imaging device

Abstract

An image forming apparatus includes a rotatable image bearing member, a developing member that develops an electrostatic latent image at a developing portion, a transfer member that transfers a developer image to a recording member at a transfer portion, and a brush provided with a plurality of substrates that contact the image bearing member downstream of the transfer portion and upstream of the developing portion in a rotation direction of the image bearing member. The developer remaining on the surface of the image bearing member is collected in the developing portion. The average distance between the substrates of the brush is greater than the average particle diameter of the developer and equal to or less than a length corresponding to a specific frequency that is visually recognizable by a user when the user observes an image formed by the image forming apparatus, with respect to a rotation axis direction of the image bearing member.

Description

Technical Field

[0001] The present invention relates to an imaging device for forming an image on a recording material. Background Technology

[0002] In electrophotographic imaging equipment, cleaner-free methods (simultaneous developing and cleaning units) are known, in which toner (developer) remaining on the photosensitive drum and not transferred from the photosensitive drum, which serves as the image-carrying component, to the recording material is collected and reused in the developing section of the developing apparatus. In cleaner-free methods, it is necessary to reduce the possibility that foreign matter such as paper fibers and fillers (hereinafter collectively referred to as "paper scraps") adhering to the photosensitive drum may adversely affect the subsequent imaging process. Japanese Patent Application Publication No. 2021-189358 describes collecting paper scraps on the photosensitive drum through a brush member contact portion on the surface of the photosensitive drum to reduce the amount of paper scraps reaching the charging and developing sections downstream of the transfer section.

[0003] When using the brush component described in the aforementioned application, if a large amount of toner accumulates on the brush component, it may eject toner clumps at a certain point, such as when the contact state of the brush component changes, or when the potential difference between the brush component and the photosensitive drum fluctuates significantly. The toner clumps ejected from the brush component are not completely collected by the developing apparatus and transferred to the recording material, which may lead to image defects.

[0004] On the other hand, if the brush component does not accumulate toner, the paper scrap collection performance may also be reduced. Paper scraps that slide across the brush component may adversely affect the subsequent imaging process, such as hindering uniform charging of the photosensitive drum surface during charging and causing image defects (black spots). Summary of the Invention

[0005] Therefore, the present invention provides an imaging device that can reduce toner buildup while ensuring the paper scrap collection performance of the brush component.

[0006] One embodiment of the present invention is an imaging device comprising: a rotatable image carrier member; a developing member configured to develop an electrostatic latent image formed on the image carrier member using a developing agent at a developing portion; a transfer member configured to transfer a developing agent image developed by the developing member from the image carrier member to a transferee at a transfer portion; and a brush contacting the image carrier member at a position downstream of the transfer portion and upstream of the developing portion relative to the rotation direction of the image carrier member, wherein the developing agent remaining on the surface of the image carrier member is collected in the developing portion, wherein, relative to the rotation axis direction of the image carrier member, the average distance between the substrates of the brush is greater than the average particle size of the developing agent and equal to or less than the length corresponding to a specific frequency that a user can visually recognize when observing an image formed by the imaging device.

[0007] Another embodiment of this invention is an imaging device, comprising: a rotatable image carrier member; a developing member configured to develop an electrostatic latent image formed on the image carrier member using a developing agent at a developing portion; a transfer member configured to transfer a developing agent image developed by the developing member from the image carrier member to a transferee at a transfer portion; and a brush that contacts the image carrier member at a position downstream of the transfer portion and upstream of the developing portion relative to the rotation direction of the image carrier member, wherein the developing agent remaining on the surface of the image carrier member is collected in the developing portion, and wherein the average distance between the substrates of the brush relative to the rotation axis of the image carrier member is greater than the average particle size of the developing agent and is equal to or less than 50 micrometers.

[0008] Other features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of an imaging device according to Embodiment 1 of this application.

[0010] Figure 2 It is a chart that displays the characteristics of human vision.

[0011] Figure 3 This is a schematic diagram of the brush component according to Embodiment 1.

[0012] Figure 4 Part (a) is a schematic diagram of the brush component according to Example 1 when viewed from the front end of the bristle material. Figure 4 Part (b) is a schematic diagram of the brush component as viewed from the upstream side of the rotation direction of the photosensitive drum.

[0013] Figure 5 Parts (a) to (c) are schematic diagrams showing the relationship between the fiber diameter of the brush bristle material and the diameter of the toner particles.

[0014] Figure 6 It is a diagram showing the arrangement of the components. Detailed Implementation

[0015] The following is a description of embodiments according to this application with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic construction example of an imaging device 100 according to one embodiment (Embodiment 1) of this application. The imaging device 100 in this embodiment is a monochrome printer.

[0017] The imaging apparatus 100 has a cylindrical photosensitive component, namely a photosensitive drum 1, which serves as an image carrier. A charging roller 2, which serves as a charging device, and a developing device 3, which serves as a developing device, surround the photosensitive drum 1. An exposure device 4, which serves as an exposure device, is provided between the charging roller 2 and the developing roller 3 shown in the figure. In addition, a transfer roller 5, which serves as a transfer device, presses against the photosensitive drum 1.

