JP2005308831A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the life of an image carrier by preventing or reducing deterioration of an image carrier due to an electrifying means which applies an AC voltage close to or in contact with the image carrier, by maintaining pealing force between developer (toner) and the image carrier, by restraining image defects and by reducing wear of the image carrier. <P>SOLUTION: The image forming apparatus 1 includes: at least the image carrier 2; the electrifying means 3 having an electrifying member that is close to or in contact with the image carrier; a lubricant supply means 103 which supplies a lubricant 102 to the image carrier downstream of a transfer means 6 in the direction of the rotation of the image carrier and upstream of the electrifying means 3; and an image carrier replacement detection means for detecting the replacement of the image carrier. An image forming method includes exerting control such that when the image carrier is replaced with a fresh one, it is passed in contact with a coating-and-uniformizing member 110 at least three times or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and more specifically, a charging unit that charges an image carrier and an electrostatic latent image is formed by exposure on the image carrier charged by the charging unit. The present invention relates to an image forming apparatus including at least an exposure unit that performs development, a development unit that develops an electrostatic latent image, a transfer unit that transfers the developed image, and a lubricant application unit.
More specifically, the present invention relates to an image forming method and an image forming apparatus for removing a deteriorated lubricant when the lubricant applied to the surface of an image carrier is deteriorated.

  Electrophotographic image formation uses a photoconductive phenomenon to form an electrostatic charge image (electrostatic latent image) on an image carrier (hereinafter referred to as a photoconductor). In this process, charged fine particles (toner) are attached by electrostatic force to form a visible image. At this time, an electrophotographic cleaning process, that is, a process of scraping off the toner remaining on the photoreceptor and the intermediate transfer belt with a cleaning brush or a cleaning blade is required.

(Conventional cleaning technology)
Conventionally, the cleaning method of an image forming apparatus in the electrophotographic method is mainly a cleaning method using a blade, and there are a large number of image forming apparatuses having cleaning means only for the blade. Some high-speed machines have a brush provided on the upstream side of the blade in order to avoid a state in which a large amount of toner is partially attached.
However, the above-described cleaning method / means has a problem that a recently developed spherical (polymerized) toner having a circularity of 0.96 or more and less than 1.00 cannot be cleaned. However, some short-life image forming apparatuses can be cleaned by devising the toner and blade.
In addition, since the spherical (polymerized) toner has a high transfer rate and a small amount of untransferred toner, there is an image forming apparatus that does not have a dedicated cleaning unit and also serves as a cleaning by a developing machine.
The polarity control means provided on the upstream side of the cleaning means has been found in old image forming apparatuses, but is rarely found recently. One of the reasons is that the technology of the cleaning means is improved and the polarity control means is not necessary, and the cost is reduced. Some of the above blades provided with a brush on the upstream side also serve as a polarity control means by applying a voltage, but the number is small.
However, many image forming apparatuses that do not have the cleaning unit described above have a polarity control unit.

(Prior art of charging)
Conventionally, as this type of image forming apparatus, there is known an apparatus that charges an image carrier and selectively erases or reduces the charge by exposure to form an electrostatic latent image on the image carrier. . As the charging means for charging the image bearing member, those using corona discharge have been the mainstream.
However, the charging means using the corona discharge has a problem that a large amount of ozone is generated, and a high voltage power source for applying a high voltage of 5 to 10 kV is necessary to perform the corona discharge. It has been difficult to reduce the cost of the image forming apparatus.
Therefore, in recent years, many contact-type charging units that contact a charging member with an image carrier without using corona discharge have been proposed as charging units that can be employed in an image forming apparatus. In this contact-type charging unit, many of the problems mentioned in the case of the charging unit using the corona discharge are eliminated, while an abnormal image called image flow is generated and the wear amount of the image carrier increases. The problem has also occurred. In addition, when alternating current is used as the applied voltage, noise is also a problem. In addition, since the charging means rubs toner or paper dust between the image carrier (photosensitive member) and the charging member, contamination is promoted, and contamination due to the contamination is also a problem. As a method for solving the above problem, for example, as disclosed in Patent Document 1, the charging voltage is controlled by using an auxiliary charging member and a charging member, so that the charging means is contaminated with toner, paper dust, or the like. There is a method for preventing the occurrence of an abnormal image called positive ghost in a cleanerless system.

(Lubricant in electrophotography)
In electrophotographic image forming apparatuses, various waxes, fluororesins (polytetrafluoroethylene, polyvinylidene fluoride, etc.) and higher fatty acid metal salts (zinc stearate, etc.) are used as the main components of the photoreceptor and intermediate transfer belt. There is a technique of applying as a lubricant. This technique is used to solve the problems that occur in the electrophotographic cleaning process.
One problem is the extension of the life of the photosensitive member and the intermediate transfer belt determined by abrasion due to mechanical rubbing with the cleaning brush and the cleaning blade, and another problem is improvement of the cleaning property. In recent years, spherical toners prepared by a polymerization method have begun to be used, but these have a uniform particle size distribution and can effectively reduce the particle size. On the other hand, there is a problem that cleaning from the photosensitive member becomes difficult.

