JP4665415B2 - 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 facsimile machine, a printer, and the like, and in particular, scrapes a residue remaining on a surface of a rotating toner image carrier carrying a toner image on the surface. Further, the present invention relates to a device provided with a cleaning blade whose tip is pressed against the surface.

  Conventionally, in the electrophotographic system, an electrostatic latent image is obtained by charging the surface of a rotating toner image carrier and irradiating the charged toner image carrier with exposure light. The toner is developed with toner of a developer including toner and an external additive to form a toner image on the surface of the toner image carrier, and the toner image formed on the surface of the toner image carrier is transferred to a predetermined transfer surface. An image composed of a fixed toner image is formed by an image forming process that is finally fixed on the recording medium.

  Foreign matter such as untransferred toner, external additives, paper powder, or discharge products generated during charging remain on the surface of the toner image carrier that has been transferred to a predetermined transfer surface. Prior to the image forming process, it is necessary to remove it by a cleaning means.

  As a cleaning method for removing a residue such as toner, a method in which a tip edge portion of a rubber cleaning blade made of urethane rubber or the like is brought into pressure contact with the surface of the toner image carrier is often used. In this method, the surface of the toner image carrier is scraped off by a cleaning blade and is also polished by residual toner particles blocked by the cleaning blade, so that the surface of the toner image carrier is refreshed. When the surface of the toner image carrier is scraped off by the cleaning blade, rubbing occurs between the surface of the toner image carrier and the tip edge portion of the cleaning blade. The friction force between the surface of the carrier and the tip edge becomes too high, and the wear of the toner image carrier is accelerated more than necessary, and the tip edge of the cleaning blade is worn and chipped, maintaining good cleaning characteristics over a long period of time. It becomes difficult to do. The toner particles and external additive particles contained in the residue act as a lubricant, and this scrubbing is kept well. However, in recent years, the particle size distribution with a small diameter due to high image quality and reduced environmental burden. Spherical toner particles having a well-distributed shape have been used, and it is known that spherical toner particles have insufficient function as a lubricant. It is also known that the spherical toner particles are difficult to clean.

Therefore, by supplying a solid lubricant to the surface of the toner image carrier, the tip edge portion of the blade is protected and wear of the toner image carrier surface is prevented from being promoted more than necessary. Attempts have been made to ensure this. When the solid lubricant is supplied to the surface of the toner image carrier, a lubricant film is formed on the surface of the toner image carrier. When supplying the solid lubricant to the surface of the toner image carrier, if the supply amount is too small, the effect of protecting the blade tip edge and the effect of preventing unnecessary wear of the toner image carrier will be insufficient. Then, the lubricant film becomes too thick, the leading edge of the blade does not reach the surface layer of the toner image carrier, and the toner image carrier cannot be refreshed, resulting in image quality defects such as image flow. It becomes easy to do. For this reason, the supply amount of the solid lubricant is often set to a ratio of 2 μg to 20 μg per A4 sheet. However, the amount of this type of solid lubricant applied to the surface of the image carrier is easily affected by the environment, and the amount of supply and scraping of the solid lubricant vary depending on the temperature and humidity. Even if the ratio is maintained, in an environment of high temperature and high humidity, as a result, excessive supply occurs and image flow tends to occur. In order to solve this problem, a technique has been proposed in which the rotation speed of rollers and brushes, which are solid lubricant supply members, is varied according to the environment to keep the lubricant supply amount constant (see Patent Document 1).
JP-A-9-62163

  However, in recent years, the life of an image forming unit incorporating a toner image carrier or the like has been extended, and even if the amount of lubricant supplied becomes the above ratio, image flow does not occur after long-term use. May occur. This is because the rubber cleaning blade has been pressed against the toner image carrier for a long period of time, causing the rubber to undergo permanent deformation, reducing the pressing force on the toner image carrier surface and reducing the scraping ability. is there.

  Further, at both ends in the axial direction of the rotation axis of the toner image carrier, a toner image is often not formed or even if it is formed, it is often a low image density toner image. The average number of toner particles in the long term is smaller than that in the central portion. For this reason, there is little polishing effect by the toner particles, it is difficult to refresh the toner image carrier, and image flow may occur even before it is used for a long time.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus that solves the above problems and refreshes a toner image carrier to suppress the occurrence of image flow.

The first image forming apparatus of the present invention that solves the above object transfers a toner image carried on the surface of a rotating toner image carrier carrying a toner image on the surface to a predetermined transfer surface, and finally In an image forming apparatus for forming an image on a recording medium by fixing on the recording medium,
A cleaning blade made of rubber, scraping off the residue remaining on the surface of the toner image carrier after the toner image is transferred to the transfer surface;
A solid lubricant supplied to the surface of the toner image carrier;
The solid lubricant is provided on the surface of the toner image carrier after the toner image is transferred to the transfer surface of the toner image carrier. A lubricant supply device for supplying
The amount of the solid lubricant supplied to the surface of the toner image carrier by the lubricant supply device decreases with an increase in the cumulative number of rotations of the toner image carrier.

  The surface to be transferred here may be a surface of the intermediate transfer member that is in contact with the toner image carrier, or may be a recording surface of a recording medium (hereinafter the same).

