JP2007309972A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use a charging roll and/or cleaning member until the end of its lifetime. <P>SOLUTION: The charging roll 14 and cleaning roll 102 are supported in a housing 118, disposed separately from the frame 53 of an image forming unit 52 in which a photoreceptor drum 12 is supported. Accordingly, the image forming unit 52 does not include the charging roll 14 and cleaning roll 102. Consequently, the image forming unit 52 is configured in a small size and at a low cost. In addition, even when the image forming unit 52 is taken out of the body of the image forming apparatus 10, when the photoreceptor drum 12 is replaced, since the charging roll 14 and cleaning roll 102 remain within the body of the image forming apparatus 10, without being taken out of the body of the image forming apparatus 10 together with the image forming unit 52; and this will not cause the charging roll 14 and cleaning roll 102 to be replaced, together with the photoreceptor drum 12 the lifetime which is shorter than the lifetime of the charging roll and the life of cleaning roll 102. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charging roll and an image forming apparatus provided with a cleaning roll for cleaning the charging roll.

  Since the charging roll for charging the surface of the photoreceptor is in direct contact with the photoreceptor, foreign matter remaining on the surface of the photoreceptor is likely to adhere to the surface of the charging roll. If foreign matter adheres to the surface of the charging roll, charging failure will occur.

  Therefore, a cleaning member made of a brush or sponge is brought into contact with the surface of the charging roll to remove dirt on the surface of the charging roll (see Patent Document 1).

In Patent Document 1, a charging roll and a cleaning member for cleaning the charging roll are disposed in a unit in which a photosensitive member and a developing member are integrally configured. For this reason, when replacing the photoreceptor, it is necessary to replace the entire unit, and even charging rolls and cleaning members that do not need to be replaced are replaced. However, since the life of the charging roll and the cleaning member is longer than the life of the photoconductor, it is a waste of resources to replace the charging roll and the cleaning member every time the photoconductor is replaced.
JP 2004-4749 A

  In view of the above problems, an object of the present invention is to use a charging roll and / or a cleaning member until the end of its life.

  The present invention according to claim 1 includes an image carrier that carries an image, a charging roll that charges the image carrier, and a cleaning member that contacts the charging roll and cleans the charging roll. The first holding means that is detachably provided in the apparatus main body and holds the image carrier, and is provided in the apparatus main body separately from the first holding means, and holds the charging roll and / or the cleaning member. And a second holding means.

  In the first aspect of the present invention, the image carrier is detachably held by the main body by the first holding means. In addition to the first holding unit, the second holding unit provided in the apparatus main body holds the cleaning member for cleaning the charging roll or both the charging roll for cleaning the image carrier and the cleaning member.

  That is, the first holding unit provided with the image carrier is configured not to hold the cleaning member or both the charging roll and the cleaning member. For this reason, the first holding means provided with the image carrier is reduced in size and configured at low cost.

  Further, when replacing the image carrier, even if the first holding means is taken out from the apparatus main body, the cleaning member remains in the apparatus main body without being taken out from the apparatus main body together with the first holding means. This prevents the cleaning member from being replaced in accordance with an image carrier having a shorter lifetime than the cleaning member. Therefore, the cleaning member can be used until the end of its life.

  Similarly, when both the charging roll and the cleaning member are held by the second holding unit, even when the first holding unit is taken out from the apparatus main body when replacing the image carrier, the charging roll and the cleaning member are The first holding means is not taken out from the apparatus main body and remains in the apparatus main body. Thus, the charging roll and the cleaning member are not exchanged according to the image carrier having a shorter life than the charging roll and the cleaning member. Therefore, the charging roll and the cleaning member can be used until their lifetime.

  The present invention described in claim 2 is characterized in that the second holding means is detachable from the apparatus main body.

  In the second aspect of the invention, the second holding means can be attached to and detached from the apparatus main body. That is, the charging roll and the cleaning member held by the second holding unit can be attached to and detached from the apparatus main body. Thereby, since the charging roll and the cleaning member can be exchanged outside the apparatus main body, the exchange work is simplified and the work time is shortened.

  The present invention described in claim 3 is characterized in that the second holding means is a housing in which the charging roll and / or the cleaning member is accommodated.