The purpose of applying a lubricant to solve these problems is to prevent toner filming (fusion), and to improve transfer efficiency and prevent poor cleaning by reducing the friction coefficient. It can be said that. For these problems, for example, the inventions disclosed in Patent Documents 2 to 5 are known, and the problem is solved by applying a lubricant on the photoreceptor to reduce the friction coefficient.
Further, in order to extend the life of the charging member and the photosensitive member, a non-contact charging device is used, and inorganic fine particles are dispersed in the photosensitive layer of the photosensitive member, and zinc stearate or the like is applied as a lubricant. There exists patent document 6 as an example which is improving wearability.
In addition, in the invention disclosed in Patent Document 7, the lubricant applied to the surface of the image carrier is adhered thinly and uniformly between the charging unit and the developing unit, and the large-diameter lubricant is used to block the lubricant. An example of an image forming apparatus having a blade-like auxiliary member is shown.

One problem is that the lubricant cannot be applied evenly on the surface of the image carrier, and wear of a part of the surface of the image carrier proceeds. On the other hand, various methods for controlling the application state of the lubricant have been proposed so far.
In Patent Document 8, after the image forming operation is completed, the photosensitive member is rotated in the reverse direction, and the lubricant stored in the upper part of the cleaning blade is dragged onto the surface of the photosensitive member to reduce the thickness of the lubricant. A method of applying the lubricant evenly has been studied.
Patent Document 9 provides an image forming apparatus capable of preventing an initial temporary lubricant consumption reduction when a process cartridge is replaced with a new one and obtaining a good image from the initial output. In this method, the image carrier, the lubricant applying means, and the toner damming member are integrated into a process cartridge that can be attached to and detached from the apparatus main body, and can exert an adsorbing force on the lubricant. Substance supply means for supplying the substance to the surface of the image carrier is provided. Then, after replacing the process cartridge with a new one, the lubricant applying means is applied so that the lubricant is applied to the surface of the image carrier before the image forming operation is started, and the substance is supplied to the surface of the image carrier. And the substance supply means.

However, this method has a problem in that the lubricant cannot be supplied to the image carrier evenly because the lubricant is attracted to the substance capable of exhibiting the adsorptive power.
In Patent Document 10, in an image forming apparatus using a toner having a small particle diameter or a fine particle toner by a polymerization method, reliability that does not cause cleaning failure or fusion throughout a durable life even when the developing cartridge is replaced. In order to provide a high-quality image forming apparatus, by applying an appropriate amount of solid lubricant to the surface of the photosensitive drum, a highly reliable image that does not cause poor cleaning or fusing throughout its lifetime It is intended to provide a forming apparatus. In this method, a solid lubricant is brought into contact with the rotating brush, the lubricant adhered to the brush is applied to the image carrier, and a lubricant film forming unit that forms a film with the lubricant on the surface of the image carrier; An image forming apparatus having a developing unit that develops the electrostatic latent image formed on the image carrier with toner, wherein the developing unit is included in a cartridge configured to be detachable from the apparatus body, and the use of the cartridge The amount of lubricant applied to the surface of the image carrier is controlled on the basis of information on the state.
In Patent Document 11, as a means for preventing the occurrence of defective cleaning, a cleaning device that does not cause defective cleaning is provided by optimizing the rotational peripheral speed of the cleaning brush that rotates in contact with the photosensitive drum. ing. In this method, a toner image formed on a photosensitive drum rotatable at a circumferential speed of at least two of a first circumferential speed and a second circumferential speed higher than the first circumferential speed is transferred to form an image, and then the photosensitive drum In the cleaning device that removes toner remaining on the photosensitive drum, when the photosensitive drum rotates at the first peripheral speed VA during image formation, the cleaning brush rotates at the first peripheral speed VB, and the photosensitive drum rotates at the second peripheral speed. When rotating at VA ′, the cleaning brush is rotated at the second peripheral speed VB ′, and at this time, the relationship is such that VA <VA ′, (VB / VA)> (VB ′ / VA ′). .

Japanese Patent Laid-Open No. 10-312098 JP 2002-244516 A JP 2002-156877 A JP 2002-55580 A JP 2002-244487 A JP 2002-229227 A Japanese Patent Laid-Open No. 10-142897 JP 11-38855 A JP 2001-343861 A JP 2002-244487 A JP 2003-36011 A

However, in the invention described in Patent Document 8, the lubricant cannot be applied evenly and does not sufficiently achieve the object. In the invention described in Patent Document 10, it is difficult to evenly apply the lubricant to the image carrier even though the amount of lubricant supplied to the image carrier can be increased or decreased.
In the invention described in Patent Document 11, even if the amount of lubricant supplied to the image carrier can be increased or decreased, it is difficult to evenly apply the lubricant to the image carrier.

  In view of the above circumstances, the present invention prevents or reduces deterioration of the image carrier by charging means that applies a close or contact alternating voltage by forming a uniform lubricant film on the image carrier. This also maintains the peeling force between the developer (toner) and the image carrier, suppresses the occurrence of abnormal images, reduces the amount of wear of the image carrier, and extends the life of the image carrier. Let it be an issue. A further object of the present invention is to provide a process cartridge having at least such charging means and lubricant supply means, and to provide an image forming apparatus having at least such charging means, lubricant supply means and cleaning means.