  According to the first image forming apparatus of the present invention, the cleaning blade accepts the problem that the scraping ability decreases due to permanent deformation, and the refreshability of the surface of the image carrier of the cleaning blade whose scraping ability decreases due to permanent deformation. In order to eliminate the factor of further reduction, the supply amount is decreased in accordance with an increase in the cumulative rotation speed of the toner image carrier. That is, when the pressing force of the cleaning blade decreases due to permanent deformation, the ability to scrape off the lubricant film formed on the surface of the toner image carrier formed by the supply of the solid lubricant also decreases. This is the same as supplying a solid lubricant. As a result, the thickness of the lubricant film is increased, the blade tip does not reach the surface layer of the toner image carrier, and the toner image carrier cannot be refreshed. Further, since the scraping ability of the cleaning blade that is permanently deformed is reduced, the increase in the thickness of the lubricant film becomes a further problem. Therefore, by reducing the supply amount in accordance with the increase in the cumulative number of rotations of the toner image carrier, even a cleaning blade having a reduced scraping ability can reach the surface layer of the toner image carrier. A thin lubricant film is formed on the surface of the toner image carrier, and the toner image carrier is refreshed by the cleaning blade while preventing the blade tip from being worn or chipped by the thin lubricant film. As a result, according to the first image forming apparatus of the present invention, the occurrence of image flow can be suppressed.

Here, the lubricant supply device passes through two regions of the toner image carrier, a region in contact with the surface after the toner image is transferred to the transfer surface and a region in contact with the solid lubricant. And rotating the rotating brush, scraping the solid lubricant with the rotating brush and applying the scraped solid lubricant to the surface,
The solid lubricant may have a shape in which the area of the contact portion in contact with the rotating brush is narrowed by being scraped by the rotating brush, or
The solid lubricant may have a layer structure in which the hardness of a contact portion in contact with the rotating brush is increased by scraping the rotating brush.

  As one aspect of the first image forming apparatus of the present invention, the lubricant supply device is configured to press the solid lubricant against the surface of the toner image carrier, and the supply amount is reduced by reducing the pressing force. Although an aspect can be considered, the supply amount can be easily reduced by using a solid lubricant having the above shape or a solid lubricant having the above layer structure as compared with the above aspect.

The second image forming apparatus of the present invention that solves the above object transfers a toner image carried on a surface of a rotating toner image carrier carrying a toner image on a surface to a predetermined transfer surface, and finally transfers the toner image. In an image forming apparatus for forming an image on a recording medium by fixing on the recording medium,
A cleaning blade having the tip thereof pressed against the surface of the toner image carrier, scraping off residues remaining on the surface after the toner image is transferred to the transfer surface;
A solid lubricant supplied to the surface of the toner image carrier;
The solid lubricant is provided on the surface of the toner image carrier after the toner image is transferred to the transfer surface of the toner image carrier. A lubricant supply device for supplying
The amount of the solid lubricant supplied to the surface of the toner image carrier by the lubricant supply device is smaller at both axial end portions than in the axial central portion of the rotation shaft of the toner image carrier. Features.

  In many cases, a toner image is not formed or the number of images formed is small at both ends in the axial direction of the rotation shaft of the toner image carrier. The number of toner particles is smaller than that. Therefore, it is difficult to refresh the toner image carrier, and if there are thick lubricant films at both ends in the axial direction, the toner image carrier is more difficult to refresh. According to the second image forming apparatus of the present invention, the lubricant film formed at both axial ends of the toner image carrier is thinner than the lubricant film formed at the axial center. The toner image carrier is refreshed at both ends in the direction. As a result, the occurrence of image flow can also be suppressed by the second image forming apparatus of the present invention.

Here, the lubricant supply device passes through two regions of the toner image carrier, a region in contact with the surface after the toner image is transferred to the transfer surface and a region in contact with the solid lubricant. And rotating the rotating brush, scraping the solid lubricant with the rotating brush and applying the scraped solid lubricant to the surface,
The solid lubricant extends in the axial direction of the rotating shaft of the toner image carrier, and the hardness of the contact portion in contact with the rotating brush is greater in the axial end portions than in the axial central portion. May be high.

  By doing so, the supply amount of the solid lubricant supplied to both end portions in the axial direction of the toner image carrier can be easily reduced as compared with the central portion in the axial direction.

The third image forming apparatus of the present invention that solves the above object transfers a toner image carried on the surface of a rotating toner image carrier carrying a toner image on the surface to a predetermined surface to be transferred. In an image forming apparatus for forming an image on a recording medium by fixing on the recording medium,
A cleaning blade having the tip thereof pressed against the surface of the toner image carrier, scraping off residues remaining on the surface after the toner image is transferred to the transfer surface;
A solid lubricant supplied to the surface of the toner image carrier;
The solid lubricant is provided on the surface of the toner image carrier after the toner image is transferred to the transfer surface of the toner image carrier. A lubricant supply device for supplying
The weight reduction rate (mg / kcycle) of the solid lubricant that decreases by being supplied to the toner image carrier during 1000 rotations of the toner image carrier is Y, and the cumulative rotation of the toner image carrier. When the number (cycle) is X,
Y = −aX + b
0.007 ≦ a ≦ 0.013
12 ≧ b ≧ 8
The relational expression represented by is established.