[0018] In this embodiment, the photosensitive drum 1 is a negatively charged organic photosensitive component. The photosensitive drum 1 has a photosensitive layer on an aluminum drum-shaped substrate. The photosensitive drum 1 is rotatable about the drum's axis and is driven by a drive unit (not shown) at a predetermined processing speed in the direction of arrow A (clockwise in the figure). In this embodiment, the processing speed corresponds to the circumferential speed (surface movement speed) of the photosensitive drum 1.

[0019] The charging roller 2 contacts the photosensitive drum 1 with a predetermined pressure to form a charging portion P1. During imaging, the charging roller 2 is supplied with a predetermined charging voltage by a high-voltage charging power supply (not shown) that serves as a charging voltage supply device, and the surface of the photosensitive drum 1 is uniformly charged to a predetermined potential. In this embodiment, the photosensitive drum 1 is charged to a negative polarity by the charging roller 2, and its charging potential (the dark area potential of the surface of the photosensitive drum 1 immediately after passing through the charging portion P1) is approximately -700 [V].

[0020] In this embodiment, the exposure device 4 is a laser scanner that outputs a laser beam corresponding to image information input from an external device (such as a host computer) and scans and exposes the surface of the photosensitive drum 1. This exposure forms an electrostatic latent image (electrostatic image) on the surface of the photosensitive drum 1 based on the image information. In this embodiment, the potential of the exposure area (bright area potential) is approximately -100 [V]. The exposure device 4 is not limited to a laser scanner but can be, for example, an LED array, in which multiple LEDs are arranged along the longitudinal direction (axial direction of the cylinder) of the photosensitive drum 1.

[0021] In this embodiment, a contact development method is used as the development method. The development apparatus 3 includes a developing roller 31 as a developer carrier, a toner supply roller 32 as a developer supply device, a developer container chamber 34 containing toner, a stirring member 33 for stirring the toner in the developer container chamber 34, and a developing blade 35. The toner (developer) supplied from the developer container chamber 34 to the developing roller 31 by the toner supply roller 32 is charged to a predetermined polarity when passing through the developing contact portion that contacts the developing blade 35. In this embodiment, a toner with a particle size of 7 micrometers and a normal charging polarity (normal polarity) of negative is used. Although a single-component non-magnetic developer composed of toner is used as the developer in this embodiment, a two-component developer containing a non-magnetic toner and a magnetic carrier can also be used as the developer. A two-component non-magnetic contact / non-contact development method can also be used.

[0022] At the opposite portion (developing portion P2) between the developing roller 31 and the photosensitive drum 1, the toner supplied by the developing roller 31 develops the electrostatic latent image formed on the photosensitive drum 1 into a toner image (developer image). During imaging, a developing high-voltage power supply (not shown), which serves as a developing voltage application device, applies a developing voltage of -400V to the developing roller 31. In this embodiment, the electrostatic latent image is developed by a reverse developing method. In other words, by attaching toner filled with the same polarity as the photosensitive drum 1 to the bright portion of the surface of the photosensitive drum 1 after the charging process, the electrostatic latent image is developed into a toner image, where the charge is reduced due to exposure by the exposure device 4 at the bright portion.

[0023] The transfer roller 5 may be suitably made of an elastic member, such as a sponge rubber formed of polyurethane rubber, ethylene propylene diene monomer (EPDM) rubber, or nitrile rubber (NBR). The transfer roller 5 is pressed against the photosensitive drum 1 to form a transfer portion N, where the photosensitive drum 1 and the transfer roller 5 are pressed together. The transfer roller 5 is connected to a high-voltage power supply (not shown) that serves as a transfer voltage application device, and a predetermined transfer voltage is applied to the transfer roller 5 at a predetermined time. For example, a corona discharge type transfer apparatus can be used as a direct transfer method transfer apparatus.

[0024] When the toner image formed on the photosensitive drum 1 reaches the transfer section N, the transfer material S stacked in the cartridge 6 is fed by the feed unit 7 and then by the alignment rollers 8 to the transfer section N. Various sizes and materials of sheets can be used as the transfer material S (recording material), such as plain paper and cardboard, plastic film, cloth, surface-treated sheets (such as coated paper), and specially shaped sheets (such as envelopes and index paper). The toner image formed on the photosensitive drum 1 is transferred onto the transfer material S by the transfer rollers 5, which are subjected to a transfer voltage.

[0025] The toner image transfer material S, after being transferred, is fed to a fixing unit 9, which serves as a fixing device. In this embodiment, the fixing unit 9 is a film fixing device equipped with a fixing film 91 having a built-in fixing heater and a thermistor (not shown) for measuring its temperature, and a pressure roller 92 for pressurizing the fixing film 91. The fixing unit 9 fixes the toner image by heating and pressurizing the transfer material S. After fixing, the transfer material S passes through the discharge roller pair 10 and is discharged from the machine.

[0026] Between the transfer section N and the charging section P1, a pre-exposure device 12 is provided as a device to eliminate static electricity on the surface of the photosensitive drum 1. This is to stabilize the discharge in the charging section P1 by balancing the uneven charge of the photosensitive drum 1 after it passes through the transfer section N, and to obtain a uniform charging potential.

