Electrostatic collection device

Abstract

An electrostatic collection device (10) comprises: a collection rotor (11) that is provided with bristles which electrostatically collect, from a cleaning target, an object to be collected; and a recovery member (12) that electrostatically recovers, from the bristles (11p), the object to be collected. The bristles (11p) of the collection rotor (11) have a density of 70-1,000 kF / inch2 <sp / >. The bristles (11p) have a thickness of 9-35 μm. The bristles (11p) have a free length of 1-14 mm. When the thickness of the bristles (11p) is represented as d (mm), the Young's modulus of the bristles (11p) is represented as E (MPa), and the free length of the bristles (11p) is represented as L (mm), the expression 1.9×10- (MPa·mm) ≤ E×d4 / L3 ≤ 1.6×10-3 (MPa·mm) is satisfied.

Description

Electrostatic Precipitator

[0001] The present invention relates to an electrostatic precipitator that collects collected matter from a cleaning target.

[0002] Conventionally, as a device for collecting dust on a floor surface, for example, an electrostatic precipitator that utilizes an electrostatic force, which is advantageous in terms of quiet operation and low exhaust resistance, has been proposed.

[0003] For example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2024-84210), an electrostatic cleaning device has been proposed. This cleaning device has a rotating brush and a rubbing member that rubs against the rotating brush in the device body, and the rotating brush is triboelectrically charged. By pushing the device body forward with respect to the floor surface, dust is triboelectrically charged positively, and the dust is electrostatically attached to and collected by the rotating brush in which negative charges have accumulated due to triboelectric charging. The dust electrostatically attached to the rotating brush is removed by a removing member arranged opposite to the rotating brush.

[0004] Further, in Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2017-156450), a technique for collecting paper powder attached to the surface of paper as a recording material by electrostatic adsorption force and removing it from the surface of the paper in an electrophotographic image forming apparatus is disclosed. [Means for Solving the Problems]

[0005] In summary, the present invention is a rotatable brush-shaped collection rotating body that includes brush hairs that contact a cleaning target to form a collection part, and electrostatically collects collected matter from the cleaning target onto the brush hairs in the collection part by rotating. It has a recovery member that contacts the brush hairs to form a recovery part and electrostatically recovers the collected matter from the brush hairs in the recovery part. The density of the brush hairs in the collection rotating body is 70 kF / inch ２ or more and 1000 kF / inch ２ or less, the thickness of the brush hairs is 9 μm or more and 35 μm or less, the free length of the brush hairs is 1 mm or more and 14 mm or less, and when the thickness of the brush hairs is d (mm), the Young's modulus of the brush hairs is E (MPa), and the free length of the brush hairs is L (mm), the following formula: 1.9×10 −６ (MPa·mm) ≤ E × d ４ / L３ ≤1.6×10 −３ It is an electrostatic precipitator that satisfies (MPa·mm).

[0006] FIG. 1 is a schematic cross-sectional view showing the schematic configuration of the cleaning device of Example 1.

[0007] FIG. 2 is a schematic view showing the state of cleaning a blackboard using the cleaning device of Example 1.

[0008] FIG. 3 is a schematic enlarged cross-sectional view of the brush portion of the brush roller.

[0009] FIG. 4 is a schematic view showing the positional relationship between the brush roller and the roller in the axial direction of the rotation axis of the brush roller, and a schematic view for explaining the intrusion amount.

[0010] FIG. 5 is a schematic view for explaining the action of the brush hairs.

[0011] FIG. 6 is a schematic view showing the state of cleaning a whiteboard using the cleaning device of Example 2.

[0012] FIG. 7 is a schematic view for explaining the composition of the ink for the whiteboard.

[0013] FIG. 8 is a cross-sectional view showing the schematic configuration of the image forming apparatus provided with the paper dust collecting device of Example 3.

[0014] FIG. 9 is a cross-sectional view showing the schematic configuration of the process cartridge provided with the paper dust collecting device of Example 3.

[0015] Hereinafter, preferred embodiments of the electrostatic precipitator 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 component parts in this embodiment.

[0016] In this embodiment, as an example of the embodiment of the electrostatic precipitator according to the present invention, it is used as a cleaning device for cleaning chalk dust on the surface of a blackboard. In this embodiment, the cleaning target of the cleaning device is a blackboard, and the object to be collected is chalk dust existing on the surface of the blackboard. <Overall configuration of the cleaning device>

[0017] Figure 1 is a schematic cross-sectional view of the cleaning device 10 of this embodiment (showing a cross-section approximately perpendicular to the rotation axis direction of the brush roller 11, which will be described later). Figure 2 is a schematic diagram showing how a user uses the cleaning device 10 of this embodiment to clean chalk dust H on the surface F of a blackboard. The cleaning device 10 of this embodiment is a manual blackboard eraser. As shown in Figures 1 and 2, the user can hold the cleaning device 10 in their hand and move it over the surface F of the blackboard, which is the surface to be cleaned, collecting chalk dust H, which is the material to be collected, from the surface F of the blackboard and cleaning the surface F of the blackboard.

[0018] The cleaning device 10 of this embodiment has a housing (frame) 1 equipped with a handle 2 and a brush cover 3. The cleaning device 10 of this embodiment also has a brush roller (rotating brush) 11 and a collection roller 12. The brush roller 11 is an example of a collection rotating body, which is a rotatable collection member that constitutes a collection means. The collection roller 12 is an example of a collection rotating body, which is a rotatable collection member that constitutes a collection means. The cleaning device 10 of this embodiment also has a blade 13 as a removal member (scraping member) and a storage section (storage container) 14. The cleaning device 10 of this embodiment also has a motor 15 as a drive source that constitutes a drive means and a battery 16 that supplies power to the motor 15 and the like. In this embodiment, rollers 17, which are intrusion amount restricting members, are provided on both ends of the brush roller 11 in the direction of the rotation axis. The housing 1 (brush cover 3) is provided with an opening 4 for taking in chalk powder H. At least a portion of each of the brush roller 11 and the roller 17 is covered by the brush cover 3 of the housing 1. In this embodiment, the recovery roller 12, blade 13, housing 14, motor 15, and battery 16 are housed inside the handle 2 of the housing 1.

[0019] A brush roller 11 and a roller 17 are provided so as to be exposed to the outside of the housing 1 (brush cover 3) through an opening 4 provided in the housing 1 (brush cover 3), and a collection roller 12, a blade 13, and a storage section 14 are provided behind them. The amount of brush bristles 11p (Figure 3), which will be described later, that penetrate the surface F of the blackboard is restricted by the roller 17, and the brush roller 11 rotates while in contact with the surface F of the blackboard (Figure 4(a)). By rotating, the brush roller 11 collects chalk dust H on the surface F of the blackboard by scraping it into the inside of the housing 1 (brush cover 3) through the opening 4 provided in the housing 1 (brush cover 3). The user can clean the surface F of the blackboard by holding the handle 2 and moving the cleaning device 10, which is in contact with the surface F of the blackboard, in the direction of arrow D1 in the figure. The cleaning device 10 can also clean the surface F of the blackboard when moved in the opposite direction to arrow D1 in the figure, for example. However, in this embodiment, it is assumed that the cleaning device 10 will be mainly moved in the direction of arrow D1 in the figure while cleaning the surface F of the blackboard, and the position and shape of the handle 2 are set accordingly. Here, the direction of arrow D1 in the figure is also referred to as the "cleaning direction D1".

