. As the brush roller 11 rotates, it rubs the surface of the recording material S with the brush portion 11a that contacts the surface of the recording material S, thereby rubbing the surface of the recording material S and the paper dust P on the recording material S, and collecting the paper dust P from the surface of the recording material S by electrostatic adhesion (electrostatic adsorption force). In this embodiment, an opposing roller 16 is positioned opposite the brush roller 11 so as to hold and transport the recording material S together with the brush roller 11. The opposing roller 16 may be configured to rotate on its own, or it may be configured to rotate in association with the rotation of the brush roller 11 (movement of the recording material S). The paper dust P collected by the brush roller 11 is collected by electrostatic adhesion (electrostatic adsorption force) on the recovery roller 12 (more specifically, the surface layer 12a of the recovery roller 12, which will be described later) which rotates while in contact with the brush roller 11. Furthermore, the paper dust P collected by the brush roller 11 is also collected by the recovery roller 12 when the brush portion 11a is flicked off the brush portion 11a as it passes through the friction portion Nc where the friction member 1a and the brush portion 11a come into contact. The paper dust P collected by the recovery roller 12 is scraped off the recovery roller 12 by the cleaning blade 13 and stored in the storage portion 14. Through the above process, the paper dust P adhering to the recording material S is removed from the recording material S. The components of the electrostatic collection device 10 will be described further below.

[0041] The brush roller 11 is a rotatable brush-shaped collecting rotating body having a brush portion 11a equipped with elastically deformable brush bristles (brush hairs) 11p (Figure 3), and a core portion (core material, core metal) 11b as a support portion that supports the brush portion 11a. The core portion 11b is composed of a cylindrical member (roller-shaped member) and is positioned opposite the opposing roller 16 such that its rotation axis direction is substantially parallel to the rotation axis direction of the opposing roller 16. The core portion 11b is rotatably supported by the housing (not shown) of the electrostatic collecting device 10 via rotation shaft portions (not shown) provided at both ends in the direction of its rotation axis. The brush portion 11a is provided on the outer circumference of the core portion 11b.

[0042] In this embodiment, the core portion 11b of the brush roller 11 is made of aluminum (aluminum or aluminum alloy), which is a metallic material that acts as a conductor (conductive material). In this embodiment, the core portion 11b of the brush roller 11 is connected to ground potential (GND) (electrically grounded). In addition, in this embodiment, the brush bristles 11p of the brush roller 11 are made of an insulating resin material that acts as an insulator (electrically insulating material). In particular, in this embodiment, the brush bristles 11p of the brush roller 11 are made of PET fibers, which are fibers made of PET (polyethylene terephthalate), a type of polyester resin. In addition, in this embodiment, the brush bristles 11p of the brush roller 11 are made of cut pile. As shown in Figure 3, the brush portion 11a of the brush roller 11 is made of a base fabric 11k and brush bristles 11p. The base fabric 11k is formed by weaving together warp threads 11t and weft threads 11y. Furthermore, brush bristles (also referred to here as "piles") 11p are provided, which are formed by cutting multiple pile threads that have been woven in by pile weaving so as to be intertwined in a U-shape with the weft threads 11y of the base fabric 11k. For example, highly flexible and bulky spun yarns are used for the warp threads 11t and weft threads 11y. The warp threads 11t and weft threads 11y constitute the base fabric 11k and also play a role in sandwiching and fixing the brush bristles 11p. The material of the fibers that constitute the base fabric 11k may be the same material as the material of the fibers that constitute the brush bristles 11p, or it may be a different material. Conductive fibers may be used as the fibers that constitute the base fabric 11k. Here, the length of the portion in which the brush bristles 11p intertwined with the weft threads 11y are freed from being fixed by the warp threads 11t and weft threads 11y and can be freely deformed is defined as the free length of the brush bristles 11p (also referred to here as "pile length" or simply "length"). The free length L of the brush bristles 11p can also be defined as the length of the portion of the brush bristles 11p that protrudes from the base fabric 11k of the brush portion 11a. This free length L of the brush bristles 11p is represented by the length when the brush bristles 11p are not deformed by pressure applied by the recovery roller 12 or the friction member 1a. Furthermore, the outer diameter of the brush roller 11 is the diameter of the circumscribed circle of the brush bristles 11p in the state where no pressure is applied, as described above.

[0043] In this embodiment, the outer diameter of the core portion 11b of the brush roller 11 is 18 mm. In this embodiment, the free length L of the brush bristles 11p of the brush roller 11 is 1.5 mm. In this embodiment, the outer diameter of the brush roller 11 is approximately 21 mm. In this embodiment, the brush bristles 11p of the brush roller 11 are made of PET fibers with a Young's modulus of 3500 MPa and a diameter (thickness) of 22 μm. In this embodiment, the cross section approximately perpendicular to the axial direction of the brush bristles 11p is approximately circular, and the diameter of the cross section approximately perpendicular to the axial direction of the brush bristles 11p can be used as the thickness of the brush bristles 11p. If the cross section approximately perpendicular to the axial direction of the brush bristles 11p is not circular, the diameter of the circumscribed circle of the cross section approximately perpendicular to the axial direction of the brush bristles 11p can be used as the thickness of the brush bristles 11p. In this embodiment, the brush portion 11a of the brush roller 11 has a pile density of 200 kF / inch. ２ The configuration is as follows. In this embodiment, the brush roller 11 is constructed by bonding the brush portion 11a (base fabric 11k on which brush bristles 11p are provided) to the core portion 11b.

[0044] Furthermore, the fixing means for fixing the brush portion 11a onto the core portion 11b is not limited to adhesive, and other fixing means such as fixing with double-sided tape may be used. Also, in this embodiment, the brush bristles 11p of the brush roller 11 are provided substantially uniformly on the outer circumference of the core portion 11b of the brush roller 11 in a range of width equivalent to the width of the recording material S with the largest length (width) in the width direction substantially perpendicular to the transport direction among the recording materials S used in the image forming apparatus 100. For example, the length in the longitudinal direction (direction of the rotation axis of the brush roller 11) of the area on which the brush bristles 11p of the brush roller 11 are provided is set to 220 mm so as to cover the entire width of the A4 size recording material S. Here, the base fabric 11k may have a thickness variation of about 1 mm (thickness in the rotational radius direction of the brush roller 11), and the free length L of the brush bristles 11p may vary by about 1 mm.

[0045] In this embodiment, the brush roller 11 rotates in the direction of arrow K1 in the figure (forward direction relative to the transport direction S1 of the recording material S) at a peripheral speed (surface movement speed) of 144 mm / sec, which is approximately 3% faster than the transport speed of the recording material S. As a result, the tips of the brush bristles 11p of the brush roller 11 and the surface of the recording material S rub against each other. The recording material S is held between the brush roller 11 and the opposing roller 16 and transported in the direction of arrow S1 in the figure while being rubbed by the brush roller 11. As a result, at the first transfer section (first transfer nip section) R1, which is the contact point between the brush roller 11 and the recording material S, paper dust P on the recording material S is transferred (collected) to the brush bristles 11p of the brush roller 11 by electrostatic adhesion force and adheres to the brush bristles 11p.

[0046] The recovery roller 12 has a surface layer 12a and a base (core material) 12b on which the surface layer 12a is provided on the outer circumference. The base 12b of the recovery roller 12 is made up of a cylindrical member (roller-shaped member) and is positioned opposite the brush roller 11 such that its rotation axis direction is substantially parallel to the rotation axis direction of the brush roller 11. The recovery roller 12 is rotatably supported in the housing (not shown) of the electrostatic collection device 10 via rotation shafts (not shown) provided at both ends in the direction of its rotation axis.

[0047] In this embodiment, the base 12b of the recovery roller 12 is formed of an insulating resin material such as ABS resin (acrylonitrile butadiene styrene resin) as an insulator. In this embodiment, the surface layer 12a of the recovery roller 12 is also formed of an insulating resin material as an insulator. In particular, in this embodiment, the surface layer 12a of the recovery roller 12 is formed of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer), which is a type of fluororesin. In this embodiment, the recovery roller 12 is electrically in a floating state.

[0048] In this embodiment, the diameter of the base 12b of the recovery roller 12 is 17 mm. Also in this embodiment, the thickness of the surface layer 12a of the recovery roller 12 is 0.5 mm. Furthermore, in this embodiment, the outer diameter of the recovery roller 12 is 18 mm. In addition, the length of the recovery roller 12 in the direction of its rotation axis is equivalent to the length of the area (region) where the brush portion 11a is provided in the direction of the rotation axis of the brush roller 11. For example, the length of the recovery roller 12 (surface layer 12a) in the longitudinal direction (direction of the rotation axis of the recovery roller 12) is set to 220 mm so as to cover the entire width of the A4 size recording material S.

[0049] In this embodiment, the recovery roller 12 rotates in the direction of arrow K2 in the figure at a peripheral speed of 144 mm / sec, which is the same peripheral speed (surface movement speed) as the brush roller 11. However, in this embodiment, the recovery roller 12 rotates such that the brush roller 11 and the recovery roller 12 move in opposite directions at the point where they face each other. The surface layer 12a of the recovery roller 12 rubs against the paper dust P on the brush bristles 11p of the brush roller 11 at the second transfer section (second transfer nip section) R2, which is the contact point between the brush roller 11 and the recovery roller 12. As a result, the paper dust P on the brush bristles 11p of the brush roller 11 is transferred (recovered) to the surface layer 12a of the recovery roller 12 by electrostatic adhesion.

[0050] Here, we will explain the mechanism by which paper dust P is transferred to the brush roller 11 and the recovery roller 12, and the selection of materials. When two materials with different positions in the triboelectric series are rubbed together, they exchange electric charges, with one becoming positively charged and the other negatively charged. The triboelectric series is a permutation of these positive and negative charges, and generally, materials that are farther apart in the triboelectric series tend to become more strongly charged.

[0051] The material used for the brush bristles 11p of the brush roller 11 is one whose position in the triboelectric series is on the negative side of the triboelectric series relative to the collected material and on the positive side of the material of the surface layer 12a of the recovery roller 12. In particular, in this embodiment, it is preferable to select a material for the brush bristles 11p whose position in the triboelectric series is on the negative side of the triboelectric series relative to the pulp fibers and filler, as far away as possible, and on the positive side relative to the material of the surface layer 12a of the recovery roller 12 (fluororesin).

