JP2007079166A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold only a preferable amount of residual toner particles on fibers to remove discharge products, with respect to a cleaning device for removing residual materials such as residual toner, which is employed in an electrophotographic system of a copying machine, a facsimile machine, a printer, or the like, and an image forming apparatus including the cleaning device. <P>SOLUTION: The cleaning device includes; a cleaning means 171 which removes the residual toner remaining on a surface 11b after toner image transfer to a transfer object face 30, of an image carrier 11 from the surface 11b; a rotating fiber member 175 which has a plurality of fibers around a revolving shaft 1751 parallel with a center axis 11a, which are brought into contact with the surface 11b after toner image transfer to a transfer object face 30, of the image carrier 11 in the upstream side of the cleaning member 171 in a cyclic movement direction of the image carrier, and is rotated around the revolving shaft 1751; and a contact member 176 brought into contact with the plurality of fibers of the rotating fiber member 175. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning device for removing residues such as residual toner, and an image forming apparatus including the cleaning device, which are employed in electrophotographic systems such as copying machines, facsimile machines, and printers.

  Conventionally, in an electrophotographic system, an electrostatic latent image is formed on the surface of a photoconductor by charging the surface of the photoconductor rotating around a central axis in a predetermined direction with a charger and irradiating the charged photoconductor surface with exposure light. The toner image formed on the surface of the photosensitive member is formed on a predetermined transfer surface (recording medium) by a toner image forming cycle in which the electrostatic latent image is formed and developed with toner by a developing device to form a toner image on the surface of the photosensitive member. Or an intermediate transfer member) and finally fixed on a recording medium, thereby forming an image composed of a fixed toner image on the recording medium.

  A plurality of types of foreign matter such as untransferred toner, external additive particles added to the toner, paper powder, or discharge products generated during charging remain on the surface of the photoreceptor after the transfer to a predetermined transfer surface. Therefore, it is necessary to remove them by a cleaning unit prior to the next toner image forming cycle.

  Various cleaning methods for removing residues such as toner have been proposed. For example, a method for removing residues mechanically by rubbing against the surface of the photoreceptor has been proposed.

  However, when this mechanical removal method is employed, a mechanical external force is applied to the surface of the photoreceptor. In addition, an electrical and mechanical external force is directly applied to the surface of the photoreceptor by a charger, a developing device, a transfer unit, and the like. For this reason, the surface of the photoconductor is required to have durability against abrasion and scratches, and in order to ensure this durability, there is a tendency to use a photoconductor having a hard surface (see, for example, Patent Document 1).

  However, if a photoconductor having a hard surface is used, it becomes difficult to mechanically remove residues from the photoconductor surface. The discharge product generated during charging adheres to the surface of the photoreceptor, and in particular, the discharge product is difficult to remove from the surface of the photoreceptor. If the discharge product adhering to the surface of the photoreceptor absorbs moisture, an image flow is caused at the time of image formation. Therefore, the discharge product must be sufficiently removed.

Therefore, conventionally, a rotating fiber body having a plurality of fibers around a rotation axis is brought into contact with the surface of the photosensitive body upstream of the cleaning means in the rotational direction of the photosensitive body, and discharge is generated by the rotating fiber body. A technique for removing an object has been proposed (see Patent Document 2).
Japanese Patent No. 3264218 JP 2002-244522 A

  By applying the technique described in Patent Document 2, residual toner particles and external additive particles are captured and held by the fibers of the rotating fiber body, and the friction between the fibers holding the toner particles and the surface of the photoreceptor is maintained. It is conceivable to remove discharge products from the surface of the photoreceptor.

  FIG. 1 is a diagram showing a cleaning device to which the technique described in Patent Document 2 is applied.

  A cleaning device 91 shown in FIG. 1 includes a cleaning brush 911 and a roll body 912 that are in contact with a surface 921 of a photosensitive drum 92 that rotates clockwise and that has been transferred to a predetermined transfer surface. The cleaning device 91 also includes a collection roll 913, a scraper member 914, and a transfer auger 915.

  The cleaning brush 911 shown in FIG. 1 has hairs (brush fibers) 9112 extending radially from a central axis 9111 extending in parallel with the rotation axis of the photosensitive drum 92. The cleaning brush 911 rotates around the central axis 9111 with the tips of the bristles 9112 biting into both the photosensitive drum surface 921 and the peripheral surface of the collecting roll 913, and residual toner particles on the photosensitive drum surface 921. t is scraped off by this hair 9112. Residual toner particles t scraped off by the bristles 9112 of the cleaning brush 911 are recovered from the cleaning brush 911 by the recovery roll 913. Further, the residual toner particles t recovered by the recovery roll 913 are scraped off from the recovery roll 913 by the scraper member 914, and the residual toner particles t scraped off are transported to a discharge port (not shown) by the transport auger 915.

  The roll body 912 is disposed on the upstream side in the photoconductor rotation direction with respect to the cleaning brush 911 that removes the residual toner particles t. For this reason, when the photosensitive drum 92 rotates, the residual toner particles t are conveyed toward the roll body 912. A roll body 912 shown in FIG. 1 is a rotating body having a plurality of fibers 9121 on its peripheral surface, and the carried residual toner particles t are captured by the fibers 9121 of the roll body 912 and held by the fibers 9121. The The discharge product adhering to the photosensitive drum surface 921 is scraped off from the photosensitive drum surface 921 by the residual toner particles t held on the roll body 912.

  Here, when a toner image having a high image density is formed, a large amount of residual toner particles t are carried to the roll body 912, so that the residual toner particles are likely to be accumulated in a lump on the roll body 912. As shown in FIG. 1, the positional relationship between the downstream cleaning brush 911 and the upstream roll body 912 is such that residual toner particles t removed by the cleaning brush 911 fall on the roll body 912 (FIG. 1). In the positional relationship, the residual toner particles t are likely to be accumulated in a lump on the roll body 912.

  FIG. 2 is a diagram illustrating a state where residual toner particles accumulated in a lump on the roll body are detached from the roll body.

  When the residual toner particles t are accumulated in a lump on the roll body 912, and the lump residual toner particles t return to the photosensitive drum surface 921, the lump residual toner particles t (portion B surrounded by a two-dot chain line in FIG. 2). May reach the cleaning brush 911, and cleaning failure by the cleaning brush 911 may occur.

  FIG. 3 is a diagram illustrating a mode in which a bias having a polarity opposite to the charging polarity of the toner particles is applied to the hair of the cleaning brush.

  Since there are residual toner particles t of both polarities on the surface 921 of the photosensitive drum 92 that has been transferred to a predetermined transfer surface, the residual toner particles t charged on the positive electrode are fibers 9121 of the roll body 912. May accumulate in a lump. As shown in FIG. 3, a bias (positive electrode bias) having a polarity opposite to the charging polarity of the toner particles (here, negative polarity) is applied to the bristles 9112 of the cleaning brush 911, and the residual toner is fed by the bristles 9112. When the particles t are electrically attracted, the lump of residual toner particles t charged on the positive electrode and the cleaning brush 911 to which the positive electrode bias is applied repel each other. Instead of being removed, the image passes through the cleaning brush 911 (see the portion C surrounded by the two-dot chain line in FIG. 3) and causes image quality defects.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a cleaning device that retains residual toner particles in an amount suitable for fibers and removes discharge products, and an image forming apparatus including the cleaning device. is there.