[0020] Figure 1 shows how chalk dust H is collected on the surface F of the blackboard. The brush roller 11 rotates in the direction of arrow K1 (counterclockwise) in the figure, driven by a drive transmission member (not shown) that constitutes a drive transmission means, with driving force transmitted from the motor 15, which constitutes a drive source that constitutes a drive means. In other words, the brush roller 11 rotates in the direction of arrow K1 (counterclockwise) in the figure, such that the direction of movement of the brush portion 11a and the relative direction of movement of the surface F of the blackboard with respect to the cleaning device 10 (opposite to the cleaning direction D1) are in opposite directions at the collection portion (first transfer portion, collection nip portion) R1, which is the contact portion between the brush portion 11a of the brush roller 11 (described later) and the surface F of the blackboard. The recovery roller 12 rotates in the direction of arrow K2 (clockwise) in the figure, with driving force transmitted from the motor 15, which constitutes a drive source that constitutes a drive means, with driving force transmitted from the drive transmission member (not shown) that constitutes a drive transmission means. In other words, the recovery roller 12 rotates in the recovery section (second transfer section, recovery nip section) R2, which is the contact section between the brush section 11a of the brush roller 11 and the recovery roller 12, such that the direction of movement of the brush section 11a and the direction of movement of the surface of the recovery roller 12 are in the forward direction. As the brush roller 11 rotates, the brush section 11a that contacts the surface F of the blackboard rubs against the surface F of the blackboard, scraping the chalk powder H adhering to the surface F of the blackboard, and collecting the chalk powder H from the surface F of the blackboard by electrostatic adhesion (electrostatic adsorption force). The chalk powder H 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) as it rotates in contact with the brush roller 11. The chalk powder H collected on the recovery roller 12 is scraped off the recovery roller 12 by the blade 13 and stored in the storage section 14. The individual components of the cleaning device 10 will be described further below.

[0021] 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 so that its rotation axis direction is substantially parallel to the surface F of the blackboard when cleaning is performed. The core portion 11b is rotatably supported by the housing 1 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.

[0022] In this embodiment, the core portion 11b of the brush roller 11 is made of a metal material, such as aluminum (aluminum or aluminum alloy), as a conductor (conductive material). In this embodiment, the brush bristles 11p of the brush roller 11 are made of an insulating resin material, 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 this embodiment, the brush bristles 11p of the brush roller 11 are made of cut pile. Figure 3 is a schematic enlarged cross-sectional view illustrating the structure of the brush portion 11a of the brush roller 11 in this embodiment. As shown in Figure 3, the brush portion 11a of the brush roller 11 is made up 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, multiple pile threads woven into the base fabric 11k are cut to form brush bristles (also referred to here as "piles") 11p, which are then 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.

[0023] The material of the fibers constituting the base fabric 11k may be the same as the material of the fibers constituting the brush bristles 11p, or it may be a different material. Conductive fibers may be used as the fibers constituting the base fabric 11k. 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 length range equivalent to the length in the rotational axis direction of the brush roller 11 (for example, about 150 to 300 mm). Here, the length of the portion in which the brush bristles 11p, which are entangled with the weft yarn 11y, are freed from being fixed by the warp yarn 11t and the weft yarn 11y and can be freely deformed is defined as the free length of the brush bristles 11p (here also called "pile length" or simply "length") L. The free length L of the brush bristles 11p can also be said to be the length of the portion of the brush bristles 11p that protrudes from the base fabric 11k of the brush portion 11a. The free length L of the brush bristles 11p is represented by the length when the brush bristles 11p are not deformed by pressure from the object to be cleaned or the collection roller 12. The outer diameter of the brush roller 11 is the diameter of the circumscribed circle of the brush bristles 11p when no pressure is applied, as described above.

[0024] In this embodiment, the free length L of the brush bristles 11p of the brush roller 11 is 3 mm. The outer diameter of the brush roller 11 is approximately 30 mm. Furthermore, 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 20 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 this cross-section can be considered 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 this cross-section can be considered the thickness of the brush bristles 11p. In this embodiment, the brush portion 11a of the brush roller 11 has a density (pile density) of 200 kF / inch of brush bristles 11p. ２The structure is configured as follows. In this embodiment, the brush roller 11 is constructed by bonding the brush portion 11a (base fabric 11k on which the brush bristles 11p are provided) to the core portion 11b. Note that the fixing means for fixing the brush portion 11a to the core portion 11b is not limited to bonding, and other fixing means such as fixing with double-sided tape may be used.

[0025] In this embodiment, the brush roller 11 rotates in the direction of arrow K1 in the figure. In this embodiment, the axial rotation speed of the brush roller 11 is set to 100 rpm. As a result, the tip of the brush bristles 11p of the brush roller 11 rubs against the surface F of the blackboard. Then, at the collection section R1, which is the contact point between the brush roller 11 and the surface F of the blackboard, the chalk powder H on the surface F of the blackboard is transferred (collected) to the brush bristles 11p of the brush roller 11 by electrostatic adhesion and adheres to the brush bristles 11p.

[0026] 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 by the housing 1 via rotation shafts (not shown) provided at both ends in the direction of its rotation axis.

[0027] In this embodiment, the base portion 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 addition, in this embodiment, the surface layer 12a of the recovery roller 12 is 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. The length of the recovery roller 12 in the direction of its rotation axis is equivalent to the length of the area (region) in the direction of the rotation axis of the brush roller 11 where the brush portion 11a is provided.

[0028] In this embodiment, the recovery roller 12 rotates in the direction of arrow K2 in the figure. The rotational speed of the recovery roller 12 may be the same as or different from that of the brush roller 11. For example, the recovery roller 12 may rotate with a peripheral speed difference such that the peripheral speed of the recovery roller 12 is faster than that of the brush roller 11 in the recovery section R2. The surface layer 12a of the recovery roller 12 rubs against the chalk powder H on the brush bristles 11p of the brush roller 11 in the recovery section R2, which is the contact area between the brush roller 11 and the recovery roller 12. As a result, the chalk powder H 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.

[0029] The blade 13 is made of a rubber material (e.g., polyurethane (urethane rubber)) as an elastic body (elastic material) having appropriate elasticity and hardness. The blade 13 is a plate-shaped member that is approximately rectangular in plan view, having 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 a predetermined thickness in the short direction, which intersects (approximately perpendicular in this embodiment) with the longitudinal direction. The length of the blade 13 in the longitudinal direction is equal to the length of the recovery roller 12 in the longitudinal direction. The blade 13 is positioned such that one end in the short 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 blade 13 is in contact with the surface of the recovery roller 12 in a counter-direction with respect to the rotation direction of the recovery roller 12. The blade 13 can be fixed to the housing 1, for example, via a blade support. The blade 13 scrapes off the chalk powder H adhering to the surface 12a of the recovery roller 12 as the recovery roller 12 rotates. The removal member is not limited to a blade-shaped member, but may be a pad-shaped member, a sheet-shaped member, a brush-shaped member, or the like.

[0030] Furthermore, the storage section 14 is provided to contain the chalk powder H scraped off the surface of the rotating recovery roller 12 by the blade 13.

[0031] Here, we will explain the mechanism by which chalk powder H is transferred to the brush roller 11 and the collection roller 12, and the selection of materials. In the collection section R1, the electrostatic force generated by the frictional charging of the brush roller 11 and the chalk powder H is utilized for the transfer of chalk powder H. Similarly, in the collection section R2, the electrostatic force generated by the frictional charging of the brush roller 11 and the collection roller 12 is utilized for the transfer of chalk powder H. When two materials with different positions on the triboelectric series are rubbed together, they exchange charges, resulting in 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 on the triboelectric series tend to be more strongly charged. In this embodiment, the materials for the brush roller 11 (brush bristles 11p) and the collection roller 12 (surface layer 12a) were selected so that their positions on the triboelectric series are in the following permutation: (positive side) chalk powder < brush roller < collection roller (negative side)

[0032] In this arrangement, the friction between the brush roller 11 and the collection roller 12 due to the rotational motion of the brush roller 11 and the collection roller 12, as well as the friction between the chalk powder H and the brush roller 11 due to the movement of the cleaning device 10, causes the chalk powder H to become more positively charged and the collection roller 12 to become more negatively charged, relative to the brush roller 11.