  In the invention according to claim 3, the cleaning member or both the charging roll and the cleaning member are accommodated in the housing. As a result, dirt on the surface of the charging roll removed by the cleaning member can be received by the housing, so that there is no possibility that the inside of the apparatus gets dirty.

  The present invention described in claim 4 is characterized in that the charging roll and / or the cleaning member are replaced based on process conditions.

  According to the fourth aspect of the present invention, the cleaning member or both the charging roll and the cleaning member are replaced based on the process conditions of the image forming apparatus. That is, by calculating the replacement time of the cleaning member or both of the charging roll and the cleaning member from the process conditions, it is possible to replace both the cleaning member or the charging roll and the cleaning member when the lifetime is exhausted.

  Since the present invention has the above configuration, the charging roll and / or the cleaning member can be used until the end of its life.

  Hereinafter, an image forming apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

  An image forming apparatus 10 according to this embodiment shown in FIG. 1 is a four-cycle full-color laser printer. As shown in the drawing, in the apparatus, a photosensitive drum 12 (image carrier) is located slightly above the center. ) Is rotatably arranged. As this photosensitive drum 12, for example, a drum made of a conductive cylinder having a diameter of about 47 mm and coated on a surface with a photosensitive layer made of OPC or the like is used. It is rotationally driven at a process speed of 150 mm / sec.

  The surface of the photosensitive drum 12 is charged to a predetermined potential by a charging roll 14 disposed almost directly below the photosensitive drum 12, and then exposed to a laser beam LB by an exposure device 16 disposed below the charging roll 14. Image exposure is performed, and an electrostatic latent image according to image information is formed.

  The electrostatic latent image formed on the photosensitive drum 12 has yellow (Y), magenta (M), cyan (C), and black (K) developing devices 18Y, 18M, 18C, and 18K in the circumferential direction. The toner is developed by a rotary developing device 18 disposed along the toner image to form a toner image of a predetermined color.

  At this time, charging, exposure, and development processes are repeated a predetermined number of times on the surface of the photosensitive drum 12 in accordance with the color of the image to be formed. In the developing process, the rotary developing device 18 rotates, and the corresponding color developing devices 18Y, 18M, 18C, and 18K move to a developing position facing the photosensitive drum 12.

  For example, when a full-color image is formed, the charging, exposing, and developing processes are performed on the surface of the photosensitive drum 12 in yellow (Y), magenta (M), cyan (C), and black (K) colors. The toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially formed on the surface of the photosensitive drum 12. When the toner image is formed, the number of rotations of the photosensitive drum 12 varies depending on the size of the image. For example, in the case of A4 size, one image is obtained by rotating the photosensitive drum 12 three times. It is formed. That is, a toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the surface of the photosensitive drum 12 every time the photosensitive drum 12 rotates three times. Is done.

  An intermediate transfer belt 20 is wound around the outer periphery of the photosensitive drum 12 for yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 12. At the primary transfer position, the images are transferred onto the intermediate transfer belt 20 by the primary transfer roll 22 while being superimposed on each other.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 20 are recorded on a recording sheet 24 fed at a predetermined timing. The images are collectively transferred by the secondary transfer roll 26.

  On the other hand, the recording paper 24 is fed out from a paper feed cassette 28 disposed at the lower part of the image forming apparatus 10 by a pickup roll 30 and is fed in a state of being fed one by one by a feed roll 32 and a retard roll 34. The toner image is transferred to the secondary transfer position of the intermediate transfer belt 20 in synchronization with the toner image transferred onto the intermediate transfer belt 20 by the registration roll 36.

  The intermediate transfer belt 20 includes a wrap-in roll 38 that specifies the wrap position of the intermediate transfer belt 20 on the upstream side in the rotational direction of the photosensitive drum 12 and a toner image formed on the photosensitive drum 12 as an intermediate transfer belt. A primary transfer roll 22 that is transferred onto the intermediate transfer belt 20, a wrap-out roll 40 that specifies the wrap position of the intermediate transfer belt 20 on the downstream side of the wrap position, and a backup that contacts the secondary transfer roll 26 via the intermediate transfer belt 20. The roll 42, the first cleaning backup roll 46 facing the cleaning device 44 of the intermediate transfer belt 20, and the second cleaning backup roll 48 are stretched with a predetermined tension, and have a predetermined process speed (about 150 mm / sec), for example, as the photosensitive drum 12 rotates. It is driven Te.

