JP4632811B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a composite machine thereof, and in particular, an image provided with a lubricant supply means for supplying a lubricant onto an image carrier. The present invention relates to a forming apparatus.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a lubricant is supplied onto an image carrier so that untransferred toner remaining on the image carrier such as a photosensitive drum is reliably cleaned by a cleaning unit. A technique is known (see, for example, Patent Document 1).

  Specifically, the untransferred toner remaining on the image carrier after the transfer process should be completely removed by a cleaning blade (cleaning unit) 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, when the toner or an external additive such as a release agent or a fluidizing agent contained in the toner passes through the gap between the cleaning blade and the image carrier, it adheres to the film on the image carrier and forms a film. Sometimes occurred.

  In response to such a problem, by applying a lubricant composed of a fatty acid metal salt or the like on the image carrier, the friction coefficient on the image carrier is reduced, and the deterioration of the cleaning blade is reduced. Since the removability of untransferred toner and external additives adhering to the body is improved, it is possible to suppress the occurrence of poor cleaning and filming over time.

  On the other hand, in Patent Document 2 and the like, when an existing image carrier installed in the image forming apparatus main body is replaced with a new one, the amount of lubricant applied on the new image carrier is initial. In order to prevent shortage, a technique for supplying a lubricant onto the image carrier immediately after the replacement with a new image carrier and before the start of the image forming operation is disclosed.

JP 2000-75745 A JP 2001-343861 A

  The conventional technology described above cannot sufficiently prevent the occurrence of filming when the existing image carrier installed in the image forming apparatus main body is replaced with a new one.

  That is, when the existing image carrier installed in the main body of the image forming apparatus is replaced with a new one, the amount of lubricant applied on the new image carrier is initially insufficient. In addition, the adhesion of toner and external additives to the image carrier could not be sufficiently reduced. Therefore, the toner and external additives are not sufficiently removed by the cleaning unit, and filming has occurred on the image carrier. Filming once generated on the image carrier is difficult to remove with a cleaning blade or the like. In addition, when filming occurs on the image carrier, a secondary defect that a white spot occurs in the solid portion of the image and an abnormal image is output occurs.

  On the other hand, in the technique disclosed in Patent Document 2 and the like, the lubricant is supplied onto the image carrier immediately after the replacement with a new image carrier and before the image forming operation is started. In addition, the effect of suppressing the occurrence of filming due to insufficient supply of lubricant can be expected to some extent.

  However, since the image carrier is integrated as a process cartridge together with the developing unit in the technique of Patent Document 2 and the like, the toner stored in the developing unit at the same time as the replacement of the image carrier is also a new one. . However, the existing toner that has been used to some extent in the developing unit and deteriorated toner has a disadvantageous effect on filming compared to a new toner, and therefore when there is deteriorated toner in the developing unit, Even if the lubricant is supplied onto the image carrier immediately after the replacement, there is a high possibility that the occurrence of filming cannot be sufficiently suppressed.

That is, when the replacement cycle of the image carrier and the developing unit is different, there is a possibility that the occurrence of filming cannot be sufficiently suppressed even if the lubricant is supplied to the new image carrier immediately after the replacement. it was high.
In recent years, in order to achieve high image quality of an output image, a small particle size / spherical toner is often used, and thus the above-mentioned problem cannot be particularly ignored.

  The present invention has been made to solve the above-described problems. Even when the exchange cycle between the image carrier and the developing unit is different, the existing image carrier installed in the image forming apparatus main body is provided. An object of the present invention is to provide an image forming apparatus capable of sufficiently suppressing the occurrence of filming when the body is replaced with a new one.

  An image forming apparatus according to a first aspect of the present invention is an image forming apparatus in which an image carrier is installed in a replaceable manner, and contains a developer composed of a carrier and a toner, and the image carrier. A developing unit that develops a latent image formed thereon to form a toner image; and a lubricant supply unit that supplies a lubricant onto the image carrier, wherein the image carrier is an existing one. When replacing with a new one, with the existing image carrier installed, a part or all of the existing toner stored in the developing unit is discharged from the developing unit and then new A control mode for supplying the toner to the developing section.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the new image bearing member is replaced when the image bearing member is replaced with a new one. In a state in which the new image carrier is not developed by the developing unit, the lubricant supply means supplies the lubricant to the new image carrier for a predetermined time. It is provided.