The features of the present invention, which is a means for solving the above problems, are listed below.
In order to achieve the above-mentioned object, the present inventors diligently studied, about the application state that can sufficiently exhibit the lubricity, particularly when using a fatty acid metal salt such as zinc stearate as a lubricant, The following findings were obtained. When a solid lubricant is applied to the surface of the photoconductor via a brush or the like, a powdery lubricant is applied to the surface of the photoconductor. However, in this state, the lubricity is not sufficiently exhibited. A leveling member is required. Based on the X-ray reflectivity with respect to the X-ray incident angle, the lubricant uniformization means is allowed to pass through the lubricant uniformizing means three times or more so that a uniform lubricant film can be formed on the image carrier. I understood. Further, by integrating the image carrier and the lubricant supply unit in the process cartridge, the contact state between the image carrier and the lubricant supply unit can be maintained.

  The present invention has been devised based on the above findings. That is, the present invention provides a solid lubricant made of a fatty acid metal salt, a lubricant supply means for scraping off the solid lubricant and coating the image on the image carrier, and a downstream side of the coating mechanism. And a lubricant uniformizing means for uniformizing the thickness of the lubricant layer applied to the lubricant. Further, the present invention is a process cartridge and an image forming apparatus using this lubricant application device.

Therefore, by the means for solving the above, the image forming apparatus of the present invention forms a uniform lubricant film on the surface of the image carrier, thereby preventing image quality deterioration and abnormal images, and The life can be extended.
In the process cartridge of the image forming apparatus according to the present invention, the image carrier and the lubricant supply means are integrated to facilitate the maintenance of the contact state between the two and contribute to the improvement of serviceability. is there.

An embodiment in which the present invention is applied to an image forming apparatus will be described.
FIG. 1 is an overall view (sectional view) of an image forming apparatus, which is an embodiment of the present invention. The image forming apparatus shown here has an image carrier (2) disposed in the main body of the image forming apparatus (1). This image carrier (2) is formed in a drum shape having a photosensitive layer on the outer peripheral surface of a cylindrical conductive base, but is an endless belt-like image carrier that is wound around a plurality of rollers and driven to rotate. (2) can also be used.
The image carrier (2) shown in FIG. 1 is driven to rotate clockwise during the image forming operation, and at this time, the image carrier is charged to a predetermined polarity by the charging means (3). Although the non-contact charging roller is used in FIG. 1, the invention is not limited to this, and a contact charging roller may be used.
The image carrier charged by the charging means (3) is irradiated with light-modulated laser light emitted from the exposure means (4), which is an example of the exposure means, thereby electrostatically irradiating the image carrier (2). A latent image is formed. In the example shown in the figure, the absolute value of the potential of the surface portion of the image carrier irradiated with the laser beam decreases, and this becomes an electrostatic latent image (image portion), and the absolute value of the potential is not irradiated with the laser beam. The part kept high becomes the background part. Next, the electrostatic latent image is visualized as a toner image with toner charged to a predetermined polarity when passing through the developing means (5). An exposure unit having an LED array, an exposure unit that illuminates a document surface and forms an image of the document image on an image carrier can also be used.
On the other hand, a transfer material made of, for example, transfer (recording) paper is sent out from the paper supply means (18), and is placed between the transfer means (6) and the image carrier (2) facing the image carrier (2). The transfer material is fed at a predetermined timing. At this time, the toner image formed on the image carrier (2) is electrostatically transferred onto the transfer material. The transfer material onto which the toner image has been transferred continues to pass through the fixing means (10). At this time, the toner image is fixed on the transfer material by the action of heat and pressure. The transfer material that has passed through the fixing means (10) is discharged to a paper discharge section. Untransferred toner remaining on the surface of the image carrier (2) without being transferred to the transfer material is removed by the cleaning means (7).
The fixing means (10) has a two-roller configuration in the figure, but there is no problem with other configurations such as a belt and roller.

The developing means (5) shown in FIG. 1 has a developing case that contains a dry developer and a developing roller that carries the developer while carrying it. As the developer, for example, a dry developer having a toner and a carrier, or a one-component developer having no carrier can be used. A developing means (5) using a liquid developer can also be adopted. The developing roller is driven to rotate in the direction of the arrow. At this time, the developer is carried on the peripheral surface of the developing roller and conveyed, and the toner in the developer carried to the developing area between the developing roller and the image carrier (2). Is electrostatically transferred to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image.
The transfer means (6) shown in FIG. 1 is composed of a transfer roller to which a transfer voltage having a polarity opposite to the charging polarity of the toner on the image carrier (2) is applied. Alternatively, a transfer means composed of a corona discharger having a corona wire can be used. Further, instead of directly transferring the toner image on the image carrier to a transfer material as a final recording medium, the toner image on the image carrier is transferred onto a transfer material comprising an intermediate transfer member, and the toner image is transferred to the transfer material. It can also be configured to transfer to the final recording medium.
Further, the cleaning means (7) shown in FIG. 1 has a cleaning member made of a fur brush (7-1) rotatably supported by the cleaning case, and these cleaning members are placed on the surface of the image carrier. The transfer residual toner that contacts and adheres to the surface is cleaned.
For the cleaning blade (7) as a cleaning means, for example, a known material such as polyurethane rubber, silicone rubber, nitrile rubber, chloroprene rubber is appropriately selected, and its elastic modulus, thickness, and contact angle with the image carrier (2). Etc. can be appropriately set and used.
Although not shown in FIG. 1, the residual charge on the image carrier may be neutralized by using a neutralizing means (8) as shown in FIG.