  Further, in the image forming apparatus of the present invention, the lubricant supply device holds a solid lubricant and is rotatably supported via a rotation shaft parallel to the rotation shaft of the rotary brush; A moment generating section for generating a moment around the rotating shaft, and the solid lubricant held in the rotating section is brought into contact with the rotating brush by the moment generated by the moment generating section. It is preferable that a support member is provided.

  In this way, the solid lubricant can be stably supplied to the surface of the toner image carrier while adjusting the supply amount.

  According to the present invention, it is possible to provide an image forming apparatus in which the toner image carrier is refreshed to suppress the occurrence of image flow.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus 1 of the present embodiment is an image forming apparatus that employs a full-color tandem method, and uses four toner image forming units corresponding to four color toners of yellow, magenta, cyan, and black, respectively. Each toner image forming unit forms a toner image of each color in synchronization with the feeding of the intermediate transfer belt, and superimposes these toner images on an intermediate transfer belt as an intermediate medium (primary transfer), on the intermediate transfer belt The toner image superimposed on the toner image is transferred (secondary transfer) to a recording medium, and fixed.

  The image forming apparatus 1 shown in FIG. 1 is a semiconductive intermediate transfer supported by four toner image forming units 10, four primary transfer rolls 20, and three support rolls 31 so as to circulate in a counterclockwise direction. The belt 30 includes a batch transfer device 40 that performs secondary transfer, and a fixing device 50 that fixes an unfixed toner image on a sheet.

  The four toner image forming units 10 are arranged side by side in the circulation direction of the intermediate transfer belt 30, and each toner image forming unit 10 is provided with a photosensitive drum 11 that rotates clockwise. Each photoconductor drum 11 is formed by laminating an undercoat layer, a charge generation layer, a charge transport layer, and a surface layer on an Al substrate on a cylinder, and the surface of the surface layer is the surface of this photoconductor drum. 11 surface. The surface of the photosensitive drum 11 is in contact with the intermediate transfer belt 30. In a region where the intermediate transfer belt 30 is in contact with the photosensitive drum 11, a primary transfer roll 20 is provided so as to sandwich the intermediate transfer belt 30 with the photosensitive drum 11, and this region is a primary transfer region.

  Here, FIG. 2 will be used together with FIG. 1 to further explain the image forming apparatus of this embodiment.

  FIG. 2 is a diagram mainly showing a schematic configuration of one of the four toner image forming units shown in FIG.

  The toner image forming unit 10 shown in FIG. 2 includes a charging device 12, an exposure device 13, a developing device 14, a cleaning device 15, and a static eliminator 16 in addition to the photosensitive drum 11. FIG. 2 schematically shows the surface layer 111 of the photosensitive drum 11.

  The charging device 12 is a non-contact charging type corotron charger. In addition, the contact charging method is adopted, and a roll-shaped charging member, a blade-shaped charging member, a belt-shaped charging member, a brush-shaped charging member, a magnetic brush-shaped charging member, etc. are provided in place of the corotron charger. May be. The surface of the photosensitive drum 11 is uniformly charged by the charging device 12. Hereinafter, an area where the photosensitive drum 11 is charged by the charging device 12 is referred to as a charging area.

  The exposure device 13 irradiates the surface of the photosensitive drum with laser light based on image information.

  The developing device 14 carries a developer container 141 that contains toner particles and a developer containing an external additive that is finer than the toner particles, and the toner particles in the developer container 141 that carry the toner particles. A developing roll 142 that rotates in contact with the developing roll 142. A toner image is formed on the surface of the photosensitive drum 11 by the developing device 14.

  When image formation is performed in the image forming apparatus 1 shown in FIG. 1, the surface of the photosensitive drum 11 is first uniformly charged by the charging device 12. Next, laser light based on image information is irradiated by the exposure device 13, and an electrostatic latent image is formed on the surface of the photosensitive drum 11. The electrostatic latent image is developed by the developing device 14 and a toner image is formed on the surface of the photosensitive drum 11. The toner image formed in this way is transferred from the surface of the photosensitive drum 11 to the surface of the intermediate transfer belt 30 in the primary transfer region. The toner images formed by the toner image forming units 10 become toner images that are overlapped on the intermediate transfer belt 30.

  1 includes a secondary transfer roll 41 disposed in pressure contact with the toner image carrying surface side of the intermediate transfer belt 30 and a backup roll 42 disposed on the back side of the intermediate transfer belt 30. The intermediate transfer belt 30 is sandwiched between these two rolls 41 and 42. A space between these two rolls 41 and 42 becomes a secondary transfer region.

  Further, the image forming apparatus 1 shown in FIG. 1 is provided with a paper tray 60, and the paper P accommodated in the paper tray 60 is sent out from the paper tray 60 by the feed roll 61, and is secondary at a predetermined timing. It is sent to the transfer area. In the secondary transfer region, the toner images overlapped on the intermediate transfer belt 30 are transferred onto the fed paper P. The fixing device 50 includes a fixing roll 51 having a heating and heating mechanism 511 and a pressure roll 52 provided so as to face the fixing roll 51. Between the fixing roll 51 and the pressure roll 52 facing each other, the paper P that has passed the secondary transfer position is conveyed. The toner constituting the toner image on the paper P is melted by the heating mechanism 511 of the fixing roll 51 and fixed on the paper P.