  According to a third aspect of the present invention, there is provided an image forming apparatus according to the second aspect, further comprising: a new article detecting unit that detects that the new image carrier is installed, and the second control mode. Starts with a detection signal from the new article detection means as a trigger.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects of the present invention, the control mode is performed only on the existing toner on the existing image carrier. The toner image is formed and the existing toner is discharged.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects of the present invention, the usage detecting means for detecting the usage of the image carrier in the apparatus main body is provided. The control mode is started when a detection result by the usage detection means reaches a predetermined value.

  An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the fifth aspect of the present invention, wherein the usage detection means is configured to operate time or image formation in a state where the image carrier is installed in the apparatus main body. This is a means for detecting the number of times.

  An image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to the fifth or sixth aspect, wherein the existing image is detected when a detection result by the usage detection means reaches a predetermined value. The fact that the carrier is at the end of its life is displayed on the display unit of the apparatus main body.

  The image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to any one of the first to seventh aspects, wherein the control mode is a toner of the developer when the control mode is started. The density is detected as the toner density at the time of replacement, and the existing toner is discharged until the toner density of the developer decreases to a predetermined value, and then the toner density of the developer increases to the toner density at the time of replacement. The new toner is replenished.

  An image forming apparatus according to a ninth aspect of the present invention is the image forming apparatus according to any one of the first to eighth aspects, wherein the lubricant supply means is a lubricant molded body in which the lubricant is solidified. And a brush-like roller in contact with the lubricant molded body and the image carrier.

  According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the lubricant supply means applies the lubricant molded body to the brush roller at a pressure of 200 mN or more. A biasing member for biasing is further provided.

  An image forming apparatus according to an eleventh aspect of the present invention is the image forming apparatus according to the ninth or tenth aspect, wherein the brush-shaped roller is in contact with the brush-shaped roller and the image carrier. The linear velocity ratio of the image carrier is configured to be in the range of 0.8 to 1.2.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the ninth to eleventh aspects, the brush-like roller cleans untransferred toner remaining on the image carrier. This is a cleaning roller.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the first to twelfth aspects, the lubricant is supplied to the image carrier by the lubricant supply means. This is performed in conjunction with the driving of the image carrier.

  An image forming apparatus according to a fourteenth aspect of the present invention is the image forming apparatus according to any one of the first to thirteenth aspects, wherein the toner has an average circularity in a range of 0.93 to 1.00. It is formed as follows.

  The image forming apparatus according to a fifteenth aspect of the present invention is the image forming apparatus according to any one of the first to fourteenth aspects, wherein the toner has a shape factor SF-1 in the range of 100 to 180. The shape factor SF-2 is formed in the range of 100 to 180.

  An image forming apparatus according to a sixteenth aspect of the present invention is the image forming apparatus according to any one of the first to fifteenth aspects, wherein the toner is a spherical toner formed in a spherical shape. It is.

The image forming apparatus according to claim 17 is the image forming apparatus according to claim 16, wherein the spherical toner has a length in the major axis direction as r1 and a length in the minor axis direction as r2. When the thickness is r3,
0.5 ≦ r2 / r1 ≦ 1.0
0.7 ≦ r3 / r2 ≦ 1.0
It is formed so that the following relationship is established.

An image forming apparatus according to an eighteenth aspect of the present invention is the image forming apparatus according to any one of the first to seventeenth aspects, wherein the toner has an average primary particle size in the range of 50 to 300 nm. Silica fine particles having a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles.

  The image forming apparatus according to claim 19 is the polyester prepolymer or polyester according to any one of claims 1 to 18, wherein the toner has a functional group containing at least a nitrogen atom. The toner material liquid in which a colorant and a release agent are dispersed in an organic solvent is crosslinked and / or elongated in an aqueous medium.

  An image forming apparatus according to a twentieth aspect of the present invention is the image forming apparatus according to any one of the first to nineteenth aspects, wherein the image carrier includes a charging unit that charges the image carrier; The process cartridge is integrated with at least one of a cleaning unit for cleaning the image carrier and the lubricant supply unit, and the process cartridge is installed in a replaceable manner with respect to the apparatus main body. Is.

  In the present invention, when the image carrier has reached the end of its life, etc., when the image carrier is exchanged from an existing one to a new one, the existing toner in the developing unit remains installed. The toner is discharged and replaced with new toner. As a result, even when the exchange cycle between the image carrier and the developing unit is different, filming occurs when the existing image carrier installed in the image forming apparatus main body is replaced with a new one. Can be provided.