[0027] Residual transfer toner remaining on the photosensitive drum 1 that was not transferred to the transfer material S is removed in the following process. The residual transfer toner is a mixture of positively charged toner and negatively charged toner, but without sufficient charge. Through discharge in the charging section P1, the residual transfer toner is recharged to a negative polarity. As the photosensitive drum 1 rotates, the residual transfer toner, recharged to a negative polarity in the charging section P1, reaches the developing apparatus 3 and is collected. Therefore, the "brush member" in this embodiment differs from the brush member used as a cleaning unit (drum cleaner) for removing residual toner from the photosensitive drum 1.

[0028] [Toner]

[0029] The toner used in this embodiment is a non-magnetic spherical toner produced by suspension polymerization, with an average particle size of 7 micrometers. The toner particle size has a certain distribution, but over 90% of the toners are between 4 and 10 micrometers. From the perspective of image accuracy and stability, toners with an average particle size of, for example, 4 to 10 micrometers can be appropriately used, with an average particle size of 6 to 8 micrometers being more suitable.

[0030] The following describes a method for measuring the average particle size dt (weight-average particle size) of a toner. The average particle size dt is measured using a Coulter Counter Mixer 3 (registered trademark, owned by Beckman Coulter Ltd., a precision particle size distribution measuring device based on pore resistance and equipped with a 100-micron pore tube), along with accompanying dedicated software for setting measurement conditions and analyzing measurement data using Beckman Coulter Mixer 3 Version 3.51 (Beckman Coulter Ltd.) with 25,000 effective measurement channels. The measurement data are then analyzed and calculated.

[0031] The electrolyte solution used for measurement is a super-grade sodium chloride dissolved in ion-exchanged water at a concentration of approximately 1% by mass; for example, ISOTON II (Beckman Coulter Ltd.) can be used.

[0032] Before measurement and analysis, configure the dedicated software as follows. In the "Change Standard Measurement Method (SOMME) screen" of the dedicated software, set the total count in control mode to 5000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle Size 10.0 μm" (Beckman Coulter). Press the Threshold / Noise Level Measurement button to automatically set the threshold and noise level. Additionally, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTONI I, and check the checkbox for rinsing the orifice tube after measurement. In the "Pulse to Particle Size Conversion Settings screen" of the dedicated software, set the interval interval to logarithmic particle size, the particle size interval to 256 particle size intervals, and the particle size range to 2 μm to 60 μm.

[0033] The specific measurement method is as follows:

[0034] (1) Place approximately 200 mL of the electrolyte solution into a 250 mL round-bottom glass beaker for the Multisizer 3. Place the beaker on the sample stage and stir the stir bar counterclockwise at 24 rpm. Then, use the "Flush Aperture" function of the dedicated software to remove dust and air bubbles from the aperture tube.

[0035] (2) Place about 30 ml of the above electrolyzed solution into a 100 ml flat-bottomed glass beaker. Add about 0.3 ml of a 10% by mass aqueous solution of "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments with pH 7, composed of nonionic surfactants, anionic surfactants and organic detergent builders, manufactured by Wako Pure Chemical Industries, Ltd.) diluted with ion-exchanged water as a dispersant.

[0036] (3) Place 3.3 liters of ion-exchanged water into the tank of a Te tora 150 ultrasonic dispersion system (manufactured by Nikkakoki Bios), which includes two oscillators with an oscillation frequency of 50 kHz, a phase shift of 180 degrees, and an electrical output of 120 watts. Add approximately 2 ml of Contaminon N to the tank.

[0037] (4) Place the beaker from (2) above into the beaker fixing hole of the ultrasonic disperser and start the ultrasonic disperser. Then, adjust the height of the beaker to maximize the resonance state of the electrolyte surface in the beaker.

[0038] (5) While irradiating the electrolyte solution in the beaker in (4) with ultrasound, add a small amount of about 10 mg of toner to the electrolyte solution and disperse it. Then, continue the ultrasonic dispersion process for another 60 seconds. For ultrasonic dispersion, the water temperature in the tank should be adjusted to between 10°C and 40°C.

[0039] (6) Using a pipette, drop the electrolyte solution of (5) above, in which the colorant is dispersed, into the round-bottom beaker of (1) above placed in the sample holder, so that the measured concentration is about 5%. Then measure until the number of particles reaches 5000.

[0040] (7) Analyze the measurement data using the dedicated software provided with the device and calculate the weight-average particle size. When the dedicated software is set to Graphics / Volume %, the "Average Diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen is the weight-average particle size. This weight-average particle size corresponds to the average particle size dt of the toner in this embodiment.