The cleaning device of the present invention that solves the above-described object conveys the toner image to the transfer area where the toner image is transferred to the transfer surface by carrying the toner image on the surface and circulatingly moving around the central axis. In the cleaning device for removing the residue remaining on the surface of the image carrier after the toner image has been transferred to the transfer surface,
Cleaning means for removing residual toner remaining on the surface of the image carrier after the toner image is transferred to the transfer surface;
A plurality of fibers that are in contact with the surface of the image carrier after the toner image is transferred to the transfer surface on the upstream side in the circulation movement direction of the image carrier from the cleaning unit are parallel to the central axis. A rotating fiber body having a rotation axis and rotating about the rotation axis;
And an abutting member that abuts against the plurality of fibers of the rotating fiber body.

  The image carrier here may be a photoconductor that is uniformly charged and then exposed to light to form an electrostatic latent image, or a toner image is primarily transferred from the photoconductor, and a recording medium. It may be an intermediate transfer member in which peeling discharge occurs during the secondary transfer to. That is, the cleaning device of the present invention can be applied as a cleaning device for the surface of the photosensitive member or a cleaning device for the surface of the intermediate transfer member.

  According to the cleaning device of the present invention, residual toner particles are captured by the plurality of fibers of the rotating fiber body from the surface of the image carrier and held between the fibers. The contact member is in contact. For this reason, the residual toner particles held on the rotating fiber body are scraped off by the abutting member as the rotating fiber body rotates, but the residual toner particles are not scraped off. Residual toner particles that have entered between the fibers remain, and the plurality of fibers of the rotating fiber body retain a residual toner particle in an amount suitable for scraping the discharge product from the surface of the image carrier. Therefore, the cleaning device of the present invention can remove the discharge products while holding the residual toner particles in an amount suitable for the fibers.

  The cleaning means here may be a cleaning blade whose tip is pressed against the surface of the image carrier, or a cleaning brush that rotates while contacting the tip of the hair with the surface of the image carrier. However, it is not limited to these blades and brushes. The rotating fiber body may be a roll formed by wrapping a cloth made of a plurality of fibers around the rotating shaft, or hairs (brush fibers) extending radially from the rotating shaft. It may have a brush shape. Further, the abutting member may be a scraper-like one whose tip is brought into contact with the plurality of fibers of the rotating fiber body, or a brush-like one whose bristle tip is brought into contact with the plurality of fibers. There may be. Moreover, you may have a foamed layer which contact | connected the said some fiber.

  In the cleaning device of the present invention, it is preferable that the rotating fiber body includes a plurality of fibers having a thickness of 10 μm or less as the plurality of fibers.

  By doing so, the surface of the rotating fiber body that is in contact with the surface of the image carrier becomes porous, and the surface of the image carrier is rubbed with the porous surface. As a result, residual toner particles are uniformly held in the extending direction of the rotating shaft, and discharge products are uniformly removed from the surface of the image carrier in the extending direction of the central axis of the image carrier. In addition, it is more preferable that the fibrous body has a width of 1.5 mm or more in the circulating movement direction on the surface of the image carrier.

The image forming apparatus of the present invention that solves the above-described object charges the surface of the photosensitive member rotating in a predetermined direction around the central axis, and irradiates the charged photosensitive member surface with exposure light, thereby statically exposing the surface of the photosensitive member. An electrostatic latent image is formed, the electrostatic latent image is developed with toner to obtain a toner image on the surface of the photoreceptor, and the toner image is transferred to a predetermined transfer surface and finally fixed on a recording medium. In an image forming apparatus for forming an image composed of a fixed toner image on the recording medium,
Cleaning means for removing residual toner remaining on the surface of the photoreceptor after the toner image is transferred to the transfer surface;
A plurality of fibers that are in contact with the surface of the photoconductor after the toner image is transferred to the transfer surface on the upstream side in the rotation direction of the photoconductor with respect to the cleaning unit have a rotation axis parallel to the central axis. A rotating fiber body having around and rotating about its rotation axis;
And an abutting member that abuts against the plurality of fibers of the rotating fiber body.

  The surface to be transferred here may be a surface of the intermediate transfer member in contact with the surface of the photosensitive member or a recording surface of a recording medium.

  According to the image forming apparatus of the present invention, since the cleaning apparatus of the present invention is provided, it is possible to remove the discharge products while holding the residual toner particles in an amount suitable for the fibers.

Further, in the image forming apparatus of the present invention, a developer containing lubricant particles smaller than toner particles and the toner particles is accommodated, and the electrostatic latent image formed on the surface of the photoreceptor is converted into toner in the developer. An embodiment with a developing device for developing with particles, or
An embodiment provided with a developer that contains abrasive particles smaller than toner particles and a developer containing the toner particles, and that develops the electrostatic latent image formed on the surface of the photoreceptor with the toner particles in the developer. Is preferred.

  In the case where the cleaning means is a cleaning blade whose tip is pressed against the surface of the photoreceptor, the former embodiment containing lubricant particles is preferable in order to suppress wear and chipping of the tip. Examples thereof include zinc stearate. Further, according to the latter embodiment including abrasive particles, abrasive particles having higher abrasive power than the toner particles are also held on the rotating fiber body together with the toner particles, so that the discharge product can be removed from the surface of the photoreceptor. It is preferable because the power is increased.

In the image forming apparatus of the present invention, a control unit that controls a speed difference between the rotation speed of the photosensitive member and the rotation speed of the rotating fiber body, or
It is also preferable that a control unit for controlling the contact pressure between the surface of the photoreceptor and the plurality of fibers of the rotating fiber body is provided.

  According to the control unit that controls the speed difference, the scraping force of the discharge product is increased by widening the speed difference, and according to the control unit that controls the contact pressure, the discharge product is increased by increasing the contact pressure. The scraping power of can be increased. Therefore, the scraping force by the rotating fiber body is adjusted by providing any of the control units.

In addition, the image forming apparatus includes a humidity or temperature, or an environment detection sensor that detects humidity and temperature,
More preferably, the control unit controls the speed difference or the contact pressure based on the detection result of the environment detection sensor.
The control unit calculates the absolute moisture content in the image forming apparatus calculated using the detection result of the environment detection sensor, the temperature based on the detection result of the environment detection sensor, and the humidity based on the detection result of the environment detection sensor. It is preferable to determine whether or not any of them exceeds a predetermined value, and if it exceeds, it is preferable to widen the speed difference or to increase the contact pressure.

  Image flow caused by the discharge product is likely to occur under high humidity conditions, and high scraping power is required under high humidity conditions. Therefore, the control unit detects that the scraping power of the discharge product needs to be increased by using any one of the parameters of the absolute water content, the temperature based on the detection result, and the humidity based on the detection result. Correspond.

  On the other hand, under low temperature and low humidity conditions, a high scraping force is not necessary under high humidity conditions.If the scraping power is higher than necessary, the surface of the photoconductor may be worn or damaged more than necessary due to excessive scraping. Since the deterioration of the rotating fiber body itself also proceeds, the control unit needs to detect and cope with the need to reduce the scraping force of the rotating fiber body using any of the above parameters. Also good.