  A belt cleaner 70 is provided on the downstream side of the batch transfer device 40, and residual toner on the intermediate transfer belt 30 is removed from the intermediate transfer belt 30 by the belt cleaner 70.

  On the other hand, on the surface layer 111 of the photosensitive drum 11 shown in FIG. 2 that has passed through the primary transfer region, residual toner that could not be transferred to the surface of the intermediate transfer belt 30 in the primary transfer region, and the residual toner. The attached external additive particles and further foreign matters such as discharge products generated during charging remain. A cleaning device 15 shown in FIGS. 1 and 2 is a device for removing these foreign substances, and is downstream of the primary transfer region in the photosensitive drum rotation direction and from the charging region in the photosensitive drum rotation direction. It is deployed at an upstream position. The cleaning device 15 includes a cleaning blade 151, a solid lubricant 152, a lubricant supply device 153, and a waste toner transport auger 154. The cleaning blade 151 is a plate-like member extending in the extending direction of the rotation shaft 11 a of the photosensitive drum 11, and the toner image is transferred to the intermediate transfer belt 30 of the photosensitive drum 11 at the leading edge portion 1511 thereof. And is in pressure contact with the surface layer 111 after. The cleaning blade 151 scrapes the surface layer 111 of the photosensitive drum 11 and dams up the residue as the photosensitive drum 11 rotates. The surface layer 111 of the photosensitive drum 11 is ground by the residual toner particles and external additives that have been dammed in addition to being scraped off by the cleaning blade 151, and the surface layer 111 is refreshed. The foreign matter removed from the photosensitive drum 11 when the cleaning blade 151 scrapes off the surface layer 111 is transported to the outside of the cleaning device 15 by the waste toner transport auger 154.

  The solid lubricant 152 shown in FIG. 2 is mainly composed of zinc stearate extending in the extending direction of the rotating shaft 11a of the photosensitive drum 11. A detailed description of the solid lubricant 152 will be described later.

  The lubricant supply device 153 illustrated in FIG. 2 includes a roll brush 1531, a rotating arm 1532, and a weight 1533. The roll brush 1531 passes through two regions, a region in contact with the surface layer 111 of the photosensitive drum 11 and a region in contact with the solid lubricant 152, and a rotation shaft 1531 a parallel to the rotation shaft 11 a of the photosensitive drum 11. It rotates around the center. The bristles of the rotating roll brush 1531 come into contact with the solid lubricant 152 to scrape the solid lubricant 152 and carry the scraped solid lubricant 152 to contact the surface layer 111 of the photosensitive drum 11. Thereby, the lubricant is applied to the surface layer 111 of the photosensitive drum 11. A lubricant film is formed on the surface layer 111 of the photosensitive drum 11 to which the lubricant is applied. The solid lubricant 152 is held by a rotation arm 1532, and the rotation arm 1532 is supported rotatably about a rotation shaft 1532 a parallel to the rotation shaft 1531 a of the roll brush 1531. It is. Further, a weight 1533 is provided on the surface of the rotating arm 1532 opposite to the surface holding the solid lubricant 152. Therefore, a moment due to the weight of the weight 1533 is generated in the rotating arm 1532, and in this lubricant supply device 153, the solid lubricant 152 held by the rotating arm 1532 is rolled by the moment due to the weight of the weight 1533. It is pressed against the hair of the brush 1531. As a result, the solid lubricant 152 is stably supplied to the surface layer 111 of the photosensitive drum 11 in the rotation axis direction of the photosensitive drum 11.

  The rotating arm 1532 and the weight 1533 may be omitted, and the solid lubricant 152 and the roll brush 1531 may be brought into contact with each other by the weight of the solid lubricant 152.

  Here, the relationship between the cumulative number of rotations of the photosensitive drum and the thickness of the surface layer of the photosensitive drum scraped by the cleaning blade will be described with reference to FIG.

  FIG. 3 shows an example of a change in the layer thickness of the surface layer of the photosensitive drum over time when the amount of solid lubricant supplied to the photosensitive drum having a diameter of 84 mm is maintained at about 8 mg per 1000 revolutions (1 kcycle) of the photosensitive drum. It is a graph to show.

  The horizontal axis of the graph shown in FIG. 3 indicates the cumulative rotation number of the photosensitive drum (photosensitive member cycle number; kcycle), and the vertical axis indicates the thickness of the photosensitive drum surface layer (photosensitive member film thickness: μm). As shown in the graph of FIG. 3, when the number of photoconductor cycles increases, the relationship between the cycle number and the film thickness deviates from the proportional relationship, and the decrease in the film thickness becomes gentle as the cycle number increases. That is, the dotted line graph shown in FIG. 3 shows the change in the film thickness of the surface layer of the photosensitive drum when the wear rate of the photosensitive drum up to 200 kcycle is maintained until the end. As indicated by the solid line graph, the wear rate of the photosensitive drum actually decreases as the number of cycles increases.