[0041] [Paper scrap removal agency]

[0042] When toner is transferred from photosensitive drum 1 to transfer material S in transfer section N, foreign matter (such as fibers and fillers, i.e., paper scraps) contained in transfer material S may adhere to photosensitive drum 1. In this embodiment, brush member 11 is configured as a paper scrap collection member (foreign matter removal member) to remove paper scraps adhering to photosensitive drum 1. Figure 1 As shown, downstream of the transfer section N and upstream of the charging section P1, the brush member 11 is configured to contact the photosensitive drum 1 in the rotational direction (arrow A). In other words, in the rotational direction of the image carrier member, the brush member 11 in this embodiment contacts the image carrier member at a position downstream of the transfer section N and upstream of the developing section P2. The brush member 11 is supported by a support member (not shown) and positioned in a fixed position relative to the photosensitive drum 1, and slides on the surface of the photosensitive drum 1 as the photosensitive drum 1 rotates.

[0043] The brush member 11 collects paper scraps transferred from the transfer material S to the photosensitive drum 1 at the transfer section N, and reduces the amount of paper scraps moving downstream of the brush member 11 to the charging section P1 and the developing device 3 along the moving direction of the photosensitive drum 1. If the paper scraps are not collected by the brush member 11, they may enter the charging section P1 and interfere with charging. In this case, after passing through the charging section P1, the surface potential of the photosensitive drum 1 becomes lower than the surrounding potential, and the area corresponding to this region on the transfer section S may be unintentionally developed into black. For example, this adverse effect manifests as black spots on a pure white image (full white image).

[0044] If the size of the uncollected paper scraps is small, the aforementioned adverse effects are less severe; however, larger paper scraps tend to exacerbate these adverse effects. The size of the uncollected paper scraps is almost identical to the size of the black dots in the image defect. As described in "Institute of Electronics, Information and Communications Engineers, Knowledge Base, S3 Group, Part 2, Chapter 5," etc. The spatial frequency that the human eye can perceive is 50-60 Hz / degree. At higher spatial frequencies, it is difficult for the human eye to perceive (…). Figure 2 ). Figure 2This demonstrates the contrast sensitivity characteristics of the human eye to sinusoidal grating patterns of different spatial frequencies. The spatial frequency at which the human eye can perceive a pattern is also known as lattice sensitivity.

[0045] Assume a typical user views an image formed on a recording material from a distance of 300mm. In this case, a 1° viewing angle is 300*2π / 360 = 5.235 (mm), and one cycle at a frequency of 50 Hz / degree is 105 micrometers. Since spatial frequency testing is based on the visibility of a black-white-black-white... striped pattern, the thickness of the black portion of the striped pattern is equivalent to 52.5 micrometers, which is half a cycle. In other words, a black area of ​​52.5 micrometers or smaller is not easily discernible to the average user.

[0046] In other words, although it depends on the user's eyesight and the distance from which the user views the image, it can be said that even if a piece of paper with a diameter of about 50 micrometers or smaller slides across the brush member 11, the user will not be able to identify the aforementioned black spots. Conversely, when a piece of paper with a diameter of about 50 micrometers or larger slides across the brush member 11, the black spots begin to become slightly visible. When the diameter of the black spots becomes larger than, for example, 100 micrometers or more, they are easily perceived as image defects. Furthermore, the more black spots there are, the worse the impression of image quality given to the user.

[0047] On the other hand, it is preferable that any residual transfer toner that has reached the brush member 11 moves downstream in the direction of rotation (arrow A) without accumulating (getting stuck) in the brush member 11, and remains attached to the photosensitive drum 1 as much as possible. If the toner adheres to and accumulates on the brush member 11, it will remain on the brush member 11 as a toner lump and will be discharged from the brush member 11 onto the photosensitive drum 1 at an undesirable time, which risks causing image defects. In the following text, the discharge of toner lump from the brush member 11 or the image defects caused by such discharge are also referred to as "toner discharge".

[0048] The toner block may be ejected from the brush member 11 for example, because the contact state between the brush member 11 and the photosensitive drum 1 changes after the drum 1 has stopped rotating and then restarted. If the surface potential of the photosensitive drum 1 fluctuates significantly as the front or rear end of the transfer material S passes through the transfer section N, the contact portion of the brush member 11 may change its contact state, causing the toner block to be ejected. If the amount of toner block ejected onto the photosensitive drum 1 is small, it can be collected by the developing device 3; however, if the amount is large, the developing device 3 may have difficulty collecting the toner. In this case, the uncollected portion of the toner block may be transferred to the transfer material S in the transfer section N, resulting in image defects.

[0049] In other words, brush component 11 should collect as much paper scraps as possible and as little toner as possible.

[0050] [Construction of brush components]

[0051] The brush component 11 in this embodiment is constructed as follows. Figure 3 An external view of the brush member 11 according to this embodiment is shown. The length of the brush member 11 in the width direction (rotation direction of the photosensitive drum 1, arrow A) is set to 5 mm. The length of the brush member 11 in the longitudinal direction (rotation axis direction of the photosensitive drum 1, arrow B) is set to 216 mm. The lengths of the brush member 11 in the longitudinal and width directions are not limited to these and can be varied according to, for example, the maximum paper width of the imaging device. The maximum feed width of the imaging device is the width of the transfer material that the imaging device can form an image on (that can be fed) has the maximum width in the rotation direction of the photosensitive drum 1.