  Further, the control unit may determine whether or not the predetermined value is exceeded when the main power supply of the image forming apparatus is turned on.

If the image forming apparatus includes a fixing device that fixes the toner image to the recording medium by applying heat to the toner image transferred to the recording medium,
The control unit may determine whether or not the predetermined value is exceeded when the sleep state of the fixing device continues for a predetermined time.

  In an image forming apparatus in which the main power supply is turned on after being placed in a high-temperature and high-humidity environment for a long time, the humidity inside the apparatus is high or heating operation for applying heat to the toner image is not performed. If the fuser sleep state continues for a predetermined time, the humidity inside the device may become high, but if the controller is as described above, it is detected that the scraping power of the discharge product needs to be increased. Can respond.

  Further, the control unit determines whether or not the predetermined value is exceeded when the main power supply of the image forming apparatus is turned on or when the sleep state of the fixing device continues for a predetermined time. As a result, when the speed difference is widened or the contact pressure is increased, it is more preferable that a toner band extending in the extending direction of the central axis is formed on the surface of the photoreceptor.

  When the main power supply of the image forming apparatus is turned on or when the sleep state of the fixing device continues for a predetermined time, the rotating fiber body is not sufficiently supplied with residual toner particles, and the rotation There is a possibility that the residual toner particles are not sufficiently held in the fibers of the fibrous body. Therefore, before entering the so-called toner image forming cycle, the control unit forms the toner band, reaches the rotating fiber body without transferring the toner band, and sufficiently retains residual toner particles on the fibers of the rotating fiber body. The discharge product can be sufficiently removed by holding the discharge.

  According to the present invention, it is possible to provide a cleaning device that retains residual toner particles in an amount suitable for fibers and removes discharge products, and an image forming apparatus including the cleaning device.

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

  FIG. 4 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  An image forming apparatus 1 shown in FIG. 4 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. 4 is a semiconductive intermediate transfer that is supported by four toner image forming units 10, four primary transfer rolls 20, and three support rolls 31 and circulates 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 photosensitive drum 11 is formed by laminating an undercoat layer, a charge generation layer, a charge transport layer, and a protective layer on a cylindrical conductive support, and the surface of the protective layer is the photosensitive layer. It corresponds to the surface of the body drum 11. The protective layer is a layer containing a compound having a crosslinked structure, and the photosensitive drum 11 shown in FIG. 4 has very high wear resistance. The surfaces of these photosensitive drums 11 are 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. A primary transfer bias is applied to the primary transfer roll 20.

  Here, FIG. 5 will be used together with FIG. 4 to further explain the image forming apparatus of this embodiment.

  FIG. 5 is a diagram mainly showing a schematic configuration of one of the four toner image forming units shown in FIG.

  In addition to the photosensitive drum 11, the toner image forming unit 10 shown in FIG. 5 includes a charger 12, an exposure device 13, a developing device 14, a pre-cleaning charger 15, a pre-cleaning static eliminator 16, a cleaning device 17, and a static eliminator. 18 is provided. FIG. 5 schematically shows the protective layer 111 of the photosensitive drum 11. The photosensitive drum 11 shown in FIG. 5 rotates around the rotation shaft 11a, so that the protective layer (photosensitive drum surface 11b) circulates around the rotation shaft 11a.

  The charger 12 is a non-contact charging type corotron charger. A charging bias is applied to the charger 12 from a charger high voltage power source 122 under the control of the charger controller 121. The exposure device 13 irradiates the photosensitive drum surface 11b with a laser beam based on image information. The developing device 14 carries a developer container 141 containing toner particles and a developer containing abrasive particles finer than the toner particles and lubricant fine particles, and a toner drum carrying the toner particles in the developer container 141. 11 has a developing roll 142 that rotates in a state of facing the surface of 11. The toner particles in the developer stored in the developer container 141 are negatively charged toner particles that are charged to the negative electrode. Further, the abrasive fine particles have higher polishing power than the toner particles, and the lubricant fine particles are zinc stearate. The toner particles are negatively charged in the developing device 14 and electrostatically move to the surface 11 b of the photosensitive drum 11.

  Here, the toner image forming cycle performed in the toner image forming unit 10 shown in FIG. 5 will be briefly described.

  When a toner image forming cycle is performed in the toner image forming unit 10 shown in FIG. 5, the photosensitive drum surface 11 b rotating in the direction of arrow R is first uniformly charged by the charger 12. Next, a laser beam 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 11b. The electrostatic latent image is developed by the developing device 14, and a toner image is formed on the surface of the photosensitive drum 11b. The toner image formed in this way is transferred from the surface of the photosensitive drum 11b to the surface of the intermediate transfer belt 30 moving in the direction of arrow C by the action of the primary transfer bias in the primary transfer region. The surface 11b that has passed through the primary transfer area of the photosensitive drum 11 passes through an area where a cleaning device 17 described later is provided, and is then neutralized by the static eliminator 18 to complete a series of toner image forming cycles. Such a toner image forming cycle is performed for each toner image forming unit 10, and the toner images formed by each toner image forming unit 10 become toner images that overlap one on the intermediate transfer belt 30.

  4 includes a secondary transfer roll 41 arranged in pressure contact with the toner image carrying surface side of the intermediate transfer belt 30 and a backup roll 42 arranged on the back side of the intermediate transfer belt 30. The batch transfer apparatus 40 shown in FIG. 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. 4 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 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, the surface 11b of the photosensitive drum 11 shown in FIG. 5 that has passed through the primary transfer region adheres to the residual toner that could not be transferred to the surface of the intermediate transfer belt 30 in the primary transfer region. A plurality of types of foreign matter such as abrasive fine particles, lubricant fine particles, and discharge products generated during charging remain. The cleaning device 17 shown in FIGS. 4 and 5 is a device for removing these plural types of foreign matters, and is located downstream of the primary transfer area in the rotational direction of the photosensitive drum and from the charging area. It is deployed at a position upstream in the rotational direction. Further, a pre-cleaning charger 15 and a pre-cleaning static eliminator 16 are provided in front of the cleaning device 17. Since residual toners of both polarities are present on the surface 111 of the photosensitive drum 11 that has passed through the primary transfer region, the residual toners of both polarities are aligned with one polarity by the pre-cleaning charger 15 to remove the pre-cleaning static eliminator. The residual potential level on the surface of the photosensitive member is lowered by 16 so that the residual toner is easily removed by the cleaning device 17. Here, the pre-cleaning charger 15 aligns the residual toner particles with the negative polarity having the same polarity as the charging polarity.

