JP2011102946A - Lubricant supply apparatus, cleaning apparatus, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant supply apparatus for eliminating the problem, wherein the quantity of a lubricant supplied to an image carrier is fluctuated, and the frictional coefficient fluctuates on a surface of the image carrier, even if various conditions fluctuate; and to provide a cleaning apparatus, a process cartridge, and an image forming apparatus. <P>SOLUTION: The lubricant supply apparatus 25 for supplying the lubricant on the image carrier 21 includes: a brush-like rotating member 25b, having a brush bristle circumferentially provided and sliding and contacting the image carrier 21; and a solid lubricant 45 for abutting against the brush bristle of the brush-like rotating member 25b. The brush-like rotating member 25b has a rotational speed which is variably controlled based on one or more conditions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lubricant supply device that supplies a lubricant onto an image carrier such as a photosensitive drum, a photosensitive belt, and an intermediate transfer belt, and a cleaning device, a process cartridge, and an image forming apparatus including the lubricant supply device. Is.

  Conventionally, in an image forming apparatus using an electrophotographic method such as a copying machine, a printer, a facsimile, or a composite machine thereof, the deposits such as untransferred toner adhered on an image carrier such as a photosensitive drum are cleaned. A technique is known that uses a lubricant supply device that supplies a lubricant onto the image carrier in order to reliably clean the device and reduce wear of the image carrier and the cleaning blade (for example, Patent Documents). 1).

  Specifically, the untransferred toner remaining on the image carrier after the transfer process should be completely removed by a cleaning blade (cleaning device) that contacts the image carrier. However, when the cleaning blade deteriorates with time due to contact with the image carrier (abrasion), cleaning failure may occur due to slipping through the gap between the cleaning blade where the untransferred toner is worn and the image carrier. Even when the cleaning blade is not deteriorated, when small toner or spherical toner is used, the toner enters a slight gap between the cleaning blade and the image carrier and eventually passes through the gap. A cleaning failure sometimes occurred. Furthermore, if toner or an external additive or paper dust contained in the toner slips through the gap between the cleaning blade and the image carrier, it adheres to the image carrier and forms a film. There was also.

  In response to such a problem, by applying a lubricant on the image carrier, the friction coefficient on the image carrier is reduced, so that deterioration of the cleaning blade and the image carrier is reduced. Since the removability of deposits such as untransferred toner adhering to the toner is improved, it is possible to suppress the occurrence of poor cleaning and filming over time.

  Specifically, in Patent Document 1 and the like, the lubricant supply device (applying member) includes a brush-like rotating member (applying brush) that makes sliding contact with the image carrier, a solid lubricant that contacts the brush-like rotating member, and a solid lubricant. It is composed of a spring that urges the brush-like rotating member. Then, the lubricant is gradually scraped off from the solid lubricant by the brush-like rotating member rotating in a predetermined direction, and the lubricant scraped off by the brush-like rotating member is applied (supplied) to the surface of the image carrier.

  On the other hand, in Patent Documents 1 and 2 and the like, when the image area of the image formed on the image carrier (photosensitive drum) is small, the toner is input to the cleaning unit to apply to the surface of the image carrier. A technique for optimizing the amount of lubricant to be supplied is disclosed.

The above-described conventional lubricant supply device is used when the image area ratio of the toner image formed on the image carrier is greatly changed, or when the brush bristles of the brush-like rotating member are deteriorated (sagging). When the environment fluctuates, the amount of lubricant supplied onto the image carrier varies, and the coefficient of friction (μ) on the surface of the image carrier may fluctuate.
In particular, if the amount of lubricant supplied from the lubricant supply device onto the image carrier is insufficient and the coefficient of friction on the surface of the image carrier increases, problems such as defective cleaning, cleaning blades, and image carriers Troubles that the body suffers damage, filming on the image carrier, silica that adheres to the image carrier and a “medaka image”, or images on the image carrier The problem that a “worm-eaten image” is generated when the image is transferred by the printer, the problem that a cleaning blade squeals in a low temperature environment, and the like become remarkable.

  The present invention has been made in order to solve the above-described problems. Even when various conditions fluctuate, the amount of lubricant supplied to the image carrier varies, and the surface of the image carrier. It is an object of the present invention to provide a lubricant supply device, a cleaning device, a process cartridge, and an image forming apparatus in which a problem that the friction coefficient of the toner fluctuates is reduced.

  A lubricant supply device according to a first aspect of the present invention is a lubricant supply device for supplying a lubricant onto an image carrier, wherein the brush bristles that are in sliding contact with the image carrier are provided around the brush. And a solid lubricant that contacts the brush bristles of the brush-like rotating member, and the brush-like rotating member is variably controlled based on a single or a plurality of conditions. is there.

  According to a second aspect of the present invention, there is provided the lubricant supply device according to the first aspect, wherein the brush-like rotating member according to an image area ratio of a toner image formed on the image carrier. The number of rotations is variably controlled.

  According to a third aspect of the present invention, there is provided the lubricant supply device according to the second aspect, wherein when the image area ratio is large, the brush-like rotating member is smaller than when the image area ratio is small. The number of rotations is variably controlled so as to increase.

  According to a fourth aspect of the present invention, there is provided the lubricant supply device according to any one of the first to third aspects, wherein the brush according to the travel distance or driving time of the brush-like rotating member. The rotational speed of the rotating member is variably controlled.

  The lubricant supply device according to claim 5 is the invention according to claim 4, wherein the travel distance or the drive time is larger when the travel distance or the drive time is small. The brush-like rotating member is variably controlled so as to increase the rotational speed.

  According to a sixth aspect of the present invention, in the lubricant supply device according to the first to fifth aspects, the rotational speed of the brush-like rotating member is variable according to the ambient temperature. It is to be controlled.

  According to a seventh aspect of the present invention, there is provided the lubricant supply device according to the sixth aspect of the invention, wherein the brush-like rotating member is higher when the ambient temperature is higher than when the ambient temperature is low. The number of rotations is variably controlled so as to increase.

  According to an eighth aspect of the present invention, a cleaning device includes the lubricant supply device according to any one of the first to seventh aspects, wherein the brush-like rotating member is a surface of the image carrier. A cleaning brush that contacts the surface of the image carrier on the downstream side in the running direction of the image carrier relative to the brush-like rotating member.

  A process cartridge according to a ninth aspect of the present invention is a process cartridge which is detachably installed on a main body of an image forming apparatus, and the cleaning apparatus and the image carrier according to the eighth aspect. It is an integrated body.