[0052] The brush component 11 has multiple bristle materials (substrates) of conductive 6-nylon filaments 11a serving as the surface of the rub-sensitive drum 1, a base fabric 11b supporting the filaments 11a, and a metal sheet 11c for attaching and securing the base fabric 11b. Besides nylon, rayon, acrylic, polyester, or other materials can be used for the filaments 11a. Conductive filaments 11a are used in this embodiment, but filaments made of insulating materials can also be used. The brush can also be made of textile brush or brush produced by electrostatic injection. A braided brush is used in this embodiment.

[0053] As the photosensitive drum 1 rotates, the brush power supply 13 (which is a device for applying voltage) Figure 1 A bias voltage (brush voltage) of -400V is applied to the metal sheet 11c in this embodiment. The polarity of this brush voltage is the same as the normal charging polarity of the toner attached to the photosensitive drum 1, thus facilitating the passage of toner on the photosensitive drum 1 without collecting it. The brush voltage should be a value having the same polarity as the normal charging polarity of the toner that has passed through the transfer portion N relative to the surface of the photosensitive drum 1. The brush member 11 can be configured such that no brush voltage is applied to it.

[0054] In this embodiment, the length of the filament 11a (bristle length) of the brush member 11 is 5 mm, and the brush member 11 is positioned to penetrate (enter) the surface of the photosensitive drum 1 by 1 mm. Here, the 1 mm penetration (entry) of the brush member 11 means that the shortest distance from the base fabric 11b to the surface of the photosensitive drum 1, measured along the protruding direction of the filament 11a relative to the base fabric 11b, is 1 mm shorter than the length of the filament 11a. In other words, this means that, assuming no interference with the photosensitive drum 1, the brush member 11 is positioned such that the tip of the filament 11a penetrates 1 mm into the virtual cylindrical surface corresponding to the surface position of the photosensitive drum 1.

[0055] The filament 11a used in this embodiment has a fineness of 6d and a density of 180kF / inch. 2 The fineness unit of brush component 11 is "d (denier)," which is the weight of 9000 meters of filament. Higher fineness indicates a larger fiber diameter. Based on microscopic observation, the fiber diameter in this embodiment is 27 micrometers. The density unit of brush component 11 is "kF / inch." 2 "," indicates the number of filaments per square inch. 1 kF / inch 2 It is a density of 1000 filaments per square inch.

[0056] Based on these values Figure 4 Parts (a) and (b) show schematic diagrams of how the brush member 11 contacts the photosensitive drum 1. Figure 4 Part (a) shows the unit area (1 mm²) of the brush member 11 when viewed from directly above (the front end of the wire 11a). 2 A schematic diagram of ). Figure 4 Part (b) is a schematic diagram of the brush component 11 as viewed from upstream in the rotation direction of the photosensitive drum 1.

[0057] In the figure, dens represents the brush density (kF / mm²). 2 D represents the fiber diameter (micrometers) of filament 11a, and I represents the average spacing (micrometers) between fibers in the longitudinal direction. The filament 11a of the brush member 11 in Example 2 has a density of 180 kF / inch. 2 The density can be converted to dens = 279 (F / mm²). 2 Since 1 inch = 25.4 mm. In this embodiment, the leading edges of the filaments 11a are isotropically distributed relative to the width direction (rotation direction of the photosensitive drum 1, arrow A) and longitudinal direction (rotation axis direction of the photosensitive drum 1, arrow B) of the brush member 11. Therefore, by taking the square root of the density dens, we can estimate how many filaments 11a are in contact with the photosensitive drum 1 for a width of 1 mm in the longitudinal direction of the photosensitive drum 1. In this embodiment, √279 = 16.7 (filaments). Since the fiber diameter of the filaments 11a is 27 micrometers, assuming that the filaments 11a are uniformly spaced, the gap between the filaments 11a (the average distance between the bristle materials, hereinafter also referred to as the average distance between fibers) is I = (1000 - 16.7 × 27) / 16.7 = 33 (micrometers).

[0058] Paper scraps larger than the average inter-fiber distance I are physically difficult to slide past the brush member 11. Paper scraps smaller than the average inter-fiber distance I can slide past the brush member 11, but if the size of the paper scrap is 50 micrometers or smaller, due to the characteristics of human vision as described above, as long as the user has the aforementioned normal field of vision, the paper scrap is unlikely to be perceived as a black dot. In other words, if the average inter-fiber distance I is 50 micrometers or smaller, it is possible to collect paper scraps of a size that the user can see. Regarding toner removability, if the average inter-fiber distance I is equal to or greater than the toner particle size, the toner can easily pass through the brush member 11. Specifically, since the average particle size of the toner is 7 micrometers, if the average inter-fiber distance I is greater than 7 micrometers, the brush member 11 is likely to allow the toner to pass through without collecting it.

[0059] [Inspection Method]

[0060] The performance of the brush component 11 in this embodiment was evaluated.