  The cleaning device 17 shown in FIG. 5 corresponds to an embodiment of the cleaning device of the present invention, and includes a cleaning brush 171, a collection roll 172, a scraper member 173, a waste toner conveying auger 174, a roll body 175, and a contact member. 176. The cleaning brush 171 has conductive bristles 1712 extending radially from a central shaft 1711 extending in parallel with the rotation shaft 11 a of the photosensitive drum 11. The cleaning brush 171 rotates around the central axis 1711 in a state in which the tip of the bristles 1712 bites into both the photosensitive drum surface 11b and the peripheral surface of the collection roll 172. The bristles 1712 of the cleaning brush 171 are applied with a positive cleaning bias having a polarity opposite to the polarity (negative polarity) in which the residual toner particles are aligned by the pre-cleaning charger 15. The hair 1712 is attracted to the hair 1712 of the cleaning brush 171 by the action of the bias and scraped off by the hair 1712. That is, the cleaning brush 171 removes residual toner particles remaining on the surface 11b that has passed through the primary transfer region of the photosensitive drum 11 from the surface 11b, and corresponds to an example of a cleaning unit according to the present invention. . In addition, the external additive particles that exhibit the polishing effect and the like that are detached from the toner particles and remain on the surface of the photosensitive drum 11b are also removed from the surface 11b by the cleaning brush 171. The cleaning brush 171 is less deteriorated with time in cleaning performance, and is more advantageous than a plate-shaped cleaning blade, particularly in a high-speed machine. Further, since the cleaning brush 171 shown in FIG. 5 is a cleaning method that actively uses an electric field, it is superior to cleaning of spherical toner, which is difficult with a cleaning blade that mechanically scrapes without using an electrical action. There is. Residual toner particles and external additive particles (hereinafter collectively referred to as residual toner components) transferred to the hair 1712 of the cleaning brush 171 are held on the hair 1712 by the action of the cleaning bias. The collection roll 172 also rotates about a central axis extending in parallel with the rotation shaft 11 a of the photosensitive drum 11, and collects the residual toner component held on the bristles 1712 of the cleaning brush 171. The scraper member 173 scrapes off the residual toner component collected by the collection roll 172 from the collection roll 172. The residual toner component scraped off by the scraper member 173 is transported to the outside of the cleaning device 17 by the waste toner transport auger 174.

  The roll body 175 is disposed upstream of the cleaning brush 171 in the photosensitive drum rotation direction. The roll body 175 is in the form of a roll formed by winding a nonwoven fabric 1752 made of a large number of fine fibers around a rotation shaft 1751 parallel to the rotation shaft 11 a of the photosensitive drum 11. The fibers are in contact with the surface 11 b of the photosensitive drum 11. That is, the roll body 175 shown in FIG. 5 has a large number of fine fibers in contact with the surface 11 b that has passed through the primary transfer region of the photosensitive drum 11, and the rotational axis 1751 parallel to the rotational axis 11 a of the photosensitive drum 11. It is a rotating fiber body that has a periphery and rotates around its rotation shaft 1751. Each of the many fine fibers has a thickness of 10 μm or less, and the peripheral surface of the roll body 175 in contact with the photosensitive drum surface 11b is porous. Further, the roll body 175 is pressed against the surface 11b of the photosensitive drum with a certain pressing pressure so as to come into contact with the rotating direction of the photosensitive drum 11 with a contact width of 1.5 mm or more. Since the roll body 175 is disposed upstream of the cleaning brush 171 that removes the residual toner component, the residual toner component is carried toward the roll body 175 by the rotation of the photosensitive drum 11. . The residual toner component is captured by the fine fibers of the roll body 175 and held between the fibers. Deposits such as discharge products adhered to the surface of the photosensitive drum 11b and the surface deterioration layer of the photosensitive member 10 due to discharge are scraped off from the surface of the photosensitive drum 11b by the residual toner component held on the fine fibers. The discharge product and the like thus scraped off adhere to the residual toner component captured by the fine fibers. In a conventional cleaning blade that is a general cleaner, the contact with the surface of the photoreceptor is a line contact, so the residual toner component is easily separated from the contact portion (blade edge tip), but the polishing effect is not improved. 175 is in contact with the photosensitive drum surface 11b in the photosensitive drum rotation direction for 1.5 mm or more, and the peripheral surface of the roll body 175 in contact with the photosensitive drum surface 11b is porous. The residual toner component is uniformly held in the body 175 in the extending direction of the rotating shaft 1751, and the discharge products are uniformly removed from the surface of the photosensitive drum 11b in the extending direction of the rotating shaft 11a of the photosensitive drum 11. .

  When a new residual toner component is conveyed to the roll body 175, the residual toner component held on the roll body 175 and the residual toner component on the photosensitive drum surface 11b that has been newly conveyed are switched. As a result, a part of the residual toner component held on the roll body 175 returns to the photosensitive drum surface 11b. The residual toner component that has returned to the surface of the photosensitive drum 11b is directed to the downstream cleaning brush 171 by the rotation of the photosensitive drum 11, and is removed from the surface of the photosensitive drum 11b by the cleaning brush 171. That is, the residual toner component to which the discharge product and the like once captured by the roll body 175 and scraped off from the surface of the photosensitive drum 11b is finally removed from the surface of the photosensitive drum 11b by the cleaning brush 171.

  The contact member 176 is a column of urethane sponge that extends in the extending direction of the rotating shaft 1751 of the roll body 175. The contact member 176 has a foam layer 1761 in contact with a plurality of fine fibers on the peripheral surface of the roll body 175.

  FIG. 6 is a diagram illustrating a state in which residual toner particles are accumulated in a lump on the roll body illustrated in FIG. 5.

  As a result of forming a toner image having a high image density on the photosensitive drum 11 shown in FIG. 6, a large amount of residual toner component t ′ (encircled by a two-dot chain line in FIG. 6) is formed on the roll body 175 shown in FIG. (See Part D). Further, a state in which the residual toner component t ′ is accumulated in a lump form in a portion of the roll body 175 shown in FIG. 6 upstream of the contact member 176 in the rotation direction (a portion surrounded by a two-dot chain line in FIG. 6). E)).

  7 is a diagram showing a state where the roll body shown in FIG. 6 is rotated, and FIG. 8 is an enlarged view of a portion F surrounded by a two-dot chain line in FIG.

  The residual toner component t ′ accumulated in a lump in the upstream portion of the rotation direction with respect to the contact member 176 is scraped off by the contact member 176 as the roll body 175 rotates, but is retained by the contact member 176. Some of the residual toner components have entered between the fibers, and the residual toner components that have entered between the fibers are not scraped off. An amount of residual toner component t ′ suitable for scraping discharge products and the like from the photosensitive drum surface 11b remains on the fiber (see FIG. 8). The residual toner component t ′ scraped off by the contact member 176 is transported to the outside of the cleaning device 17 by the waste toner transport auger 174 shown in FIG.

  FIG. 9 is a diagram illustrating a state in which the residual toner component held on the roll body illustrated in FIG. 7 is replaced with a new residual toner component.

  From the roll body 175 in which the holding amount of the residual toner component t ′ is adjusted by the contact member 176, the lump of the residual toner component T ′ does not return on the surface of the photosensitive drum 11b. An amount of residual toner component t ′ that can be sufficiently removed by the cleaning brush 171 (see the portion G surrounded by the two-dot chain line in FIG. 9) returns to the surface of the photosensitive drum 11b. As a result, the residual toner component t ′ that has returned to the photosensitive drum surface 11 b is reliably removed from the photosensitive drum surface 11 b by the cleaning brush 171.