The toner of the present invention preferably has an average circularity of 0.93 to 1.00. When the average circularity is less than 0.93, the toner is separated from the spherical shape, the dot reproducibility is deteriorated, and the releasability is deteriorated because the number of contact points with the photosensitive member as the image carrier increases. The transfer rate decreases.
The toner of the present invention is a toner whose average circularity is 0.93 or more and whose projected shape is close to a circle, has excellent dot reproducibility, and can obtain a high transfer rate.
The average circularity of the toner is a value obtained by optically detecting particles and dividing by the perimeter 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). In a predetermined container, 100 to 150 mL of water from which impure solids are removed in advance is added, 0.1 to 0.5 mL of a surfactant is added as a dispersant, and about 0.1 to 9.5 g of a measurement sample is further added. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the concentration and dispersion of the dispersion are set to 3,000 to 10,000 / μL, and the shape and distribution of the toner are measured.

Hereinafter, the lubricant supply means will be described.
The lubricating member (102) is appropriately supplied to the image carrier by the fur brush (7-1). Normally, the lubrication member (102) is continuously supplied. However, the lubrication member (102) is constituted by a general cam, an electromagnetic clutch or the like so as to be in contact with or separated from the fur brush (7-1), and intermittent supply is performed. Also good. Further, the torque of the image carrier, the current of the drive motor, the reflectance of the image carrier, and the like may be monitored so that the lubricating member is supplied only when necessary.
Further, as shown in FIG. 3, the lubricating member (102) may be supplied to the image carrier using a lubricant supply means (103) different from the fur brush (7-1). Further, as shown in FIG. 4, after the lubricating member (102) is supplied to the image carrier, the lubricating member may be thinned on the image carrier using the lubricant uniformizing means (110).
The lubricant supply means (103) abuts the lubricating member (102) on, for example, a rotating brush or a rotating roll that comes into contact with the image carrier (2), and supplies the lubricant via the rotating brush or the like to the image carrier (2). However, from the viewpoint of downsizing and cost reduction of the apparatus, the lubricant may be supplied in direct contact with the image carrier (2).
In the present invention, the lubricant supply means (103) uses a rotating brush. However, the present invention is not limited to this, and there is no problem even if other members such as a rotating roller are used.

As the lubricant to be supplied, a fatty acid metal salt can be used, and it can be used in the form of powder or solid depending on the supply mode to the image carrier. In order to eliminate problems such as scattering, it is desirable to use it in a solid form.
Examples of the metal element constituting the fatty acid metal salt include zinc, lithium, sodium, calcium, magnesium, aluminum, lead, and nickel. Examples of the fatty acid constituting the fatty acid metal salt include stearin. Examples include acids, lauric acid, and palmitic acid.
Of these, zinc stearate is preferable when used as a solid prismatic shape, and calcium stearate is preferable when it is spherical.

2 to 8 show examples of the image forming apparatus when the lubricant supply mode is performed. However, the lubricant supply mode can be applied to other than the drawings shown here.
The configuration of FIG. 2 is the simplest configuration and is also used for image forming apparatuses currently distributed in the market. The lubricant is applied by bringing the lubricating member (102) into contact with the fur brush (7-1) for cleaning the transfer residual toner on the image carrier. In addition, a cleaning blade (7) for removing toner that could not be completely removed by the fur brush (7-1) is provided on the downstream side in the rotation direction of the image carrier. The cleaning blade (7) has a function of removing the transfer residual toner and applying the lubricant while reducing the thickness of the lubricant.
The configuration shown in FIG. 3 has a separate lubricant supply means (103) in addition to the configuration shown in FIG. With this structure, the lubricant can be applied more easily by applying the lubricant after removing the toner.
The configuration of FIG. 4 adds lubricant uniformizing means (110) to the configuration of FIG. By adopting such a structure, it is easy to make the lubricant uniform.
The configuration of FIG. 5 is a configuration in which the fur brush (7-1) is removed from the configuration of FIG. Although the performance of removing the transfer residual toner is deteriorated, it has a sufficiently usable cleaning property.
The configuration of FIG. 6 is a configuration in which the fur brush (7-1) is removed from the configuration of FIG. Although the performance of removing the transfer residual toner is deteriorated, it has a sufficiently usable cleaning property.
The configuration of FIG. 7 is a configuration in which the cleaning blade (7) is removed from the configuration of FIG. The removal performance of the transfer residual toner is lowered, and if a voltage is applied to the fur brush (7-1) or a brush roller is further added before the fur brush (7-1), the cleaning blade (7) Equivalent cleaning performance can be demonstrated. However, with a small number of image forming apparatuses at a low speed, cleaning performance within a range that can be used as an image forming apparatus can be obtained by using only the fur brush (7-1).
The configuration of FIG. 8 is a configuration in which the cleaning blade (7) is removed from the configuration of FIG. The cleaning performance is the same as that described with reference to FIG. 7, and the uniformity of the lubricant is superior to that of FIG.