[0061] Using Century Star Paper (product name, manufactured by CENTURY PULP AND PAPER) as the transfer material S, 5000 sheets were printed. Every 100 sheets, a completely white image (pure white image) was printed after the original black image (pure black image). Paper scrap collectability was determined based on the maximum number of speckled images appearing in the pure white image. In this embodiment, when the number of visible black specks is greater than 10, paper scrap collectability is determined as X (unacceptable); when the number is between 3 and 10, it is determined as △ (acceptable); and when the number is less than 3, it is determined as ○ (good).

[0062] For toner ejection, after printing six consecutive images (five full-surface halftone images and one pure white image), the toner ejection performance is checked for image defects caused by toner ejection in the pure white image. If no toner ejection defects are observed, the toner ejection performance is rated as 0 (acceptable); if obvious toner ejection defects are observed, the toner ejection performance is rated as X (unacceptable). When the toner ejection performance is 0, even after 11 consecutive prints of 10 full-surface halftone images and 1 pure white image, if no toner ejection defects are observed in the pure white image, the image is judged as ◎ (good).

[0063] Table 1 shows the relationship between the construction of the brush component 11 in the above study and the performance of paper scrap collection and toner discharge.

[0064] [Table 1]

[0065]

[0066] As shown in Table 1, the construction of Example 1 demonstrates excellent performance in both paper scrap collection and toner discharge. Table 1 also includes results from the following examples, variations, and comparative examples.

[0067] As a variation 1-1, a fineness of 4d and a density of 240kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 21 micrometers, and the average distance between fibers was 31 micrometers. All conditions except for the brush component 11 were the same as in Example 1. As in Example 1, excellent performance in both paper scrap collection and toner discharge was confirmed.

[0068] As variations 1-2, a fineness of 4d and a density of 180kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 21 micrometers, and the average distance between fibers was 39 micrometers. All conditions except for the brush component 11 were the same as in Example 1. As in Example 1, excellent performance in both paper scrap collection and toner discharge was confirmed.

[0069] In Example 1 and its variations described above, the average distance I between fibers is narrow enough to collect paper scraps that the user may perceive as image defects, and good results have been achieved in terms of paper scrap collection. Furthermore, since the average distance I between fibers is greater than the toner size (7 micrometers), good results have also been achieved in terms of toner discharge.

[0070] In Example 2, brush component 11 was prepared using filaments 11a with a finer particle size than those in Example 1 as the bristle material. The fineness was 2d and the density was 180 kF / inch. 2 The fiber diameter is 15 micrometers, and the average distance between fibers is 45 micrometers. Other conditions are the same as in Example 1.

[0071] Evaluation of the brush component 11 in this embodiment shows that it is excellent in paper scrap collection and even superior to Example 1 in terms of toner discharge.

[0072] As a variant example 2-1, a fineness of 2d and a density of 240kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 15 micrometers, and the average distance between fibers was 37 micrometers. All conditions except for the brush component 11 were the same as in Example 1. As in Example 2, this variant exhibited excellent paper scrap collection performance, and its toner discharge performance was even better than that of Example 1.

[0073] The above-described Example 2 and its variations used filaments 11a with a finer diameter than those in Example 1. This is believed to further enhance the expulsion of the toner compared to Example 1. Figure 5Parts (a) to (c) show the relationship between the dimensions of filament 11a and toner t. The surface of the photosensitive drum 1 moves from bottom to top along the direction of arrow A in the figure. Figure 5 Parts (a) to (c) show the behavior of the toner t when the fiber diameter D of the filament 11a of the brush member 11 is varied at three levels.

[0074] In the figure, dt represents the diameter of the toner (micrometers).

[0075] like Figure 5 As shown in part (a), when D < 3dt, even if the toner t impacts the filament 11a of the brush member 11, the curvature of the filament 11a is large (the radius of curvature of the filament 11a surface is small) from the perspective of the toner t, and the toner t is unstable on the filament 11a. Therefore, due to the adhesion force with the photosensitive drum 1 or the frictional force received from the photosensitive drum 1, the toner t moves to one side of the filament 11a (one side of the filament 11a in the longitudinal direction of the brush member 11). The filament 11a cannot adsorb and retain the toner that has moved to the side, and as a result, the toner t is not collected by the filament 11a and easily slides downstream of the brush member 11a.

[0076] When D = 3dt, as Figure 5 As shown in part (b), the curvature of the filament 11a decreases (the radius of curvature of the surface of the filament 11a increases), and the surface area of ​​the photosensitive drum 1 facing the feed direction increases, making it easier for the filament 11a to retain the toner t. Figure 5 As shown in part (c), when D>>3dt, filament 11a can easily retain more toner, and the retained toner will deposit more toner.

[0077] As described above, Examples 2 and Variation 2-1, with a fiber diameter D of 15 micrometers and less than three times the average toner particle size of 7 micrometers, are considered to have particularly excellent toner discharge performance.

[0078] As a comparative example 1, a fineness of 6d and a density of 70kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 27 micrometers, and the average distance between fibers was 69 micrometers. All conditions except for the brush component 11 were the same as in Example 1. In this comparative example, the average distance between fibers was greater than the 50-micrometer diameter of paper scraps visible as image defects, resulting in significantly worse paper scrap collection compared to the above-described examples and variations.