[0033] The chalk dust H adhering to the surface F of the blackboard becomes positively charged through friction with the brush roller 11 (brush bristles 11p). In addition, the chalk dust H scraped off the surface F of the blackboard by the brush roller 11 is electrostatically attracted to the brush roller 11 (brush bristles 11p).

[0034] Then, as the brush roller 11 rotates and the chalk powder H reaches the collection section R2, the positively charged chalk powder H is transferred to the collection roller 12 (surface layer 12a), which is more negatively charged than the brush roller 11. In other words, the surface layer 12a of the collection roller 12 is charged with a potential greater than the absolute value of the brush bristles 11p of the brush roller 11 on the same polarity side (negative side) relative to the chalk powder H, and electrostatically collects the positively charged chalk powder H from the brush bristles 11p.

[0035] As the material of the brush hairs 11p of the brush roller 11, in addition to satisfying the conditions of this triboelectric series, it is preferable that the material has durability and abrasion resistance. As such materials that satisfy the conditions of the above triboelectric series, polyester, acrylic, polypropylene, PET, polyurethane, etc. are preferable. Therefore, in this embodiment, PET is used as the material of the brush hairs 11p of the brush roller 11.

[0036] Further, as the material of the surface layer 12a of the recovery roller 12, in addition to satisfying the conditions of the above triboelectric series, it is preferable that the material has durability and abrasion resistance. Therefore, in this embodiment, PFA is used as the material of the surface layer 12a of the recovery roller 12. Note that the resin material constituting the surface layer 12a of the recovery roller 12 is not limited to fluororesin, and may be silicone resin or the like. Further, the fluororesin is not limited to PFA, and for example, PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene - hexafluoropropylene copolymer), ETFE (tetrafluoroethylene - ethylene copolymer), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene - ethylene copolymer), etc. may be used.

[0037] Here, it can be said that the higher the volume resistivity of the material of the brush hairs 11p of the brush roller 11, the more advantageous it is for adsorbing and collecting the chalk powder H. Therefore, in this embodiment, as the material of the brush hairs 11p of the brush roller 11, an insulator with a volume resistivity of 10 １３ (Ω·m) or more is used. Also, it can be said that the higher the volume resistivity of the material of the surface layer 12a of the recovery roller 12, the more advantageous it is for adsorbing and recovering the chalk powder H. Therefore, in this embodiment, as the material of the surface layer 12a of the recovery roller 12, an insulator with a volume resistivity of 10 １３ (Ω·m) or more is used.

[0038] Note that an insulator refers to a substance with a resistance value of 10 ８ (Ω·m) or more, preferably 10 １０ (Ω·m) or more. However, typically, an insulator has a resistivity of 10１６ 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).

[0039] Furthermore, values ​​such as the diameter (thickness), length (free length), pile density, Young's modulus, and outer diameter of the brush roller 11p can each be represented by the average value of a sufficient number of measurements. The Young's modulus can be measured using a commercially available measuring device (tensile testing machine) (for example, the Shimadzu AGX tensile testing machine), or a nominal value related to the material may be used. <Roller configuration>

[0040] The configuration of the roller 17 as an intrusion amount regulating member in this embodiment will now be described. Figure 4(a) is a schematic diagram showing the positional relationship between the brush roller 11 and the roller 17 in the width direction (direction of the rotation axis of the brush roller 11) of the cleaning device 10. Figure 4(b) is a schematic diagram for explaining the amount D of intrusion of the brush bristles 11p of the brush roller 11 into the surface F of the blackboard.

[0041] As shown in Figure 4(a), rollers 17 with a smaller diameter than the outer diameter of the brush roller 11 are held at both ends of the brush roller 11 in the direction of its rotation axis. The rollers 17 are configured to rotate freely relative to the brush roller 11. When the cleaning device 10 is brought into contact with the surface F of the blackboard to collect chalk dust H from the surface F of the blackboard, the rollers 17 come into contact with the surface F of the blackboard. As a result, half the difference between the outer diameter of the brush roller 11 and the outer diameter of the rollers 17 becomes the amount D that the brush bristles 11p of the brush roller 11 penetrate into the surface F of the blackboard.

[0042] As shown in Figure 4(b), the amount D that the brush bristles 11p penetrate into the object to be cleaned (in this embodiment, the surface F of the blackboard) can be defined as the value obtained by subtracting the nearest neighbor distance C between the root of the free length L of the brush bristles 11p (base fabric 11k) and the object to be cleaned from the free length L of the brush bristles 11p. The ratio of the amount D that penetrates into the object to be cleaned (= D / L × 100) (%) to the free length L of the brush bristles 11p is also called the penetration rate. The penetration rate of the brush bristles 11p into the object to be cleaned (in this embodiment, the surface F of the blackboard) can be appropriately set in the range of, for example, 20 to 80%. If this penetration rate is too low, the brush bristles 11p may not be able to scrape off the object to be cleaned (in this embodiment, chalk powder H) sufficiently. Also, if this penetration rate is too high, there is a possibility that the brush bristles 11p may undergo plastic deformation, for example. In this embodiment, the target value of the penetration rate was set to 50%. The penetration rate can be represented, for example, 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 the "~" in the numerical range indicates that the values ​​before and after that value are included.

[0043] Furthermore, the means for restricting the amount of brush bristles 11p that penetrate the object to be cleaned is not limited to the roller 17. For example, as a means for restricting the amount of penetration, a stopper portion, which is part of the brush cover 3, may be provided, and the amount of penetration may be restricted by this stopper hitting the object to be cleaned. Also, the amount of brush bristles 11p that penetrate the collection roller 12 (penetration rate) can be set in the same way as the amount of brush bristles 11p that penetrate the object to be cleaned (penetration rate). <Composition of brush bristles>

[0044] It is preferable to use brush bristles 11p with a Young's modulus E of 2000 to 9900 MPa, and more preferably with a Young's modulus E of 2100 to 5000 MPa. The pile density of the brush bristles 11p is 70 to 1000 kF / inch. ２ Preferably, it is 70-500 kF / inch ２It is more preferable that the brush bristles 11p have a diameter (thickness) of 9 to 35 μm, and more preferably 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.

[0045] Furthermore, as mentioned above, the material for the brush bristles 11p is preferably a resin such as polyester, acrylic, polypropylene, PET, or polyurethane, considering durability and abrasion resistance in addition to cleaning properties. 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>

[0046] Verification experiments were conducted to verify the effects of this embodiment (Example 1-1), as well as embodiments (Examples 1-2 to 1-10) and comparative examples (Comparative Examples 1-1 to 1-6) with different brush bristle 11p configurations from this embodiment. In all examples, the outer diameter of the brush roller 11 was 30 mm, and the axial rotation speed of the brush roller 11 was 100 rpm.

[0047] In this example (Example 1-1), the brush bristles 11p have a pile density of 200 kF / inch. ２ A specimen with a diameter (thickness) of 20 μm and a length (free length) of 3 mm was used.

[0048] In Examples 1-2, 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.

[0049] In Examples 1-3, 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.

[0050] In Examples 1-4, 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.

[0051] In Examples 1-5, 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.

[0052] In Examples 1-6, 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.

[0053] In Examples 1-7, 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.

[0054] In Examples 1-8, 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.

[0055] In Examples 1-9, 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.

[0056] In Examples 1-10, the brush bristles 11p had a pile density of 200 kF / inch. ２ A specimen with a diameter of 35 μm and a length of 14 mm was used.