Embodiment.
Hereinafter, the best mode 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 represents a cleaning unit for collecting untransferred toner on the photosensitive drum 21.

  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 feeding unit 66 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 integrated with a photosensitive drum 21, a charging unit 22, and a cleaning unit 25 (with a lubricant molded body 45 and the like provided therein). Is. The process cartridges 20Y, 20M, 20C, and 20BK are exchanged with respect to the apparatus main body 1 in a predetermined exchange cycle based on the life of the photosensitive drum 21. Similarly, the developing devices 23Y, 23M, 23C, and 23BK are also replaced with a predetermined replacement cycle with respect to the apparatus main body 1 based on the lifetime of the developer. Note that the process cartridges 20Y, 20M, 20C, and 20BK and the developing devices 23Y, 23M, 23C, and 23BK are naturally replaced when a component is damaged in addition to a predetermined replacement 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 to the surface of the photosensitive drum 12 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 to 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 developing process reaches a position facing the intermediate transfer belt 27 after passing through a position facing the photo sensor 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 unit 25. The untransferred toner remaining on the photosensitive drum 21 is collected by the cleaning unit 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 FIGS. FIG. 2 is a cross-sectional view showing the image forming section, and FIG. 3 is a cross-sectional view in the longitudinal direction (the direction perpendicular to the paper surface of FIG. 2) showing the developing device.
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 unit 25 integrally in a case 26.
Here, the photosensitive drum 21 has a base tube made of aluminum as a base layer, and a CGL layer (charge generation layer), a CTL layer (charge transport layer), and the like are formed thereon.

  The cleaning unit 25 is a cleaning blade 25 a that contacts the photosensitive drum 21, a cleaning roller 25 b as a brush roller, a lubricant molded body 45 that contacts the cleaning roller 25 b, and an urging member that biases the lubricant molded body 45. The compression spring 46, the scraper 47 that contacts the cleaning 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, the untransferred toner remaining on the photosensitive drum 21 is mechanically scraped and collected in the cleaning unit 25.

The cleaning roller 25 b (brush-shaped roller) is formed by winding brush fibers around the outer periphery of the core metal, and the brush is in contact with the surface of the photosensitive drum 21. As a result, the untransferred toner remaining on the photosensitive drum 21 is scraped off by the brush and collected in the cleaning unit 25.
Note that a predetermined voltage may be applied to the cleaning roller 25b by using the brush of the cleaning roller 25b as a conductive brush. In this case, the toner on the photosensitive drum 21 is electrostatically removed by the cleaning roller 25b to which a voltage is applied.

  The scraper 47 contacts the brush of the cleaning roller 25b and scrapes off the toner collected by the cleaning roller 25b into the cleaning unit 25. The toner scraped off is transported to a discharge port by a transport auger (not shown), and then transported to a waste toner bottle (not shown) installed outside the image forming unit.

The lubricant molded body 45 is obtained by solidifying (molding) a lubricant such as zinc stearate in a block shape, and is in contact with the cleaning roller 25 b with a predetermined pressure by the spring force of the compression spring 46. Thus, the molded lubricant 45 is appropriately scraped off by the brush roller 25b, and the scraped lubricant is supplied (applied) onto the photosensitive drum 21 by the cleaning roller 25b. That is, the supply of the lubricant onto the photosensitive drum 21 is performed in conjunction with the rotational driving of the photosensitive drum 21 and the cleaning roller 25b.
The compression spring 46 is set so that the lubricant molded body 45 contacts the cleaning roller 25b with a pressure of 200 mN or more. As a result, the lubricant is supplied onto the photosensitive drum 21 without excess or deficiency.

  As described above, the lubricant molded body 45, the cleaning roller 25b, and the compression spring 46 function as a lubrication supply unit that supplies the lubricant onto the photosensitive drum 21. Therefore, the cleaning roller 25b functions as a lubricant supply unit in addition to a function as a cleaning unit that cleans untransferred toner on the photosensitive drum 21. Here, the linear velocity ratio of the photosensitive drum 21 to the cleaning roller 25b at the contact position between the cleaning roller 25b and the photosensitive drum 21 is set to be in the range of 0.8 to 1.2. Thereby, suitable cleaning property and lubricant supply property are ensured.

  The configuration of the lubricant supply means is not limited to that of the present embodiment. For example, a configuration in which the lubricant molded body 45 is brought into direct contact with the surface of the photosensitive drum 21 or powdered lubrication is possible. It is also possible to supply the agent to the surface of the photosensitive drum 21.