[0052] Therefore, in this embodiment, the brush bristles 11p of the brush roller 11 are made of PET resin. When the brush bristles 11p of the brush roller 11 and the paper dust P rub against each other in the first transfer section R1, the brush bristles 11p become negatively charged and the paper dust P becomes positively charged. As a result, the brush bristles 11p of the brush roller 11 can electrostatically attract and collect the paper dust P. The higher the volume resistivity of the material of the brush bristles 11p of the brush roller 11, the more advantageous it is for attracting and collecting the paper dust P. Therefore, in this embodiment, the material of the brush bristles 11p of the brush roller 11 has a volume resistivity of 10 １３ An insulator with a resistance of (Ω・m) or higher is used.

[0053] The material used for the surface layer 12a of the recovery roller 12 is one whose position in the triboelectric series is on the negative side of the triboelectric series, and also on the negative side of the material of the napped surface 11a of the brush roller 11. In particular, in this embodiment, it is preferable to select a material for the surface layer 12a whose position in the triboelectric series is further away from the pulp fibers and filler on the negative side, with the material of the brush bristles 11p of the brush roller 11 (PET in this embodiment) in between. For this reason, in this embodiment, the surface layer 12a of the recovery roller 12 is formed of fluororesin (PFA in this embodiment). In the second transfer section R2, the amount of charge per unit area of ​​the surface layer 12a of the recovery roller 12 becomes greater than that of the brush bristles 11p. As a result, the paper dust P is transferred to the recovery roller 12. In other words, the surface layer 12a of the recovery roller 12, which is charged with a potential greater in absolute value than the brush bristles 11p of the brush roller 11 and on the same polarity side (negative side) as the paper dust P, can electrostatically attract and recover the positively charged paper dust P. The higher the volume resistivity of the material of the surface layer 12a of the recovery roller 12, the more advantageous it is for attracting and recovering the paper dust P. Therefore, in this embodiment, the material of the surface layer 12a of the recovery roller 12 has a volume resistivity of 10 １３ An insulator with a resistance of (Ω・m) or higher is used.

[0054] Note that an insulator has a resistance value of 10 ８ (Ω·m) or more, preferably 10 １０ This refers to materials with a resistivity of (Ω·m) or greater. However, typically, insulators have a resistivity of 10 １６ It is less than or equal to (Ω·m). Also, a conductor is defined as having a resistivity of 10 −６ (Ω·m) or less, typically 10 −８ This refers to a substance with a mass of approximately (Ω·m).

[0055] The cleaning blade 13 is made of a rubber material (for example, polyurethane (urethane rubber)) as an elastic body (elastic material) having appropriate elasticity and hardness. The cleaning blade 13 is a plate-shaped member that is approximately rectangular in plan view and has a predetermined length in the longitudinal direction, which is arranged along the rotation axis direction of the recovery roller 12 (approximately parallel in this embodiment), and in the short direction, which intersects this longitudinal direction (approximately perpendicular in this embodiment), and has a predetermined thickness. The length of the cleaning blade 13 in the longitudinal direction is equivalent to the length of the recovery roller 12 in the longitudinal direction.

[0056] The cleaning blade 13 is positioned such that one end in the shorter direction, the free end (tip), is located upstream of the other end, the fixed end (base), in the direction of movement of the surface of the recovery roller 12, and the free end is in contact with the surface of the recovery roller 12. In other words, the cleaning blade 13 is in contact with the surface of the recovery roller 12 in a counter-direction to the rotation direction of the recovery roller 12. The cleaning blade 13 can be fixed to the housing (not shown) of the electrostatic collection device 10 via a cleaning blade support made of, for example, plated steel sheet. The cleaning blade 13 scrapes off paper dust P that has adhered to the surface layer 12a of the recovery roller 12 and moved downstream of the second transfer section R2 in the rotation direction of the recovery roller 12, as the recovery roller 12 rotates. Note that the removal member is not limited to a blade-shaped member, but may be, for example, a pad-shaped member, a sheet-shaped member, a brush-shaped member, etc.

[0057] Furthermore, the storage section 14 is provided to contain the paper dust P scraped off the surface of the rotating recovery roller 12 by the cleaning blade 13.

[0058] The configuration and operation of the friction mechanism 1 provided in the electrostatic collection device 10 of this embodiment will be described in detail below. (3) Configuration of the friction mechanism

[0059] Next, the sliding mechanism 1 in this embodiment will be described. Figure 4 is a schematic cross-sectional view of the vicinity of the sliding mechanism 1 (showing a cross-section approximately perpendicular to the rotation axis direction of the brush roller 11).

[0060] The sliding mechanism 1 comprises a sliding member (sliding plate) 1a made of a flexible plate-shaped member that slides against the brush bristles 11p as the brush roller 11 rotates, and a fixing member 1b for fixing (supporting) the sliding member 1a.

[0061] In this embodiment, the abrasive member 1a is made of aluminum (aluminum or aluminum alloy), which is a metallic material that acts as a conductor (conductive material). In this embodiment, the abrasive member 1a is connected to ground potential (GND) (electrically grounded). The abrasive member 1a is a plate-shaped member that is approximately rectangular in plan view, having a predetermined length in the longitudinal direction (approximately parallel in this embodiment) along the rotation axis direction (first direction) of the brush roller 11, and a predetermined thickness in the short direction (second direction) that intersects (approximately perpendicular in this embodiment) with this longitudinal direction. The length of the abrasive member 1a in the longitudinal direction is equivalent to the length of the area where the brush bristles 11p are provided in the rotation axis direction of the brush roller 11. The abrasive member 1a is inclined such that one end in the short direction, the free end (tip) 1a1, is located downstream in the direction of movement of the brush portion 11a of the brush roller 11, compared to the other end, the fixed end (base) 1a2. Furthermore, at least a portion of the sliding member 1a, from the tip end 1a1 to the base end 1a2 in the short direction, is in contact with the brush bristles 11p of the brush roller 11.

[0062] The fixing member 1b is a rod-shaped member with a substantially rectangular cross-section that is substantially perpendicular to the longitudinal direction (the direction of the rotation axis of the brush roller 11), and is fixed to the housing (not shown) of the electrostatic collection device 10. The sliding member 1a is fixed to the fixing member 1b at least a portion of the area from the base end 1a2 side to the tip end 1a1 side in the short direction. In this embodiment, the sliding member 1a is fixed to the fixing member 1b by adhesive bonding. Note that the fixing means for fixing the sliding member 1a to the fixing member 1b is not limited to adhesive bonding, and other fixing means such as fixing with double-sided tape, welding, or fastening may be used. The fixing member 1b may be made of, for example, a metal material or a resin material.

[0063] The friction member 1a is positioned in a friction portion (friction nip portion) Nc located downstream of the first transfer portion R1 and upstream of the second transfer portion R2 in the rotational direction of the brush roller 11, so as to contact the brush bristles 11p of the brush roller 11. Furthermore, the friction member 1a is inclined so that its tip portion 1a1 is located downstream of its base portion 1a2 in the rotational direction of the brush roller 11. The friction member 1a is in contact with the brush portion 11a of the brush roller 11 such that at least a portion of the area from the tip portion 1a1 side to the base portion 1a2 side penetrates the brush portion 11a of the brush roller 11. As a result, the friction member 1a frictions against the brush bristles 11p of the brush roller 11 as the brush roller 11 rotates.

[0064] In this embodiment, the abrasive member 1a is made of an aluminum plate (a plate-shaped member made of aluminum material) with a thickness t of 100 μm. The length of the portion of the abrasive member 1a that is freed from being fixed by the fixing member 1b and can be freely deformed is defined as the free length F of the abrasive member 1a. The free length F of the abrasive member 1a can also be defined as the length of the portion of the abrasive member 1a that protrudes from the fixing member 1b in the short direction of the abrasive member 1a. In this embodiment, the free length F of the abrasive member 1a is 10 mm. The region of the abrasive member 1a other than the region of the free length F is fixed to the fixing member 1b with an adhesive or the like. The tip portion 1a1 of the abrasive member 1a penetrates the brush portion 11a of the brush roller 11, which rotates in the direction of arrow K1 in the figure, so as to tilt the brush bristles 11p.

[0065] The brush bristles 11p of the brush roller 11 are bent by the friction member 1a as the brush roller 11 rotates, and then quickly return to their original shape (elastically deformed and returned to their original shape) as they pass through the friction member 1a. At that time, the paper dust P attached to the brush bristles 11p of the brush roller 11 is flown in the direction of arrow J in the figure (outward in the direction of the rotational radius of the brush roller 11 and downstream in the direction of the rotation of the brush roller 11) and adheres to the surface of the recovery roller 12. In this embodiment, the rotational direction K1 of the brush roller 11 and the rotational direction K2 of the recovery roller 12 are set so that the brush roller 11 and the recovery roller 12 move in opposite directions (counter direction) in the second transfer section R2. Therefore, the paper dust P that has flown from the brush bristles 11p of the brush roller 11 to the surface of the recovery roller 12 is suppressed from reattaching to the brush bristles 11p in the second transfer section R2.

[0066] Furthermore, it is preferable that the friction member 1a is positioned so as to contact the brush roller 11 at a position within 90° upstream of the brush roller 11 in the rotational direction, and more preferably within 45°, with respect to the straight line passing through the rotational center of the brush roller 11 and the rotational center of the recovery roller 12, when viewed along the rotational axis direction of the brush roller 11. This makes it easier for the paper dust P ejected from the brush bristles 11p to adhere to the recovery roller 12.

[0067] In this way, the friction member 1a causes the paper dust P to fly away from the brush bristles 11p of the brush roller 11 in the direction of arrow J in the figure, and the paper dust P adheres to the surface of the recovery roller 12. Also, in the second transfer section R2, the paper dust P is electrostatically transferred from the brush bristles 11p of the brush roller 11 to the surface of the recovery roller 12, and the paper dust P adheres to the surface of the recovery roller 12. In this embodiment, the paper dust P is attached from the brush bristles 11p of the brush roller 11 to the surface of the recovery roller 12 by both of these methods. In the second transfer section R2, of the paper dust P attached to the brush bristles 11p of the brush roller 11, only the paper dust P that substantially comes into contact with the surface layer 12a of the recovery roller 12 is transferred to the surface of the recovery roller 12. In contrast, by causing the paper dust P attached to the brush bristles 11p of the brush roller 11 to fly away with the friction member 1a, the paper dust P can be moved from the brush roller 11 to the recovery roller 12 in addition to the transfer of paper dust P in the second transfer section R2. This improves the recovery rate of paper dust P from the brush roller 11 to the recovery roller 12. (4) Configuration of the friction member

[0068] Next, the structure of the sliding member 1a will be further explained. Figure 5 is a schematic enlarged cross-sectional view of the vicinity of the tip portion 1a1 of the sliding member 1a.