  The blade used for the lubricant uniformizing means (110) may be made of the same material as the cleaning blade (7). That is, a known material such as polyurethane rubber, silicone rubber, nitrile rubber, or chloroprene rubber may be used as the material. The elastic modulus is preferably 20 to 80%, the thickness is 1 to 6 mm, and the contact angle with the image carrier is preferably about 15 to 45 °.

The rotation direction of the fur brush (7-1) in contact with the lubricant supply means (103) and the lubricating member (102) in FIGS. 2 to 8 is preferably rotated clockwise, but is rotated counterclockwise. Also good. In addition, when the speed of the surface of the image carrier is V1, it is preferable to set the speed V2 of the brush roller within the range of the following formula.
0.5V1 ≦ V2 ≦ 5V1 (where V1 ≠ V2) (1)
Moreover, when using a brush roller, the density of the brush is preferably 2000 / cm ² or more and 10,000 / cm ² or less, and more preferably 3000 / cm ² or more and 8000 / cm ^2. . The lower limit of the above range is a value determined based on the result of no abnormal image appearing on the image carrier in the experiment. The upper limit of the above range only indicates a manufacturing limit, but manufacturing technology will increase in the future, and higher densities may be possible. Therefore, the upper limit is not particularly limited.

Regarding the state of the lubricant on the image carrier (2), the element ratio [%] of the metal element contained in the fatty acid metal salt present on the surface of the image carrier is measured by XPS.
1.52 × 10 ⁻⁴ × {Vpp−2 × Vth} × f / v [%] (2)
If it is above, it turns out that the quality change (white turbidity) of the to-be-charged body (photosensitive body) can be prevented.
(Where Vpp is the amplitude [V] of the AC component applied to the charging member, f is the frequency [Hz] of the AC component applied to the charging member, and Gp is the closest distance [μm] between the surface of the charging member and the surface of the object to be charged) , V is the moving speed [mm / sec] of the surface of the member to be charged facing the charging member, Vth is the discharge start voltage, and the value of Vth is the film pressure of the member to be charged d [μm], Is expressed as 312 + 6.2 × (d / εopc + Gp / εair) + √ (7737.6 × d / ε) is there)

As shown in FIG. 2, a structure in which small particles are applied to the image carrier (2) with a fur brush (7-1) and the small particles are rubbed with a cleaning blade (7) as shown in FIG. Then, it has been grasped by experiments of the present inventors that a thin film cannot be easily formed. Further, it is known that a thin film once formed does not easily peel off and cannot be removed. Therefore, if a thin film of lubricant is formed when the image forming apparatus is used for the first time or when the image carrier (2) is replaced, cleaning with the fur brush (7-1) as described above is performed thereafter. With the configuration of the blade (7), the thin film can be maintained for a certain period.
However, although the change in the thin film of the lubricant due to the contact object around the image carrier (2) is small, it is known that the change in the film due to the direct discharge of the charging means (3) or the like is large. Therefore, when charging is performed using a charging roller, it is desirable to always perform the coating operation after forming the protective film in the lubricant supply mode.

表１は、ブラシ及びブレードによる潤滑剤の塗布回数と、その膜圧との関係を示したものである。但し膜厚は、エリプソメータにより、ＺｎＳＴの屈折率１．５、吸収係数０と仮定して測定した結果である。
表１から、１回の塗布では平均膜厚が４．９ｎｍで塗布が不充分であることが分かる。
また、１０回の塗布ならば、十分な膜厚となっていると推測される。 Table 1 and FIGS. 9 and 10 show the results of experiments conducted on the mechanism for forming a thin film on the image carrier (2).

Table 1 shows the relationship between the number of times the lubricant is applied by the brush and the blade and the film pressure. However, the film thickness is a result of measurement with an ellipsometer on the assumption that the refractive index of ZnST is 1.5 and the absorption coefficient is 0.
From Table 1, it can be seen that the coating is insufficient with an average film thickness of 4.9 nm in one coating.
Moreover, if it is applied 10 times, it is estimated that the film thickness is sufficient.