  Furthermore, the image forming apparatus 1 shown in FIG. 4 also includes an environment detection sensor 81 and a control unit 82. An environment detection sensor 81 shown in FIG. 4 detects humidity or temperature in the image forming apparatus 1 or humidity and temperature. Further, the control unit 82 shown in FIG. 4 controls the entire image forming apparatus 1. Here, the control for cleaning the residue on the photosensitive drum 11 will be described. The rotational speed of the photosensitive drum 11 and the rotational speed of the roll body 175 are variable. Further, the pressing pressure of the roll body 175 against the photosensitive drum surface 11b is also variable. The control unit 82 controls the rotation speed and the pressing pressure when controlling the cleaning of the residue existing on the photosensitive drum surface 11b. That is, the control unit 82 controls the speed difference between the rotational speed of the photosensitive drum 11 and the rotational speed of the roll body 175, or controls the contact pressure between the photosensitive drum surface 11b and the plurality of fine fibers of the roll body 175. Control. If the speed difference is widened by the control unit 82, the scraping force of the discharge product by the roll body 175 is increased, and conversely if the speed difference is reduced, the scraping force of the discharge product by the roll body 175 is weakened. . Further, if the contact pressure is increased by the control unit 82, the scraping force of the discharge product by the roll body 175 is also increased. Conversely, if the contact pressure is weakened, the scraping force of the discharge product by the roll body 175 is also decreased. . Therefore, the scraping force by the roll body 175 is adjusted by the control unit 82 shown in FIG.

  The control unit 82 controls the speed difference or the contact pressure based on the detection result of the environment detection sensor 81. For example, the control unit 82 has at least one set value in which the speed difference is a preset speed difference with respect to humidity or humidity and temperature detected by the environment detection sensor 81. The same applies to the contact pressure, and the control unit 82 sets at least a set value such that the contact pressure becomes a preset contact pressure with respect to humidity or humidity and temperature detected by the environment detection sensor 81. Have one or more. In addition, the control unit 82 determines in advance the absolute moisture content in the image forming apparatus 1 calculated using the detection result of the environment detection sensor 81 and the humidity or humidity and temperature based on the detection result of the environment detection sensor 81. When the main power supply of the image forming apparatus 1 is changed from the OFF state to the ON state under the condition of the specified value or more, or at the start-up when the sleep state of the fixing device 50 shown in FIG. After the speed difference is set to a specified value or more and the specified time or the number of rotations of the photosensitive drum 11 reaches the specified number, the speed difference is made less than the specified value, or the speed difference is replaced with the speed difference. The contact pressure is set to a specified value or more, and after the specified time or the number of rotations of the photosensitive drum 11 reaches the specified number, the contact pressure is made less than the specified value. Image flow caused by the discharge product is likely to occur under high humidity conditions, and high scraping power is required under high humidity conditions. In an image forming apparatus in which the main power source is turned on after being placed in a high temperature and high humidity environment for a long time, the humidity in the apparatus is high, or heating by a heating mechanism 511 built in the fixing roll 51 is performed. If the sleep state in which the operation is not performed continues for a predetermined time, the humidity in the apparatus may become high. Therefore, the control unit 82 uses one of the parameters based on the detection result of the environment detection sensor 81 at the timing when the main power supply of the image forming apparatus is turned on or when the sleep state of the fixing device 50 continues for a predetermined time. And detecting and responding to the need to increase the scraping power of the discharge product. On the other hand, if the scraping force is higher than necessary, the surface of the photosensitive drum 11b may be worn or damaged more than necessary due to excessive scraping, and further deterioration of the fine fibers of the roll body itself may progress. Alternatively, after the number of rotations of the photosensitive drum 11 reaches a specified number, the speed difference and the contact pressure are made less than the specified values.

  Further, the control unit 82 determines that the value of any parameter based on the detection result of the environment detection sensor 81 is equal to or greater than a specified value and the main power source is switched from the OFF state to the ON state, or the sleep state of the fixing device is equal to or longer than the specified time. In the subsequent case, a toner band is formed on the photosensitive drum surface 11b before entering the toner image forming cycle. When the main power supply of the image forming apparatus 1 is turned on or when the sleep state of the fixing device 50 continues for a predetermined time, the residual toner component is not sufficiently supplied to the roll body 175 and the roll body 175 is not supplied. There is a possibility that the residual toner component is not sufficiently held in the fine fibers. Therefore, before entering the toner image forming cycle, the control unit 82 forms a toner band extending in the extending direction of the rotation shaft 11a of the photosensitive drum 11, and reaches the roll body 175 without transferring the toner band. By sufficiently retaining the residual toner component in the fine fibers of the roll body 175, the discharge product can be sufficiently removed.

  Subsequently, a modification of the cleaning device 17 described so far will be described. In the following, components having the same names as those of the components of the image forming apparatus shown in FIG.

  FIG. 10 is a view showing a cleaning device in which the contact member is changed to a scraper member, and FIG. 11 is a view showing a cleaning device in which the contact member is changed to a brush member.

  The contact member 176 shown in FIG. 5 is a urethane sponge column, but the contact member 176 shown in FIG. 10 is a scraper member in which the tip 176a is brought into contact with the fine fibers of the roll body 175. Further, the contact member 176 shown in FIG. 11 is a toothbrush-like brush member in which the tip of the bristles 1765 extending in one direction is in contact with the fine fibers of the roll body 175. In any of the contact members 176 shown in FIGS. 10 and 11, the residual toner component accumulated in a lump on the fine fibers of the roll body 175 is suitable for scraping discharge products and the like from the surface 11b of the photosensitive drum. The remaining toner component t ′ is left and scraped off, and the lump of the residual toner component does not return onto the surface of the photosensitive drum 11b, and the photosensitive drum surface 11b is firmly cleaned by the cleaning brush 171.

  FIG. 12 is a view showing a cleaning device provided with a cleaning blade instead of the cleaning brush.

  In the above description, the cleaning brush, which is a brush member, has been described as a cleaning unit that removes residual toner components remaining on the surface 11b that has passed through the primary transfer region of the photosensitive drum 11 from the surface 11b. Alternatively, a plate-like cleaning blade 179 having elasticity may be used. The cleaning blade 179 shown in FIG. 12 extends in the extending direction of the rotating shaft of the photosensitive drum 11 in a state in which the leading edge portion 1791 is pressed against the photosensitive drum surface 11b. The cleaning blade 179 mechanically scrapes off residual toner components remaining on the surface 11b of the photosensitive drum without using an electrical action as the photosensitive drum 11 rotates.

  Lubricant fine particles, which are zinc stearate in the developer, are contained in the residual toner component and suppress the occurrence of wear and chipping at the leading edge portion 1791 of the cleaning blade 179.

Heretofore, an example in which the invention of the cleaning device of the present invention is applied to the cleaning device 17 that cleans the surface 11b of the photosensitive drum 11 that has passed the primary transfer region has been described. In the second transfer to the belt, peeling discharge occurs, and as a result, the discharge product may adhere to the intermediate transfer belt 30. Therefore, the present invention is a belt cleaner for cleaning the intermediate transfer belt 30 shown in FIG. 70 can also be applied.
(Example)
EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following description, “parts” means “parts by weight” unless otherwise specified.
Example 1
As a testing machine, an image forming apparatus having the same basic configuration as that of the image forming apparatus shown in FIG. 1 was used. Details are shown below.
[Photosensitive drum]
First, a cylindrical aluminum substrate having an outer diameter of 84 mmφ subjected to a honing treatment was prepared. Next, 100 parts of a zirconium compound (trade name: Orgatics ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.), 10 parts of a silane compound (trade name: A1100, manufactured by Nihon Unicar Co., Ltd.), 400 parts of isopropanol, and 200 parts of butanol are mixed. Thus, a coating solution for forming the undercoat layer was obtained. This coating solution was dip-coated on an aluminum substrate and dried by heating at 150 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.1 μm.