  An image forming apparatus according to a tenth aspect of the present invention includes the lubricant supply device according to any one of the first to seventh aspects and the image carrier.

  An image forming apparatus according to an eleventh aspect of the present invention includes the cleaning apparatus according to the eighth aspect and the image carrier.

  In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing unit (developing device) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. It is defined as a unit in which at least one of the cleaning unit (cleaning device) and the image carrier are integrated and detachably installed on the image forming apparatus main body.

  In the present invention, since the rotation speed of the brush-like rotating member is variably controlled based on one or more conditions, the amount of lubricant supplied to the image carrier varies, and the surface friction of the image carrier is increased. It is possible to provide a lubricant supply device, a cleaning device, a process cartridge, and an image forming apparatus in which a problem that the coefficient fluctuates is reduced.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an image forming unit in the image forming apparatus of FIG. 1. (A) The graph which shows the relationship between the linear velocity of a brush-like roller, and a lubricant consumption rate, and (B) The graph which shows the relationship between the linear velocity of a brush-like roller, and the surface friction coefficient of a photosensitive drum. (A) The graph which shows the relationship between an image area ratio and the rotation speed of a brush-like roller, and (B) The graph which shows the relationship between an image area ratio and the surface friction coefficient of a photosensitive drum. (A) The graph which shows the relationship between the travel distance of a brush-like roller, and rotation speed, (B) The graph which shows the relationship between the travel distance of a brush-like roller, and the surface friction coefficient of a photoconductive drum. (A) The graph which shows the relationship between ambient temperature and the rotation speed of a brush-like roller, and (B) The graph which shows the relationship between ambient temperature and the surface friction coefficient of a photosensitive drum.

Embodiment.
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is an apparatus main body of a color copying machine as an image forming apparatus, 2 is a writing section (exposure section) that emits laser light based on input image information, and 20Y, 20M, 20C, and 20BK are colors (yellow, magenta). , Cyan, and black), 21 is a photosensitive drum as an image carrier accommodated in each of the process cartridges 20Y, 20M, 20C, and 20BK, 22 is a charging unit that charges the photosensitive drum 21, Reference numerals 23Y, 23M, 23C, and 23BK denote developing devices (developing units) that develop the electrostatic latent image formed on the photosensitive drum 21, and 24 denotes a toner image formed on the photosensitive drum 21 to the intermediate transfer belt 27. A transfer bias roller 25 for transferring, a cleaning device (cleaning unit) for collecting untransferred toner on the photosensitive drum 21, Show.

  In addition, 27 is an intermediate transfer belt on which toner images of a plurality of colors are transferred in an overlapping manner, 28 is a second transfer bias roller for transferring the toner image formed on the intermediate transfer belt 27 to the recording medium P, and 29 is an intermediate transfer belt. 27 is an intermediate transfer belt cleaning unit that collects untransferred toner, 30 is a conveyance belt that conveys a recording medium P on which a four-color toner image is transferred, and 32Y, 32M, 32C, and 32BK are developing devices 23Y and 23M. , 23C and 23BK, a toner replenishing unit for replenishing toner of each color, 51 a document conveying unit for conveying the document D to the document reading unit 55, 55 for a document reading unit for reading image information of the document D, 61 for transfer paper, etc. A paper feed unit for storing the recording medium P, and a fixing unit 66 for fixing an unfixed image on the recording medium P are shown.

Here, each of the process cartridges 20Y, 20M, 20C, and 20BK is a unit in which the photosensitive drum 21, the charging unit 22, and the cleaning device 25 (with a lubricant supply device installed therein) are integrated. is there. The process cartridges 20Y, 20M, 20C, and 20BK are exchanged with respect to the apparatus main body 1 in a predetermined exchange cycle. Similarly, the developing devices 23Y, 23M, 23C, and 23BK are also exchanged with respect to the apparatus main body 1 in a predetermined exchange cycle.
Image formation of each color (yellow, magenta, cyan, black) is performed on the photosensitive drum 21 in each of the process cartridges 20Y, 20M, 20C, and 20BK.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport roller of the document transport unit 51 and placed on the contact glass 53 of the document reading unit 55. Then, the document reading unit 55 optically reads the image information of the document D placed on the contact glass 53.

  Specifically, the document reading unit 55 scans the image of the document D on the contact glass 53 while irradiating light emitted from the illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, an image processing unit (not shown) performs color conversion processing, color correction processing, spatial frequency correction processing, and the like on the basis of RGB color separation image signals, so that yellow, magenta, cyan, and black are processed. Get color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. Then, laser light (exposure light) based on the image information of each color is emitted from the writing unit 2 toward the photosensitive drums 21 of the corresponding process cartridges 20Y, 20M, 20C, and 20BK.

On the other hand, the four photosensitive drums 21 rotate in the clockwise direction in FIG. First, the surface of the photosensitive drum 21 is uniformly charged at a position facing the charging unit 22 (a charging process). Thus, a charged potential is formed on the photosensitive drum 21. Thereafter, the surface of the charged photosensitive drum 21 reaches the irradiation position of each laser beam.
In the writing unit 2, laser light corresponding to the image signal is emitted from the light source corresponding to each color. The laser light is incident on the polygon mirror 3 and reflected, and then passes through the lenses 4 and 5. The laser light after passing through the lenses 4 and 5 passes through different optical paths for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  The laser beam corresponding to the yellow component is reflected by the mirrors 6 to 8 and then irradiated onto the surface of the photosensitive drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 21 by the polygon mirror 3 that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 21 charged by the charging unit 22.

  Similarly, the laser beam corresponding to the magenta component is reflected by the mirrors 9 to 11 and then irradiated to the surface of the photosensitive drum 21 of the second process cartridge 20M from the left side of the paper, thereby causing an electrostatic latent image corresponding to the magenta component. An image is formed. The cyan component laser light is reflected by the mirrors 12 to 14 and then irradiated onto the surface of the photosensitive drum 212 of the third process cartridge 20C from the left side of the drawing to form a cyan component electrostatic latent image. The black component laser light is reflected by the mirror 15 and then irradiated on the surface of the photosensitive drum 21 of the fourth process cartridge 20BK from the left side of the paper, thereby forming an electrostatic latent image of black component.