  Table 1 below shows changes in the amount of biting into the surface layer of the photosensitive drum by the cleaning blade.

  As shown in Table 1, a decrease in the wear rate can be considered as one factor that the pressing force against the surface layer of the photosensitive drum is reduced and the scraping ability of the cleaning blade is reduced. The decrease in the pressing force is considered to be due to the permanent deformation of the cleaning blade. Further, when the pressing force of the cleaning blade is reduced, the ability to scrape the lubricant film formed on the surface layer of the photosensitive drum is also reduced. Therefore, even if the supply amount is kept at 8 mg / kcycle, the surface layer is effectively more effectively applied to the surface layer. The solid lubricant is supplied, and as a result, the film thickness of the lubricant film is increased and the blade tip cannot reach the surface layer of the toner image carrier.

  Depending on the image forming pattern of the developer, when the supply amount of the solid lubricant is about 8 mg / kcycle, the pressing pressure of the cleaning blade is about 1.9 gf / mm. If it is below, it tends to be too low wear. The appropriate amount of lubricant on the photosensitive drum surface layer is determined by the balance between the amount of lubricant supplied by a brush or the like and the amount of scraping from the photosensitive drum surface layer when the developer is cleaned. As described above, when the pressing force of the cleaning blade decreases with time, the scraping force also decreases, and therefore the amount of lubricant on the surface layer of the photosensitive drum tends to increase even if the amount of lubricant supplied is similar. is there. For this reason, when the solid lubricant is applied, if the amount of biting of the cleaning blade decreases, the wear rate tends to decrease extremely particularly in the portion where the low image density continues, and image flow tends to occur. It is done.

  FIG. 4 is a graph showing the relationship between the wear rate of the photosensitive drum surface layer and the amount of lubricant supplied.

  The horizontal axis of the graph of FIG. 4 indicates the lubricant supply amount (μg / PV) per print, and the vertical axis indicates the wear rate (nm / kcycle) of the surface layer of the photosensitive drum. Also, in the graph of FIG. 4, the curve connecting the circled plots shows the relationship between the wear rate and the lubricant supply amount when the cumulative rotation speed of the photosensitive drum is 0 to 200 kcycles. The curve connecting the two indicates the relationship between the wear rate and the lubricant supply amount when the cumulative rotation speed of the photosensitive drum is 200 to 400 kcycle, and the curve connecting the plots of the square marks indicates the cumulative rotation speed of the photosensitive drum. Shows the relationship between the wear rate and the lubricant supply amount between 400 and 200 kcycles. It can be seen from the curve connecting the circled plots that the wear rate decreases with an increase in the amount of lubricant supplied even when the cumulative number of rotations of the photosensitive drum is up to 200 kcycles. It can also be seen that the wear rate is lower when the cumulative number of revolutions is larger even with the same amount of lubricant supplied.

From the above, as an index for determining a suitable supply amount of the solid lubricant to the surface layer of the photosensitive drum, the solid lubrication which is reduced by being supplied to the photosensitive drum during 1000 revolutions of the photosensitive drum. If the weight reduction rate (mg / kcycle) of the agent is Y and the cumulative rotation number (cycle) of the photosensitive drum is X,
Y = −aX + b
0.007 ≦ a ≦ 0.013
12 ≧ b ≧ 8
The relational expression represented by In the image forming apparatus 1 shown in FIG. 1, this relational expression is established.

  FIG. 5 is a view when the solid lubricant shown in FIG. 2 is sectioned in a direction orthogonal to the extending direction.

  The solid lubricant 152 shown in FIG. 2 has a substantially trapezoidal cross section. Although not shown in FIG. 5, the roll brush 1531 shown in FIG. 2 is disposed below the solid lubricant 152 shown in FIG. 5, and the bottom surface 1521 of the solid lubricant 152 having a substantially trapezoidal cross section is provided on the roll brush. The surface is scraped by 1531. Therefore, in the solid lubricant 152 shown in FIG. 2, as the scraping by the roll brush 1531 proceeds, the area of the bottom surface 1521 gradually decreases. For this reason, the scraping amount of the roll brush 1531 is reduced, and as a result, the amount of solid lubricant applied to the photosensitive drum 11 is also reduced. The roll brush 1531 rotates when the photosensitive drum 11 rotates. In the lubricant supply device 153 shown in FIG. 2, the amount of solid lubricant applied to the photosensitive drum 11 is such that the photosensitive drum 11 has a coating amount. It decreases gradually as the cumulative number of revolutions of the drum 11 increases. Therefore, according to the image forming apparatus 1 of the present embodiment, the permanent deformation of the cleaning blade 151 progresses as the cumulative number of rotations of the photosensitive drum 11 increases, while it is formed on the surface layer 111 of the photosensitive drum 11. The film thickness of the lubricant film is reduced. As a result, even with the cleaning blade 151 whose scraping ability has decreased due to permanent deformation, a thin lubricant film is formed so that the leading edge portion 1511 reaches the surface layer 111 of the photosensitive drum 11, and the thin lubricant film forms the leading edge. The photosensitive drum 11 is refreshed by the cleaning blade 151 while preventing the edge portion 1511 from being worn or chipped. Thereby, in the image forming apparatus 1 shown in FIG. 1, generation | occurrence | production of an image flow is suppressed.