[0069] The tip 1a1 of the abrasive member 1a penetrates the brush portion 11a of the brush roller 11 to a depth D, so as to bend the brush bristles 11p, which have a free length L and move in the direction of arrow K1 in the figure. Here, the depth D is the distance from the trimmed peak of the brush bristles 11p, which are cut pile yarns, in the radial direction of rotation of the brush roller 11, to the edge of the surface of the abrasive member 1a on the brush roller 11 side (lower side in the figure) (the edge of the tip 1a1). The depth D corresponds to the amount of penetration of the abrasive member 1a into the brush portion 11a of the brush roller 11 (hereinafter also referred to as "the amount of penetration of the abrasive member 1a" or simply "the amount of penetration"). Furthermore, the penetration rate is defined as the ratio of the amount of penetration D of the abrasive member 1a to the free length L of the brush bristles 11p, expressed by the following formula: D / L × 100 (%).

[0070] It is desirable that the brush bristles 11p, after being bent by the friction member 1a, rapidly recover when passing through the friction member 1a. Microscopic observation of the behavior of the brush bristles 11p during recovery revealed the following: For the brush bristles 11p to recover rapidly and sufficiently dislodge the paper dust P electrostatically attached to them, a penetration rate of 20% or more is preferable. If the penetration rate is less than 20%, it is difficult to obtain sufficient acceleration when the brush bristles 11p recover. Conversely, if the penetration rate exceeds 50%, the brush bristles 11p undergo plastic deformation, delaying the recovery time and making it difficult to sufficiently dislodge the paper dust P electrostatically attached to them. Therefore, a penetration rate of 50% or less is preferable. Based on the above results, a penetration rate of 20% or more and 50% or less is preferable, and 30% or more and 40% or less is more preferable. In this embodiment, the target value (target value) for the penetration rate was set to 35%, which is the midpoint between the minimum value of 20% and the maximum value of 50%. The penetration rate can be represented by the average value of a sufficient number of measurements (e.g., 3 to 10 points) taken during one rotation of the brush roller 11. Note that "~" in relation to the numerical range means that the values ​​before and after that value are included.

[0071] The penetration rate of the brush bristles 11p into the surface of the cleaning target (recording material S) or the recovery roller 12 can be appropriately set within a range of, for example, 20 to 80%. For example, it can be set to 50%. In this case, the amount of penetration corresponds to the value obtained by subtracting the distance between the cleaning target (recording material S) or the recovery roller 12 at the position closest to the base (base fabric 11k) of the free length L of the brush bristles 11p and the base (the closest contact distance between the base and the cleaning target or recovery roller 12). The penetration rate can then be defined as the ratio of this amount of penetration to the free length of the brush bristles 11p.

[0072] Here, for example, in order to efficiently clean fine particles such as paper dust that are to be collected and adhere to a cleaning target (surface to be cleaned) having an uneven surface such as the surface of paper, it is preferable to rub the cleaning target with a brush roller 11 whose brush bristles 11p are relatively thin and short. However, when the material to be collected adheres to relatively short brush bristles 11p, such as those with a free length L of 4 mm or less, as mentioned above, if there is a difference in height (unevenness) at the base of the brush bristles 11p, it may become difficult to obtain a stable flight rate for the material to be collected.

[0073] Figure 6 is a schematic cross-sectional view of the vicinity of the tip portion 1a1 of the abrasive member 1a to illustrate the height difference (unevenness) at the base portion of the brush bristles 11p. As shown in Figure 6, height differences (unevenness) at the base portion of the brush bristles 11p can occur due to eccentricity of the core portion 11b of the brush roller 11, mechanical precision of the parts, and variations in the thickness of the base fabric 11k and adhesive of the brush portion 11a. Furthermore, when the free length L of the brush bristles 11p is relatively short (for example, 4 mm or less), this height difference (unevenness) cannot be ignored, and the amount of penetration (penetration rate) may change during the rotation of the brush roller 11. For example, when the particle size of the fine particles to be collected becomes smaller, and the non-electrostatic adhesion force of the collected particles to the brush bristles 11p becomes relatively larger, it is important to ensure that the amount of penetration (penetration rate) is appropriate for the length of the brush bristles 11p. When the amount of intrusion (intrusion rate) changes, it can become difficult to stably disperse the paper dust P that has electrostatically adhered to the brush bristles 11p.

[0074] For example, the height of the outer surface of the core portion 11b of the brush roller 11 has slight undulations due to the eccentricity of the rotating shaft portion of the brush roller 11 and other component precision issues. Furthermore, there is a difference in height u (mm) between the highest point (the outermost position in the radial direction of rotation of the brush roller 11) and the lowest point (the innermost position in the radial direction of rotation of the brush roller 11) of the outer surface of the core portion 11b. When the tolerances of the parts are added up, the value of height u can be about 1 mm. In such cases, when the free length L of the brush bristles 11p is short (for example, 4 mm or less), this difference in height (undulation) becomes significant and cannot be ignored.

[0075] In this case, if the sliding member 1a is made of a fixed rigid body, it is difficult to maintain a nearly constant penetration amount (penetration rate). In contrast, as in this embodiment, if the sliding member 1a is made of a flexible plate-shaped member, the sliding member 1a can bend appropriately to follow the above-mentioned height difference (unevenness), thereby maintaining an appropriate penetration amount (penetration rate).

[0076] Figure 6(a) shows the state in which the abrasive member 1a is in contact with the brush bristles 11p at a position corresponding to the lowest position of the core portion 11b of the brush roller 11. At this time, the amount of deflection σ of the abrasive member 1a is σ1. Here, the amount of deflection σ of the abrasive member 1a is expressed as the distance traveled by the tip on the tip portion 1a1 side due to the deflection of the abrasive member 1a when viewed along the longitudinal direction of the abrasive member 1a (the distance between the positions of the tip on the tip portion 1a1 side before and after the deflection). As the brush roller 11 rotates in the direction of arrow K1 in the figure, the contact position of the brush roller 11 with the abrasive member 1a changes. Figure 6(b) shows the state in which the abrasive member 1a is in contact with the brush bristles 11p at a position corresponding to the highest position of the core portion 11b of the brush roller 11. At this time, the amount of deflection σ of the abrasive member 1a is σ2. In other words, the amount of deflection σ2 of the abrasive member 1a is different in magnitude from σ1.

[0077] In this embodiment, the electrostatic collection device 10 is configured such that the rate of change (%) of the contact pressure of the sliding member 1a against the brush roller 11 (hereinafter also referred to as "contact pressure of the sliding member 1a" or simply "contact pressure") when the amount of deflection σ of the sliding member 1a changes by 1 mm is less than or equal to a predetermined value. Here, the rate of change of the contact pressure when the amount of deflection σ of the sliding member 1a changes by 1 mm is also simply referred to as the "rate of change of contact pressure". As a result, even if the amount of deflection σ of the sliding member 1a changes by 1 mm as the sliding member 1a deflects to follow the above height difference (unevenness), it is possible to keep the penetration amount (penetration rate) approximately constant. Based on the results of verification experiments described later, in this embodiment, the electrostatic collection device 10 is configured such that the rate of change of the contact pressure when the amount of deflection σ of the sliding member 1a changes by 1 mm is 20% or less. The percentage change in contact pressure can be expressed by the following formula, {(C2 - C1) / C1} × 100, where C1 is the contact pressure C before the change in deflection σ, and C2 is the contact pressure C after the change in deflection σ.

[0078] Figure 7 is a schematic diagram illustrating the method (measuring device) for measuring contact pressure. First, the sliding mechanism 1 (sliding member 1a and fixing member 1b), which has been cut so that the width in the direction corresponding to the longitudinal direction of the sliding member 1a in the electrostatic collection device 10 is 1 cm, is set on a stand 17 whose height can be adjusted in the direction of the arrow in the figure (up and down direction in the figure). Then, the sliding member 1a is brought into contact with the load sensor 18 when the amount of deflection σ is zero. Next, the fixing member 1b is moved by the stand 17 in the direction in which the sliding member 1a is deflected and the sliding member 1a pushes the load sensor 18 (up in the figure), and the output value (N) of the load sensor 18 is read. Then, the load (N) obtained from the load sensor 18 is replaced with the linear pressure per unit length (1 cm). The value of the linear pressure obtained in this way is taken as the contact pressure (N / cm).

[0079] Figure 8 is a graph showing the relationship between the travel distance of the base 17 and the contact pressure obtained by the measurement method described above in this embodiment (Embodiment 1-1). In this embodiment (Embodiment 1-1), a sliding member 1a made of aluminum with a thickness of 100 μm is brought into contact with the brush roller 11 at a contact pressure (1.0 N / cm) under the conditions of a free length of 10 mm, a contact angle of 45°, and a travel distance of 6 mm for the base 17. The contact angle is represented by the angle between the straight line extending the surface of the sliding member 1a in the portion fixed to the fixing member 1b (the surface of the sliding member 1a when it is not deformed by the brush roller 11) when viewed along the longitudinal direction of the sliding member 1a, and the tangent to the core portion 11b of the brush roller 11 at the position where this line intersects. Under the conditions of this embodiment (Embodiment 1-1), the rate of change in the contact pressure, which can be determined from the slope of the straight line showing the relationship between the travel distance of the base 17 and the contact pressure as shown in Figure 8, was 18%. The results of the verification experiment will be described later, but it is preferable that the rate of change in the contact pressure of the tip portion 1a1 of the sliding member 1a against the brush roller 11, which is necessary to change the amount of deflection σ of the sliding member 1a by 1 mm, is 20% or less. However, the rate of change in contact pressure may be 0%.

[0080] Figure 9 is a schematic diagram illustrating a method (measuring device) for measuring the rate of change in penetration amount. In the contact pressure measuring device shown in Figure 7, the load sensor 18 is replaced with the brush portion 11a (base fabric 11k and brush bristles 11p) of the brush roller 11. The brush portion 11a can be the one before it is attached to the core portion 11b, or the one that has been removed from the core portion 11b. First, the amount of deflection σ of the sliding member 1a is set to the desired amount of deflection σ, and the sliding mechanism 1 (sliding member 1a and fixing member 1b) is set on the base 17. Next, the sliding member 1a is further deflected, and the fixing member 1b is moved 1 mm by the base 17 in the direction that pushes the brush portion 11a with the sliding member 1a (upwards in the figure), and the height of the brush bristles 11p in the portion pushed by the sliding member 1a before and after the movement is measured with a height gauge. This measures the change in penetration amount (distance, depth) D. Then, the percentage change in the penetration rate (= D / L × 100) before and after the above movement is calculated. Here, the percentage change in the penetration rate when the deflection amount σ of the sliding member 1a changes by 1 mm is also simply called the "percentage change in penetration rate" or the "percentage change in penetration amount". The percentage change in penetration amount can be expressed by the following formula, {(X2 - X1) / X1} × 100, where X1 is the penetration rate X before the movement of the base 17 and X2 is the penetration rate X after the movement of the base 17.