  In addition to zinc stearate, the lubricant forming the lubricant molding 46 is lead oleate, zinc oleate, copper oleate, cobalt stearate, iron stearate, copper stearate, zinc palmitate, Fatty acid metal salts such as copper palmitate and zinc linolenate, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polytrifluorochloroethylene, dichlorodifluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoro A fluorine-based resin such as an ethylene-oxafluoropropylene copolymer can be used. Metal stearate is a particularly suitable material as a lubricant for reducing the coefficient of friction on the photosensitive drum 21, and zinc stearate is a more suitable material.

  The charging unit 22 is a charging roller formed by covering an outer periphery of a conductive metal core with a medium 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. Referring to FIG. 3, the developing roller 23a includes a magnet 23a1 that is fixed inside and forms a magnetic pole on the peripheral surface of the roller, and a sleeve 23a2 that rotates around the magnet 23a1. A plurality of magnetic poles are formed on the developing roller 23a (sleeve 23a2) by the magnet 23a1, 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.
The carrier C in the developer G has a resin coating layer on the surface of the core material. As the core material of the carrier C, spherical ferrite particles having an average particle diameter of 50 μm can be used. As a material for the resin coating layer of the carrier C, a silicone resin in which an aminosilane coupling agent is dispersed can be used.
Specifically, the carrier C is manufactured as follows.
First, an aminosilane coupling agent and a silicone resin are dispersed in toluene. Then, the dispersion liquid prepared is spray-coated on the core material in a heated state, baked and cooled to prepare a carrier C having an average film thickness of the resin coating layer of 0.2 μm.

In the present embodiment, in order to achieve high image quality and high definition of the output image, toner T (spherical / small particle size toner) having a spherical shape and a small particle size is used.
Specifically, the toner T is formed so that the average circularity is in the range of 0.93 to 1.00.
Here, the average circularity of the toner T is a value obtained by optically detecting toner particles and dividing by the circumference of an equivalent circle having the same projected area. Specifically, the measurement is performed using a flow type particle image analyzer “FPIA-2000” (manufactured by Sysmex Corporation). Water (100 to 150 mL) from which impure solids have been removed in advance is placed in a predetermined container, and a surfactant (0.1 to 0.5 mL) is added as a dispersant. Furthermore, a measurement sample (about 0.1 to 9.5 g) is added. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the shape and distribution of the toner are measured at a dispersion concentration of 3,000 to 10,000 / μL.

The toner T of the present embodiment is formed such that the shape factor SF-1 is in the range of 100 to 180 and the shape factor SF-2 is in the range of 100 to 180. As a result, it is possible to suppress a decrease in cleaning performance while maintaining high transfer efficiency.
Here, the shape factor SF-1 indicates the sphericity of the toner particles, and is obtained by the following equation.
SF-1 = (M ² / S) × (100π / 4)
In the above formula, M is the maximum particle size (the largest particle size among the sparse particle sizes) on the toner particle projection surface, and S is the area of the toner particle projection surface. Therefore, toner particles having a shape factor SF-1 of 100 are true spheres, and the sphericity decreases as the value increases from 100.

The shape factor SF-2 indicates the degree of unevenness of the toner particles, and is obtained by the following equation.
SF-2 = (N ² / S) × (100 / 4π)
In the above formula, N is the circumference of the projection surface of the toner particles, and S is the area of the projection surface of the toner particles. Therefore, the toner particles having the shape factor SF-2 of 100 have no irregularities, and the irregularities increase as the value increases from 100.
The shape factor SF-1 and the shape factor SF-2 are obtained by analyzing a toner particle photograph taken with a scanning electron microscope “S-800” (manufactured by Hitachi, Ltd.) and an image analyzer “LUSEX3” (manufactured by Nireco). )

Further, in the toner T of the present embodiment, when the length in the major axis direction is r1, the length in the minor axis direction is r2, and the thickness is r3 (r1 ≧ r2 ≧ r3).
0.5 ≦ r2 / r1 ≦ 1.0
0.7 ≦ r3 / r2 ≦ 1.0
The relationship is established.

Here, when the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, since the toner is separated from the true spherical shape, dot reproducibility and transfer efficiency are lowered, and high quality is achieved. The image quality cannot be obtained. Further, when the ratio of the thickness to the short axis (r3 / r2) is less than 0.7, the toner becomes nearly flat and a high transfer rate cannot be obtained. In particular, when the ratio of the thickness to the short axis (r3 / r2) is 1.0, the toner becomes a rotating body having the long axis as the rotation axis, and the fluidity of the toner can be improved.
In addition, r1, r2, and r3 are calculated | required by taking a photograph by changing the angle of a visual field with a scanning electron microscope (SEM), and observing and measuring it.