Thereafter, the surface of the photosensitive drum 21 on which the electrostatic latent images of the respective colors are formed reaches positions facing the developing devices 23Y, 23M, 23C, and 23BK, respectively. Then, the respective color toners are supplied from the developing devices 23Y, 23M, 23C, and 23BK onto the photosensitive drum 21, and the latent image on the photosensitive drum 21 is developed (this is a developing step).
Thereafter, the surface of the photosensitive drum 21 after the development process reaches the position facing the intermediate transfer belt 27 after passing the position facing the photosensor 41 (see FIG. 2). Here, the transfer bias roller 24 is installed at each facing position so as to contact the inner peripheral surface of the intermediate transfer belt 27. Then, at the position of the transfer bias roller 24, the images of the respective colors formed on the photosensitive drum 21 are sequentially superimposed and transferred onto the intermediate transfer belt 27 (first transfer step).

Then, the surface of the photosensitive drum 21 after the first transfer process reaches a position facing the cleaning device 25. Then, the untransferred toner remaining on the photosensitive drum 21 is collected by the cleaning device 25 (this is a cleaning process).
Thereafter, the surface of the photosensitive drum 21 passes through a static elimination unit (not shown), and a series of image forming processes on the photosensitive drum 21 is completed.

On the other hand, the surface of the intermediate transfer belt 27 on which the images of the respective colors on the photosensitive drum 21 are transferred in an overlapping manner travels in the direction of the arrow in the drawing and reaches the position of the second transfer bias roller 28. Then, the full-color image on the intermediate transfer belt 27 is secondarily transferred onto the recording medium P at the position of the second transfer bias roller 28 (second transfer step).
Thereafter, the surface of the intermediate transfer belt 27 reaches the position of the intermediate transfer belt cleaning unit 29. Then, the untransferred toner on the intermediate transfer belt 27 is collected by the intermediate transfer belt cleaning unit 29, and a series of transfer processes on the intermediate transfer belt 27 is completed.

Here, the recording medium P at the position of the second transfer bias roller 28 is transported from the paper feeding unit 61 via the transport guide 63, the registration roller 64, and the like.
Specifically, the transfer paper P fed by the paper feed roller 62 from the paper feed unit 61 that stores the recording medium P passes through the conveyance guide 63 and is guided to the registration roller 64. The recording medium P that has reached the registration roller 64 is conveyed toward the position of the second transfer bias roller 28 in synchronization with the toner image on the intermediate transfer belt 27.

Thereafter, the recording medium P on which the full-color image is transferred is guided to the fixing unit 66 by the conveyance belt 30. In the fixing unit 66, the color image is fixed on the recording medium P at the nip between the heating roller 67 and the pressure roller 68.
Then, the recording medium P after the fixing process is discharged as an output image by the paper discharge roller 69 to the outside of the apparatus main body 1, and a series of image forming processes is completed.

Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIG.
FIG. 2 is a cross-sectional view showing the image forming unit. The four image forming units installed in the apparatus main body 1 have substantially the same structure except that the color of the toner T used in the image forming process is different. Therefore, the alphabet of reference numerals in the process cartridge, the developing device, and the toner replenishing unit. (Y, M, C, BK) is omitted for illustration.
As shown in FIG. 2, the process cartridge 20 mainly contains a photosensitive drum 21 as an image carrier, a charging unit 22, and a cleaning device 25 integrally in a case 26.

Here, the photosensitive drum 21 as an image bearing member is a negatively charged organic photosensitive member, in which a photosensitive layer or the like is provided on a drum-shaped conductive support.
Although not shown, the photosensitive drum 21 has a conductive support as a base layer, an undercoat layer as an insulating layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a protective layer (surface layer) sequentially. Are stacked.
As the conductive support (base layer) of the photosensitive drum 21, a conductive material having a volume resistance of 10 ¹⁰ Ωcm or less can be used.

The photosensitive layer of the photosensitive drum 21 can have a laminated structure or a single layer structure.
First, a case where the photosensitive layer has a laminated structure including a charge generation layer and a charge transport layer will be described.
The charge generation layer is a layer mainly composed of a charge generation material. A known charge generation material can be used for the charge generation layer. Specifically, as the charge generation material, monoazo pigment, disazo pigment, trisazo pigment, perylene pigment, perinone pigment, quinacridone pigment, quinone condensed polycyclic compound, squalic acid dye, other phthalocyanine pigment, na A phthalocyanine pigment, an azulenium salt dye, or the like can be used. These charge generation materials can be used alone or in combination of two or more.
In the charge generation layer, the charge generation material is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is dispersed on the conductive support (or below). It is formed by applying on the pulling layer and drying. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The thickness of the charge generation layer is suitably about 0.01 to 5 μm (more preferably about 0.1 to 2 μm).

  The charge transport layer can be formed by dissolving or dispersing the charge transport material and the binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. If necessary, one or more plasticizers, leveling agents, antioxidants and the like can be added. The amount of the charge transport material is suitably 20 to 300 parts by weight (preferably 40 to 150 parts by weight) with respect to 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably 25 μm or less from the viewpoint of resolution and responsiveness. The lower limit varies depending on the image forming process (particularly, charging potential), but is preferably 5 μm or more.

Next, a case where the photosensitive layer has a single layer structure will be described.
The photosensitive layer having a single-layer structure is obtained by dissolving or dispersing the above-described charge generating substance, charge transporting substance, binder resin, etc. in an appropriate solvent and coating it on a conductive support (or undercoat layer). It can be formed by drying. You may comprise from a charge generation material and binder resin, without containing a charge transport material. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
As the binder resin, in addition to the binder resin used when the charge transport layer is formed, a binder resin used when the charge generation layer is formed may be mixed and used. Furthermore, polymer charge transport materials can also be used favorably. The amount of the charge generating material is preferably 5 to 40 parts by weight with respect to 100 parts by weight of the binder resin, and the amount of the charge transporting material is preferably 0 to 190 parts by weight (more preferably 50 to 150 parts by weight).
The photosensitive layer with a single-layer structure is a dip coating method or spray coating method in which a coating solution in which a charge generating material and a binder resin are dispersed together with a charge transporting material using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane by a dispersing machine. It can be formed by coating with bead coat, ring coat or the like. The film thickness of the photosensitive layer is suitably about 5 to 25 μm.

  The undercoat layer of the photosensitive drum 21 is generally composed mainly of a resin. However, considering that the photosensitive layer is applied with a solvent on these resins, it has a high solvent resistance with respect to a general organic solvent. A resin is desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. A fine powder pigment of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential. In addition, these undercoat layers can be formed using an appropriate solvent and coating method in the same manner as the photosensitive layer described above. The thickness of the undercoat layer is suitably about 0 to 5 μm.