  Here, in order to reduce the size of the image forming apparatus 10, the intermediate transfer belt 20 is configured such that a cross-sectional shape on which the intermediate transfer belt 20 is stretched is a flat and elongated substantially trapezoidal shape.

  The intermediate transfer belt 20 is provided in the image forming unit 52. The image forming unit 52 includes the photosensitive drum 12, the intermediate transfer belt 20, a plurality of rolls 22 (primary transfer rolls), 38, 40, 42, 46, and 48 that stretch the intermediate transfer belt 20, and the intermediate transfer belt. 20, a cleaning device 44 for 20 and a cleaning device 78 for the photosensitive drum 12 to be described later. Then, as shown in FIG. 2, the upper cover 54 of the image forming apparatus 10 is opened, and a handle (not shown) provided on the upper portion of the image forming unit 52 is lifted by hand to form an image on the entire image forming unit 52. It can be removed from the device 10.

  The photosensitive drum 12 is detachable from the image forming unit 52 in a state where the image forming unit 52 is detached from the main body of the image forming apparatus 10. Therefore, the photoconductor unit 98 and the intermediate transfer belt 20 can be replaced separately according to their lifetimes. The mounting structure of the photosensitive drum 12 will be described later.

  On the other hand, the cleaning device 44 for the intermediate transfer belt 20 includes a scraper 58 disposed so as to come into contact with the surface of the intermediate transfer belt 20 stretched by the first cleaning backup roll 46, and a second cleaning backup roll 48. And a cleaning brush 60 disposed so as to be in pressure contact with the surface of the stretched intermediate transfer belt 20. Residual toner and paper dust removed by the scraper 58 and the cleaning brush 60 are contained in the cleaning device 44. It has come to be collected.

  The cleaning device 44 is disposed so as to be able to swing counterclockwise in the drawing with the swing shaft 62 as the center. Until the secondary transfer of the final color toner image is completed, the intermediate transfer belt is provided. It is configured to retreat to a position separated from the surface of the surface 20 and to contact the surface of the intermediate transfer belt 20 when the secondary transfer of the final color toner image is completed.

  Further, the recording paper 24 onto which the toner image has been transferred from the intermediate transfer belt 20 is conveyed to a fixing device 64 and is heated and pressurized by the fixing device 64 to fix the toner image on the recording paper 24. Thereafter, in the case of single-sided printing, the recording paper 24 on which the toner image has been fixed is discharged as it is onto a discharge tray 68 provided at the top of the image forming apparatus 10 by a discharge roll 66.

  On the other hand, in the case of double-sided printing, the recording paper 24 on which the toner image is fixed on the first surface (front surface) by the fixing device 64 is not directly discharged onto the discharge tray 68 by the discharge roll 66 but is discharged by the discharge roll 66. With the rear end portion of the recording paper 24 being held, the discharge roller 66 is reversed, the conveyance path of the recording paper 24 is switched to the double-sided paper conveyance path 70, and the double-sided paper conveyance path 70 is disposed. In the state where the front and back of the recording paper 24 are reversed by the transport roller 72 thus transferred, the recording paper 24 is again transported to the secondary transfer position of the intermediate transfer belt 20 and the toner image is transferred to the second surface (back surface) of the recording paper 24. . Then, the toner image on the second surface (back surface) of the recording paper 24 is fixed by the fixing device 64, and the recording paper 24 is discharged onto the discharge tray 68.

  Furthermore, a manual feed tray 74 can be attached to the side surface of the image forming apparatus 10 so as to be freely opened and closed. An arbitrary size and type of recording paper 24 placed on the manual feed tray 74 is fed by a paper feed roll 76, and a secondary transfer position of the intermediate transfer belt 20 via a transport roll 73 and a registration roll 36. The image can be formed on the recording paper 24 of any size and type.