  Subsequently, two modified examples of the solid lubricant shown in FIG. 2 will be described with reference to FIGS. 6 and 7. The solid lubricant in any of the modifications is mainly composed of zinc stearate extending in the extending direction of the rotating shaft 11a of the photosensitive drum 11. Moreover, each figure of FIG. 6 and FIG. 7 shows the figure when the solid lubricant is cross-sectioned in a direction perpendicular to the extending direction, and the lower surface of the solid lubricant is a roll. The surface is scraped off by the brush 1531.

  FIG. 6 is a view showing a first modification of the solid lubricant shown in FIG.

  The solid lubricant 155 shown in FIG. 6 has a rectangular parallelepiped shape provided with a notch groove 1552. The cross-sectional shape of the solid lubricant 155 shown in FIG. 6 is a substantially rectangular shape provided with a notch. The notch groove 1552 shown in FIG. 6 is provided on the surface of the solid lubricant 155 opposite to the surface (bottom surface 1551) scraped by the roll brush 1531, that is, the upper surface 1553, and the solid lubricant 155. Is recessed toward the bottom surface 1551 over the entire length in the extending direction. Therefore, when the scraping of the solid lubricant 155 shown in FIG. 6 by the roll brush 1531 progresses and the level of the bottom surface 1551 reaches the level where the notch groove 1552 is provided, the area of the bottom surface 1551 is equal to the area of the notch groove 1552. Narrow. As a result, the amount of scraping of the roll brush 1531 is reduced by the amount the scraping area is reduced. As a result, the amount of solid lubricant applied to the photosensitive drum 11 is also reduced. In the solid lubricant 155 in this modification, the depth of the notch groove 1552 is determined so that the level of the bottom surface 1551 reaches the level at which the notch groove 1552 is provided when the cleaning blade 1 is permanently deformed. . Therefore, in the image forming apparatus in which the solid lubricant 155 of this modification is provided, the photosensitive drum 11 is exposed to the photosensitive drum 11 when the cumulative number of rotation reaches a certain number of rotations or more and the permanent deformation of the cleaning blade 151 begins to occur. The amount of lubricant supplied to the surface layer 111 of the body drum 11 is reduced. As a result, even if the cleaning blade 151 starts to be permanently deformed, the lubricant is not excessively supplied and the photosensitive drum 11 is refreshed by the cleaning blade 151 while preventing the tip edge portion 1511 from being worn or chipped. . Thereby, even in the image forming apparatus provided with the solid lubricant 155 of the first modified example, occurrence of image flow can be suppressed.

  FIG. 7 is a view showing a second modification of the solid lubricant shown in FIG.

  The solid lubricant 156 shown in FIG. 7 has a rectangular parallelepiped shape with a two-layer structure. The solid lubricant 156 shown in FIG. 7 is provided with a low hardness lubricant layer 1562 having a low hardness on the surface (bottom surface 1561) scraped by the roll brush 1531, and on the low hardness lubricant layer 1562. A high hardness lubricant layer 1563 having a higher hardness than the low hardness lubricant layer 1562 is provided. Therefore, when the cumulative number of rotations of the photosensitive drum 11 is small, the roll brush 1531 scrapes off the solid lubricant from the low-hardness lubricant layer 1562, but when the low-hardness lubricant layer 1562 is scraped off, the roll brush 1531 The solid lubricant is scraped off from the hardness lubricant layer 1563. As a result, the amount of scraping of the roll brush 1531 decreases as the hardness of the lubricant increases, and as a result, the amount of solid lubricant applied to the photosensitive drum 11 also decreases. In the solid lubricant 156 shown in FIG. 7, the low hardness lubrication is performed so that the scraping of the roll brush 1531 shifts from the low hardness lubricant layer 1562 to the high hardness lubricant layer 1563 when the cleaning blade 1 is permanently deformed. The thickness of the agent layer 1562 is determined. Therefore, in the image forming apparatus provided with the solid lubricant 156 according to the second modification, when the cumulative rotation number of the photosensitive drum 11 reaches a certain rotation number or more and the cleaning blade 151 starts to be permanently deformed, The supply amount of the lubricant film formed on the surface layer 111 of the photosensitive drum 11 is reduced. As a result, even if the cleaning blade 151 starts to be permanently deformed, the photosensitive drum 11 is refreshed by the cleaning blade 151 while preventing the tip edge portion 1511 from being worn or chipped by the stable lubricant film. Thereby, even in the image forming apparatus provided with the solid lubricant 156 of the second modified example, occurrence of image flow can be suppressed.