  Next, the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum is 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and Mix 1 part of hydroxygallium phthalocyanine with a strong diffraction peak at 28.3 °, 1 part of polyvinyl butyral (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.), and 100 parts of n-butyl acetate, and paint with glass beads. Dispersion was carried out with a shaker for 1 hour to obtain a coating solution for forming a charge generation layer. This coating solution was dip-coated on the undercoat layer and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Next, 2 parts of a charge transport material represented by the following formula (I), 3 parts of a polymer compound having a structural unit represented by the following formula (II) (viscosity average molecular weight 39,000), and 20 parts of chlorobenzene By mixing, a coating liquid for forming a charge transport layer was obtained.

  This charge transport layer forming coating solution was applied onto the charge generation layer by a dip coating method and heated at 110 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm.

  Next, 2 parts of the compound represented by the following formula (III), 3 parts of Resist Top PL4852 (manufactured by Gunei Chemical), 0.1 part of hindered phenol antioxidant (AO-80: manufactured by Asahi Denka) , 0.2 part of fluorine graft polymer (ZX007C: manufactured by Fuji Kasei) and 0.1 part of fluorine coupling agent (KBM-7803: manufactured by Shin-Etsu Chemical) are mixed and dissolved in 10 parts of isopropyl alcohol to form a protective layer. A coating solution was obtained.

This protective layer-forming coating solution is applied onto the charge transport layer by a ring-type dip coating method, air-dried at room temperature for 30 minutes, and then cured by heat treatment at 135 ° C. for 1 hour to provide a protective film having a thickness of about 5 μm. A layer was formed. The photoreceptor drum thus obtained was incorporated. The rotational speed (peripheral speed) of the photosensitive drum was 264 mm / s.
[Developer / Toner]
The toner and developer used by FujiCerox DocuCenterColor450 were used as they were.
[Charger]
A Fuji Xerox Color DocuTech 60V corotron charger itself was used. The applied current was applied by constant current control of DC-900 μA.
[Developer]
In the housing of Fuji Xerox Color DocuTech 60V, the developer and toner were replaced with those of DocuCenterColor450.
[Pre-cleaning charger]
An applied current was applied by constant current control of DC-82 μA using a Corotron charger of Color DocuTech 60V itself manufactured by FujiXerox.
[Non-cleaning static eliminator]
A light emitting diode was used.
[Cleaning device]
<Roll body>
A non-woven fabric (fiber thick) made by Nippon Bileen Co., Ltd. (material model number WP8085) on a peripheral surface of a urethane foam roll (Inoac Corporation, material model number RR26, F hardness 58 °, thickness 3.5 mm) having an outer diameter (diameter) of 17.0 mm (3: 5 to 5 μm, thickness 0.42 mm) was used.

The amount of biting of this roll into the photosensitive drum was about 1.2 mm, and the rotation direction was the same as the rotation direction of the photosensitive drum in the region in contact with the photosensitive drum. The rotational speed (peripheral speed) of the roll body / rotational speed (peripheral speed) of the photosensitive drum was set to 0.7.
<Contact member>
A columnar urethane foam was used.
<Cleaning brush>
A roll-shaped brush member having an outer diameter (diameter) of 15.0 mm was used.
Brush material (UUN made by original yarn Unitika): 12 nylon, fiber thickness: 2 denier, electric resistance: 1 × 10 ⁵ Ω, hair length: 1.5 mm, fiber density: 120 × 10 ³ /6.45 cm ² , the amount of biting into the photoconductor drum: about 0.5 mm, the peripheral speed: 60 mm / s, the rotation direction: the region in contact with the photoconductor drum, the direction opposite to the rotation direction of the photoconductor drum, the brush application bias: + 250V
<Recovery roll>
Material: phenol resin in which conductive carbon is dispersed, electric resistance: 1 × 10 ⁶ Ω, flexural modulus (JIS K7171: 94): 100 MPa, wear amount (JIS K6902): 2 mg, Rockwell hardness (JIS K7202: 95, M scale): 120, biting amount into the cleaning brush: 1.0 mm, peripheral speed: 70 mm / s, applied bias: -800 V
<Scraper member>
Material: SUS304, thickness: 80 μm, amount of biting into the collecting roll: 1.3 mm, free length (free length): 8.0 mm
Using the image forming apparatus having the above-described configuration, about 12,000 A4 horizontal feed charts having a band-like image with a density of cin of 50% are printed, and after being left for about 12 hours, an image sample immediately after the apparatus is started (such as full-tone halftone) The image quality was evaluated. The environment was high temperature and high humidity conditions (28 ° C., 85% RH), which is a frequent condition of image flow. In this evaluation, evaluation was performed on two points, “image flow” and “cleaning failure”, which are typical image quality defects. The evaluation results are shown in Table 1.

In Table 1, a circle indicates that an image quality failure has occurred, and a cross indicates that an image quality failure has occurred.
(Example 2)
The rotation speed (peripheral speed) of the roll body provided in the cleaning device is variable in the range of 30 mm / s to 250 mm / s, and the roll body rotation speed (peripheral speed) and the photosensitive drum rotation speed (peripheral speed). The same image forming apparatus as that in Example 1 was used except that the speed difference between the first and second speeds could be changed. Here, the speed difference between the rotational speed (peripheral speed) of the roll body and the rotational speed (peripheral speed) of the photosensitive drum is referred to as the rotational speed (peripheral speed) of the roll body / the rotational speed (peripheral speed) of the photosensitive drum. The speed ratio SR is regarded as a speed ratio SR for each cleaning device of each color toner image forming unit. That is, the cleaning device for the toner image forming unit for yellow (sometimes simply referred to as “Y”) sets the speed ratio SR to 0.9, and the cleaning device for the toner image forming unit of magenta (sometimes simply referred to as “M”). In the cleaning device for a toner image forming unit of cyan (sometimes simply referred to as C color), the speed ratio SR is set as 0.4 and black (sometimes simply referred to as K color). In the toner image forming unit cleaning apparatus, the speed ratio SR is set to 0.1.

  Here, in order to measure the wear rate of the photosensitive drum, the photosensitive drum was rotated 50000 in each environment shown in Table 2 below under conditions 1 to 16 where the combinations of temperature and humidity were different.

  In addition, after 50000 rotations, left in an experimental environment for 8 hours, and at the beginning of the morning, a halftone (A3 size) with an image density of 30% was collected, and it was confirmed whether there was any image omission or image flow at that time. The results are summarized for each speed ratio SR and shown in Tables 3 to 6.

In the column of Deletion in Tables 3 to 6 above, a circle indicates that the image quality without image omission and image flow is obtained, and an x mark indicates that some omission or image flow occurs. It represents the case where it was. The abrasion rate (unit: nm / kcy) represents the amount of abrasion (unit: nm) of the photosensitive drum per 1000 rotations (kcy) of the photosensitive drum. The amount of wear was measured using a Fischer scope MMS manufactured by Eddy Current Fischer.
(Example 3)
The following experiment was conducted using the image forming apparatus used in Example 2 as a test machine.