[0057] In Comparative Example 1-1, 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.

[0058] In Comparative Examples 1-2, 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.

[0059] In Comparative Examples 1-3, 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.

[0060] In Comparative Examples 1-4, 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.

[0061] In Comparative Examples 1-5, 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.

[0062] In Comparative Examples 1-6, 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>

[0063] As shown in the configurations of each example above, brush rollers 11 with different bristle density (pile density), bristle diameter (thickness), and bristle length (free length) were prepared. Then, the cleaning performance of chalk adhering to the surface F of a blackboard was evaluated using a cleaning device 10 equipped with each of the brush rollers 11 described above. 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. In addition, in each of the above examples, the rollers 17 were replaced so that the penetration rate (the ratio of the amount of penetration D to the length (free length) L of the bristle 11p) was 50%.

[0064] The cleanability of the blackboard was evaluated as follows: School Chalk White manufactured by Umajirushi Co., Ltd. was used as the chalk, and the MAJI series plain blackboard manufactured by Umajirushi Co., Ltd. was used as the blackboard. Three horizontal lines were drawn on the surface F of the blackboard with chalk, and the amount of remaining cleaning after erasing once with an eraser for chalkboards manufactured by Umajirushi Co., Ltd. was used as the baseline. The amount of remaining cleaning after cleaning the same horizontal lines with the cleaning device 10 was then visually observed. If the amount of remaining cleaning was the same as the baseline, it was rated as △ (usable); if the amount of remaining cleaning was less than the baseline, it was rated as ○ (good); and if the amount of remaining cleaning was more than the baseline, it was rated as × (poor). Cleanability was evaluated on a three-point scale. <Evaluation Results>

[0065] Table 1 shows the composition of the brush bristles 11p and the results of the cleaning performance evaluation.

[0066] The reasons for the results shown in Table 1 will be explained using Figure 5. To improve the cleaning performance of the cleaning device (blackboard eraser), the density (pile density), diameter, and scraping force of each individual brush bristle (11p) are considered important.

[0067] If the pile density is too sparse, the opportunities for contact between the chalk powder H and the brush bristles 11p are reduced, which is thought to decrease cleaning efficiency. Conversely, if the pile density is too high, the movement of the brush bristles 11p is restricted, reducing the ability to scrape out the chalk powder H near the collection section (collection nip section) R1, which is thought to decrease cleaning efficiency. Even when using brush bristles 11p with a diameter of 20 μm and a length of 3 mm, which provide good cleaning efficiency, as in Example 1-1, the pile density is 50 kF / inch. ２ In this case, it can be seen that the cleaning performance decreases due to the pile density being too sparse (Comparative Example 1-1). Also, the pile density is 1000 kF / inch ２ Even when densely packed, the pile density is 500 kF / inch ２ It can be seen that the cleanability tends to decrease compared to the case shown (Examples 1-4).

[0068] Based on the results of the verification experiments mentioned above, the pile density is 70-1000 kF / inch ２ Preferably, it is 70-500 kF / inch ２ It is more preferable that the pile density satisfies these conditions.

[0069] Regarding the diameter (thickness) 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 surface F of the blackboard to scrape out the chalk powder H. Therefore, it is considered that cleaning performance is improved when the diameter of the brush bristles 11p is sufficiently small. Figure 5(a) is a schematic diagram showing how chalk powder H adheres to the surface F of the blackboard. The surface F of the blackboard has fine irregularities, and when lines are drawn on the surface F of the blackboard with chalk, the chalk adheres to the surface F as if being scraped off. Therefore, when erasing lines drawn on the surface F of the blackboard with chalk, it is desirable to scrape out the chalk powder H that is adhering to the fine irregularities of the surface F of the blackboard. Figure 5(b) is a schematic diagram showing the relationship between the brush bristles 11p and the surface F of the blackboard. The surface roughness of the surface F of the blackboard is specified in JIS S6007 as having a maximum contour curve height of 14 μm to 19 μm or less, and the measured average length Rsm of the surface roughness was 50 to 90 μm. If the diameter of the brush bristles 11p is too large, the brush bristles 11p cannot penetrate into the recesses of the blackboard surface F, making it difficult to scrape out the chalk dust H, and thus reducing cleaning efficiency. In Comparative Example 1-2, with a brush bristle diameter of 50 μm, the tip of the brush bristles 11p could not penetrate deep into the recesses of the blackboard surface F, which is thought to have resulted in reduced cleaning efficiency.

[0070] On the other hand, if the diameter of the brush bristles 11p is too small, even if the tip of the brush bristles 11p can get into the recesses of the surface F of the blackboard, the force that scrapes out the chalk dust H will be weak. Furthermore, the brush bristles 11p become thinner and more prone to bending, which can prevent the tip of the brush bristles 11p from getting into the recesses of the surface F of the blackboard, or make the brush bristles 11p more susceptible to permanent deformation. As a result, the cleaning performance is likely to decrease.

[0071] Based on the results of the verification experiments described above, the diameter (thickness) 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 can be obtained.

[0072] The length (free length) of the brush bristles 11p is thought to be determined by the force that scrapes off the chalk dust H adhering to the fine irregularities on the surface F of the blackboard. Focusing on the movement of a single brush bristle 11p, first, when the brush roller 11 rotates and the brush bristles 11p come into contact with the surface F of the blackboard, the frictional force between the brush bristles 11p and the surface F of the blackboard makes the tip of the brush bristles 11p appear to be fixed to the surface F of the blackboard. As the brush roller 11 rotates further, since the tip of the brush bristles 11p is fixed to the surface F of the blackboard, the flexibility of the brush bristles 11p increases, and the reaction force that tries to return the brush bristles 11p to their original position increases. When the reaction force that tries to return the brush bristles 11p to their original position becomes greater than the frictional force acting between the surface F of the blackboard and the tip of the brush bristles 11p, the tip of the brush bristles 11p begins to move as if stroking the surface F of the blackboard. This force becomes the force that scrapes off the chalk dust H.

[0073] Figure 5(c) is a schematic diagram illustrating the behavior of the brush bristles 11p using a cantilever beam model. When the brush bristles 11p before deformation (solid line) are deformed to a deflection amount A (mm) (dotted line), assuming the brush bristles 11p is a cylinder with diameter d (mm), the reaction force Z is expressed by the following equation 1. In equation 1, 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 1)

[0074] Young's modulus is the tensile modulus and is determined by the material. As mentioned above, in each of the above examples, the Young's modulus of the brush bristles 11p is 3500 MPa. Although the amount of deflection A is indeterminate due to the frictional force between the surface F of the blackboard 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 the 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, respectively. 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 chalk dust H adhering to the surface F of the blackboard, and as a result, the cleaning performance 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 bending, causing the brush bristles 11p to move even with only a slight bend, overcoming the frictional force between the tip of the brush bristles 11p and the surface F of the blackboard. As a result, the distance over which the brush bristles 11p move with force is shortened, which is thought to reduce cleaning efficiency.

[0075] 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. When the length of the brush bristles 11p satisfies these conditions, good cleaning performance can be obtained.

[0076] 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 2. In equation 2, 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 2)

[0077] 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 move with momentum, allowing the brush bristles 11p to exhibit strong restorative force after bending. As a result, good cleaning performance is obtained.

[0078] In this embodiment, a configuration using positively charged chalk with calcium sulfate as the main raw material has been described. If calcium carbonate is used as the main raw material and negatively charged chalk is used, nylon or the like may be used as the material for the brush bristles 11p of the brush roller 11, and the cleaning device may be constructed with materials in a charge series that is in the opposite direction to that of this embodiment.