[0079] As a comparative example 2, a fineness of 4d and a density of 120kF / inch were prepared. 2The brush component 11 was tested, and its performance was examined. The fiber diameter was 21 micrometers, and the average distance between fibers was 52 micrometers. All conditions except for the brush component 11 were the same as in Example 1. In this comparative example, the average distance between fibers was slightly greater than the 50-micrometer diameter of the paper scraps visible as image defects, resulting in slightly poorer paper scrap collection.

[0080] As a comparative example 3, a fineness of 2d and a density of 120kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 15 micrometers, and the average distance between fibers was 58 micrometers. All conditions except for the brush component 11 were the same as in Example 1. In this comparative example, the average distance between fibers was greater than the 50-micrometer diameter of paper scraps visible as image defects, resulting in slightly poorer paper scrap collection. However, due to the small fiber diameter, for use... Figure 5 The reasons explained in parts (a) to (c) are that the toner discharge is very good.

[0081] As a comparative example 4, a fineness of 10 d and a density of 70 kF / inch were prepared. 2 The brush component 11 was tested, and its performance was examined. The fiber diameter was 35 micrometers, and the average distance between fibers was 61 micrometers. All conditions except for the brush component 11 were the same as in Example 1. In this comparative example, the average distance between fibers I was greater than the 50-micrometer paper scrap diameter, which is visible as an image defect, resulting in poor paper scrap collection. Furthermore, since the fiber diameter D was 5 times larger than the average particle size dt of the toner, which is 3 times larger than the average particle size dt of the toner, therefore… Figure 5 The situation shown in part (c) is that D >> 3dt, resulting in poor toner discharge. Therefore, a fiber diameter D less than 5 times the average particle size dt of the toner (D < 5dt) is preferred for suppressing toner discharge.

[0082] The above results indicate that embodiments and variations in which the average inter-fiber distance is greater than the average particle size dt (7 micrometers) of the toner and less than the length corresponding to human grid vision (50 micrometers) prevent image defects caused by paper scraps and also exhibit excellent resistance to toner extrusion. In other words, embodiments according to this application can reduce toner accumulation while ensuring the paper scrap collection performance of the collecting component.

[0083] Furthermore, Example 2 and Variation 2, in which the fiber diameter D is less than three times the average particle size dt of the toner (D<3dt), showed particularly excellent toner discharge.

[0084] Although no significant differences were observed in the verification in Table 1, it is believed that the smaller the size of the paper scraps from the brush component 11, the less noticeable the image defects caused by the paper scraps become, even if the user's vision or viewing distance fluctuates. Therefore, an average inter-fiber distance of, for example, 45 micrometers or less is preferred, and 40 micrometers or less is even more preferred.

[0085] Although the toner can pass through the brush member 11 if the average inter-fiber distance is greater than the average particle size of the toner, it is believed that the toner will pass through more easily if the average inter-fiber distance is sufficiently greater than the average particle size than if it is close to the average particle size. From the viewpoint of more reliably reducing toner discharge, it is appropriate, for example, if the average inter-fiber distance of the brush member 11 is at least twice the average toner particle size (7 micrometers), or more preferably at least four times the average toner particle size.

[0086] We have already discussed the preferred value of the average interfiber distance I in the direction perpendicular to the moving direction of the photosensitive drum surface (arrow A) (the longitudinal direction of the brush member 11). The spacing between the bristles of the brush member 11 in the moving direction of the photosensitive drum surface is explained below. The distance between the bristle material in the moving direction of the photosensitive drum surface (average interfiber distance) should be wider than the average interfiber distance I in the longitudinal direction. This allows the toner reaching the brush member 11 to flow more smoothly downstream along the moving direction on the surface of the photosensitive drum 1, making toner discharge less likely. Since the average interfiber distance I (i.e., the fiber spacing in the longitudinal direction of the brush member 11) is important for the collectability of paper scraps, collectability of paper scraps can be maintained even if the fiber spacing in the moving direction of the photosensitive drum surface is slightly wider.

[0087] Specifically, in the case of the textile brush used in Example 1, such as Figure 6 As shown, brush component 11 ( Figure 6 The arrangement of the bristle material bundles at each point on the left should be relatively sparse relative to the direction of movement of the photosensitive drum surface (arrow A), and relatively dense relative to the longitudinal direction of the brush member 11 (arrow B). The position of the bristle material bundles is the starting point of the bundle of bristle 11a supported at the same point on the base fabric 11b.

[0088] If the distance between the strands in the direction of movement on the surface of the photosensitive drum is PA, and the distance between the strands in the longitudinal direction (arrow B) of the brush member 11 is PB, then PA > PB is sufficient. In this figure, it is assumed that, viewed from the normal direction of the base fabric 11b, the filaments 11a in each strand extend almost equally (i.e., isotropically) in all directions, and the number of filaments 11a in each strand is also almost equal.

[0089] In the above embodiments, assuming that the printer user is a general user, such as an office or home printer user, the average distance between the fibers of the brush member 11 is 50 micrometers or less, which corresponds to the grid vision when viewing an image with the naked eye from a distance of 30 cm. However, this is not a limitation; depending on the application of the imaging device, it is normal to view the printed image from a position farther (or closer) than 30 cm. Therefore, the preferred value of the average distance between the fibers of the brush member 11 can vary depending on the average viewing distance of the images primarily output by the imaging device.