The protective layer of the photosensitive drum 21 is for reducing mechanical wear on the surface of the photosensitive drum 21.
The protective layer in the present embodiment is formed of a binder resin having a crosslinked structure. The crosslinked structure is a three-dimensional network structure formed by using a reactive monomer having a plurality of crosslinking functional groups in one molecule and causing a crosslinking reaction using light or thermal energy. The binder resin having this network structure exhibits high wear resistance. From the viewpoint of electrical stability, printing durability, and life, a monomer having a charge transporting ability can be used in whole or in part as the reactive monomer. By using such a monomer, a charge transport site is formed in the network structure, and the function as a protective layer is sufficiently exhibited.

Examples of the reactive monomer having charge transporting ability include a compound containing at least one charge transporting component and a silicon atom having a hydrolyzable substituent in the same molecule, and a charge transporting component in the same molecule. A compound containing a hydroxyl group, a compound containing a charge transporting component and a carboxyl group in the same molecule, a compound containing a charge transporting component and an epoxy group in the same molecule, a charge transporting component in the same molecule And a compound containing an isocyanate group can be used. These charge transport materials having a reactive group may be used alone or in combination of two or more.
A reactive monomer having a triarylamine structure can also be used as the monomer having a charge transporting ability because of its high electrical and chemical stability and high carrier mobility.
In addition, monofunctional and bifunctional polymerizable monomers and polymerizable oligomers are used in combination for viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, low surface energy, friction coefficient reduction, and other functions. You can also. As these polymerizable monomers and oligomers, known ones can be used.

  The protective layer is formed by polymerizing or crosslinking the hole transporting compound using heat or light. When performing the polymerization reaction by heat, there are cases where the polymerization reaction proceeds only with thermal energy and a polymerization initiator is required, but in order to advance the reaction efficiently at a lower temperature, the initiator Is preferably added. In the case of polymerization by light, it is preferable to use ultraviolet light as light, but the reaction rarely proceeds only by light energy, and a photopolymerization initiator is generally used in combination. The polymerization initiator in this case mainly absorbs ultraviolet rays having a wavelength of 400 nm or less, generates active species such as radicals and ions, and initiates polymerization. In addition, it is also possible to use together the heat | fever and photoinitiator mentioned above.

The protective layer having a network structure formed in this manner has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and may become cracked if it is too thick. In such a case, the protective layer has a laminated structure, a protective layer made of a low molecular weight dispersion polymer is formed on the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure is formed on the upper layer (surface side). You may do it.
As described above, in this embodiment, since the hard protective layer formed of the binder resin having a crosslinked structure is provided on the surface of the photosensitive drum 21, the function as the photosensitive drum 21 is not impaired. In addition, it is possible to prevent the photoconductor film from being scraped by the cleaning blade 25a and the brush-like roller 25b.

  Referring to FIG. 2, the charging unit 22 is a charging roller formed by covering an outer periphery of a conductive metal core with an intermediate resistance elastic layer. A predetermined voltage is applied to the charging roller 22 from a power supply unit (not shown), thereby uniformly charging the surface of the opposing photosensitive drum 21.

  The developing device (developing unit) 23 mainly faces the first conveying screw 23b via the developing roller 23a facing the photosensitive drum 21, the first conveying screw 23b facing the developing roller 23a, and the partition member 23e. The second conveying screw 23c and a doctor blade 23d facing the developing roller 23a are configured. The developing roller 23a includes a magnet that is fixed inside and forms a magnetic pole on the circumferential surface of the roller, and a sleeve that rotates around the magnet. A plurality of magnetic poles are formed on the developing roller 23a (sleeve) by the magnet, and the developer G is carried on the developing roller 23a.

In the developing device 23, a two-component developer G composed of carrier C and toner T is accommodated.
As the toner T, a spherical toner having a circularity of 0.980 or more is used to improve the image quality. The “circularity” is an average circularity measured by a flow type particle image analyzer “FPIA-2000” (manufactured by Toa Medical Electronics Co., Ltd.). Specifically, 0.1 to 0.5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance. Further, about 0.1 to 0.5 g of a measurement sample (toner) is added. Thereafter, the suspension in which the toner is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the dispersion liquid concentration is set to 3000 to 10000 / μl in the above-described analyzer. Then, the shape and distribution of the toner are measured.

As the spherical toner, it is possible to use an irregularly shaped toner (pulverized toner) whose shape is distorted by a pulverization method that has been widely used so far, which is spheroidized by heat treatment or the like, or a toner manufactured by a polymerization method. it can.
When such a spherical toner is used, conventionally, there is a case where a slight gap between the cleaning blade 25a and the photosensitive drum 21 enters the gap and eventually passes through the gap, resulting in poor cleaning. However, in this embodiment, in order to improve the toner peelability (removability) on the photosensitive drum 21 by applying the lubricant to the surface of the photosensitive drum 21 by the lubricant supply devices 25b and 45 to 47, Occurrence of cleaning failure is suppressed.

  The cleaning device 25 includes a cleaning blade 25 a that contacts the photosensitive drum 21, a brush-like roller 25 b as a brush-like rotating member around which the brush bristles are provided around the photosensitive drum 21, and a solid that contacts the brush-like roller 25 b. A lubricant 45, a compression spring 46 that urges the solid lubricant 45 toward the brush roller 25b, a scraper 47 that contacts the brush roller 25b, and the like.

  The cleaning blade 25a is made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 21 at a predetermined angle and a predetermined pressure. As a result, deposits such as untransferred toner adhering to the photosensitive drum 21 are mechanically scraped and collected in the cleaning device 25.

  The brush-like roller 25b serving as the brush-like rotating member has brush hairs wound around the outer periphery of the core metal, and the brush hairs are in contact with the surface of the photosensitive drum 21 in the clockwise direction of FIG. Rotate. Thus, the lubricant is supplied from the solid lubricant onto the photosensitive drum 21 via the brush-like roller 25b. Thus, the brush-like roller 25b, the solid lubricant 45, and the compression spring 46 function as a lubricant supply device.

On the other hand, the brush-like roller 25b also functions as a cleaning brush that scrapes off deposits such as untransferred toner that adhere to the photosensitive drum 21. More specifically, deposits such as untransferred toner adhering to the photosensitive drum 21 are scraped off by the brush-like roller 25 b and then scraped off by the scraper 47 and collected in the cleaning device 25. Here, as the deposits adhered to the photosensitive drum 21, in addition to the untransferred toner, paper dust generated from the recording medium P (paper), discharge products generated on the photosensitive drum 21 during discharge by the charging unit 22. And additives added to the toner.
In the present embodiment, a predetermined voltage can be applied to the brush roller 25b. In such a case, deposits on the photosensitive drum 21 can be electrostatically removed by the brush-like roller 25b to which a voltage is applied.
The configuration and operation of the lubricant supply devices 25b and 45 to 47 will be described in more detail later.