[0079] Thus, in this embodiment, the electrostatic collection device (cleaning device) 10 includes a rotatable brush-shaped collection rotating body 11, which is equipped with brush bristles 11p that come into contact with 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, and a collection member (collection roller) 12 that comes into contact with 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. Furthermore, in this embodiment, the density of the brush bristles 11p in the collection rotating body 11 of the electrostatic collection device 10 is 70 kF / inch ２ Above, 1000kF / inch ２ The following conditions apply: the thickness of the brush bristles 11p is between 9 μm and 35 μm, the free length of the brush bristles 11p is between 1 mm and 14 mm, and when the thickness of the brush bristles 11p is d (mm), the Young's modulus of the brush bristles 11p is E (MPa), and the free length of the brush bristles 11p is L (mm), then the following equation holds: 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３The (MPa·mm) requirement is met. In this embodiment, the electrostatic collection device 10 is configured such that when the amount of penetration of the brush bristles 11p into the cleaning target is calculated by subtracting the nearest-neighbor distance between the base of the free length region of the brush bristles 11p and the cleaning target from the free length of the brush bristles 11p, the ratio of the amount of penetration to the free length of the brush bristles 11p (penetration rate) is 20% or more and 80% or less. In this embodiment, there is a restricting part (roller) 17 that contacts the cleaning target to restrict the amount of penetration. In this embodiment, the density of brush bristles 11p in the collection rotating body 11 is 70 kF / inch ２ Above, 500kF / inch ２ The following is more preferable, and the thickness of the brush bristles 11p is more preferably 15 μm or more and 35 μm or less. In this embodiment, the electrostatic collection device 10 collects chalk dust as the material to be collected from the blackboard as the cleaning target. In this embodiment, the recovery member 12 is rotatable and, by rotating, recovers the material to be collected from the rotating collection body 11 in the recovery section R2.

[0080] As described above, according to this embodiment, the ability to collect materials (chalk dust in this embodiment) adhering to a surface to be cleaned (the surface of a blackboard in this embodiment) with minute irregularities can be improved by the cleaning device (a manual blackboard eraser in this embodiment). Thus, the cleaning device (electrostatic collection device) of this embodiment can stably collect materials regardless of the shape or material of the surface to be cleaned.

[0081] 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.

[0082] In this embodiment, the electrostatic collection device according to the present invention is used as a cleaning device to clean at least some components of the ink on the surface of a whiteboard (here, also simply referred to as "ink"), as an example of its embodiment. In this embodiment, the object to be cleaned by the cleaning device is a whiteboard, and the object to be collected is the ink present on the surface of the whiteboard. <Summary of this embodiment>

[0083] Figure 6 is a schematic diagram showing how a user uses the cleaning device 10 of this embodiment to clean the ink from the surface of a whiteboard. In this embodiment, in Figure 6, the surface to be cleaned F is the surface of the whiteboard, and the object to be collected H is the ink.

[0084] In Example 1, the cleaning device 10 was desired to use a brush roller 11 to scrape off and collect chalk powder, which is the object to be collected, that is adhering to the fine irregularities on the surface of the blackboard, which is the surface to be cleaned F. In contrast, in this example, the surface to be cleaned F is the surface of a whiteboard, which is smooth, and is a major difference from Example 1. Also, in this example, the object to be collected H is ink, which is another difference from Example 1.

[0085] Figure 7 illustrates the composition of a typical whiteboard ink (referred to simply as "ink" here). Before drying, ink H contains a solvent 20, a pigment 21, a resin 22, and a release agent 23. Figure 7(a) shows the state immediately after ink H is applied to the surface F of a whiteboard by drawing lines with ink H. Immediately after ink H is applied to the surface F of the whiteboard, the solvent 20 evaporates into the air, and its amount decreases. During this time, the release agent 23, which is made of a material with high affinity for the surface F of the whiteboard, moves towards the surface F of the whiteboard. A few seconds after ink H is applied to the surface F of the whiteboard, as shown in Figure 7(b), the solvent 20 has substantially evaporated into the air and disappeared. Then, the release agent 23 is unevenly distributed on the surface F side of the whiteboard, and the pigment 21 and resin 22 are unevenly distributed on the side of ink H opposite to the surface F of the whiteboard (the surface side of ink H). When erasing ink H drawn on the surface F of a whiteboard, it is common practice to remove and recover the pigment 21 and resin 22 from the surface F of the whiteboard using a whiteboard eraser made of nonwoven fabric or similar material. In addition, much of the release agent 23 remains on the surface F of the whiteboard, making it less likely for any ink H to remain when erasing ink H drawn on the surface F of the whiteboard again.

[0086] Ink for whiteboards like this generally tends to stick to itself. Therefore, one of the challenges when cleaning the ink H on the surface F of a whiteboard using the cleaning device 10 is that the following phenomenon is likely to occur: In the cleaning direction D1, downstream of the collection section (collection nip section) R1, the ink H grows larger as it is collected by the brush roller 11. Then, the aggregated clumps of ink H tend to slide down the surface F of the whiteboard and fall off.

[0087] The pile density of the brush bristles 11p constituting the brush roller 11 is set to 70-1000 kF / inch, as in Example 1. ２Even within this range, a reasonable effect in suppressing the above problems can be obtained. However, in this embodiment, it is more preferable that the pile density of the brush bristles 11p constituting the brush roller 11 be in the range of 100 to 1000 kF / inch. In this embodiment as well, the diameter (thickness) of the brush bristles 11p is preferably 9 to 35 μm, and more preferably 15 to 35 μm. Other conditions may also be the same as in Example 1. The results of the verification experiment will be described later. <Examples and Comparative Examples>

[0088] Verification experiments were conducted to verify the effects of this embodiment (Example 2-1), as well as embodiments (Examples 2-2 to 2-7) and comparative examples (Comparative Examples 2-1 to 2-6) with different brush bristle 11p configurations from this embodiment. In all examples, the outer diameter of the brush roller 11 was 30 mm, and the axial rotation speed of the brush roller 11 was 100 rpm.

[0089] In this example (Example 2-1), the brush bristles 11p have a pile density of 100 kF / inch. ２ A specimen with a diameter (thickness) of 20 μm and a length (free length) of 3 mm was used.

[0090] 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.

[0091] In Examples 2-3, 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.

[0092] In Examples 2-4, 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.

[0093] 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 35 μm and a length of 14 mm was used.

[0094] In Example 2-6, the brush bristles 11p were used, and the pile density was 200 kF / inch. ２A specimen with a diameter of 20 μm and a length of 6 mm was used.

[0095] 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 1.5 mm was used.

[0096] In Comparative Example 2-1, the brush bristles were set to 11p, and the pile density was 1500 kF / inch. ２ A specimen with a diameter of 20 μm and a length of 3 mm was used.

[0097] 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.

[0098] 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 6 μm and a length of 1 mm was used.

[0099] 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 20 μm and a length of 7 mm was used.

[0100] 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 35 μm and a length of 1 mm was used.

[0101] 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 and ink aggregate fallout>

[0102] Brush rollers 11 with different bristle density 11p, diameter (thickness) 11p, and length (free length) 11p were prepared as in the above examples. Then, the cleaning performance of ink adhering to the surface F of the whiteboard and the fall of ink aggregates were evaluated using the cleaning device 10 equipped with the brush rollers 11 of the above examples. In 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. In addition, in the above examples, the rollers 17 were replaced so that the penetration rate (ratio of penetration amount D to length (free length) L of the bristle 11p) was 50%.