[0081] Under the conditions of this embodiment (Embodiment 1-1), the rate of change in the penetration amount according to the measurement method described above was 20%. The results of the verification experiment will be described later, but it is preferable that the rate of change in the penetration amount of the tip portion 1a1 of the sliding member 1a into the brush roller 11, which is necessary to change the deflection amount σ of the sliding member 1a by 1 mm, is 20% or less. Note that the rate of change in the penetration amount may be 0%.

[0082] The function of the abrasive member 1a described above can be summarized. For example, the tip 1a1 of the abrasive member 1a, which is made of a flexible plate-shaped member, is inserted into a brush roller 11 having relatively thin and short brush bristles 11p, and brought into contact with it in a state where it is bent by a desired amount of deflection (i.e., a desired contact pressure). The deflection of this abrasive member 1a follows the height difference (unevenness) of the base portion of the brush bristles 11p, and an appropriate contact pressure can be continuously applied without causing plastic deformation of the brush bristles 11p, while obtaining a sufficient effect of flicking off the collected material from the brush bristles 11p. As a result, the collected material attached to the brush bristles 11p can be stably ejected.

[0083] Furthermore, the diameter, free length, pile density, and Young's modulus of the brush bristles 11p, the outer diameter of the brush roller 11 and the recovery roller 12, the thickness, free length, Young's modulus, contact pressure, and penetration amount (penetration rate) of the abrasive member 1 can each be represented by the average value of a sufficient number of measured values. In addition, the Young's modulus can be measured using a commercially available measuring device (tensile testing machine) (for example, a Shimadzu Corporation AGX tensile testing machine), or a nominal value for the material may be used. (5) Verification of the effect <Verification experiment>

[0084] Verification experiments were conducted to verify the effects of this embodiment (Embodiment 1-1), as well as embodiments and comparative examples in which the configuration of the sliding member 1a differs from that of this embodiment (Embodiment 1-1). Specifically, sliding members 1a were formed using aluminum and SUS (stainless steel), varying their thickness and free length, and verification experiments were conducted under a total of eight conditions: Embodiments 1-1, 1-2, 1-3, 1-4 and Comparative Examples 1-1, 1-2, 1-3, 1-4. The configuration, measurement results, and evaluation results for each example are shown in Table 1.

[0085] Table 1 shows the material, thickness, and design length of the abrasive member 1a for each example. Table 1 also shows the rate of change of contact pressure measured by the method shown in Figure 7.

[0086] Figures 10(a) and 10(b) are graphs showing the relationship between the travel distance of the platform 17 and the contact pressure, measured by the method shown in Figure 7 to determine the rate of change of this contact ratio. Figure 10(a) shows the relationship for Examples 1-1, 1-2, 1-3, and 1-4, and Figure 10(b) shows the relationship for Comparative Examples 1-1, 1-2, 1-3, and 1-4. The travel distance values ​​of the platform 17 for each example shown in Table 1 are the travel distances of the platform 17 determined to aim for the same contact pressure of 1.0 N / cm as in this example (Example 1-1). This allows the average value (central value) of the penetration rate for each example to be unified to 35%. Table 1 also shows the rate of change of the penetration amount measured by the method shown in Figure 9. The percentage change in the amount of penetration for each example shown in Table 1 represents the percentage change in the amount of penetration when the amount of deflection σ of the sliding member 1a is further deflected by 1 mm (the base 17 is moved by 1 mm) from the amount of deflection σ of the sliding member 1a when the sliding member 1a is in contact with the brush roller 11 at the movement distance of the base 17 determined as described above.

[0087] For example, if the eccentricity of the core portion 11b of the brush roller 11 is large, in a configuration with a large rate of change in contact pressure, the recovery rate of paper dust P from the brush roller 11 to the recovery roller 12 may decrease at either the upper or lower limit of the contact pressure. When the recovery rate of paper dust P from the brush roller 11 to the recovery roller 12 decreases, it may become difficult for the electrostatic collection device 10 to sufficiently recover the paper dust P from the recording material S. As a result, as the amount of paper dust P present on the photosensitive drum 101 increases, the paper dust P is recovered by the developer 104 along with the toner, and the charge level of the toner in the developer 104 may decrease. As a result, fogging, where a thin layer of toner adheres to areas that do not normally form an image (non-image areas), may occur beyond the acceptable range. In the verification experiment, configurations with different rates of change in contact pressure and intrusion amount were evaluated after durability tests to see whether the occurrence of fogging could be sufficiently suppressed. <Evaluation Method>

[0088] Durability tests were conducted using an image forming apparatus 100 in which the eccentricity of the core metal 11b of the brush roller 11 in the electrostatic collection device 10 was set to 1.0 mm (approximately the upper limit of normal manufacturing tolerances).

[0089] Then, after the durability test, it was evaluated whether or not image defects caused by paper dust P occurred. The durability test was conducted as follows: The amount of toner in the developing unit 104 was reduced to half of its full capacity, and an accelerated test was performed in a high temperature and high humidity environment (32.5°C / 80%RH) in which 10,000 horizontal lines (lines along the width direction of the recording material S) with a print density of 1% were printed in single-sheet intermittent mode. Single-sheet intermittent mode means that a job to print one sheet at a time is executed intermittently. Then, a solid white image was printed on the next sheet of recording material S after the completion of the accelerated test and used for evaluating fogging. For measuring fogging, a reflectance densitometer, REFLECMETER MODEL TC-6DS manufactured by Tokyo Denshoku Co., Ltd., was used. The reflectance of standard paper and paper with a solid white image printed on it (sample) was measured at five locations in the width direction of the recording material S, and the maximum value among the five locations was adopted to calculate the fogging using the following formula. A green filter was used as the filter for measuring the reflectance.

[0090] Haze (reflectance: %) = reflectance on standard paper (%) - reflectance of non-image area of ​​sample (%)

[0091] Furthermore, the amount of fouling was evaluated according to the following criteria: ○ (Good): Fouling less than 1.0% △ (Slightly Poor): Fouling 1.0% or more, less than 3.0% × (Poor): Fouling 3.0% or more <Evaluation Results>

[0092] In Examples 1-1, 1-2, 1-3, and 1-4, the evaluation result for fouling was ○ (good). In all of these examples, the rate of change of contact pressure was 20% or less, and the rate of change of penetration amount was 20% or less. Although not shown in Table 1, the evaluation result for fouling was also ○ (good) when the rate of change of contact pressure was 20%. It is thought that these results were obtained for the following reasons. In other words, in these examples, the abrasive member 1a can follow the height difference (unevenness) of the core portion 11b by appropriately flexing in both the state shown in Figure 6(a) and the state shown in Figure 6(b), and maintain an appropriate amount of penetration. As a result, in these examples, the abrasive member 1a can maintain an appropriate contact pressure that does not cause plastic deformation of the brush bristles 11p while obtaining a sufficient effect of flicking away the paper dust P from the brush bristles 11p. As a result, in these examples, the friction member 1a can stably disperse the paper dust P attached to the brush bristles 11p, and consequently, the electrostatic collection device 10 can effectively recover the paper dust P from the recording material S.

[0093] On the other hand, in Comparative Example 1-1, the evaluation result for fouling was △ (slightly poor), and in Comparative Examples 1-2, 1-3, and 1-4, the evaluation result for fouling was × (poor). In all of these examples, the rate of change of contact pressure exceeded 20%, and the rate of change of penetration amount also exceeded 20%. Although not shown in Table 1, when the rate of change of contact pressure exceeded 20%, there was a tendency for the evaluation result for fouling to be △ (slightly poor) or × (poor). Also, although not shown in Table 1, when the rate of change of penetration amount exceeded 20%, there was a tendency for the evaluation result for fouling to be △ (slightly poor) or × (poor). It is thought that these results were obtained for the following reasons. In other words, in these examples, the appropriate flexibility of the sliding member 1a obtained in Examples 1-1, 1-2, 1-3, and 1-4 could not be obtained, and the appropriate penetration amount could not be maintained. Therefore, in these examples, the friction member 1a has difficulty stably dispersing the paper dust P attached to the brush bristles 11p, and as a result, it becomes difficult to adequately recover the paper dust P from the recording material S with the electrostatic collection device 10.

[0094] Based on the results of the verification experiments described above, it was found that in order to effectively recover paper dust P from the recording material S using the electrostatic collection device 10, the following is important. Specifically, it is important to appropriately set the thickness and free length of the abrasive member 1a so that the rate of change of contact pressure when the deflection amount σ of the abrasive member 1a changes by 1 mm is 20% or less, or the rate of change of penetration amount is 20% or less. Since contact pressure and penetration amount are correlated, the configuration of the abrasive member 1a can be set from the viewpoint of contact pressure or from the viewpoint of penetration amount (it may also be set from the viewpoint of both). In other words, by appropriately setting the thickness and free length of the abrasive member 1a and setting the rate of change of contact pressure when the deflection amount σ of the abrasive member 1a changes by 1 mm to 20% or less, the above effect can be obtained. Here, based on the results of the verification experiments described above, it can be said that the rate of change of contact pressure is more preferably 15% or less, and even more preferably 10% or less. Furthermore, by appropriately setting the thickness and free length of the abrasive member 1a, and setting the rate of change in the amount of penetration when the deflection amount σ of the abrasive member 1a changes by 1 mm to 20% or less, the above effects can be obtained. Also, based on the results of the verification experiments described above, it can be said that the rate of change in the amount of penetration is more preferably 15% or less, and even more preferably 10% or less. In any case, as mentioned above, the average value of the penetration rate during one rotation of the brush roller 11 is preferably 20% or more and 50% or less, and more preferably 30% or more and 40% or less. In other words, the above effects can be obtained by configuring the system so that the average value of the penetration rate during one rotation of the brush collection rotating body is 20% or more and 50% or less, and the rate of change in the penetration rate during one rotation of the brush roller 11 is 20% or less.