In addition, the toner T of the present embodiment is a small particle size toner having a volume average particle size of 3 to 8 μm. Furthermore, when the volume average particle diameter is Dv μm and the number average particle diameter is Dn μm,
1.00 ≦ Dv / Dn ≦ 1.40
The one formed so that the relationship is established is used. By using a small particle size toner, the toner can be densely attached to the latent image. Further, by narrowing the particle size distribution, the toner charge amount distribution becomes uniform, a high-quality image with little background fogging can be obtained, and the transfer rate can be increased.
The volume average particle diameter and number average particle diameter of the toner are typically measured by a coal counter type particle size distribution measuring device “Coulter Counter TA-2” (manufactured by Coulter Co.) or “Coulter Multisizer 2” (Coulter). Can be used.

In addition, the toner T in the present embodiment includes a binder resin (toner base particles) containing a modified polyester, a release agent such as carnauba wax, a colorant such as carbon black, and the like. Further, an external additive such as silica is externally added to the toner T. In particular, the fluidity of the toner particles is obtained by using toner T in which silica fine particles having an average primary particle size in the range of 50 to 300 nm and a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles. In addition, developability and chargeability can be improved.

Here, the spherical / small particle size toner T described above is manufactured as follows.
First, a toner material liquid in which a polyester prepolymer having a functional group containing at least a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is prepared. Then, the toner material liquid is crosslinked and / or elongated in an aqueous medium to produce toner particles.
The spherical and small particle size toner formed in this way achieves high image quality and high definition of the output image, but reduces the margin of cleaning performance with respect to the cleaning unit 25. Therefore, the lubricant supply means 25b, 45, and 46 in the present embodiment play a major role.

The above-described image forming process will be described in more detail with a focus on the developing process.
The developing roller 23a rotates in the direction of the arrow in FIG. As shown in FIG. 3, the developer G in the developing device 23 is generated by the rotation of the first conveying screw 23 b and the second conveying screw 23 c arranged so as to interpose the partition member 23 e therebetween in the arrow direction. It circulates in the longitudinal direction while being agitated and mixed with the toner T replenished from the replenishing section 32 through the toner replenishing port 23f (circulation in the direction of the broken arrow in FIG. 3).

  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 unit 25 by the cleaning blade 25a and the cleaning roller 25b.

  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. Further, the toner replenishing port 23f is provided at one end in the longitudinal direction of the second transport screw 23c (the left-right direction in FIG. 3) and above the second transport screw 23c.

  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 control performed when the photosensitive drum 21 is replaced, which is characteristic in this embodiment, will be described in detail.
In the present embodiment, when the photosensitive drum 21 (process cartridge 20) has reached the end of its life and is to be replaced with a new one, the developing device is installed with the existing photosensitive drum 21 immediately before replacement. The existing toner stored in the toner bottle 23 is discharged from the developing device 23, and then new toner in the toner bottle 33 is replenished to the developing device 23 (hereinafter, such toner replacement is referred to as "control mode" as appropriate). .)

  Further, after the control mode is completed, the existing photosensitive drum 21 (process cartridge 20) is taken out, and a new photosensitive drum 21 (process cartridge 20) is installed in the apparatus main body 1, and the developing process by the developing device 23 is performed. The lubricant is supplied to the new photosensitive drum 21 by the lubricant supply means 25b, 45, and 46 for a predetermined time (hereinafter referred to as the initial lubricant forcibly performed before image formation as described above). The supply is called “second control mode”.)

  Specifically, referring to the flowchart of FIG. 4, first, when image formation (printing) is started (step S1 to step S2), it is determined whether the photosensitive drum 21 has reached the end of its life (step S1). S3). Specifically, in the apparatus main body 1, the cumulative operation time and the number of image formations (number of sheets to be passed) for the existing photosensitive drum 21 are counted by a control unit that functions as a usage detection unit. When the counted operation time (or the number of image formations) reaches a predetermined value, it is determined that the existing photosensitive drum 21 has reached the end of its life.