  Then, the 3rd modification of the solid lubricant shown in FIG. 2 is demonstrated. The modification described so far is an example that exhibits an effect when the accumulated rotational speed of the photosensitive drum 11 increases. However, the third modified example is effective regardless of the cumulative rotational speed of the photosensitive drum 11. It is an example that demonstrates. That is, at both ends in the axial direction of the rotating shaft 11a of the photosensitive drum 11 shown in FIG. 2, a toner image is not formed, or even if it is formed, the number of times of image formation is small. The number of toner particles is smaller at both ends in the axial direction than in the central portion in the axial direction. Therefore, there is a problem that the polishing effect by the toner particles is reduced at both ends in the axial direction of the photosensitive drum 11 and it is difficult to refresh the surface layer 111. In the third modification, the accumulated rotational speed of the photosensitive drum 11 is increased. Regardless, the refreshability of the surface layer 111 at both axial ends of the photosensitive drum 11 is improved.

  FIG. 8 is a view showing a third modification of the solid lubricant shown in FIG.

  The solid lubricant 157 shown in FIG. 8 is also mainly composed of zinc stearate extending in the extending direction of the rotating shaft 11 a of the photosensitive drum 11. 8 shows the solid lubricant viewed from the roll brush 1531 side shown in FIG. That is, the horizontal direction in FIG. 8 is the extending direction of the rotating shaft 11a of the photosensitive drum shown in FIG. 2. In the solid lubricant 157 shown in FIG. The surface 1571 is scraped off. The solid lubricant 157 shown in FIG. 8 has a high hardness portion 1572 at both ends of the solid lubricant 157 in the extending direction of the rotating shaft 11a of the photosensitive drum 11, and a low hardness at the center portion sandwiched between the both ends. A portion 1573 is included. The high hardness portion 1572 is a portion having a higher hardness than the low hardness portion 1573. Therefore, when the roll brush 1531 scrapes off the solid lubricant 157 shown in FIG. 8, the scraping amount scraped from the high hardness portion 1572 at both end portions is smaller than the scraping amount scraped from the low hardness portion 1573 at the center portion. As a result, the thickness of the lubricant film formed on both end portions of the photosensitive drum 11 is thinner than the thickness of the lubricant film formed on the central portion in the extending direction of the rotating shaft 11a. For this reason, even if the number of toner particles is small, both end portions in the axial direction of the surface layer 111 are refreshed to the same extent as the central portion. Thereby, even in the image forming apparatus provided with the solid lubricant 157 of the third modified example, occurrence of image flow can be suppressed.

(Example)
Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
In DocuCenterColor500 manufactured by Fuji Xerox Co., Ltd., ZnSt is brought into contact with a disturber brush located upstream of the cleaning blade in the rotational direction of the photosensitive drum by a self-weight type (total weight 15 g) in which ZnSt is attached to a single support holder. A toner image forming unit modified so as to supply ZnSt onto the surface of the photosensitive drum via a disturber brush was used. The cleaning blade is made of urethane rubber with a thickness of 2.0 mm and a free length of 9 mm. It has a setting angle of 28 °, a biting amount of 1.2 mm against the surface of the photosensitive drum, and a pressure of 2.86 g / mm with respect to the photosensitive drum rotation direction. To contact the counter direction. ZnSt as the solid lubricant has a substantially trapezoidal cross section as shown in FIG. 5 and is arranged so that the bottom surface (the surface with the larger area) described with reference to FIG. 5 is in contact with the brush. Therefore, in the first embodiment, the amount of the solid lubricant applied to the photosensitive drum 11 gradually decreases as the cumulative number of revolutions of the photosensitive drum 11 increases.

  In this experiment, outputting 3 A4 full-color images was 1 job, and a total of 74,000 images were output. At this time, from the start of the experiment, 24,000 sheets (approximately 200 kcycle in the cumulative rotation speed of the photosensitive drum), 491,000 sheets (approximately 400 kcycle in the cumulative rotation speed of the photosensitive drum), and 74,000 sheets (photosensitive body) The ZnSt weight and the film thickness of the surface layer of the photosensitive drum were measured at the time of output of approximately 600 kcycles as the cumulative number of revolutions of the drum.

(Comparative Example 1)
Except that the ZnSt was changed to a rectangular parallelepiped having a substantially rectangular cross section, the same experiment as in Example 1 was performed and measurement was performed. In other words, in Comparative Example 1, the amount of solid lubricant scraped by the roll brush 1531 is always substantially constant even when the cumulative number of revolutions of the photosensitive drum 11 is increased. The supply amount to 11 is always constant regardless of the cumulative number of rotations of the photosensitive drum 11.

  FIG. 9 is a graph showing the relationship between the cumulative number of rotations of the photosensitive drum and the wear rate of the surface layer of the photosensitive drum.

  The horizontal axis of the graph shown in FIG. 9 indicates the cumulative rotation speed (kcycle) of the photosensitive drum, and the vertical axis indicates the wear rate (nm / kcycle) of the surface layer of the photosensitive drum. Further, in the graph of FIG. 9, the solid line connecting the circled plots indicates the result of Example 1, and the dotted line connecting the triangular mark plots indicates the result of Comparative Example 1.

  Table 2 below shows changes in the amount of biting of the cleaning blade into the surface layer of the photosensitive drum in each of Example 1 and Comparative Example 1.