[0095] The preferred range for the thickness and free length of the sliding member 1a may vary depending on the material of the sliding member 1a. The thickness and free length of the sliding member 1a can be set appropriately as long as the preferred settings in terms of contact pressure and penetration amount as described above can be achieved.

[0096] For example, based on the results of the verification experiments described above, if the material of the abrasive member 1a is aluminum, the thickness of the abrasive member 1a is preferably 100 μm or less. Furthermore, based on the results of the verification experiments described above, it can be said that in this case the thickness of the abrasive member 1a is more preferably 80 μm or less. The lower limit of the thickness of the abrasive member 1a is determined from the viewpoint of obtaining an appropriate penetration rate, but if the material of the abrasive member 1a is aluminum, the thickness of the abrasive member 1a is preferably, for example, 20 μm or more. Furthermore, based on the results of the verification experiments described above, if the material of the abrasive member 1a is aluminum, the free length of the abrasive member 1a is preferably 10 mm or more. Furthermore, based on the results of the verification experiments described above, it can be said that in this case the free length of the abrasive member 1a is more preferably 12 mm or more. Furthermore, the upper limit of the free length of the abrasive member 1a is determined from the viewpoint of obtaining an appropriate penetration rate, but if the material of the abrasive member 1a is aluminum, the free length of the abrasive member 1a is preferably, for example 50 mm or less.

[0097] Furthermore, in the verification experiment described above, for example, when the material of the abrasive member 1a is SUS, the thickness of the abrasive member 1a is preferably 50 μm or less. Furthermore, based on the results of the verification experiment described above, it can be said that in this case the thickness of the abrasive member 1a is more preferably 30 μm or less. The lower limit of the thickness of the abrasive member 1a is determined from the viewpoint of obtaining an appropriate penetration rate, but when the material of the abrasive member 1a is SUS, the thickness of the abrasive member 1a is preferably, for example, 10 μm or more. Furthermore, based on the results of the verification experiment described above, when the material of the abrasive member 1a is SUS, the free length of the abrasive member 1a is preferably 15 mm or more. Furthermore, based on the results of the verification experiment described above, it can be said that in this case the free length of the abrasive member 1a is more preferably 17 mm or more. Furthermore, the upper limit of the free length of the abrasive member 1a is determined from the viewpoint of obtaining an appropriate penetration rate, but when the material of the abrasive member 1a is SUS, the free length of the abrasive member 1a is preferably, for example 75 mm or less. <Consideration using a cantilever beam model>

[0098] Next, we will consider more detailed conditions for realizing a configuration in which the change rate of the contact pressure is 20% or less. Here, we will consider the deflection and contact pressure of the friction member 1a using a cantilever beam model.

[0099] Using the schematic diagram of FIG. 11, the formula of the cantilever beam model will be explained. Assume that a beam with a length (free length) F (mm) indicated by a dotted line (corresponding to the free length F portion of the friction member 1a) is provided with the upper side fixed in the figure. Then, as a result of applying a load Q to the tip of the beam in the direction of the arrow in the figure (corresponding to the deflection direction of the friction member 1a), it is deflected by the amount of deflection σ (mm) from its original shape and becomes the shape indicated by the solid line. When the Young's modulus of the friction member 1a is E (MPa) and the second moment of area is I (mm ４ ), the amount of deflection σ (mm) is expressed by the following formula 1. σ = (Q × F ３ ) / (3 × E × I) ··· (Formula 1)

[0100] The second moment of area I (mm ４ ) is determined by the cross-sectional shape. When the width (length in the longitudinal direction) of the friction member 1a is h (mm) and the thickness is t (mm), it is expressed by the following formula 2. I = (h × t ３ ) / 12 ··· (Formula 2)

[0101] From Formula 1 and Formula 2, the load Q is expressed by the following formula 3 using the amount of deflection σ. Q = (E × h × σ × t ３ ) / (4 × F ３ ) ··· (Formula 3)

[0102] In this model, since the amount of deflection σ = intrusion amount and the load Q = contact pressure, the slope of the straight line showing the relationship between the moving distance of the table 17 and the contact pressure shown in FIG. 8 is the change amount of the load Q when the amount of deflection σ changes by 1 mm. The condition for this slope to be 0.2 (MPa) or less (corresponding to a contact pressure change rate of 20% or less) is expressed by the following formula 4. (E × h × t ３ ) / (4 × F ３ ) ≤ 0.2 (MPa) ··· (Formula 4)

[0103] When the load Q is the pressure per centimeter width (linear pressure) N / cm, the condition excluding the width h from Formula 4 is expressed by the following formula 5. (E × t ３ ) / (4 × F３ )≦0.02 (MPa) (Formula 5)

[0104] Table 2 shows typical conditions under which the above slope becomes 0.02 (MPa). Here, examples are shown for aluminum, which has a relatively low Young's modulus among metals, SUS, which has a relatively high Young's modulus, and PET as the resin material. The conditions of Equation 5 can be satisfied if at least one of the following conditions is met: the thickness t of the sliding member 1a is thinner than the value shown in Table 2, or the required free length F is greater than the value shown in Table 2.

[0105] In this embodiment, a metal material was used for the friction member 1a, but it is also possible to make the paper dust P fly from the brush bristles 11p if a resin material is used. However, when a resin material is used, the surface of the friction member 1a is more likely to become charged and cause unwanted discharges than when a metal material is used. Therefore, it is preferable to use a resin with sufficiently low electrical resistance (such as a conductive resin) as the resin material. It is even more preferable to use a metal material, and it is even more preferable to connect it to another metal part or to electrically ground it in order to dissipate the charge.

[0106] Thus, in this embodiment, the electrostatic collection device 10 includes a rotatable brush-shaped collection rotating body, equipped with brush bristles 11p that contact the object to be cleaned to form a collection section R1, and a collection rotating body (brush roller) 11 that electrostatically collects the object to be collected from the object to be cleaned onto the brush bristles 11p in the collection section R1 by rotating; a collection member (collection roller) 12 that contacts the brush bristles 11p to form a collection section R2, and electrostatically collects the object to be collected from the brush bristles 11p in the collection section R2; a sliding member 1a made of a flexible plate-shaped member that contacts the brush bristles 11p downstream of the collection section R1 and upstream of the collection section R2 in the rotation direction of the collection rotating body 11, and slides against the brush bristles 11p as the collection rotating body 11 rotates; and a fixing member 1b to which the sliding member 1a is fixed. Furthermore, in this embodiment, the friction member 1a contacts the brush bristles 11p at its tip portion 1a1, which is one end in a second direction intersecting the first direction, which is the rotation axis direction of the collection rotating body 11, and its base portion 1a2, which is the other end in the second direction, is fixed to the fixing member 1b. The tip portion 1a1 is positioned at an inclination such that it is located downstream of the base portion 1a2 in the rotation direction of the collection rotating body 11, and by allowing the brush bristles 11p to bend and then return to their original state as the collection rotating body 11 rotates, it is possible to propel the object to be collected from the brush bristles 11p toward the collection member 12. In this embodiment, the electrostatic collection device 10 is configured such that when the amount of bending of the friction member 1a causes the tip portion 1a1 to move, the amount of bending is defined as the amount of bending, and the load that the tip portion 1a1 receives from the brush bristles 11p is defined as the contact pressure, the rate of change of the contact pressure when the amount of bending changes by 1 mm is 20% or less. In this embodiment, the electrostatic collection device 10 is configured such that the average value of the penetration rate during one rotation of the collection rotating body 11 is 20% or more and 50% or less, where the penetration amount is defined as the distance from the top of the brush bristles 11p at the position where it contacts the friction member 1a, assuming that the brush bristles 11p are not bent by the friction member 1a, to the end of the side of the friction member 1a on the side of the collecting rotating body 11 in the second direction, and the penetration rate is defined as the ratio of the penetration amount to the free length of the brush bristles 11p.

[0107] In other words, in this embodiment, the electrostatic collection device 10 is configured such that the rate of change in the penetration rate when the amount of deflection changes by 1 mm is 20% or less. Also in this embodiment, the electrostatic collection device 10 is configured such that the average value of the penetration rate during one rotation of the collection rotating body 11 is 20% or more and 50% or less. Furthermore, in this embodiment, the electrostatic collection device 10 is configured such that the average value of the penetration rate during one rotation of the collection rotating body 11 is 20% or more and 50% or less, and the rate of change in the penetration rate during one rotation of the collection rotating body 11 is 20% or less. Also, when the Young's modulus of the sliding member 1a is E (MPa), the thickness of the sliding member 1a is t (mm), and the free length of the sliding member 1a is F (mm), the following equation, (E × t ３ ) / (4xF ３ The configuration can satisfy ) ≤ 0.02 (MPa). In this embodiment, the friction member 1a is made of a metal material. In this case, it is preferable that the friction member 1a is electrically connected to a component made of a metal material or electrically grounded. In this embodiment, the collection member 12 is rotatable and rotates in the collection section R2 such that the direction of movement of the brush bristles 11p and the surface of the collection member 12 move in opposite directions, thereby collecting the material to be collected from the collection rotating body 11. In this embodiment, the electrostatic collection device 10 collects the material to be collected, including paper dust, from the recording material S which is the object to be cleaned, in an image forming apparatus 100 that forms an image on the recording material S.

[0108] As described above, according to this embodiment, even if a change occurs in the distance between the base portion of the brush bristles 11p of the brush roller 11 and the friction member 1a, it is possible to stably disperse the paper dust P attached to the brush bristles.

[0109] Next, other embodiments of the present invention will be described. The basic configuration and operation of the image forming apparatus in this embodiment are the same as those of the image forming apparatus in Embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements that are the same as or corresponding to those in the image forming apparatus in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0110] In this embodiment, more detailed conditions for the preferred configuration of the brush roller 11 will be described. <Composition of brush bristles>

[0111] In order to achieve high transfer efficiency of paper dust P from the recording material S to the brush roller 11 in the first transfer section R1, and to achieve a high flight rate of paper dust P from the brush roller 11 to the recovery roller 12 when the brush bristles 11p pass through the friction section Nc, it is preferable to select brush bristles 11p with appropriate rigidity. If the rigidity of the brush bristles 11p is too low, it is difficult to obtain sufficient restoring force of the brush bristles 11p, and if the rigidity of the brush bristles 11p is too high, it is difficult to bend the brush bristles 11p significantly. For example, in order to increase the flight rate of paper dust P from the brush roller 11 to the recovery roller 12, it is preferable to set the rigidity of the brush bristles 11p appropriately. As will be described later, the same applies to increasing the transfer efficiency of paper dust P from the recording material S to the brush roller 11. In this embodiment, examples of the configuration of brush bristles 11p having an appropriate range of rigidity will be mainly described.