  The speed ratio SR is set to 0.9 so that the wear rate of the photoconductor is minimized, and after running the photoconductor drum 15000 times in an environment of a temperature of 30 ° C. and a humidity of 90%, the main power supply of the test machine Was turned off and allowed to stand for 8 hours, and then the deletion extracted image was sampled. At this time, before starting the image forming operation, the idle rotation cycle in which the photosensitive drum and the roll body are idled is not performed, and the rotation speed of the photosensitive drum is changed to 20 rotations, 40 rotations, and 60 rotations. The test was performed when the rotation cycle was performed. In the idling cycle, the rotation speed of the photosensitive drum and the rotation speed of the roll body were the same as those during image formation, the charger was not operated, and the pre-cleaning charger was operated. Also in this case, the speed ratio SR is made different for each cleaning device for each color toner image forming unit, the speed ratio SR is set to 0.9 for the cleaning device for the Y color toner image forming unit, and the cleaning of the M color toner image forming unit is performed. The speed ratio SR is 0.7 in the apparatus, the speed ratio SR is 0.4 in the cleaning apparatus for the C toner image forming unit, and the speed ratio SR is 0.1 in the cleaning apparatus for the K toner image forming unit. did. Further, in Tests 3-1 to 3-4, a toner band for one rotation of the photosensitive drum is formed before the idling cycle is performed, and the toner band is sent to the cleaning device without being transferred. In Test 3-8, the toner band was not formed before the idling cycle. Since it was confirmed whether there was any image omission or image flow, the results are shown in Tables 7 and 8 divided by the presence or absence of toner band formation.

Table 7 shows the results of Tests 3-1 to 3-4 in which toner band formation was performed, and Table 8 shows the results of Tests 3 to 5 to Test 3-8 in which toner band formation was not performed. In Tables 7 and 8, the ◯ mark represents the case where image quality without image omission and image flow was obtained, and the X mark represents the case where some omission or image flow occurred.
Example 4
The same image forming apparatus as in Example 1 was used, except that the pressing force of the roll body against the surface of the photosensitive drum was changed for each cleaning device of each color toner image forming unit. Here, the pressing force of the roll body in the cleaning device of the Y toner image forming unit is 9.8 mN / mm, and the pressing pressure of the roll body in the cleaning device of the M toner image forming unit is 19.6 mN / mm. The pressing force of the roll body in the cleaning device for the C-color toner image forming unit was 29.4 mN / mm, and the pressing pressure of the roll body in the cleaning device for the K-color toner image forming unit was 39.2 mN / mm. .

  Also in Example 4, the wear rate of the photosensitive drum was measured in the same manner as in Example 2, and further, it was confirmed whether there was any image omission or image flow in the same manner as in Example 2. The results are summarized for each pressing pressure and shown in Tables 9 to 12.

In the column of Deletion in Table 9 to Table 12 above, a circle indicates that an image quality without image omission and image flow is obtained, and an x mark indicates occurrence of white omission or image flow even in part. It represents the case where it was. The wear rate (unit: nm / kcy) represents the amount of wear (nm) of the photosensitive drum per 1000 revolutions of the photosensitive drum. The amount of wear was measured using a Fischer scope MMS manufactured by Eddy Current Fischer.
(Example 5)
The following experiment was conducted using the image forming apparatus used in Example 4 as a test machine.

  The pressing pressure of the roll to the surface of the photosensitive drum is set to 9.8 mN / mm so that the wear rate of the photosensitive member is minimized, and the photosensitive drum is set to 15000 in an environment of a temperature of 30 ° C. and a humidity of 90%. After rotating, the main power supply of the testing machine was turned off and allowed to stand for 8 hours, and then the depression extraction image was sampled. At this time, before the image forming operation is started, the idle rotation cycle in which the photosensitive drum and the roll body are idled is not performed, and the rotation speed of the photosensitive drum is changed to 20, 40, and 60 rotations. The test was performed in the same manner as in Example 3 when the idling cycle was performed. Here, the pressing pressure is made different for each cleaning device for each color toner image forming unit, and the pressing pressure is set to 9.8 mN / mm for the cleaning device for the Y color toner image forming unit. The pressing pressure is 19.6 mN / mm in the cleaning device, the pressing pressure is 29.4 mN / mm in the cleaning device for the C toner image forming unit, and the pressing pressure is used in the cleaning device for the K toner image forming unit. Was 39.2 mN / mm. Further, in Tests 5-1 to 5-4, a toner band for one rotation of the photosensitive drum is formed before the idle rotation cycle is performed, and the toner band is sent to the cleaning device without being transferred. In Test 5-8, the toner band was not formed before the idling cycle. Since it was confirmed whether there was any image omission or image flow, the results are shown in Table 13 and Table 14 divided according to the presence or absence of toner band formation.

Table 13 shows the results of Tests 5-1 to 5-4 where toner band formation was performed, and Table 14 shows the results of Tests 5-5 to Test 5-8 where toner band formation was not performed. In Tables 13 and 14, a circle mark represents a case where image quality without image omission and image flow was obtained, and a x mark represents a case where white omission or image flow occurred even in part.
(Comparative Example 1)
The same test and evaluation as in Example 1 were performed using the same image forming apparatus as in Example 1 except that both the roll body and the contact member were removed from the cleaning device of the image forming apparatus used in Example 1. went. The results are shown in Table 1.
(Comparative Example 2)
Tests and evaluations similar to those in Example 1 were performed using the same image forming apparatus as in Example 1 except that only the contact member was removed from the cleaning device of the image forming apparatus used in Example 1. The results are shown in Table 1.

  In Comparative Example 1, since the roll body was removed, the discharge product could not be sufficiently removed from the surface of the photosensitive drum, and the discharge product adhering to the surface of the photosensitive drum absorbed moisture and image flow occurred. Think. Further, in Comparative Example 2 in which the contact member is removed while leaving the roll body, it is considered that residual toner components are accumulated in a lump on the roll body and cannot be removed by the cleaning brush, resulting in poor cleaning. On the other hand, in Example 1, neither an image flow nor a cleaning failure occurred, and a good result was obtained. This good result is attributed to the fact that the roll body retained a suitable amount of residual toner particles on the fine fibers and firmly removed the discharge products.

  Further, in Tables 3 to 6 and Tables 9 to 12, when some white spots or image flow occurred, a cross was marked. However, in any test in these tables, the roll body and the contact Since the contact member is provided, there is no problem in actual use. Hereinafter, when the results shown in these tables are analyzed while performing a relative comparison, it can be seen that the higher the temperature and humidity conditions, the worse the depletion and the lower the photoconductor wear rate. Conversely, it can be seen that the lower the temperature and humidity, the higher the rate of wear of the photoconductor and the shorter the life of the photoconductor. Furthermore, in the photoconductive drum used this time, it has been found that if the wear rate is set to 5.0 nm / kcy or more, the depletion can be completely avoided.

  Further, as the speed difference between the photosensitive drum and the roll body is increased, or as the pressing pressure between the photosensitive drum and the roll body is increased, the wear rate of the photosensitive drum is increased, and the depression is suppressed. It was confirmed that the effect was great.