As a result, when it is determined that the photosensitive drum 21 has not reached the end of its life, the flow after step S2 is repeated.
On the other hand, when it is determined that the photosensitive drum 21 has reached the end of its life, the toner concentration (toner concentration at the time of replacement) in the developing device 23 at that time is detected by the magnetic sensor 40, and the magnetic The output value (V1) of the sensor 40 is stored (step S4). At the same time, the display unit of the apparatus main body 1 displays that the photosensitive drum 21 has reached the end of its life and that the control mode is executed.

  Thereafter, the power supply unit is controlled so that the charging potential on the photosensitive drum 21 by the charging unit 22 and the developing bias applied to the developing device 23 become the same potential (step S5). Then, without replenishing new toner from the toner replenishing unit 32, the existing toner in the developing device 23 is attached to the photosensitive drum 21, and the existing toner is discharged from the developing device 23 (step S6).

Note that the method of attaching the existing toner in the developing device 23 onto the photosensitive drum 21 positively causes background contamination due to the existing toner on the photosensitive drum with the charging potential and the developing bias set to the same potential as described above. In addition to the above-described method, a method of forming a toner image (for example, a solid image) having a high image ratio on the photosensitive drum 21 and actively consuming existing toner in the same manner as in the normal image formation operation. Can be used.
Here, the above-described control mode is preferably performed under process conditions such that the carrier C accommodated in the developing device 23 does not adhere to the photosensitive drum 21.

While the existing toner is being discharged, the toner density in the developing device 23 is detected by the magnetic sensor 40, and it is determined whether the output value (V) of the magnetic sensor 40 has decreased to a predetermined value (V2) (step S7). ). In the present embodiment, the predetermined value (V2) described above is set to a value corresponding to a toner concentration of about 1% by weight.
As a result, when it is determined that the output value (V) of the magnetic sensor 40 has not decreased to the predetermined value (V2), the flow after step S6 is repeated (existing toner is continuously discharged).

On the other hand, when it is determined that the output value (V) of the magnetic sensor 40 has decreased to the predetermined value (V2), the existing toner discharge is stopped and the toner supply unit 32 enters the developing device 23. The supply of new toner is started (step S8).
During supply of new toner, the toner density in the developing device 23 is detected by the magnetic sensor 40, and it is determined whether the output value (V) of the magnetic sensor 40 has increased (returned) to the initial value (V1). (Step S9).
As a result, if it is determined that the output value (V) of the magnetic sensor 40 has not increased to the predetermined value (V1), the flow after step S8 is repeated (new toner replenishment is continued).

On the other hand, when it is determined that the output value (V) of the magnetic sensor 40 has increased to the predetermined value (V1), the supply of new toner is stopped and the control mode ends. At this time, the toner T of the developer G in the developing device 23 is in a state where the existing one is almost replaced with a new one.
Thereafter, a display prompting the replacement of the photosensitive drum 21 is displayed on the display unit of the apparatus main body 1, and the photosensitive drum 21 is replaced (step S10).

  Thereafter, it is determined by the new article detecting means of the apparatus main body 1 whether the replaced photosensitive drum 21 is a new one (step S11). As a result, if it is determined that the replaced photoconductor drum 21 is not a new one, a display for prompting replacement to the new photoconductor drum 21 is displayed on the display unit (step S12).

  On the other hand, when it is determined that the replaced photoconductor drum 21 is a new one, the second control mode is started as a new product process using the detection signal of the new product detection means as a trigger (step S13). ). Specifically, the charging potential and the developing bias are controlled so that the toner does not adhere to the photosensitive drum 21, and the lubricant is supplied to the new photosensitive drum 21 by the lubricant supplying means 25b, 45, 46 for a predetermined time. . The supply of the lubricant to the new photoconductor drum 21 is preferably performed by rotating the photoconductor drum 21 30 times or more. As a result, the friction coefficient of the surface of the new photoconductor drum 21 becomes 0.4 or less, and the occurrence of filming and cleaning failure can be prevented in advance. In the present embodiment, since the existing toner that adversely affects filming is discharged and the toner in the developing device 23 is replaced with a new one in the control mode described above, the photoconductor The occurrence of filming immediately after drum replacement can be reliably suppressed.

  The new article detecting means is a sensor that optically detects whether or not the claw member is deformed by providing a claw member on the flange of the photosensitive drum 21 that is deformed when the photosensitive drum 21 is attached to the apparatus main body 1. This can be achieved by installing in the apparatus main body 1.