  As shown in FIG. 9, compared to Comparative Example 1, in Example 1, the decrease in the wear rate is suppressed. This can also be seen from the abrasion amount of the surface layer of the photosensitive drum shown in Table 2. In particular, in Comparative Example 1, the wear rate is remarkably reduced after 400 kcycle where the sag of the cleaning blade becomes large. In Comparative Example 1, image flow occurred in an image after 400 kcycle. On the other hand, in Example 1, no image flow occurred in an image after 400 kcycle.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a view mainly showing a schematic configuration of one toner image forming unit among four toner image forming units shown in FIG. 1. 6 is a graph showing an example of a change in the layer thickness of the surface layer of the photosensitive drum over time when the amount of solid lubricant supplied to the photosensitive drum having a diameter of 84 mm is maintained at about 8 mg per 1000 revolutions (1 kcycle) of the photosensitive drum. . 6 is a graph showing the relationship between the wear rate of the surface layer of the photosensitive drum and the amount of lubricant supplied. It is a figure when the solid lubricant shown in FIG. 2 is sectioned in the direction orthogonal to the extending direction. It is a figure which shows the 1st modification of the solid lubricant shown in FIG. It is a figure which shows the 2nd modification of the solid lubricant shown in FIG. It is a figure which shows the 3rd modification of the solid lubricant shown in FIG. 6 is a graph showing the relationship between the cumulative number of rotations of the photosensitive drum and the wear rate of the surface layer of the photosensitive drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Toner image forming unit 11 Photoconductor drum 12 Charging device 13 Exposure device 14 Developing device 15 Cleaning device 16 Charger 20 Primary transfer roll 30 Intermediate transfer belt 40 Batch transfer device 50 Fixing device 60 Paper tray 70 Belt cleaner 151 Cleaning Blade 1511 Tip Edges 152, 155, 156, and 157 Solid Lubricant 153 Lubricant Supply Device 154 Waste Toner Transport Auger 1531 Roll Brush 1532 Rotating Arm 1533 Weight

Claims (4)

A toner image carried on the surface of a rotating toner image carrier carrying a toner image on the surface,
In an image forming apparatus for forming an image on a recording medium by transferring to a predetermined transfer surface and finally fixing on the recording medium,
A cleaning blade made of rubber having a tip pressed against the surface of the toner image carrier, scraping off residues remaining on the surface after the toner image is transferred to the transfer surface;
A solid lubricant supplied to the surface of the toner image carrier;
The solid lubricant is disposed on the upstream side in the rotation direction of the toner image carrier relative to the cleaning blade, and the surface of the toner image carrier after the toner image is transferred to the transfer surface. A lubricant supply device for supplying
Rotation in which the lubricant supply device rotates through two regions, a region in contact with the surface of the toner image carrier after the toner image is transferred to the transfer surface and a region in contact with the solid lubricant. A brush, and by rotating the rotating brush, the solid lubricant is scraped off by the rotating brush and applied to the surface.
The supply amount of the solid lubricant by the lubricant supply device to the surface of the toner image carrier reaches a rotational speed at which the cumulative rotational speed of the toner image carrier reaches a certain value, and the cleaning blade is permanently deformed. An image forming apparatus characterized in that the amount of lubricant supplied is reduced from the time of occurrence . A toner image carried on the surface of a rotating toner image carrier carrying a toner image on the surface is transferred to a predetermined transfer surface and finally fixed on the recording medium, whereby an image is formed on the recording medium. In an image forming apparatus for forming
A cleaning blade made of rubber having a tip pressed against the surface of the toner image carrier, scraping off residues remaining on the surface after the toner image is transferred to the transfer surface;
A solid lubricant supplied to the surface of the toner image carrier;
The solid lubricant is disposed on the upstream side in the rotation direction of the toner image carrier relative to the cleaning blade, and the surface of the toner image carrier after the toner image is transferred to the transfer surface. A lubricant supply device for supplying
Rotation in which the lubricant supply device rotates through two regions, a region in contact with the surface of the toner image carrier after the toner image is transferred to the transfer surface and a region in contact with the solid lubricant. A brush, and by rotating the rotating brush, the solid lubricant is scraped off by the rotating brush and applied to the surface.
The solid lubricant has a rectangular parallelepiped shape in which a notch groove is provided on the surface opposite to the surface of the contact portion in contact with the rotating brush, or low hardness lubrication with low hardness on the surface side in contact with the rotating brush. The agent layer is provided, and has a two-layer structure in which a high-hardness lubricant layer having a higher hardness than the low-hardness lubricant layer is provided on the low-hardness lubricant layer,
The supply amount of the solid lubricant by the lubricant supply device to the surface of the toner image carrier reaches a rotational speed at which the cumulative rotational speed of the toner image carrier reaches a certain value, and the cleaning blade is permanently deformed. An image forming apparatus characterized in that the amount of lubricant supplied is reduced from the time of occurrence . The solid lubricant, said the time the permanent deformation occurs in the cleaning blade, so that the supply amount of the level of the bottom surface of the solid lubricant is reached the level at which the slit is provided said solid lubricant is reduced The image forming apparatus according to claim 2, wherein a depth of the notch groove is determined.   The solid lubricant is formed in the low-hardness lubricant layer so that scraping of the rotary brush shifts from the low-hardness lubricant layer to the high-hardness lubricant layer when the cleaning blade is permanently deformed. The image forming apparatus according to claim 2, wherein the thickness is determined.

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