  FIG. 13 is a graph showing the relationship between the speed ratio SR under a typical environment and the wear rate of the photosensitive drum used this time. FIG. 14 shows the pressing pressure under a typical environment and the photosensitive drum used this time. It is a graph which shows the relationship of wear rate in.

  The typical environment mentioned here refers to three environments of 10 ° C., 15% Rh, 20 ° C., 50% Rh, 30 ° C., and 90% Rh. Also, the vertical axis of each graph represents the wear rate of the photosensitive drum, and the horizontal axis of the graph of FIG. 13 represents the speed ratio of the rotational speed (peripheral speed) of the roll body / the rotational speed (peripheral speed) of the photosensitive drum. SR is shown, and the horizontal axis of the graph of FIG. 14 indicates the pressing pressure of the roll body against the surface of the photosensitive drum. Although the speed ratio SR is shown in FIG. 13, the speed difference between the photosensitive drum and the roll body increases as the speed ratio SR decreases from 1.

  Here, the control unit of the image forming apparatus used in the second embodiment is provided with a table as shown in the following Table 15 in which the speed ratio SR with respect to the combination of temperature and humidity is defined in advance, and the image forming apparatus includes the table. A similar experiment was performed by varying the rotation speed of the roll body according to the above table with respect to the output from the installed environment detection sensor.

  Here, a running experiment was performed in which the photosensitive drum was rotated 35,000 times in the three environments of 10 ° C., 15% Rh, 20 ° C., 50% Rh, 30 ° C., and 90% Rh, and finally 105,000 rotations. . As a result, the depletion never occurred until the end of the experiment, and the wear rate of the photoconductor was 5.5 nm / kcy, and even if the environment changed, the increase in the wear rate could be suppressed. Since the photosensitive drum used this time has a protective layer of 5 μm, it was possible to obtain a life expectancy of 900000 revolutions as a photosensitive drum.

  Further, the control unit of the image forming apparatus used in Example 4 is provided with a table as shown in the following Table 16 in which the pressing force (unit: mN / mm) for the combination of temperature and humidity is defined in advance. A similar experiment was performed by varying the pressing pressure according to the table with respect to the output from the environment detection sensor installed in the image forming apparatus.

  Here again, a running experiment was performed in which the photosensitive drum was rotated 35,000 times and finally 105,000 rotated under three environments of 10 ° C., 15% Rh, 20 ° C., 50% Rh, 30 ° C., and 90% Rh. . As a result, the depletion never occurred until the end of the experiment, and the wear rate of the photoconductor was 5.5 nm / kcy, and even if the environment changed, the increase in the wear rate could be suppressed. Since the photosensitive drum used this time has a protective layer of 5 μm, it was possible to obtain a life expectancy of 900000 revolutions as a photosensitive drum.

  Further, in Tables 7 and 8, and Tables 13 and 14, when some white spots or image flow occurred, x marks were given. In any of the tests in these tables, the roll body and the contact member Is provided, so there is no problem in practical use. Hereinafter, when the results shown in these tables are analyzed while performing relative comparison, the refresh operation of the photosensitive drum before the next image operation is performed even in a state where the wear of the photosensitive drum is reduced during the image forming operation. In this case, it is possible to more reliably suppress image defects by polishing the protective layer of the deteriorated photosensitive drum by increasing the speed difference between the photosensitive drum and the roll body or by increasing the pressing pressure of the roll body. It was confirmed that it was possible. In this case, supplying the toner band to the roll body before the refresh operation increases the refresh effect and shortens the idling cycle. Furthermore, when the toner band is formed, the primary transfer roll is retracted, the primary transfer bias is not turned on, the output is reduced, and the toner amount supplied to the roll body is substantially increased, thereby suppressing toner consumption. It is efficient because the length of the toner band can be shortened. With the introduction of this refresh cycle, it is possible to realize the suppression of the depression under high temperature and high humidity conditions while suppressing the wear of the photosensitive drum during the normal image formation.

It is a figure which shows the cleaning apparatus to which the technique described in patent document 2 is applied. FIG. 4 is a diagram illustrating a state in which residual toner particles accumulated in a lump on a roll body are detached from the roll body. It is a figure which shows the aspect which applied the bias of the reverse polarity to the charging polarity of a toner particle to the hair of a cleaning brush. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 5 is a diagram mainly showing a schematic configuration of one of the four toner image forming units shown in FIG. 4. FIG. 6 is a diagram illustrating a state in which residual toner particles are accumulated in a lump on the roll body illustrated in FIG. 5. It is a figure which shows a mode that the roll body shown in FIG. 6 rotated, It is an enlarged view of the part F enclosed with the dashed-two dotted line in FIG. It is a figure which shows a mode that replacement with the residual toner component hold | maintained at the roll body shown in FIG. 7 and a new residual toner component was performed. It is a diagram showing a cleaning device in which the contact member is changed to a scraper member, It is a figure which shows the cleaning apparatus which changed the contact member into the brush member. It is a figure which shows the cleaning apparatus which provided the cleaning blade instead of the cleaning brush. It is a graph which shows the relationship between the speed ratio SR in a typical environment, and the abrasion rate in the photosensitive drum used this time. It is a graph which shows the relationship between the pressing pressure in a typical environment, and the abrasion rate in the photosensitive drum used this time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Toner image forming unit 11 Photosensitive drum 12 Charging device 13 Exposure device 14 Developing device 15 Charger before cleaning 16 Charger before cleaning 17 Cleaning device 171 Cleaning brush 175 Roll body 1751 Rotating shaft 1752 Nonwoven fabric 176 Contact member 18 Static eliminator 20 Primary transfer roll 30 Intermediate transfer belt 40 Batch transfer device 50 Fixing device 60 Paper tray 70 Belt cleaner

Claims (2)

A toner image is carried on the transfer surface of an image carrier that conveys the toner image to a transfer area where the toner image is transferred to the transfer surface by carrying the toner image on the surface and circulatingly moving around the central axis. In a cleaning device for removing from the surface the residue remaining on the surface after the transfer
Cleaning means for removing residual toner remaining on the surface of the image carrier after the toner image is transferred to the transfer surface;
A plurality of fibers that are in contact with the surface of the image carrier after the toner image is transferred to the transfer surface on the upstream side in the circulation movement direction of the image carrier relative to the cleaning unit are parallel to the central axis. A rotating fibrous body having a rotation axis and rotating about the rotation axis;
A cleaning device comprising: an abutting member abutting against a plurality of fibers of the rotating fiber body. An electrostatic latent image is formed on the surface of the photoconductor by charging the surface of the photoconductor rotating in a predetermined direction around the central axis and irradiating the charged photoconductor surface with exposure light. An image composed of a toner image fixed on the recording medium by developing with toner to obtain a toner image on the surface of the photoconductor, transferring the toner image to a predetermined transfer surface, and finally fixing the toner image on the recording medium. In an image forming apparatus for forming
Cleaning means for removing residual toner remaining on the surface of the photoreceptor after the toner image is transferred to the transfer surface;
A plurality of fibers that are in contact with the surface of the photoconductor after the toner image is transferred to the transfer surface on the upstream side in the rotation direction of the photoconductor with respect to the cleaning unit have a rotation axis parallel to the central axis. A rotating fiber body having around and rotating about the rotation axis;
An image forming apparatus comprising: an abutting member abutting against a plurality of fibers of the rotating fiber body.

Images