(About X-ray reflectivity measurement results for zinc stearate film on substrate)
FIG. 9 is a graph obtained by performing reflectance measurement on a film on a substrate using X-rays.
The vertical axis represents the reflection intensity and the horizontal axis represents the X-ray incident angle, and a peak is observed where the reflection of the film surface and the substrate overlaps.
From FIG. 9, it is presumed that the peak is very small in one application and the film thickness is not sufficient.
In addition, there is a difference in reflection intensity between 3 times of application and 10 times of application, and it is judged that the film thickness is insufficient even after 3 times of application.
Therefore, it is estimated that a sufficient film is formed after 10 coatings.
From these facts, an appropriate number of times of application T considering the reduction of the control time is expressed by the following formula (3).
3 <T ≦ 10 Formula (3)
T is an integer. The number of times of application is replaced with the number of rotations of the image carrier (2).
FIG. 10 shows a state after removal after application.
Although it is not removed at all in 10 times, it can be estimated that it is removed a little in 50 times.
At this time, if the transfer means has a contact / separation mechanism with respect to the image carrier, it is better to keep them apart. Similarly, the developing means should be separated if there is a contact / separation mechanism.
After the image carrier is rotated to form the lubricant thin film as described above, a pre-preparation rotation is performed, an image forming operation is performed thereafter, a post-preparation rotation is performed, and the image forming operation is terminated.

  From the experimental results shown in Table 1 and FIGS. 9 and 10, it can be understood that the thin film is not easily formed, and that the thin film once formed cannot be easily shaved. Therefore, when the image forming apparatus is used for the first time or when the image carrier is replaced, it is appropriate if the lubricant uniformizing means (including the application brush and the leveling blade) is passed three times or more. It was found that a thin film can be formed, and it is highly effective in cleaning properties and prevention of influence by charging. In particular, considering time reduction of this control, etc., it may be 3 times or more and 10 times or less.

The lubricant supply mode of the present invention (control for passing the lubricant supply means (103) and the lubricant uniformizing means (110) at least three times or more) will be described based on the flowcharts of FIGS.
When the image forming apparatus (1) receives the print command signal, it determines whether or not the image carrier has been replaced after the previous print command signal. If the image carrier (2) is not replaced, a pre-preparation rotation for performing normal image formation is performed, an image formation operation is performed thereafter, a post-preparation rotation is performed, and the image formation operation is terminated. .
The preparatory rotation here refers to raising the temperature of the fixing unit, determining the voltage applied to the charging unit (3), determining the voltage applied to the developing unit, and adjusting the toner density. . In addition, the color image forming apparatus may include color adjustment, image position adjustment, and the like. In the post-preparation rotation, cleaning of toner remaining on the image carrier after image formation, neutralization of the image carrier, and the like are performed.
If the image carrier (2) has been replaced, the lubricant supply mode is entered. The lubricant supply mode is a mode for forming a thin film of lubricant on the image carrier (2).
Instead of the lubricant supply mode, a protective film may be applied at the time of assembly at the factory or at the time of manufacturing the image carrier.

In the flowchart of FIG. 12, the lubricant supply mode as described above is carried out when a certain period of time has elapsed or a certain number of sheets have been reached since the replacement of the image carrier (2). A certain period or a certain number of sheets means a period until the lubricant thin film is partially peeled or the entire film thickness is reduced. The period and the number of sheets vary depending on the type and amount of toner to be used and the type of recording paper in the case of direct transfer, so it is preferable to set the period and the number of sheets assuming the shortest case.
As an experimental example in the case of not direct transfer, the lubricant thin film was maintained when the lubricant supply mode was carried out with about 50 sheets. Based on the result as described above, the shortest period may be calculated from the number of prints per day.

The set value of the applied voltage in the flowcharts of FIGS. 11 and 12 will be described.
The applied voltage setting values of the charging means (3) and the developing means (5) when the developing means (5) has no contact / separation mechanism and the charging means (3) uses a proximity or contact charging member will be described below. To do.
For example, the charge potential (Vh) of the image carrier (2) during general image formation is -800V, the potential of the exposed printing portion is -150V, and the applied voltage of the developing means (5) is -450V. There is a case where the charging polarity of the toner is negative charging, and the case where it is assumed that the applied voltage to the developing means (5) is applied also in the lubricant supply mode is as follows:
The applied voltage (Vch) to the charging means (3) is a range of Vch in which the AC voltage is not superimposed on the charging means (3) and the charging potential (Vh) of the image carrier (2) is expressed by the following formula (4). Is good. In short, it is preferable to set the charging potential (Vh) of the image carrier (2) to a value lower than the voltage applied to the developing means. Furthermore, it is better to set it to a value (-550 V) or less which is about 100 V lower than the voltage applied to the developing means (5) (-450 V in the above).
-450V>Vh> -800V (4)
However, the lower limit of −800 V is possible up to the upper limit if the charging means (3) has more charging capability. For example, if there is a charging ability up to -1200V, there is no problem even at -1200V.
With such a value, toner adhesion to the image carrier (2) can be prevented, and a lubricant thin film can be easily formed.
The applied voltage (Vch) to the charging means (3) satisfying the above expression (4) varies depending on the thickness of the photosensitive film of the image carrier (2), etc., but the image carrier (2) used in the experiment. Then, it was a value as shown in the following formula (5).
−1150V>Vch> −1500V (5)
Next, assuming that the voltage applied to the developing means (5) is grounded without applying the voltage at the time of image formation in the lubricant supply mode, the voltage applied to the charging means (3) is shown below. For (Vch), an AC voltage is not superimposed on the charging means, and the range of Vch in which the charging potential (Vh) of the image carrier (2) is expressed by the following equation (6) is good. Furthermore, it is better to set it to a value (−100 V) or less that is about 100 V lower than the voltage applied to the developing means (5) (0 V in the above).
0V>Vh> −800V (6)
However, the lower limit of −800 V is possible up to the upper limit if the charging means (3) has more charging capability. For example, if there is a charging ability up to -1200V, there is no problem even at -1200V.
With such a value, toner adhesion to the image carrier (2) can be prevented, and a lubricant thin film can be easily formed.
The applied voltage (Vch) to the charging means (3) satisfying the above expression (6) varies depending on the thickness of the photosensitive film of the image carrier (2), etc. The value was as shown in 7).
0V ≧ Vch> −1500V (7)
However, in the above formula (7), discharge occurs between the charging means (3) and the image carrier (2), and the formation of a lubricant thin film on the image carrier (2) is hindered. Accordingly, the better condition for preventing the discharge between the charging means (3) and the image carrier (2) is the Vch range represented by the following formula (8). The following discharge start voltage varies depending on the film thickness of the image carrier (2) and the like, but is about 700 V in absolute value.
0V ≧ Vch> − (discharge start voltage) (8)
Here, an example in the case of negative charging is shown, but in the case of positive charging, the inequality sign is basically reversed.
An image forming apparatus that implements the lubricant supply mode does not necessarily have a static eliminating unit, but it is more preferable to have the static eliminating unit.