[0103] The cleanability of the whiteboard was evaluated as follows: A nickel enamel board manufactured by PLUS Corporation was used as the whiteboard, and a PLUS Corporation whiteboard marker (medium tip, black) was used as the ink. Three horizontal lines were drawn on the surface F of the whiteboard with the ink, and the amount of remaining cleaned after erasing once with the cleaning device 10 was visually observed. If there was no remaining cleaned area, it was marked with ○ (good), and if any remaining cleaned area was visible, it was marked with × (poor). In addition to the evaluation of cleanability, 20 horizontal lines were drawn on the surface F of the whiteboard with the ink, and the presence or absence of ink clumps falling was observed when the cleaning device 10 was moved from top to bottom. If no ink clumps fell, it was marked with ○ (good), and if ink clumps fell, it was marked with × (poor). <Evaluation Results>

[0104] Table 2 shows the composition of the brush bristles 11p and the evaluation results for cleaning performance and the shedding of ink aggregates.

[0105] The reasons for obtaining the results shown in Table 2 will be explained below.

[0106] If the pile density is too sparse, the opportunities for contact between the brush bristles 11p and the ink H are reduced, which is thought to decrease cleaning efficiency. Even when using brush bristles 11p with a diameter of 20 μm and a length of 3 mm, which provide good cleaning efficiency for blackboards, as in the aforementioned Example 1-1, the pile density is 70 kF / inch. ２In this case, the cleanability of the whiteboard tended to decrease due to the slightly sparse pile density (Example 2-2). On the other hand, when the pile density was 1500 kF / inch ２ When the pile density was increased, cleaning was easier, but clumps of ink fell off (Comparative Example 2-1). This is thought to be due to the following reason: Although the high pile density allows for the removal of ink H from the surface F of the whiteboard, the excessively high pile density restricts the movement of the brush bristles 11p, causing the ink H on the surface F of the whiteboard to come into contact only with the tips of the brush bristles 11p.

[0107] As a result, the ink H is less likely to be collected by the brush bristles 11p, and the ink H accumulates downstream of the collection section (collection nip section) R1 in the cleaning direction D1. When a certain amount of ink H has accumulated, it falls off the surface F of the whiteboard as an aggregated mass of ink.

[0108] Based on the results of the verification experiments mentioned above, the pile density is 70-1000 kF / inch ２ Even so, a reasonable effect can be obtained, but 100-1000 kF / inch ２ It is more preferable to do so. By satisfying these conditions in pile density, good cleanability can be obtained while suppressing the shedding of ink aggregates.

[0109] Regarding the diameter (thickness) of the brush bristles 11p, if the diameter of the brush bristles 11p is too large, even if the pile density is high, tiny gaps will form between the whiteboard surface F and the brush bristles 11p, which is thought to reduce cleaning efficiency. On the other hand, if the diameter of the brush bristles 11p is too small, although it is possible to peel off the ink H from the whiteboard surface F, the contact pressure between the brush bristles 11p and the ink H will be weak, making it difficult to efficiently collect the ink H into the brush roller 11. As a result, it is thought that ink aggregates are more likely to fall off.

[0110] 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 20 to 35 μm. By satisfying these conditions for the diameter of the brush bristles 11p, good cleaning performance can be obtained while suppressing the fall of ink aggregates.

[0111] Similar to Example 1, the material of the fibers constituting the brush bristles 11p is preferably a resin such as polyester, acrylic, polypropylene, PET, or polyurethane, considering durability and abrasion resistance in addition to cleaning properties. The Young's modulus of general resins is 2000 to 9900 MPa, and among these, resins such as polyester, acrylic, polypropylene, PET, and polyurethane, which have excellent durability and abrasion resistance, have a Young's modulus of 2100 to 5000 MPa.

[0112] The length (free length) of the brush bristles 11p is thought to be related to the force that peels off the ink H adhering to the surface F of the whiteboard, and the force that breaks up clumps of ink H upstream of the collection section (collection nip section) R1 in the cleaning direction D1, so that the ink H does not form aggregate clumps.

[0113] Similar to Example 1, if we consider one of the brush bristles 11p as a cantilever beam model, the reaction force Z is E × d ４ / L ３ A correlation can be observed. When the diameter of the brush bristles 11p is thicker and the length is shorter, the reaction force Z is higher, which increases the force that scrapes off the ink H adhering to the surface F of the whiteboard and the force that breaks up the ink clumps. As a result, it is thought that the cleaning performance and the fall of ink clumps will improve. However, if the diameter of the brush bristles 11p is thicker and the length of the brush bristles 11p is too short, the reaction force will be stronger for the same amount of deflection, and once the brush bristles 11p have deflected to a certain extent, they will overcome the frictional force between the tip of the brush bristles 11p and the surface F of the whiteboard and move. As a result, the distance that the brush bristles 11p move with force is shortened, and as a result, it is thought that the cleaning performance will decrease.

[0114] 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 can be achieved while suppressing the fall of ink aggregates.

[0115] 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 2. In equation 2, 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 2)

[0116] By configuring the brush bristles 11p to satisfy these conditions, good cleaning performance can be achieved while suppressing the falling of ink clumps.

[0117] Thus, in this embodiment, the electrostatic collection device (cleaning device) 10 has a density of brush bristles 11p on the collection rotating body 11 of 100 kF / inch. ２ Above, 1000kF / inch ２ The following is more preferable. In this embodiment, the electrostatic collection device 10 collects ink as the object to be collected from the whiteboard as the object to be cleaned.

[0118] As described above, this embodiment provides good cleanability of the whiteboard and suppresses the formation of large clumps from ink particles adhering to each other. As a result, good cleanability can be achieved while suppressing the falling of ink clumps from the brush roller 11. In other words, this embodiment allows for good recovery of collected materials such as ink by suppressing the falling of collected materials such as ink as clumps using the cleaning device.

[0119] 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 paper dust collection device for collecting paper dust from a recording material in an image forming apparatus that forms an image on the recording material, as an example of its embodiment. In the electrostatic collection device (paper dust collection device) of this embodiment, elements having the same or corresponding functions or configurations as those of the electrostatic collection device (cleaning device) of Embodiments 1 and 2 are denoted by the same reference numerals as in Embodiments 1 and 2, and detailed descriptions are omitted. In this embodiment, the object to be cleaned by the electrostatic collection device (paper dust collection device) is the recording material on which an image is formed in the image forming apparatus, and the object to be collected is paper dust. <Image forming apparatus>

[0120] The configuration of the image forming apparatus in this embodiment will now be described. Figure 8 is a cross-sectional view showing the schematic configuration of the electrophotographic image forming apparatus 30 in this embodiment. Figure 9 is a cross-sectional view showing the schematic configuration of the process cartridge 35 used in the image forming apparatus 30 in this embodiment. In this embodiment, the image forming apparatus 30 is a monochrome laser beam printer 30. In this embodiment, paper dust adhering to the sheet P before it passes through the contact area with the photosensitive drum 37, which will be described later, is collected by a paper dust collection device 70 composed of an electrostatic collection device, thereby reducing the amount of paper dust adhering to the photosensitive drum 37. This suppresses the occurrence of problems such as image defects caused by paper dust adhering to the photosensitive drum 37 in excess of the permissible amount.

[0121] The image forming apparatus 30 has a feeding unit 40 for supplying a sheet P, which is a sheet-like recording material (recording medium, transfer material) such as paper, into the image forming apparatus 30. The image forming apparatus 30 also has an exposure device 41 as an exposure means and a process cartridge 35 that forms a toner image (toner image, developer image) to be transferred onto the sheet P. The process cartridge 35 is detachable from the main body 31 of the image forming apparatus 30 and can be replaced, for example, when the toner runs out. The image forming apparatus 30 also has a transfer roller 47 as a transfer means for transferring the toner image from a photosensitive drum 37 provided on the process cartridge 35 to the sheet P. Furthermore, the image forming apparatus 30 has a fixing device 42 as a fixing means for fixing the toner image transferred onto the sheet P to the sheet P. In this embodiment, a paper dust recovery device 70 is provided on the process cartridge 35.