Then, after the end of the second control mode, other initial processing is performed on the new photosensitive drum 21 (step S14). Specifically, image density adjustment, positional deviation adjustment between a plurality of photosensitive drums, and the like are performed.
Thus, the initial processing for the new photoconductor drum 21 is completed, and normal image formation is performed. Then, the new photosensitive drum 21 is used as the existing photosensitive drum, and the flow after step S2 is repeated again.

  As described above, according to the present embodiment, when the photosensitive drum 21 has reached the end of its life, etc., when the photosensitive drum 21 is replaced with a new one, the existing photosensitive member is replaced. With the drum 21 installed, the existing toner in the developing device 23 is discharged and replaced with new toner. Further, after the lubricant is sufficiently supplied to the new photoconductor drum 21 initially, image formation is started. As a result, even if the replacement cycle of the photosensitive drum 21 and the developing device 23 (developer G) is different, the existing photosensitive drum 21 installed in the apparatus main body 1 is replaced with a new one. Sometimes filming can be sufficiently suppressed.

FIG. 5 is a chart showing the conditions and results of Examples and Comparative Examples performed to confirm the effects of the present embodiment described above.
Example 1 uses the image forming apparatus according to the present embodiment to perform a control mode (replacement of existing toner and new toner), a second control mode (initial lubricant supply to a new photosensitive drum), It has been done.
In Comparative Example 1, neither the control mode nor the second control mode was performed. In the comparative example 2, only the second control mode is performed without performing the control mode. In Comparative Example 3, only the control mode is performed without performing the second control mode.

In Example 1 and Comparative Examples 1 to 3, after replacement with a new photosensitive drum, a solid part (image area ratio 100% part) and a white part (image area ratio 0% part) exist in the sheet passing direction. 500 vertical band charts were printed, and then the filming state on the new photoconductor drum was observed, and the friction coefficient on the surface of the new photoconductor drum was measured by the Euler belt method.
In the control mode, a solid portion was formed on the photosensitive drum 21 and the existing toner was discharged. The lubricant molded body 45 was made of zinc stearate, and the pressing force against the cleaning roller 25b was 1000 mN. The linear speed ratio of the photosensitive drum 21 to the cleaning roller 25b was 1.0.

  As shown in the results of FIG. 5, in Comparative Example 1 and Comparative Example 3, it was confirmed that filming occurred at a position corresponding to 100% part (solid part) of the new photosensitive drum 21. Also in Comparative Example 2, it was confirmed that a little filming occurred at a position corresponding to 100% portion (solid portion) of the new photosensitive drum 21. On the other hand, in Example 1, the occurrence of filming could not be confirmed. As described above, it was found that the occurrence of filming could not be sufficiently suppressed by implementing only one of the control mode and the second control mode, and the effect of the present embodiment was confirmed.

  Note that the coefficient of friction on the surface of the photosensitive drum 21 is higher in the 100% portion (solid portion) than in the 0% portion (white portion). This is because the untransferred toner remaining on the photosensitive drum 21 is larger in the 100% portion than in the 0% portion. That is, when a large amount of untransferred toner is input to the cleaning unit 25, it adheres to the cleaning roller 25b, and the efficiency of supplying the lubricant in the lubricant supply means 25b, 45, 46 decreases. Therefore, the friction coefficient on the photosensitive drum 21 is increased.

  In the present embodiment, the life of the photosensitive drum 21 is detected based on the operation time and the number of image formations, and the control mode and the second control mode are performed before and after the replacement of the photosensitive drum 21. On the other hand, when an abnormality occurs in the photosensitive drum 21 (process cartridge 20), the abnormality can be detected and the control mode and the second control mode can be performed before and after the replacement of the photosensitive drum 21. . Also in this case, the same effect as this embodiment can be obtained.

  In the present embodiment, the photosensitive drum 21 is integrated with the charging unit 22 and the cleaning unit 25 to configure the process cartridge 20. On the other hand, the process cartridge 20 can be configured by integrating the photosensitive drum 21 with only one of the charging unit 22 and the cleaning unit 25. Further, the photosensitive drum 21 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, effects similar to those of the present embodiment can be obtained by performing the above-described control mode and second control mode.

  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 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. It is sectional drawing which looked at the developing device to the longitudinal direction. It is a flowchart which shows the control performed at the time of photoconductor drum replacement | exchange. It is a graph which shows the conditions and results of Examples and Comparative Examples.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20, 20Y, 20M, 20C, 20BK Process cartridge,
21 photosensitive drum (image carrier), 22 charging unit,
23, 23Y, 23M, 23C, 23BK Developing device (developing unit),
25 Cleaning section,
25a Cleaning blade,
25b Cleaning roller (brush roller, lubricant supply member),
45 Lubricant molded body (lubricant supply means),
46 compression spring (biasing member),
47 Scraper,
G Two-component developer (developer), T toner, C carrier.