The toner of the present invention preferably has an average circularity of 0.93 to 1.00. When the average circularity is less than 0.93, the toner is separated from the spherical shape, the dot reproducibility is deteriorated, and the number of contact points with the photoconductor as the image carrier (2) increases, so that the releasability. Deteriorates and the transfer rate decreases.
The toner of the present invention is a toner whose average circularity is 0.93 or more and whose projected shape is close to a circle, has excellent dot reproducibility, and can obtain a high transfer rate.
The average circularity of the toner is a value obtained by optically detecting particles and dividing by the perimeter 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). In a predetermined container, 100 to 150 mL of water from which impure solids are removed in advance is added, 0.1 to 0.5 mL of a surfactant is added as a dispersant, and about 0.1 to 9.5 g of a measurement sample is further added. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the concentration and dispersion of the dispersion are set to 3,000 to 10,000 / μL, and the shape and distribution of the toner are measured.

  In the image forming apparatus shown in FIG. 13, the casing for rotatably supporting the charging means (3) and the cleaning case for supporting the cleaning means (7) are configured as an integral unit case, and an image is carried by this unit. The body (2) is assembled rotatably. In this way, an image forming unit in which the charging means (3) and the image carrier (2) are integrally assembled is constituted, and the image forming unit is detachably attached to the image forming apparatus main body. Yes. (Refer to FIG. 14) The charging means (3) and the image carrier (2) are assembled in the unit case in a state where the minute gap G 1 is kept constant, while the minute gap G 1 is kept constant. The image unit can be attached to and detached from the image forming apparatus main body. For this reason, it is possible to prevent a problem that the size of the minute gap G greatly fluctuates when the image forming unit is attached and detached. The image carrier (2) and the charging means (3) may be configured to be detachable from the main body of the image forming apparatus (1). According to this configuration, the image carrier (2) and the charging means (3 ) May change when attaching and detaching, and uniform charging may not be possible.

In addition to the charging means (3), the image forming unit of this example has a contact member that contacts the image carrier (2). In the example shown in FIG. 13, as described above, the cleaning case and the casing are formed as an integral unit case, and the lubricant supply means (103) is assembled to the unit case. Although not shown, it is better to assemble the charging means and the lubricant removing means integrally with the unit case.
The members constitute contact members that contact the image carrier (2), and these contact members can be attached to and detached from the main body of the image forming apparatus (1) separately from the charging member (3). However, in this case, when the contact member is attached or detached, these members move while being in contact with the image carrier (2), so that a large external force is applied to the image carrier (2). There is a risk that the gap G 1 fluctuates. On the other hand, if the contact member is also an element of the image forming unit, when the image forming unit is attached to and detached from the main body of the image forming apparatus (1), the cleaning blade, the lubricant supplying means (103) and the lubricant removing means are used. These contact members are also attached and detached, so that these members do not move relative to the image carrier (2), so that there is no possibility that the minute gap G will fluctuate greatly. The occurrence of scratches on 2) can also be prevented.

  Further, the image bearing member (2) is an organic photoreceptor having a surface layer reinforced with a filler such as alumina powder of 0.1 μm or less, an organic photoreceptor using a cross-linked charge transport material, or both. When the organic photoconductor is characterized, the surface hardness is increased and the wear resistance is improved, so that the lifetime can be greatly extended.