The image forming process described above will be described in more detail with reference to FIG.
The developing roller 23a rotates in the direction of the arrow in FIG. The developer G in the developing device 23 is supplied from the toner replenishing portion 32 to the toner replenishing port by the rotation of the first transport screw 23b and the second transport screw 23c arranged with the partition member 23e interposed therebetween. It circulates in the longitudinal direction while being agitated and mixed with the toner T replenished through 23f (in the direction perpendicular to the paper surface of FIG. 2).

  Then, the toner T that is frictionally charged and adsorbed on the carrier C is carried on the developing roller 23 a together with the carrier C. The developer G carried on the developing roller 23a then reaches the position of the doctor blade 23d. The developer G on the developing roller 23a is adjusted to an appropriate amount at the position of the doctor blade 23d, and then reaches a position facing the photosensitive drum 21 (developing area).

  Thereafter, in the development area, the toner T in the developer G adheres to the electrostatic latent image formed on the surface of the photosensitive drum 21. Specifically, the toner T is latently exposed by the electric field formed by the potential difference (development potential) between the latent image potential (exposure potential) of the image area irradiated with the laser light L and the development bias applied to the development roller 23a. Adhere to the image.

  Thereafter, most of the toner T adhering to the photosensitive drum 21 in the developing process is transferred onto the intermediate transfer belt 27. The untransferred toner T remaining on the photosensitive drum 21 is collected in the cleaning device 25 by the cleaning blade 25a and the brush-like roller 25b. Although not shown, the untransferred toner recovered in the cleaning device 25 is transported toward the waste toner recovery container by the transport coil.

  Here, a toner replenishing unit 32 provided in the apparatus main body 1 includes a toner bottle 33 configured to be replaceable, and a toner hopper unit 34 that holds and rotates the toner bottle 33 and replenishes the developing device 23 with new toner T. And is composed of. Also, a new toner T (any one of yellow, magenta, cyan, and black) is accommodated in the toner bottle 33. In addition, a spiral protrusion is formed on the inner peripheral surface of the toner bottle 33.

  The new toner T in the toner bottle 33 is appropriately replenished into the developing device 23 from the toner replenishing port 23f as the toner T (existing toner) in the developing device 23 is consumed. . The toner T in the developing device 23 is consumed indirectly or directly by the reflective photosensor 41 facing the photosensitive drum 21 and the magnetic sensor 40 installed below the second conveying screw 23c of the developing device 23. Detected.

  Here, in the present embodiment, the toner density (TC) is controlled to be within a predetermined range. Specifically, toner replenishment is performed so that the detection results of the magnetic sensor 40 and the reflection type photosensor 41 have an output value corresponding to the above-described toner density range (the ratio of the toner T in the developer G). The toner is supplied from the unit 32 to the developing device 23 through the toner supply port 23f.

Hereinafter, the configuration and operation of the lubricant supply devices 25b and 45 to 47, which are characteristic in the present embodiment, will be described in detail.
As shown in FIG. 2, the lubricant supply devices 25 b and 45 to 47 are installed integrally with the cleaning device 25. The lubricant supply device includes a brush-like roller 25b (cleaning brush) as a brush-like rotating member around which brush bristles are provided around the photosensitive drum 21, a solid lubricant 45 abutting on the brush-like roller 25b, solid lubricant A compression spring 46 that urges the agent 45 toward the brush-like roller 25b, a scraper 47 that contacts the brush-like roller 25b, and the like. In addition to the original cleaning function, the cleaning blade 25a also has a function of thinning the lubricant applied to the photosensitive drum 21 by the brush roller 25b.

The brush-like roller 25b has a length (bristles) of 0.2 to 20 mm (preferably 0.5 to 10 mm) in which brush hairs are planted on a base cloth in a spiral shape on a core metal Wrapped.
When the length of the brush hair exceeds 20 mm, the brush hair falls down in a predetermined direction due to repeated rubbing with the photosensitive drum 21 over time, and the scraping property of the solid lubricant 45 or from the photosensitive drum 21 is reduced. Toner removability is reduced. On the other hand, if the length of the bristle is less than 0.2 mm, the physical contact force with respect to the solid lubricant 45 and the photosensitive drum 21 is insufficient. Therefore, it is preferable that the length of the bristle is in the above range.

The brush-like roller 25b rotates so as to come into contact with the photosensitive drum 21 rotating in the clockwise direction in FIG. 2 in the counter direction (clockwise rotation in FIG. 2). The brush-like roller 25b is disposed so as to be in sliding contact with the solid lubricant 45 and the photosensitive drum 21, and the brush-like member 25b rotates to scrape off the lubricant from the solid lubricant 45 and lubricate it. An agent is applied on the photosensitive drum 21.
A compression spring 46 is disposed behind the solid lubricant 45 in order to eliminate contact unevenness between the brush-like roller 25b and the solid lubricant 45, and urges the solid lubricant 45 to the brush-like roller 25b. Yes.

In the present embodiment, the solid lubricant 45 is formed of zinc stearate. Specifically, the solid lubricant 45 is preferably prepared by dissolving a lubricating oil additive mainly composed of zinc stearate, having no side effects due to overcoating and having sufficient lubricity.
Zinc stearate is a typical lamellar crystal powder. A lamellar crystal has a layered structure in which amphiphilic molecules are self-organized, and when a shearing force is applied, the crystal breaks along the layers and is slippery. Therefore, the surface of the photosensitive drum 21 can be made low in friction. That is, the surface of the photosensitive drum 21 can be effectively covered with a small amount of lubricant by the lamellar crystal that uniformly receives the shearing force and covers the surface of the photosensitive drum 21.

  In addition to the zinc stearate, the solid lubricant 45 includes stearic acid groups such as barium stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate and the like. The thing which has can be used. In addition, the same fatty acid group zinc oleate, barium oleate, lead oleate, the same compound as stearic acid, zinc palmitate, barium palmitate, lead palmitate, the following compound similar to stearic acid May be used. In addition, caprylic acid, linolenic acid, corinolenic acid and the like can be used as the fatty acid group. In addition, waxes such as candelilla wax, canrunauba wax, rice wax, wax, coconut oil, beeswax, and lanolin can also be used. These easily become organic solid lubricants and have good compatibility with the toner.