[0112] To improve the efficiency of transferring paper dust P from the recording material S to the brush roller 11 in the first transfer section R1, it is preferable to scrape off the paper dust P adhering to the fine irregularities of the paper fibers with the brush bristles 11p. Focusing on the movement of a single brush bristle 11p, first, when the brush bristle 11p comes into contact with the paper fibers due to the rotation of the brush roller 11, the tip of the brush bristle 11p is seemingly fixed to the paper fibers due to the frictional force between the brush bristle 11p and the paper fibers. As the brush roller 11 rotates further, since the tip of the brush bristle 11p is fixed to the paper fibers, the flexibility of the brush bristle 11p increases, and the reaction force that causes the brush bristle 11p to return to its original position increases. When the reaction force that causes the brush bristle 11p to return to its original position becomes greater than the frictional force acting between the paper fibers and the tip of the brush bristle 11p, the tip of the brush bristle 11p begins to move as if stroking the surface of the paper fibers. This force becomes the force that scrapes off the paper dust P.

[0113] Figure 12 is a schematic diagram illustrating the behavior of the brush bristles 11p using a cantilever beam model. When the brush bristles 11p before deformation (dotted line) are deformed to a deflection amount A (mm) (solid line), assuming the brush bristles 11p is a cylinder with diameter d (mm), the reaction force Z is expressed by the following equation 6. In equation 6, E is Young's modulus (MPa) and L is the length (free length) of the brush bristles 11p (mm). The deflection amount A is represented by the distance the tip of the brush bristles 11p moves due to the deflection (the distance between the positions of the tip before and after deflection). Z = A × E × d ４ / L ３ ...(Formula 6)

[0114] Young's modulus is the tensile modulus and is determined by the material. Although the amount of deflection A is indeterminate due to the frictional force between the paper fibers and the brush bristles 11p, and the binding of the brush bristles 11p to each other, it can be seen that the reaction force Z is correlated with Young's modulus E, the fourth power of the diameter of the brush bristles 11p, and the reciprocal of the cube of the length of the brush bristles 11p. The larger the diameter of the brush bristles 11p and the shorter the length of the brush bristles 11p, the higher the reaction force. Therefore, it is thought that the larger the diameter of the brush bristles 11p and the shorter the length of the brush bristles 11p, the greater the force with which the brush bristles 11p scrape off the paper dust P attached to the paper fibers, and as a result, the efficiency of transferring the paper dust P from the recording material S to the brush roller 11 is also improved. However, if the diameter of the brush bristles 11p is too large and the length of the brush bristles 11p is too short, the reaction force will be stronger for the same amount of deflection, causing the brush bristles 11p to move even with only a slight deflection, overcoming the frictional force between the tip of the brush bristles 11p and the paper fibers. As a result, the distance over which the brush bristles 11p move with force is shortened, and consequently, the transfer efficiency of paper dust P from the recording material S to the brush roller 11 is thought to decrease.

[0115] The mechanism for improving the flight rate from the brush roller 11 to the recovery roller 12 when the brush bristles 11p pass through the friction section Nc is similar. As mentioned above, the tip 1a1 of the friction member 1a enters the brush section 11a in such a way that it bends the brush bristles 11p. Then, after being bent by the friction member 1a, the brush bristles 11p rapidly return to their original shape as they pass through the friction member 1a. As a result, the paper dust P attached to the brush bristles 11p flies in the direction of arrow J in Figure 3 and adheres to the surface of the recovery roller 12. In this case as well, the restoring force of the brush bristles 11p trying to return to their original shape becomes the force that propels the paper dust P. The restoring force is determined by the balance between the magnitude of the reaction force and the distance the brush bristles 11p move rapidly. It is thought that the reaction force will be higher if the diameter of the brush bristles 11p is larger and the length of the brush bristles 11p is shorter, and as a result, the flight rate will also be improved. However, if the diameter of the brush bristles 11p is too large and the length of the brush bristles 11p is too short, the reaction force will be stronger for the same amount of deflection, causing the brush bristles 11p to move even with only a slight deflection, overcoming the frictional force between the tip of the brush bristles 11p and the sliding member 1a. As a result, the distance over which the brush bristles 11p move with force is shortened, and consequently, the rate at which paper dust P is launched from the brush roller 11 to the collection roller 12 is thought to decrease.

[0116] For the brush bristles 11p, it is preferable to use bristles with a diameter (thickness) of 9 to 35 μm, and more preferably bristles with a diameter of 15 to 35 μm. Furthermore, the length (free length) of the brush bristles 11p is preferably 1 to 14 mm. The results of the verification experiment will be described later.

[0117] The pile density of brush bristles 11p is 70-1000 kF / inch. ２ Preferably, it is 70-500 kF / inch ２It is more preferable that the pile density is too sparse, as this reduces the opportunities for the brush bristles 11p to come into contact with the paper dust, thus reducing cleaning performance. Conversely, if the pile density is too high, the movement of the brush bristles 11p is restricted, which is thought to reduce cleaning performance. Furthermore, the Young's modulus of the brush bristles 11p is preferably 2000 to 9900 MPa, and more preferably 2100 to 5000 MPa. Considering durability and abrasion resistance in addition to cleaning performance, it is preferable to use resins such as polyester, acrylic, polypropylene, PET, and polyurethane as the material for the brush bristles 11p. The Young's modulus of general resins is 2000 to 9900 MPa, and among these, the Young's modulus of resins such as polyester, acrylic, polypropylene, PET, and polyurethane, which have excellent durability and abrasion resistance, is 2100 to 5000 MPa. <Examples and Comparative Examples>

[0118] Verification experiments were conducted to verify the effects of this embodiment (Example 2-1), as well as embodiments (Examples 2-2 to 2-10) and comparative examples (Comparative Examples 2-1 to 2-6) that differ from this embodiment in the configuration of the brush bristles 11p.

[0119] In Examples 2-1 to 2-10 and Comparative Examples 2-1 to 2-6, the abrasive member 1a was made of an aluminum plate with a thickness t of 100 μm. In Examples 2-1 to 2-10 and Comparative Examples 2-1 to 2-6, the free length F of the abrasive member 1a was 10 mm, and the penetration rate of the abrasive member 1a into the brush portion 11a of the brush roller 11 was 35%.

[0120] In this example (Example 2-1), the brush bristles 11p have a pile density of 200 kF / inch. ２ A specimen with a diameter of 20 μm and a length (free length L) of 3 mm was used.

[0121] In Example 2-2, the brush bristles 11p were used, and the pile density was 70 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 3 mm was used.

[0122] In Examples 2-3, the brush bristles 11p were used, and the pile density was 500 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 3 mm was used.

[0123] In Examples 2-4, the brush bristles 11p were used, and the pile density was 1000 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 3 mm was used.

[0124] In Examples 2-5, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 15 μm and a length of 3 mm was used.

[0125] In Example 2-6, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 9 μm and a length of 1 mm was used.

[0126] In Example 2-7, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 35 μm and a length of 3 mm was used.

[0127] In Example 2-8, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 6 mm was used.

[0128] In Example 2-9, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 35 μm and a length of 1.5 mm was used.

[0129] In Example 2-10, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 35 μm and a length of 14 mm was used.

[0130] In Comparative Example 2-1, the brush bristles were set to 11p, and the pile density was 50 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 3 mm was used.

[0131] In Comparative Example 2-2, the brush bristles were set to 11p, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 50 μm and a length of 3 mm was used.

[0132] In Comparative Example 2-3, the brush bristles were set to 11p, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 9 μm and a length of 3 mm was used.

[0133] In Comparative Example 2-4, the brush bristles were set to 11p, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 35 μm and a length of 1 mm was used.

[0134] In Comparative Example 2-5, the brush bristles were set to 11p, and the pile density was 200 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 7 mm was used.

[0135] In Comparative Example 2-6, the brush bristles were set to 11p, and the pile density was 200 kF / inch. ２ A sample with a diameter of 35 μm and a length of 15 mm was used. <Evaluation of cleanability>

[0136] Brush rollers 11 with different bristle density, bristle diameter, and bristle length were prepared, as in the configurations of each example above. Then, the cleaning efficiency of paper dust P from the recording material S (transfer efficiency of paper dust P from the recording material S to the brush roller 11) was evaluated using the image forming apparatus 100 equipped with each of the brush rollers 11 of the above examples. In each of the above examples, PET was used as the material for the bristle 11p, and the Young's modulus of the bristle 11p was 3500 MPa.

[0137] The cleanability of paper dust P was evaluated as follows. Office 70 (Canon, product name), which is paper, was used as the recording material S. After printing 10 solid white images, the paper dust P collected by the cleaning blade 13 was observed. The cleanability of the paper dust P was evaluated on a four-point scale: × (poor) if there was 1 or fewer collected paper dust particles, △ (slightly poor) if there were 2 to 4 particles, ○ (good) if there were 5 to 9 particles, and ◎ (very good) if there were 10 or more particles. <Evaluation of flight rate>

[0138] As described in the examples above, the flight rate of paper dust P from the brush roller 11 to the recovery roller 12 was evaluated using brush rollers 11 with different brush bristle bristle 11p configurations. As described above, in each of the examples above, PET was used as the material for the brush bristle bristle 11p, and the Young's modulus of the brush bristle 11p was 3500 MPa.

[0139] The flight rate was determined by the following method. As shown in Figure 13, first, the opposing roller 16 was removed from the electrostatic collection device 10, and the brush roller 11 and the recovery roller 12 were positioned in a non-contact manner. Next, the brush roller 11 was removed from the electrostatic collection device 10, and paper dust P was attached to its surface (brush bristles 11p). The paper dust P used was a typical type (including pulp fibers, talc, and other fillers) generated from ordinary paper used in the image forming apparatus 100. The weight of the brush roller 11 with the attached paper dust P was measured using an electronic balance. This weight was defined as the "initial amount of paper dust attached" to the brush roller 11. Next, the brush roller 11 was attached to the electrostatic collection device 10, and with the brush roller 11 and the recovery roller 12 in a non-contact manner as described above, the electrostatic collection device 10 was rotated without paper being passed through it. The idle rotation time was controlled to be the time it takes for the brush roller 11 to complete one rotation. After idle rotation, the brush roller 11 is removed from the electrostatic collection device 10, and its weight is measured using an electronic balance. This weight is defined as the "residual paper dust amount," which is the amount of paper dust P remaining on the brush roller 11. The flight rate is then calculated using the following equation 8. Flight rate (%) = (1 - residual paper dust amount / initial paper dust amount) × 100 ... (Equation 8) <Evaluation Results>

[0140] Table 3 shows the composition of the brush bristles 11p and the evaluation results for cleaning performance and flight rate.