[0090] For example, in the case of large-format printers primarily used for printing posters, the average viewing distance is considered to be greater than 30 cm. In this case, if a user views the image formed on the recording material from a distance of 1 meter, the length corresponding to the spatial frequency that the user can recognize (the diameter of the visible black dot) will be approximately 175 micrometers, and therefore the average distance between the fibers of the brush member 11 will be 175 micrometers or less. Conversely, in the case of imaging devices that primarily output images typically viewed using a magnifying glass, for example, the length corresponding to the spatial frequency that the user can recognize (the diameter of the visible black dot) is less than 52.5 micrometers. In this case, it is conceivable to set the average distance between the fibers of the brush member 11 to a predetermined value of less than 50 micrometers.

[0091] The above embodiments have been described using a monochrome printer as an example, but this technology can also be applied to direct transfer color printers. For example, a direct transfer color printer is an imaging device in which multiple processing units are arranged along the feed path of the recording material, and each processing unit is equipped with an image-carrying member (photosensitive drum). In this case, a color image is formed on the recording material by sequentially transferring toner images of each color formed in each processing unit onto the recording material.

[0092] In the above embodiments, a direct transfer method configuration was described, in which the toner image is directly transferred from the photosensitive drum 1 (image carrier) to the transfer material (recording material) serving as the transfer body. However, this technique can also be applied to intermediate transfer imaging devices. In the case of the intermediate transfer method, the transfer member refers to, for example, a transfer roller (primary transfer roller), which performs the primary transfer of the toner image from the photosensitive drum 1, which serves as the image carrier, to the intermediate transfer material, which serves as the transfer object. As the intermediate transfer member, an annular belt member stretched on multiple rollers can be used. The toner image that has been initially transferred to the intermediate transfer member is then transferred a second time from the intermediate transfer member to the sheet (recording material) via a secondary transfer device (e.g., a secondary transfer roller), which forms a secondary transfer clamping portion between the intermediate transfer member and the secondary transfer roller. In this intermediate transfer method configuration, by replacing the transfer roller in the above embodiments with the primary transfer roller, the same effect as in the above embodiments can be obtained.

[0093] According to the present invention, the accumulation of toner can be reduced while ensuring the paper scrap collection performance of the brush component.

[0094] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be interpreted in the broadest sense so as to encompass all such variations and equivalent structures and functions.

Claims

1. An imaging device, comprising: Image-carrying components capable of rotation; The developing member is configured to develop the electrostatic latent image formed on the image carrier member using a developing agent at the developing portion; A transfer member is configured to transfer a developer image developed by a developing member from an image carrier member to a transferable member at a transfer portion. and The brush, whose rotational direction relative to the image-carrying component is downstream of the transfer section and upstream of the developing section, contacts the image-carrying component. The developer remaining on the surface of the image-bearing component is collected in the developing section, and Among them, the average distance between the substrates of the brush is greater than the average particle size of the developer, and equal to or less than 50 micrometers, relative to the rotation axis direction of the image carrier component.

2. The imaging device according to claim 1, wherein the average distance is equal to or less than 45 micrometers.

3. The imaging device according to claim 1, wherein, When the fiber diameter of the substrate of the brush is defined as D (micrometers) and the average particle size of the developer is defined as d (micrometers), the condition D < 5d is satisfied.

4. The imaging device according to claim 1, wherein, When the fiber diameter of the substrate of the brush is defined as D (micrometers) and the average particle size of the developer is defined as d (micrometers), the condition D < 3d is satisfied.

5. The imaging device according to claim 1, wherein, The free ends of the brush substrate are isotropically distributed relative to the rotation axis of the image carrier member and the rotation direction of the image carrier member, and The average distance is the square root of the substrate density.

6. The imaging device according to claim 1, wherein, The average distance of the brush substrate relative to the rotation direction of the image carrier member is greater than the average distance of the brush substrate relative to the rotation axis direction of the image carrier member.

7. The imaging apparatus of claim 1 further includes a voltage application unit configured to apply a voltage to the brush, the polarity of which is the same as the normal charging polarity of the developer passing through the transfer portion relative to the surface potential of the image carrier member.

8. The imaging device according to claim 1, wherein, The material being transferred is the recording material.

9. The imaging device according to claim 1, wherein, The component being transferred is an intermediate transfer component, and The imaging device also includes a secondary transfer component configured to transfer the toner image transferred to an intermediate transfer component onto the recording material.

10. The imaging apparatus of claim 1, further comprising a charging member configured to charge the surface of an image-bearing member. The charging component charges the surface of the image carrier component by contacting the surface of the image carrier component.

11. The imaging device according to claim 1, wherein, The density of the substrate of the brush is greater than 120 kF / inch. 2 .

12. The imaging device according to claim 1, wherein, The density of the substrate of the brush is equal to or greater than 180 kF / inch. 2 .

Images