1 is a schematic configuration diagram of an image forming apparatus for carrying out an image forming method according to the present invention. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied. It is a X-ray reflectivity measurement result about the coating frequency dependence of a film thickness. It is a X-ray reflectivity measurement result about the coating frequency dependence of a film thickness. It is a flowchart which shows an example of lubricant supply mode. It is a flowchart which shows an example of lubricant supply mode. 1 is an example of an image forming apparatus having a process cartridge of the present invention. 1 is an example of an image forming apparatus 1 to which the present invention is applied. 1 is an example of an image forming apparatus 1 to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image carrier 3 Charging means 4 Exposure means 5 Development means 6 Transfer means 7 Cleaning means 7-1 Fur brush 8 Static elimination means 10 Fixing means 15 Recording paper 16 Conveying belt 17 Intermediate transfer body 18 Paper feed means 19 Process Cartridge 102 Lubrication member 103 Lubricant supply means 110 Lubricant equalization means

Claims (16)

At least an image carrier;
A charging means having a charging member in proximity or contact;
Image forming comprising: a lubricant supplying means for applying a lubricant; and a lubricant uniformizing means for forming a thin film on the image carrier on the downstream side of the transfer means in the rotation direction of the image carrier and upstream of the charging means. In the method
The image forming method includes:
Having detection means for detecting replacement of the image carrier;
An image forming method, comprising: passing a lubricant supply unit and / or a lubricant uniformizing unit at least three times or more when detecting replacement. At least an image carrier;
A charging means having a charging member in proximity or contact;
Image forming comprising: a lubricant supplying means for applying a lubricant; and a lubricant uniformizing means for forming a thin film on the image carrier on the downstream side of the transfer means in the rotation direction of the image carrier and upstream of the charging means. In the method
The image forming method includes:
It has a counter that counts time or the number of printed sheets,
An image forming method comprising passing a lubricant supply unit and / or a lubricant uniformizing unit at least three times or more for a certain period or for every certain number of printed sheets. The image forming method according to claim 1 or 2,
The image forming method includes:
An image forming method characterized in that when passing through the lubricant supplying means and / or the lubricant uniformizing means at least three times or more, the applied voltage to the charging member is only a direct current component not containing an alternating current component or non-applied. . The image forming method according to claim 3.
The image forming method includes:
An image forming method, wherein a voltage applied to a charging member is only a direct current component and lower than a discharge start voltage. In the image forming method according to claim 3 and 4,
The image forming method includes:
The absolute value of the applied voltage of the developing means when the applied voltage of the developing means is 0 V or when the lubricant supplying means and / or the lubricant uniformizing means are passed at least three times from the applied voltage of the developing means at the time of image formation. An image forming method characterized by lowering the value. The image forming method according to claim 1,
The image forming method includes:
An image forming method, wherein the image carrier has a protective layer on a surface layer. The image forming method according to any one of claims 1 to 6,
The image forming method includes:
An image forming method, wherein the toner used in the developing means is a spherical toner having a circularity of 0.96 or more and less than 1.0. The image forming method according to any one of claims 1 to 7,
The image forming method includes:
An image forming method comprising: a process cartridge that integrally supports at least an image carrier and a lubricant supply unit and is detachable from an image forming apparatus main body. At least an image carrier;
A charging means having a charging member in proximity or contact;
Image forming comprising: a lubricant supplying means for applying a lubricant; and a lubricant uniformizing means for forming a thin film on the image carrier on the downstream side of the transfer means in the rotation direction of the image carrier and upstream of the charging means. In the device
The image forming apparatus includes:
Having detection means for detecting replacement of the image carrier;
An image forming apparatus comprising: a control unit that causes the lubricant supply unit and / or the lubricant uniformizing unit to pass at least three times or more at the time of replacement detection. At least an image carrier;
A charging means having a charging member in proximity or contact;
Lubricant supply comprising a lubricant supply means for applying a lubricant and a lubricant uniformizing means for forming a thin film on the image carrier on the downstream side of the transfer means in the rotation direction of the image carrier and upstream of the charging means. And an image forming apparatus comprising:
The image forming apparatus includes:
It has a counter that counts time or the number of printed sheets,
An image forming apparatus comprising: a control unit that causes the lubricant supply unit and / or the lubricant uniformizing unit to pass at least three times or more for a certain period or for every certain number of printed sheets. The image forming apparatus according to claim 9 or 10, wherein:
The image forming apparatus includes:
An image forming apparatus, wherein a voltage applied to a charging member is only a direct current component not including an alternating current component or non-applied. The image forming apparatus according to claim 11.
The image forming apparatus includes:
The voltage applied to the charging member is only a direct current component and lower than the discharge start voltage.
An image forming apparatus. The image forming apparatus according to claim 11 or 12,
The image forming apparatus includes:
The absolute value of the applied voltage of the developing unit when the applied voltage of the developing unit is 0 V or the lubricant supplying unit and / or the lubricant uniformizing unit is passed at least three times from the applied voltage of the developing unit at the time of image formation. An image forming apparatus characterized by lowering the height. 14. The image forming apparatus according to claim 9, wherein:
The image forming apparatus includes:
An image forming apparatus, wherein the image carrier has a protective layer on a surface layer. The image forming apparatus according to any one of claims 9 to 14,
The image forming apparatus includes:
An image forming apparatus, wherein the toner used in the developing means is a spherical toner having a circularity of 0.96 or more and less than 1.0. The image forming apparatus according to any one of claims 9 to 15,
The image forming apparatus includes:
An image forming apparatus comprising: a process cartridge that integrally supports at least an image carrier and a lubricant supply unit and is detachable from a main body of the image forming apparatus.

Images