[0141] Regarding the diameter of the brush bristles 11p, it is preferable that one of the brush bristles 11p constituting the brush roller 11 enters the fine irregularities of the paper fibers to scrape out the paper dust P. Therefore, it is thought that cleaning performance is improved when the diameter of the brush bristles 11p is sufficiently small. If the diameter of the brush bristles 11p is too large, the brush bristles 11p cannot enter the recesses of the paper fibers, making it difficult to scrape out the paper dust and thus reducing cleaning performance. In Comparative Example 2-2, with a brush bristle diameter of 50 μm, the tip of the brush bristles 11p could not enter deep into the recesses of the paper fibers, which is thought to have resulted in reduced cleaning performance.

[0142] On the other hand, if the diameter of the brush bristles 11p is too small, even if the tips of the brush bristles 11p can penetrate deep into the recesses of the paper fibers, the force that scrapes out the paper dust P will be weak. Furthermore, the thinner the brush bristles 11p become, the more easily they bend, preventing the tips of the brush bristles 11p from penetrating the recesses of the paper fibers, or making the brush bristles 11p more susceptible to permanent deformation. As a result, the cleaning performance is likely to decrease.

[0143] Based on the results of the verification experiments described above, the diameter of the brush bristles 11p is preferably 9 to 35 μm, and more preferably 15 to 35 μm. When the diameter of the brush bristles 11p satisfies these conditions, good cleaning performance and flight rate can be obtained.

[0144] Furthermore, regarding the length of the brush bristles 11p, due to the mechanism described above, shorter bristles tend to improve cleaning performance and flight efficiency. However, if they are too short, the distance the brush bristles 11p travel at high speed becomes shorter, which tends to decrease cleaning performance and flight efficiency.

[0145] Based on the results of the verification experiments described above, the length (free length) of the brush bristles 11p is preferably 1 to 14 mm, and more preferably 3 to 14 mm. By satisfying these conditions for the length of the brush bristles 11p, good cleaning performance and flight efficiency can be obtained.

[0146] Furthermore, based on the results of the verification experiments described above, it is preferable that the brush bristles 11p be configured to satisfy the following equation 7. In equation 7, E is Young's modulus (MPa), d is the diameter (thickness) of the brush bristles 11p (mm), and L is the length (free length) of the brush bristles 11p (mm). 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３ (MPa·mm) ... (Equation 7)

[0147] By configuring the brush bristles 11p to satisfy these conditions, the rigidity of the brush bristles 11p can be set within a range suitable for cleaning. This balances the magnitude of the reaction force with the distance the brush bristles 11p travel rapidly, allowing the brush bristles 11p to exhibit a strong restorative force after being deflected by the abrasive member 1a. As a result, high cleaning efficiency can be achieved in the first transfer section R1, and a high flight rate can be achieved when the brush bristles 11p pass through the abrasive section Nc.

[0148] Thus, in this embodiment, when the thickness of the brush bristles 11p is d (mm), the free length of the brush bristles 11p is L (mm), and the Young's modulus of the brush bristles 11p is E (MPa), the electrostatic collection device 10 is given by the following equation: 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３ The configuration is designed to satisfy (MPa·mm).

[0149] As described above, this embodiment provides the same effects as in Embodiment 1, while also improving ease of cleaning and flight efficiency.

[0150] Next, other embodiments of the present invention will be described. In this embodiment, the electrostatic collection device according to the present invention is used as a cleaning device (vacuum cleaner, manual vacuum cleaner) for cleaning floors, as an example of its embodiment. In the electrostatic collection device (cleaning device) of this embodiment, elements having the same or corresponding functions or configurations as those of the electrostatic collection device (paper dust collection device) of Embodiments 1 and 2 are denoted by the same reference numerals as in Embodiments 1 and 2, and detailed descriptions are omitted.

[0151] The general configuration of the electrostatic collection device in this embodiment is the same as that of the electrostatic collection devices in Embodiments 1 and 2, but the object to be cleaned and the object to be collected differ between the electrostatic collection device in this embodiment and those in Embodiments 1 and 2. In Embodiments 1 and 2, the object to be cleaned was the recording material (paper) on which images are formed in the image forming apparatus, and the object to be collected was paper dust. In this embodiment, however, the object to be cleaned is the floor, and the object to be collected is dust.

[0152] The dust on the floor mainly consists of fibers, sebum, and minerals, and its particle size is similar to that of paper dust. The fibers, sebum, and minerals are all located on the positive side of the triboelectric series, which is more positive than the PET used as the material for the brush bristles 11p in Examples 1 and 2. Therefore, when the brush bristles 11p (PET) and the dust rub against each other in the first transfer section R1, the brush bristles 11p become negatively charged, and the dust becomes positively charged. As a result, dust can be electrostatically collected in the same configuration as in the case of paper dust P.

[0153] Figure 14 is a schematic external perspective view of the cleaning device (hereinafter also referred to as the "electrostatic collection device") 200 of this embodiment. In this embodiment, the target of cleaning by the electrostatic collection device 200 is the floor Y, and the collected material is dust G (Figure 15) etc. (hereinafter simply referred to as "dust") present on the floor Y.

[0154] The electrostatic dust collection device 200 comprises a device body 201 and a handle 202 connected to the device body 201. The user can clean the floor (floor surface, surface to be cleaned) Y by holding the handle 202 and pushing the device body 201, which is placed on the floor Y, in the direction of arrow D1 in the figure. The electrostatic dust collection device 200 can also clean the floor Y when the device body 201 is pulled back in the opposite direction to arrow D1 in the figure. However, in this embodiment, it is assumed that the floor Y will be cleaned mainly by pushing the device body 201 in the direction of arrow D1 in the figure, and the mounting position and range of motion of the handle 202 relative to the device body 201 are set accordingly. Here, the direction of arrow D1 in the figure is also called the "cleaning direction D1". In the cleaning direction D1, the front of the housing (frame) 206 of the device body 201 is provided with an opening 203 for taking dust G into the housing 206.

[0155] Figure 15 is a schematic cross-sectional view of the electrostatic collection device 200 of this embodiment (showing a cross-section approximately perpendicular to the rotation axis direction of the brush roller 11). The floor Y is, for example, a thick-film type antistatic rigid urethane resin-based floor coating material (product name: Chemiconduct VC, ABC Corporation), and dust G is adhering to the surface of the floor Y.

[0156] The main body 201 of the electrostatic dust collection device 200 includes a brush roller 11, a friction mechanism 1, a recovery roller 12, a cleaning blade 13, and a storage section (storage container) 14. The main body 201 of the electrostatic dust collection device 200 also includes a motor 204 as a drive source that constitutes the driving means, and a battery 205 that supplies power to the motor 204 and the like. The electrostatic dust collection device 200 also has a housing 206 that houses these components inside. The brush roller 11 rotates to collect dust G from the floor Y by sweeping it into the housing 206 through an opening 203 provided in the housing 206.

[0157] A brush roller 11 is provided so as to be exposed to the outside of the housing 206 through an opening 203 in the housing 206 of the main body 201 of the device, and behind it are a friction mechanism 1, a recovery roller 12, a cleaning blade 13, and a housing 14. The functions and configurations of the brush roller 11, friction mechanism 1, recovery roller 12, cleaning blade 13, and housing 14 in this embodiment are the same as those in Embodiment 1. The brush roller 11 is driven by a drive transmission member (not shown) that constitutes a drive transmission means, and rotates in the direction of arrow K1 in the figure (clockwise) at a peripheral speed (surface movement speed) of, for example, 144 mm / sec. In this embodiment, the brush bristles 11p of the brush roller 11 are provided substantially uniformly on the outer circumference of the core portion 11b of the brush roller 11 in a range of length equivalent to the length in the rotation axis direction of the brush roller 11 (for example, about 150 to 300 mm). In this embodiment, the brush roller 11 rotates at the contact point with the floor Y such that the direction of movement of the brush portion 11a and the relative direction of movement of the floor Y with respect to the device body 201 (opposite to the cleaning direction D1) are in opposite directions. In this embodiment, the peripheral speed of the brush roller 11 is set to a speed that is sufficiently faster than the speed at which the user moves the device body 201 on the floor Y while holding the handle 202 and pushing it in the cleaning direction D1. Although the difference in friction speed is larger compared to the configuration of Embodiment 1, the floor Y has relatively high abrasion resistance, unlike the recording material (paper), so there is no particular problem in increasing the number of friction cycles.

[0158] With this configuration, dust G adhering to the floor Y is electrostatically transferred (collected) to the brush roller 11 in the first transfer section (collection section) where the brush roller 11 and the floor Y come into contact. The dust G collected on the brush roller 11 is electrostatically transferred (collected) to the collection roller 12 in the second transfer section (collection section) R2 where the brush roller 11 and the collection roller 12 come into contact. In addition, the dust G collected on the brush roller 11 is also collected by the collection roller 12 when the brush portion 11a passes through the sliding section Nc where the sliding member 1a of the sliding mechanism 1 and the brush portion 11a of the brush roller 11 come into contact. After that, the dust G collected by the collection roller 12 is scraped off by the cleaning blade 13 and collected in the storage section 14. The floor Y can then be continuously cleaned by moving the device body 201 by moving it with the handle 202.

[0159] Thus, in this embodiment, the electrostatic collection device 200 collects dust and other materials from the object to be cleaned.

[0160] When fine dust particles were scattered on the floor Y and cleaned using the electrostatic collection device 200 of this embodiment, good cleaning performance (transfer efficiency) in the first transfer section R1 and a good flight rate when the brush bristles 11p of the brush roller 11 passed through the friction section Nc were obtained.

[0161] Furthermore, by configuring the electrostatic collection device according to the present invention as a manual vacuum cleaner that allows the user to clean by holding the handle 202, the applications of the electrostatic collection device are broadened, and it can be used for a variety of purposes, not just floors. The electrostatic collection device may also be configured as a lightweight, handheld cleaning device (vacuum cleaner, handheld vacuum cleaner) for cleaning surfaces such as walls, desks, displays, blackboards, and whiteboards.

[0162] Furthermore, in this embodiment, the electrostatic collection device is a manual vacuum cleaner configured to be pushed by the user, but it may also be a robotic vacuum cleaner configured to move on its own. [Other]

[0163] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the embodiments described above.