When the solid lubricant 45 is applied to the surface of the photosensitive drum 21 via the brush-like roller 25b, a powdery lubricant is applied to the surface of the photosensitive drum 21, but the lubricity is sufficient in this state. Since it is not exhibited, the cleaning blade 25a functions as a member for uniformizing the lubricant. The cleaning blade 25a forms a film of the lubricant on the photosensitive drum 21, and the lubricant exhibits its lubricity sufficiently.
At this time, the finer the powdery lubricant applied by the brush roller 25b, the thinner the thin film on the photosensitive drum 21 by the cleaning blade 25a.

On the other hand, if the powdery lubricant contains coarse powder, removal of toner from the photosensitive drum 21 by the cleaning blade 25a may be hindered. Furthermore, streak-like scratches are generated on the photosensitive drum 21, which shortens the life of the photosensitive drum 21.
In this embodiment, since the brush bristles of the brush-like roller 25b are configured to come into close and uniform contact with the solid lubricant 45 as will be described later, coarse powder is applied to the powder-like lubricant. The included defects will be reduced.

Here, in the present embodiment, referring to FIG. 2, drive motor 70 that rotationally drives brush-like roller 25b (brush-like rotating member) is a variable speed (variable rotation speed) motor. Then, the rotational speed of the brush-like roller 25b is variably controlled based on a plurality of conditions (or a single condition) by the control unit 75 that controls the drive motor 70.
Specifically, the rotational speed of the brush roller 25b depends on the image area ratio of the toner image (image) formed on the photosensitive drum, the travel distance of the brush roller 25b, and the ambient temperature (atmosphere temperature). Variable control.

Hereinafter, the characteristic control described above will be described in detail with reference to FIGS.
FIG. 3A is a graph showing the relationship between the linear velocity of the brush-like roller 25b and the lubricant consumption rate in the lubricant supply device. FIG. 3B is a graph showing the relationship between the linear velocity of the brush-like roller 25 b and the surface friction coefficient of the photosensitive drum 21.
Here, the linear velocity of the brush-like roller 25b is the linear velocity at the sliding contact position with the photosensitive drum 21, and is proportional to the rotational speed of the brush-like roller 25b. Further, the “lubricant consumption rate” is a consumption amount (application amount) of the lubricant with respect to a certain travel distance (in units of 1 km) of the photosensitive drum 21. The surface friction coefficient (μ) of the photosensitive drum 21 is measured by an Euler type friction coefficient measuring method.
From the experimental results shown in FIG. 3A, it can be seen that the lubricant consumption rate by the lubricant supply device increases as the rotation speed (linear speed) of the brush-like roller 25b increases. Further, from the experimental results shown in FIG. 3B, the surface of the photosensitive drum 21 increases with the increase in the amount of lubricant supplied to the photosensitive drum 21 as the rotational speed (linear speed) of the brush roller 25b increases. It turns out that a friction coefficient becomes small.
In this embodiment, the surface friction of the photosensitive drum 21 is controlled as well as the supply amount (application amount) of the lubricant to the photosensitive drum 21 by changing the rotation speed of the brush roller 25b in this way. Utilizing that the coefficient can be controlled, the surface friction coefficient of the photosensitive drum 21 is stably optimized even when various conditions fluctuate.

In the present embodiment, first, when the image area ratio of the toner image formed on the photosensitive drum 21 is large, the rotational speed of the brush roller 25b is higher than when the image area ratio is small. Variable control.
As in the present embodiment, the brush-like roller 25b (brush-like rotating member) that supplies the lubricant onto the photosensitive drum 21 is upstream of the cleaning blade 25a (upstream in the rotational direction of the photosensitive drum 21). ), Untransferred toner before reaching the position of the cleaning blade 25a is input to the brush roller 25b. The toner adhesion state on the brush roller 25 b greatly affects the lubricant polishing ability of the brush roller 25 b for the solid lubricant 45 and the lubricant supply ability of the brush roller 25 b for the photosensitive drum 21. That is, when the image area (image area ratio) of the toner image formed on the photosensitive drum 21 is large, the amount of untransferred toner that remains on the photosensitive drum 21 and is input to the brush roller 25b also increases. Thus, the solid lubricant 45 is easily scraped off by the brush roller 25b due to the toner polishing effect, but the amount of lubricant supplied to the photosensitive drum 21 by the brush roller 25b is reduced. Therefore, the surface friction coefficient (μ) of the photosensitive drum 21 increases.

  This is as shown by the circled (dashed line) graphs in FIGS. 4 (A) and 4 (B). That is, as shown in FIG. 4A, when the rotation speed of the brush-like roller 25b is controlled to be constant regardless of the image area ratio (control in the conventional apparatus), FIG. As shown in B), as the image area ratio increases, the surface friction coefficient of the photosensitive drum 21 increases. Then, as the surface friction coefficient of the photosensitive drum 21 increases, a defect that causes a cleaning failure, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, and a problem that filming occurs on the photosensitive drum 21. In addition, a problem that a “medaka image” is generated due to silica adhering to the photosensitive drum 21, a problem that a “worm-eaten image” is generated when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, There arises a problem that the cleaning blade 25a squeals in a low temperature environment.

On the other hand, in the present embodiment, as indicated by the graph of ■ (solid line) in FIG. 4A, the rotational speed of the brush roller 25b is variably controlled according to the size of the image area ratio (image area). is doing. Specifically, the control is variably performed so that the number of rotations of the brush-like roller 25b increases as the image area ratio increases.
Here, the “image area ratio” is calculated based on image information when an electrostatic latent image is formed on the photosensitive drum 21 by the writing unit 2. Specifically, from the operating rate (duty) of the writing unit 2 that irradiates the laser light L onto the photosensitive drum 21, the control unit 75 sets the image area ratio (= area occupied by the image to which the toner adheres / image formation). Possible total area) is calculated. Then, based on the image area ratio calculated by the control unit 75, the drive motor 70 is controlled, and the rotation speed of the brush-like roller 25b is optimized.
By performing such control, the surface friction coefficient of the photosensitive drum 21 is stably optimized regardless of the change in the image area ratio, as indicated by the solid (solid line) graph in FIG. 4B. be able to. As a result, a problem that causes defective cleaning, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, a problem that filming occurs on the photosensitive drum 21, and silica adheres to the photosensitive drum 21. Thus, there is a problem that a “medaka image” occurs, a problem that a “worm-eaten image” occurs when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, or a problem that the cleaning blade 25a squeals in a low temperature environment. , Etc. are suppressed.
In the present embodiment, when the image area ratio of the image formed on the photosensitive drum 21 is large, the brush-shaped roller 25b is variably controlled so that the number of rotations is high. On the other hand, when the toner T containing zinc stearate is used as the toner T used in the development process, the surface friction coefficient of the photosensitive drum 21 is reduced when the image area is higher than when the image area is low. When the image area ratio of the image formed on the photosensitive drum 21 is small, it is preferable to variably control the rotational speed of the brush roller 25b to be high.