[0122] The feeding unit 40 is located at the bottom of the image forming apparatus 30 and includes a feeding tray 43 as a recording material storage unit, a feeding roller 45 as a feeding member, and a separation roller 44 as a separation transport member. The sheets P stored in the feeding tray 43 are fed out by the feeding roller 45, separated one by one by the separation roller 44, and then transported by a transport roller (not shown). The sheets P being transported by the transport roller have their leading edges abut against the nip portion of the stopped synchronous transport member, the register roller 46, to correct any skew. Subsequently, the sheets P are transported by the register roller 46 towards the transfer nip portion (image transfer portion) Nt formed by the photosensitive drum 37 and the transfer roller 47 provided on the process cartridge 35. <Image Forming Operation>

[0123] The photosensitive drum 37, which is a drum-shaped (cylindrical) photoreceptor (electrophotographic photoreceptor) acting as an image carrier, is driven to rotate clockwise in Figure 6 during the image formation process. The surface of the rotating photosensitive drum 37 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging device 48, which acts as a charging means. The charged surface of the photosensitive drum 37 is exposed to laser light corresponding to the image data emitted from the exposure device 41. As a result, an electrostatic latent image (electrostatic image) corresponding to the image data is formed on the surface of the photosensitive drum 37.

[0124] The electrostatic image formed on the surface of the photosensitive drum 37 is developed (visualized) by a developing device 39, which is a developing means, when toner T is supplied as a developer. The developing device 39 includes a developing container 50 for containing toner T and a developing roller 38 as a developer carrier. The developing device 39 carries the toner in the developing container 50 onto the surface of the developing roller 38 and transports it to the part facing the photosensitive drum 37. The developing device 39 then supplies the toner T carried on the developing roller 38 to the electrostatic latent image formed on the surface of the photosensitive drum 37. As a result, the toner T adheres to the electrostatic latent image formed on the surface of the photosensitive drum 37 and is made visible (developed), forming a toner image on the surface of the photosensitive drum 37. In this embodiment, toner charged with the same polarity as the charging polarity of the photosensitive drum 37 (negative polarity in this embodiment) adheres to the exposed area of ​​the surface of the photosensitive drum 37, where the absolute value of the potential has decreased after being uniformly charged and then exposed.

[0125] Meanwhile, the sheet P is transported to a transfer nip portion Nt formed between the photosensitive drum 37 and the transfer roller 47, in time with the formation of the toner image on the surface of the photosensitive drum 37. Then, at the transfer nip portion Nt, the toner image is transferred from the surface of the photosensitive drum 37 to the surface of the sheet P, which is being transported while being held between the photosensitive drum 37 and the transfer roller 47. During the transfer, a transfer voltage with the opposite polarity to the normal charging polarity of the toner, which is the main charging polarity of the toner during development, is applied to the transfer roller 47. The toner T that remains on the surface of the photosensitive drum 37 and is not transferred to the sheet P is scraped off by the cleaning blade 61, which is a cleaning member constituting the cleaning means, as the photosensitive drum 37 rotates, and is collected in the waste toner container 62. In this way, the surface of the photosensitive drum 37 is cleaned.

[0126] The sheet P onto which the toner image has been transferred is transported to the fixing device 42. The fixing device 42 heats and pressurizes the sheet P as it passes through the fixing device 42, thereby fixing (melting and solidifying) the toner image onto the surface of the sheet P. After passing through the fixing device 42, the sheet P is transported by the transport roller 51, which is a transport member, and then discharged (output) onto the discharge tray 53, which is a discharge unit located at the top of the image forming apparatus 30, by the discharge roller 52, which is a discharge member.

[0127] In this embodiment, the process cartridge 35 is configured to include a photosensitive drum 37, a charging device 48, a developing device 39, a cleaning blade 61, a waste toner container 62, and a paper dust collection device 70, etc. <Paper dust collection device>

[0128] In the image forming apparatus 30 of this embodiment, the surface of the photosensitive drum 37 is in direct contact with paper, which is often used as a sheet P, making it easy for paper dust to adhere to the surface of the photosensitive drum 37. Paper dust contains pulp fibers (cellulose extracted from hardwoods and softwoods), which are the main raw materials of paper. In addition to pulp fibers, paper dust 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. For example, if paper dust gets stuck between the cleaning blade 61 and the photosensitive drum 37, it may cause image defects due to inadequate cleaning. Also, for example, if paper dust is collected in the developing device 39, it may reduce the charge level of the toner in the developing device 39, causing a phenomenon called fogging, where a thin layer of toner adheres to non-image areas, to exceed acceptable limits.

[0129] Therefore, the image forming apparatus 30 in this embodiment is configured to collect paper dust from the surface of the sheet P before it is transported to the contact area (transfer nip portion Nt) with the photosensitive drum 37 by a paper dust collection device 70. In this embodiment, the paper dust collection device 70 is located downstream of the feed tray 43 and upstream of the transfer nip portion Nt in the transport direction of the sheet P. In particular, in this embodiment, as described above, the paper dust collection device 70 is provided on the process cartridge 35.

[0130] As shown in Figure 9, the paper dust collection device 70 is composed of a brush roller 11, a collection roller 12, a blade 13, a storage section (paper dust collection container) 14, and the like. The brush roller 11, the collection roller 12, and the blade 13 each have the same or corresponding functions or configurations as those in Examples 1 and 2.

[0131] The brush roller 11 rotates in the direction of the arrow in Figure 9 (clockwise) when the driving force is transmitted from a motor (not shown) which is a drive source constituting the driving means provided on the main body of the device 31 by a drive transmission member (not shown) which is a drive transmission means constituting the driving means. The recovery roller 12 rotates in the direction of the arrow in Figure 9 (counterclockwise) when the driving force is transmitted from a motor (not shown) which is a drive source constituting the driving means constituting the driving means provided on the main body of the device 31 by a drive transmission member (not shown) which is a drive transmission means constituting the driving means. In other words, in this embodiment, the brush roller 11 rotates in the collection section R1, which is the contact point between the brush portion 11a and the sheet P, such that the direction of movement of the brush portion 11a and the direction of movement (conveying direction) of the sheet P are in the forward direction. In this embodiment, the recovery roller 12 rotates in the recovery section R2, which is the contact point between the brush portion 11a of the brush roller 11 and the recovery roller 12, 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 the forward direction. The brush roller (rotating brush) 11, which has a brush roller shape as a collecting rotating body, is positioned to come into contact with the sheet P as the sheet P passes over it, and collects paper dust, which is the material to be collected, that adheres to the surface of the sheet P. The paper dust collection device 70 may be provided with means for restricting the amount of brush bristles 11p to penetrate the sheet P, which is the material to be cleaned, such as a roller 17 (restricting part), as in the first embodiment. 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, within a width range 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 30.

[0132] Paper dust is often positively charged. Therefore, in this embodiment, as in Embodiment 1, PET was used as the material for the brush bristles 11p constituting the brush roller 11, and PFA was used as the material for the surface layer 12a of the recovery roller 12. Also in this embodiment, as in Embodiment 1, the Young's modulus of the brush bristles 11p formed from PET is 3500 MPa. Furthermore, in this embodiment, the pile density of the brush bristles 11p is 200 kF / inch ２The diameter (thickness) of brush bristles 11p is 20 μm, and the length (free length) of brush bristles 11p is 3 mm.