[0164] In the above-described embodiment, the collection rotating body and the recovery rotating body were brush rollers or rollers, but collection rotating bodies and recovery rotating bodies composed of endless belt members may also be used. For example, a belt member provided with brush bristles can be used as the collection rotating body. Also, a belt member provided with the same surface layer as in the above-described embodiment can be used as the recovery rotating body.

[0165] Furthermore, while the image forming apparatus using the electrostatic collection device in Examples 1 and 2 was a monochrome image forming apparatus, it is not limited to this. The image forming apparatus may be, for example, a color image forming apparatus equipped with multiple image forming units, each having an image carrier. Also, the image forming apparatus is not limited to a cleanerless configuration that does not have a dedicated cleaning device for removing residual toner from the image carrier. Even when a cleaning device is provided, if paper dust adheres to the image carrier, the paper dust may get trapped between the cleaning member and the image carrier, causing problems such as poor cleaning. Therefore, it is effective to collect paper dust from the recording material using an electrostatic collection device, as in Examples 1 and 2. The image forming apparatus may also be, for example, an inkjet type image forming apparatus.

[0166] Furthermore, in Example 3, the collection rotating body and recovery rotating body of the cleaning device were driven by a motor, but this is not the only option. For example, the cleaning device may have a configuration in which the collection rotating body and recovery rotating body are rotated by the rotational force transmitted from wheels that rotate as the cleaning device moves in contact with the object to be cleaned. In such a configuration, the cleaning device may not have a drive source.

[0167] The electrostatic dust collection device can be used for a variety of purposes other than those described in the above embodiments. For example, in an image forming apparatus, the electrostatic dust collection device can be used to collect paper dust adhering to the surface of an image carrier by configuring it to bring a collection rotating body into contact with the image carrier. In this case, the image carrier is not limited to a photosensitive drum, but may be, for example, an intermediate transfer belt that transports a toner image, which has been primarily transferred from the photosensitive drum, to a recording material for secondary transfer. Also, for example, in an image forming apparatus, the electrostatic dust collection device can be used to collect paper dust from the surface of rollers or belts (paper feed rollers, transport rollers, transport belts, etc.) that transport recording material by configuring it to bring a collection rotating body into contact with the surface of the rollers or belts. Furthermore, the electrostatic dust collection device can be used as a cleaning device in various manufacturing facilities, for example, for cleaning glass substrates or various insulators and conductors that are to be cleaned.

[0168] Furthermore, the rotation direction and peripheral speed of the collection rotating body are not limited to those of the embodiments described above. The collection rotating body may rotate such that the brush bristles of the collection rotating body move in either the forward or reverse direction relative to the object being cleaned at the contact point with the object being cleaned. Also, the peripheral speed of the collection rotating body may be faster or slower than that of the embodiments described above. Similarly, the rotation direction and peripheral speed of the recovery rotating body are not limited to those of the embodiments described above. The recovery rotating body may rotate such that the surface of the recovery rotating body moves in either the forward or reverse direction relative to the brush bristles of the collection rotating body at the contact point with the collection rotating body. Also, the peripheral speed of the recovery rotating body may be faster or slower than that of the embodiments described above.

[0169] Furthermore, the method for implanting the brush bristles onto the core of the collecting rotating body is not limited to that described in the above-described embodiment, and any available method can be used. For example, the brush bristles may be implanted directly onto the outer surface of the core.

[0170] Furthermore, the resin material constituting the brush bristles is not limited to PET, but may also be other polyester resins, or urethane resins, acrylic resins, polyethylene resins, polypropylene resins, etc. Also, the resin material constituting the surface layer of the recovery roller is preferably fluororesin from the viewpoint of transfer efficiency, but is not limited to this, and may also be silicone resin, for example. Furthermore, the fluororesin is not limited to PFA, but may also be PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene-ethylene copolymer), etc.

[0171] According to the present invention, a developing apparatus capable of suppressing the occurrence of image defects is provided.

[0172] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0173] This application claims priority based on Japanese Patent Application No. 2024-169719, filed on September 29, 2024, and all of its contents are incorporated herein by reference.

Claims

1. A rotatable brush-shaped collecting rotating body comprising: brush bristles that contact the object to be cleaned to form a collection section, and which, by rotating, electrostatically collects the object to be collected from the object to be cleaned onto the brush bristles in the collection section; a collection member that contacts the brush bristles to form a recovery section, and which electrostatically recovers the object to be collected from the brush bristles in the recovery section; a sliding member formed of a flexible plate-shaped member that contacts the brush bristles downstream of the collection section and upstream of the recovery section in the rotation direction of the collecting rotating body, and slides against the brush bristles as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed. The abrasive collecting device is configured such that the abrasive member contacts the brush bristles at a tip, which is one end in a second direction intersecting the first direction which is the rotation axis direction of the collecting rotating body, and the base end, which is the other end in the second direction, is fixed to the fixing member, and the tip is positioned at an inclination such that it is located downstream of the base end in the rotation direction of the collecting rotating body, and the device allows the brush bristles to bend and then return to their original position as the collecting rotating body rotates, thereby enabling the collected object to be launched from the brush bristles toward the collection member, and when the distance the tip moves due to the bending of the abrasive member is defined as the amount of bending, and the load the tip receives from the brush bristles is defined as the contact pressure, the rate of change of the contact pressure when the amount of bending changes by 1 mm is 20% or less.

2. The electrostatic collection device according to claim 1, wherein the distance from the top of the brush bristles at the position in contact with the abrasive member, assuming that the brush bristles are not bent by the abrasive member, to the end of the side of the side of the collecting rotating body of the abrasive member in the second direction is defined as the penetration amount, and the ratio of the penetration amount to the free length of the brush bristles is defined as the penetration rate, and the average value of the penetration rate during one rotation of the collecting rotating body is 20% or more and 50% or less.

3. A rotatable brush-shaped collecting rotating body comprising: brush bristles that contact the object to be cleaned to form a collection section, and which, by rotating, electrostatically collects the object to be collected from the object to be cleaned onto the brush bristles in the collection section; a collection member that contacts the brush bristles to form a collection section, and which electrostatically collects the object to be collected from the brush bristles in the collection section; a sliding member made of a flexible plate-shaped member that contacts the brush bristles downstream of the collection section and upstream of the collection section in the rotation direction of the collecting rotating body, and slides against the brush bristles as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed. The abrasive collecting device is configured such that the abrasive member contacts the brush bristles at a tip, which is one end in a second direction intersecting the first direction which is the rotation axis direction of the collecting rotating body, and the base end, which is the other end in the second direction, is fixed to the fixing member, and the tip is positioned at an inclination such that it is located downstream of the base end in the rotation direction of the collecting rotating body, and the abrasive collecting device is configured such that it is possible to propel the object to be collected from the brush bristles toward the collection member by allowing the brush bristles to return to their original position after being bent as the collecting rotating body rotates, and the abrasive collecting device is configured such that when the abrasive member contacts the brush bristles, assuming that the brush bristles are not bent by the abrasive member, the distance from the top of the brush bristles at the position in contact with the abrasive member to the end of the tip in the second direction on the side of the surface of the abrasive member on the side of the collecting rotating body is the penetration amount, the ratio of the penetration amount to the free length of the brush bristles is the penetration rate, and the distance the tip moves due to the bending of the abrasive member is the deflection amount, the rate of change of the penetration rate when the deflection amount changes by 1 mm is 20% or less.

4. The electrostatic collection device according to claim 3, wherein the average value of the penetration rate during one rotation of the collection rotating body is 20% or more and 50% or less.

5. A rotatable brush-shaped collecting rotating body comprising: brush bristles that contact the object to be cleaned to form a collection section, and which, by rotating, electrostatically collects the object to be collected from the object to be cleaned onto the brush bristles in the collection section; a collection member that contacts the brush bristles to form a collection section, and which electrostatically collects the object to be collected from the brush bristles in the collection section; a sliding member made of a flexible plate-shaped member that contacts the brush bristles downstream of the collection section and upstream of the collection section in the rotation direction of the collecting rotating body, and slides against the brush bristles as the collecting rotating body rotates; and a fixing member to which the sliding member is fixed. The abrasive collecting device is configured such that the abrasive member contacts the brush bristles at a tip, which is one end in a second direction intersecting the first direction which is the rotation axis direction of the collecting rotating body, and the base end, which is the other end in the second direction, is fixed to the fixing member, and the abrasive member is inclined so that the tip is located downstream of the base end in the rotation direction of the collecting rotating body, and the abrasive member allows the brush bristles to bend and then return to their original position as the collecting rotating body rotates, thereby enabling the collected material to fly from the brush bristles toward the collection member, and the amount of penetration is defined as the distance from the top of the brush bristles at the position in contact with the abrasive member (assuming the brush bristles are not bent by the abrasive member) to the end of the abrasive member on the side of the abrasive member facing the collecting rotating body in the second direction, and the ratio of the amount of penetration to the free length of the brush bristles is defined as the penetration rate, the average value of the penetration rate during one rotation of the collecting rotating body is 20% or more and 50% or less, and the rate of change of the penetration rate during one rotation of the collecting rotating body is 20% or less.

6. When the Young's modulus of the sliding member is E (MPa), the thickness of the sliding member is t (mm), and the free length of the sliding member is F (mm), the following equation holds: (E × t ３ ) / (4xF ３ The electrostatic collection device according to any one of claims 1 to 5, satisfying ) ≤ 0.02 (MPa).

7. When the thickness of the brush bristles is d (mm), the free length of the brush bristles is L (mm), and the Young's modulus of the brush bristles is E (MPa), the following equation holds: 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３ An electrostatic collection device according to any one of claims 1 to 5 that satisfies (MPa·mm).

8. The electrostatic collection device according to any one of claims 1 to 5, wherein the sliding member is formed of a metal material.

9. The electrostatic collection device according to claim 8, wherein the sliding member is electrically connected to a component made of a metal material.

10. The electrostatic collection device according to claim 8, wherein the friction member is electrically grounded.

11. The electrostatic collection device according to any one of claims 1 to 5, wherein the collection member is rotatable, and the collection member rotates in the collection section such that the direction of movement of the brush bristles and the surface of the collection member move in opposite directions, thereby collecting the object to be collected from the collection rotating body.

12. An electrostatic collection device according to any one of claims 1 to 5, in an image forming apparatus for forming an image on a recording material, wherein the device collects the object to be collected, including paper dust, from the recording material which is to be cleaned.

13. An electrostatic collection device according to any one of claims 1 to 5, for collecting the object to be collected, including dust, from the object to be cleaned.

Images