In the present embodiment, secondly, the brush-like roller 25b is variably controlled so that the rotational speed of the brush-like roller 25b is higher when the travel distance of the brush-like roller 25b is larger than when the travel distance is small. The “travel distance” is the total travel distance (cumulative travel distance) since the start of use of the lubricant supply device.
When the brush-like roller 25b is used for a long period of time, the deterioration (sagging) of the brush hair of the brush-like roller 25b increases. The degree of stickiness of the brush roller 25b greatly affects the lubricant polishing ability of the brush roller 25b with respect to the solid lubricant 45 and the lubricant supply ability of the brush roller 25b with respect to the photosensitive drum 21. That is, when the travel distance of the brush-like roller 25b is increased and the bristle of the brush hair is increased, the solid lubricant 45 is hardly scraped by the brush-like roller 25b and is supplied to the photosensitive drum 21 by the brush-like roller 25b. Reduces the amount of lubricant. Therefore, the surface friction coefficient (μ) of the photosensitive drum 21 increases.

  This is as shown by the circled (dashed line) graphs in FIGS. 5 (A) and 5 (B). That is, as shown in FIG. 5A, when the rotational speed of the brush roller 25b is controlled to be constant regardless of the travel distance of the brush roller 25b (control in the conventional apparatus). As shown in FIG. 5B, the surface friction coefficient of the photosensitive drum 21 increases as the travel distance increases. Then, as the surface friction coefficient of the photosensitive drum 21 increases, a defect that causes a cleaning failure, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, and a problem that filming occurs on the photosensitive drum 21. In addition, a problem that a “medaka image” is generated due to silica adhering to the photosensitive drum 21, a problem that a “worm-eaten image” is generated when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, There arises a problem that the cleaning blade 25a squeals in a low temperature environment.

On the other hand, in the present embodiment, as shown by the graph of ■ (solid line) in FIG. 5 (A), the brush-like roller 25b according to the travel distance of the brush-like roller 25b (brush bristle set). The number of rotations is variably controlled. Specifically, variable control is performed so that the rotational speed of the brush-like roller 25b increases as the travel distance increases.
Here, the “travel distance” is calculated by the control unit 75 by multiplying the linear speed (or the number of rotations) of the brush-like roller 25b by the accumulated drive time. Then, based on the travel distance calculated by the control unit 75, the drive motor 70 is controlled, and the rotation speed of the brush-like roller 25b is optimized.
By performing such control, the photosensitive drum 21 is irrelevant to the travel distance of the brush-like roller 25b (the bristle of the brush bristles), as shown by the graph of ■ (solid line) in FIG. 5B. It is possible to stably optimize the surface friction coefficient. As a result, a problem that causes defective cleaning, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, a problem that filming occurs on the photosensitive drum 21, and silica adheres to the photosensitive drum 21. Thus, there is a problem that a “medaka image” occurs, a problem that a “worm-eaten image” occurs when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, or a problem that the cleaning blade 25a squeals in a low temperature environment. , Etc. are suppressed.
In the present embodiment, when the travel distance of the brush-like roller 25b is large, the brush-like roller 25b is variably controlled so that the number of rotations becomes high. On the other hand, when the driving time of the brush-like roller 25b is long, it can be variably controlled so that the number of rotations of the brush-like roller 25b is increased. In the present embodiment, control is performed so that the rotational speed of the brush-like roller 25b gradually increases with time, so that the travel distance during the same drive time becomes larger with time than with the initial time. However, since there is no change in the settling of the brush hair over time, the drive time of the brush roller 25b is used as a substitute characteristic, and the rotational speed of the brush roller 25b can be variably controlled based on this. It becomes possible. The “driving time” at this time is a total driving time (cumulative driving time) after the use of the lubricant supply device is started.

Further, in the present embodiment, thirdly, when the ambient temperature (atmosphere temperature) is high, the control is variably controlled so that the rotational speed of the brush-like roller 25b is higher than when the ambient temperature is low.
Depending on the usage environment (ambient temperature) of the brush roller 25b, the strength of the bristle of the brush roller 25b varies. The firmness of the brush bristles of the brush roller 25b greatly affects the lubricant polishing ability of the brush roller 25b with respect to the solid lubricant 45 and the lubricant supply ability of the brush roller 25b with respect to the photosensitive drum 21. That is, when the ambient temperature becomes low and the stiffness of the brush hair of the brush-like roller 25b becomes strong, the solid lubricant 45 is easily scraped by the brush-like roller 25b and is supplied to the photosensitive drum 21 by the brush-like roller 25b. Increases the amount of lubricant. Therefore, the surface friction coefficient (μ) of the photosensitive drum 21 decreases. On the other hand, when the ambient temperature increases and the stiffness of the brush hair of the brush roller 25b becomes weak, the solid lubricant 45 becomes difficult to be scraped off by the brush roller 25b, and the photosensitive drum 21 is applied to the photosensitive drum 21 by the brush roller 25b. The amount of lubricant supplied is reduced. Therefore, the surface friction coefficient (μ) of the photosensitive drum 21 increases.

  This is as shown by the circled (dashed line) graphs in FIGS. 6 (A) and 6 (B). That is, as shown in FIG. 6A, when the rotation speed of the brush roller 25b is controlled to be constant regardless of the ambient temperature (control in a conventional apparatus), FIG. ), The surface friction coefficient of the photosensitive drum 21 increases as the ambient temperature increases. Then, as the surface friction coefficient of the photosensitive drum 21 increases, a defect that causes a cleaning failure, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, and a problem that filming occurs on the photosensitive drum 21. In addition, a problem that a “medaka image” is generated due to silica adhering to the photosensitive drum 21, a problem that a “worm-eaten image” is generated when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, There arises a problem that the cleaning blade 25a squeals in a low temperature environment.