[0133] Here, the surface roughness Rzjis of typical office paper is about 20 μm, which is close to the surface of the blackboard that was cleaned in Example 1. And, similar to the surface of the blackboard described in Example 1, paper dust that easily falls off the paper adheres to the fine irregularities on the surface of the paper. The brush bristles 11p of the brush roller 11 penetrate these irregularities on the surface of the paper, allowing the paper dust to be collected electrostatically. Therefore, the density, diameter (thickness), and length (free length) of the brush bristles 11p, which are the same as in Example 1, are suitable for collecting paper dust from the sheet P.

[0134] Specifically, for example, the pile density of brush bristles 11p is 70-1000 kF / inch ２ It is preferable to do so. This ensures contact opportunities between the brush bristles 11p and the paper dust, while suppressing a decrease in the ability to scrape off paper dust due to excessive pile density causing the brush bristles 11p to restrain each other. Furthermore, for example, it is preferable that the diameter of the brush bristles 11p be 9 to 35 μm. This makes it easier for the brush bristles 11p to penetrate the irregularities on the surface of the paper and scrape off paper dust. Furthermore, for example, it is preferable that the brush bristles 11p be configured such that they satisfy the following equation 2, where the diameter (thickness) is d (mm), the Young's modulus is E (MPa), and the length (free length) is L (mm): 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３ (MPa·mm) ... (Equation 2)

[0135] This makes it easier to scrape off paper dust by appropriately adjusting the scraping ability of the paper dust and the distance the brush bristles 11p travel across the paper surface. In this embodiment, other preferred and more preferred conditions regarding the brush bristles 11p of the brush roller 11 can also be the same as in Example 1.

[0136] The paper dust collected by the brush roller 11 is transferred to the collection roller 12 by electrostatic force, as in Example 1, scraped off by the blade 13, and collected in the storage section 14.

[0137] In this embodiment, in order to reduce stress caused by friction between the sheet P and the brush roller 11, the rotation direction of the brush roller 11 is set to be in the same direction as the conveying direction of the sheet P.

[0138] Thus, in this embodiment, the electrostatic collection device (paper dust collection device) 70 is provided in the image forming apparatus 30 that forms an image on the recording material (sheet) P, and collects paper dust as the object to be collected from the recording material P, which is the object to be cleaned.

[0139] With the above configuration, paper dust that easily detaches from the sheet P is collected by the brush roller 11, transferred to the collection roller 12, scraped off by the blade 13, and collected in the storage section 14. By collecting the paper dust from the sheet P before it passes through the contact area with the photosensitive drum 37, the amount of paper dust adhering to the photosensitive drum 37 can be reduced. This makes it possible to suppress the occurrence of problems such as image defects caused by paper dust adhering to the photosensitive drum 37 in excess of the permissible amount.

[0140] In this embodiment, the process cartridge 35 was configured to include a paper dust collection device 70, but the configuration is not limited to this. For example, the paper dust collection device 70 may be provided at a position along the transport path of the sheet P before it passes through the contact area with the photosensitive drum 37 of the main body of the device 31. [Other]

[0141] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the embodiments described above.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] Furthermore, in Examples 1 and 2, the collection rotating body and the recovery rotating body of the cleaning device were driven by a motor, but this is not the only way to go. For example, the cleaning device may have a configuration in which the collection rotating body and the recovery rotating body are rotated by the rotational force transmitted from wheels that come into contact with the object to be cleaned and rotate as the cleaning device moves. In such a configuration, the cleaning device may not have a drive source.

[0146] Furthermore, while the cleaning devices in Examples 1 and 2 were used to clean blackboards and whiteboards, respectively, they are not limited to these. The cleaning device may be used to clean any surface to be cleaned, such as walls, desks, or display surfaces. Also, while the cleaning devices in Examples 1 and 2 were handheld, they are not limited to these. The cleaning device may be, for example, a manual vacuum cleaner in which the user holds a handle attached to a device body placed on the floor and pushes it forward to clean the floor. Moreover, the cleaning device is not limited to manual devices that are held or pushed by the user, but may also be a self-propelled robotic vacuum cleaner.

[0147] Furthermore, although the image forming apparatus using the electrostatic collection device in Example 3 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 having multiple image forming units, each equipped with an image carrier. The image forming apparatus may also be a cleanerless configuration that does not have a dedicated cleaning device for removing residual toner from the image carrier. In a cleanerless configuration, residual toner is collected in the developing device, so if paper dust adheres to the image carrier, it is easily collected in the developing device and can cause a decrease in the toner's charge level. Therefore, it is effective to collect the paper dust with a paper dust collection device. The image forming apparatus may also be, for example, an inkjet type image forming apparatus.

[0148] Furthermore, the electrostatic dust collection device can be used for a variety of purposes other than those described above. 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 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 a roller or belt (paper feed roller, transport roller, transport belt, etc.) that transports a recording material by configuring it to bring a collection rotating body into contact with the surface of the roller or belt. Furthermore, the electrostatic dust collection device can be used as a cleaning device in various manufacturing facilities, for example, for cleaning glass substrates and various insulators and conductors. For example, it can be applied to removing dust from the surface of display glass substrates and semiconductor wafers, and to removing dust from the surface of electrostatic adsorption stages that hold these substrates in a vacuum chamber, and the effects of the present invention can be obtained in the same way.

[0149] According to the present invention, a developing apparatus capable of suppressing the occurrence of image defects is provided.

[0150] 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.

[0151] This application claims priority based on Japanese Patent Application No. 2024-169718, 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; and 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, wherein the density of the brush bristles in the collecting rotating body is 70 kF / inch ２ Above, 1000kF / inch ２ The following conditions apply: The thickness of the brush bristles is 9 μm or more and 35 μm or less; the free length of the brush bristles is 1 mm or more and 14 mm or less; and when the thickness of the brush bristles is d (mm), the Young's modulus of the brush bristles is E (MPa), and the free length of the brush bristles is L (mm), then the following equation holds: 1.9 × 10 −６ (MPa・mm)≦E×d ４ / L ３ ≤ 1.6 × 10 −３ An electrostatic collection device that satisfies (MPa·mm).

2. The electrostatic collection device according to claim 1, wherein when the amount of penetration of the brush bristles into the cleaning target is defined as the value obtained by subtracting the nearest distance between the root of the free length region of the brush bristles and the object to be cleaned from the free length of the brush bristles, the ratio of the amount of penetration to the free length of the brush bristles is 20% or more and 80% or less.

3. The electrostatic collection device according to claim 2, further comprising a regulating part that contacts the object to be cleaned and regulates the amount of intrusion.

4. The density of the brush bristles in the collecting rotating body is 70 kF / inch ２ Above, 500kF / inch ２ The electrostatic collection device according to claim 1, wherein the thickness of the brush bristles is 15 μm or more and 35 μm or less.

5. The electrostatic collection device according to claim 4, which collects chalk dust as the object to be collected from a blackboard as the object to be cleaned.

6. The density of the brush hairs in the collection rotor is 100 kF / inch ２ or more and 1000 kF / inch ２ or less. The electrostatic collection device according to claim 1 7. The electrostatic collection device according to claim 6, which collects ink as the object to be collected from a whiteboard as the object to be cleaned.

8. The electrostatic collection device according to any one of claims 1 to 3, for collecting chalk dust as the object to be collected from a blackboard as the object to be cleaned.

9. The electrostatic collection device according to any one of claims 1 to 3, which collects ink as the object to be collected from a whiteboard as the object to be cleaned.

10. An electrostatic collection device according to any one of claims 1 to 3, provided in an image forming apparatus for forming an image on a recording material, and capable of collecting paper dust as the object to be collected from the recording material as the object to be cleaned.

11. The electrostatic collection device according to any one of claims 1 to 3, wherein the collection member is rotatable, and by rotating, the collection unit collects the object to be collected from the collection rotating body.

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