Claims (20)

An image forming apparatus in which an image carrier is installed interchangeably,
A developer that contains a developer composed of a carrier and a toner, and that develops a latent image formed on the image carrier to form a toner image;
A lubricant supply means for supplying a lubricant onto the image carrier,
When the image carrier is replaced from a new one to a new one, a part or all of the existing toner stored in the developing unit is removed while the existing image carrier is installed. An image forming apparatus comprising a control mode for discharging from a developing unit and then supplying new toner to the developing unit. When the existing image carrier is replaced with a new one, the lubrication is performed without developing the new image carrier by the developing unit in a state where the new image carrier is installed. The image forming apparatus according to claim 1, further comprising a second control mode in which a lubricant is supplied to the new image carrier by an agent supply unit for a predetermined time. New article detecting means for detecting that the new image carrier is installed,
The image forming apparatus according to claim 2, wherein the second control mode is started by using a detection signal of the new article detection unit as a trigger. 4. The control mode according to claim 1, wherein the control mode is a mode in which a toner image consisting only of the existing toner is formed on the existing image carrier and the existing toner is discharged. An image forming apparatus according to claim 1. A usage detecting means for detecting the usage of the image carrier in the apparatus main body,
The image forming apparatus according to claim 1, wherein the control mode is started when a detection result by the usage detection unit reaches a predetermined value. 6. The image forming apparatus according to claim 5, wherein the usage detection means is means for detecting an operation time or the number of times of image formation in a state where the image carrier is installed in the apparatus main body. 7. The display unit of the apparatus body according to claim 5 or 6, wherein when the detection result by the usage detection means reaches a predetermined value, a message indicating that the existing image carrier is at the end of its life is displayed. The image forming apparatus described. In the control mode, the toner density of the developer at the start of the control mode is detected as a replacement toner density, and the existing toner is discharged until the toner density of the developer decreases to a predetermined value. 8. The image forming apparatus according to claim 1, wherein after that, the new toner is supplied until the toner density of the developer increases to the toner density at the time of replacement. 2. The lubricant supply means includes: a lubricant molded body in which a lubricant is solidified; and a brush-like roller that comes into contact with the lubricant molded body and the image carrier. The image forming apparatus according to claim 8. The image forming apparatus according to claim 9, wherein the lubricant supply unit further includes a biasing member that biases the lubricant molded body with respect to the brush-shaped roller with a pressure of 200 mN or more. The linear velocity ratio of the image carrier to the brush roller at the contact position between the brush roller and the image carrier is configured to be in a range of 0.8 to 1.2. The image forming apparatus according to claim 9 or 10. The image forming apparatus according to claim 9, wherein the brush roller is a cleaning roller that cleans untransferred toner remaining on the image carrier. The image formation according to claim 1, wherein the supply of the lubricant to the image carrier by the lubricant supply unit is performed in conjunction with the driving of the image carrier. apparatus. The image forming apparatus according to claim 1, wherein the toner is formed so that an average circularity is in a range of 0.93 to 1.00. 15. The toner according to claim 1, wherein the toner is formed so that the shape factor SF-1 is in the range of 100 to 180 and the shape factor SF-2 is in the range of 100 to 180. The image forming apparatus according to any one of the above. The image forming apparatus according to claim 1, wherein the toner is a spherical toner formed in a spherical shape. The spherical toner has a major axis length of r1, a minor axis length of r2, and a thickness of r3.
0.5 ≦ r2 / r1 ≦ 1.0
0.7 ≦ r3 / r2 ≦ 1.0
The image forming apparatus according to claim 16, wherein the image forming apparatus is formed so as to satisfy the following relationship. 2. The toner according to claim 1, wherein silica particles having an average primary particle diameter in the range of 50 to 300 nm and a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles. The image forming apparatus according to claim 1. In the toner, a toner material liquid in which a polyester prepolymer having a functional group containing at least a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is crosslinked and / or extended in an aqueous medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed. The image carrier is integrated with at least one of a charging unit for charging the image carrier, a cleaning unit for cleaning the image carrier, and the lubricant supply unit to form a process cartridge. And
20. The image forming apparatus according to claim 1, wherein the process cartridge is installed so as to be exchangeable with respect to the apparatus main body.

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