On the other hand, in the present embodiment, as indicated by the graph (1) (solid line) in FIG. 6 (A), the rotational speed of the brush roller 25b is variably controlled according to the ambient temperature. Specifically, the control is variably controlled so that the number of rotations of the brush-like roller 25b increases as the ambient temperature increases.
Here, the “ambient temperature” is detected by a temperature sensor 78 installed in the apparatus main body 1. Then, the result detected by the temperature sensor 78 is sent to the control unit 75, and the drive motor 70 is controlled by the control unit 75 based on the result, and the rotation speed of the brush roller 25b is optimized.
By performing such control, the surface friction coefficient of the photosensitive drum 21 can be stably optimized regardless of the ambient temperature as shown by the solid (solid) graph in FIG. 6B. Can do. As a result, a problem that causes defective cleaning, a problem that damage to the cleaning blade 25a and the photosensitive drum 21 increases, a problem that filming occurs on the photosensitive drum 21, and silica adheres to the photosensitive drum 21. Thus, there is a problem that a “medaka image” occurs, a problem that a “worm-eaten image” occurs when an image on the photosensitive drum 21 is transferred onto the intermediate transfer belt 27, or a problem that the cleaning blade 25a squeals in a low temperature environment. , Etc. are suppressed.

  In the present embodiment, the image area ratio of the toner image formed on the photosensitive drum, the travel distance of the brush roller 25b, and the ambient temperature (atmosphere temperature) are each based on three conditions. The rotational speed of the brush roller 25b is variably controlled. Here, when at least two of the three conditions are mutually contradictory (for example, when the image area ratio is high and the ambient temperature is low), the control unit 75 From the data shown in FIGS. 4 to 6, the rotational speed of the brush roller 25b so that the surface friction coefficient of the photosensitive drum 21 becomes an optimum value (in the present embodiment, μ≈0.11). Is variably controlled.

In the present embodiment, the image area ratio of the toner image formed on the photosensitive drum, the travel distance of the brush roller 25b, and the ambient temperature (atmosphere temperature) are each based on three conditions. Thus, the rotational speed of the brush roller 25b is variably controlled. In contrast, any one of the three conditions of the image area ratio of the toner image formed on the photosensitive drum, the travel distance of the brush roller 25b, and the ambient temperature (atmosphere temperature) is selected. The rotational speed of the brush-like roller 25b can be variably controlled based only on the condition or based on any two conditions.
Even in such a case, the surface friction coefficient of the photosensitive drum 21 can be stably optimized as in the present embodiment.

  In the present embodiment, the image area ratio of the toner image formed on the photosensitive drum, the travel distance of the brush roller 25b, and the ambient temperature (atmosphere temperature) are each based on three conditions. The rotational speed of the brush roller 25b is variably controlled. However, the application of the present invention is not limited to the above three conditions. That is, it is possible to perform variable control of the rotational speed of the brush roller 25b by adding other conditions that affect the lubricant supply performance of the brush roller 25b (or by using other conditions alone). For example, when the ambient humidity affects the lubricant supply performance of the brush roller 25b, the rotational speed of the brush roller 25b can be variably controlled according to the ambient humidity.

  As described above, according to the present embodiment, since the rotational speed of the brush-like roller 25b (brush-like rotating member) is variably controlled based on a predetermined condition, the photosensitive drum 21 (image carrier). It is possible to reduce a problem that the amount of lubricant supplied to the upper surface varies and the friction coefficient of the surface of the photosensitive drum 21 varies.

In the present embodiment, the cleaning device 25 (or the lubricant supply device) is integrated with the photosensitive drum 21 and the charging unit 22 to constitute the process cartridge 20 to make the image forming unit compact and perform maintenance work. We aim to improve sex. Thus, in a compact process cartridge, a lubricant supply device having a small number of parts and a simple configuration as in the present embodiment is particularly useful.
Note that the cleaning device 25 (or the lubricant supply device) may be configured to be replaceable in the apparatus main body 1 as a single unit without being a component of the process cartridge. Even in such a case, the same effect as the present embodiment can be obtained.
In the present embodiment, the present invention is applied to an image forming apparatus equipped with a two-component developing type developing device 23 using a two-component developer. However, a one-component developing type using a one-component developer is used. Of course, the present invention can also be applied to an image forming apparatus equipped with the developing device 23.
Furthermore, in the present embodiment, the present invention is applied to a lubricant supply device that supplies a lubricant to a photosensitive drum as an image carrier. However, the photosensitive belt or intermediate transfer belt as an image carrier is lubricated. Naturally, the present invention can also be applied to a lubricant supply device that supplies a lubricant.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 image forming apparatus body (apparatus body),
20, 20Y, 20M, 20C, 20BK Process cartridge,
21 Photosensitive drum (image carrier),
25 Cleaning device (lubricant supply device),
25a Cleaning blade,
25b brush-like roller (brush-like rotating member, cleaning brush),
45 solid lubricant,
46 compression spring,
47 Scraper,
70 Drive motor.

JP 2006-139111 A JP 2003-241570 A

Claims (11)

A lubricant supply device for supplying a lubricant onto an image carrier,
A brush-like rotating member around which brush bristles slidingly contact the image carrier;
A solid lubricant that contacts the brush bristles of the brush-like rotating member;
With
The lubricant supply device according to claim 1, wherein the rotational speed of the brush-like rotating member is variably controlled based on one or more conditions.   The lubricant supply device according to claim 1, wherein the rotational speed of the brush-like rotating member is variably controlled in accordance with an image area ratio of a toner image formed on the image carrier.   3. The lubricant supply according to claim 2, wherein when the image area ratio is large, the number of rotations of the brush-like rotating member is variably controlled so as to be higher than when the image area ratio is small. apparatus.   The lubricant supply device according to any one of claims 1 to 3, wherein the number of rotations of the brush-like rotating member is variably controlled according to a travel distance or a driving time of the brush-like rotating member. .   5. The variable control is performed such that when the travel distance or the drive time is large, the number of rotations of the brush-like rotating member is higher than when the travel distance or the drive time is small. The lubricant supply device according to 1.   The lubricant supply device according to any one of claims 1 to 5, wherein the rotational speed of the brush-like rotating member is variably controlled in accordance with an ambient temperature.   The lubricant supply according to claim 6, wherein the lubricant supply is variably controlled so that the rotational speed of the brush-like rotating member is higher when the ambient temperature is higher than when the ambient temperature is low. apparatus. The lubricant supply device according to any one of claims 1 to 7,
The brush-like rotating member is a cleaning brush that cleans the surface of the image carrier,
A cleaning apparatus comprising a cleaning blade that contacts the surface of the image carrier on the downstream side of the image carrier with respect to the brush-like rotating member. A process cartridge that is detachably installed on the main body of the image forming apparatus,
9. A process cartridge in which the cleaning device according to claim 8 and the image carrier are integrated.   An image forming apparatus comprising the lubricant supply device according to claim 1 and the image carrier.   An image forming apparatus comprising the cleaning device according to claim 8 and the image carrier.

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