  The surface of the photosensitive drum 12 after the toner image transfer process is completed is cleaned by the cleaning blade 80 of the cleaning device 78 disposed obliquely below the photosensitive drum 12 every time the photosensitive drum 12 rotates once. Residual toner, paper dust, and the like are removed to prepare for the next image forming process.

  As shown in FIG. 3, a charging roll 14 is disposed below the photosensitive drum 12 so as to be in contact with the photosensitive drum 12. The charging roll 14 has a charging layer 14B formed around a conductive shaft 14A, and the shaft 14A is rotatably supported by a housing 118 described later.

  A roll-shaped cleaning roll 102 that contacts the surface of the charging roll 14 is provided below the charging roll 14 opposite to the photosensitive drum 12. The cleaning roll 102 is configured by forming a sponge layer 102B around the shaft 102A, and the shaft 102A is rotatably supported by the housing 118.

  The cleaning roll 102 is pressed against the charging roll 14 with a predetermined load, and the sponge layer 102 </ b> B is elastically deformed along the peripheral surface of the charging roll 14 to form the nip portion N.

  The photosensitive drum 12 is driven to rotate clockwise (in the direction of arrow 2) in FIG. 3 by a motor (not shown), and the charging roll 14 is driven to rotate in the direction of arrow 4 by the rotation of the photosensitive drum 12. Further, the roll-shaped cleaning roll 102 is driven to rotate in the direction of the arrow 6 by the rotation of the charging roll 14. The mounting structure of the charging roll 14 and the cleaning roll 102 will be described later.

  As the cleaning roll 102 is driven to rotate, dirt (foreign matter) such as toner and external additives attached to the surface of the charging roll 14 is cleaned by the cleaning roll 102. When the foreign matter is taken into the cell of the sponge layer 102B and the collected foreign matter is aggregated to an appropriate size, it is returned from the cleaning roll 102 to the photosensitive drum 12 via the charging roll 14, It is considered that the cleaning performance is continuously maintained by being collected by the cleaning device 78 that cleans the photosensitive drum 12.

  In such a cleaning roll 102, free-cutting steel, stainless steel, or the like is used as the material of the shaft 102A, and the material and the surface treatment method are appropriately selected according to applications such as slidability. In addition, a non-conductive material may be processed by a general process such as a plating process and subjected to a conductive process, or may be used as it is. Further, since the cleaning roll 102 comes into contact with the charging roll 14 through the sponge layer 102B with an appropriate nip pressure, the shaft diameter having sufficient rigidity with respect to a material having a strength with little bending at the nip or a shaft length. Is selected.

  The sponge layer 102B has a cylindrical shape and is made of a foam having a porous three-dimensional structure. The sponge layer 102B is selected from those made of foamable resin or rubber such as polyurethane, polyethylene, polyamide, or polypropylene. The sponge layer 102B efficiently cleans foreign substances such as external additives by driven sliding friction with the charging roll 14, and at the same time, the surface of the charging roll 14 is not scratched by rubbing of the sponge layer 102B. In order to prevent tearing and breakage, it is particularly preferable to use polyurethane that is strong in tearing and tensile strength. Note that the cleaning member of the cleaning roll 102 may be constituted by a blade, a brush, a waste cloth, or the like in addition to the sponge.

  The charging roll 14 is formed by sequentially forming a conductive elastic layer and a surface layer as a charging layer 14B on a conductive shaft 14A.

  As the material of the shaft 14A, free-cutting steel, stainless steel or the like is used, and the material and the surface treatment method are appropriately selected according to the use such as slidability, and the material having no conductivity is generally plated. It may be processed by an appropriate process and a conductive process may be performed.

  The conductive elastic layer constituting the charging layer 14B of the charging roll 14 may be, for example, an elastic material such as rubber having elasticity, a conductive material such as carbon black or ionic conductive material for adjusting the resistance of the conductive elastic layer, or the like. Accordingly, materials that can be usually added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, and fillers such as silica and calcium carbonate, may be added. It is formed by coating the peripheral surface of the conductive shaft 14 </ b> A with a mixture in which materials usually added to rubber are added. As a conductive agent for the purpose of adjusting the resistance value, a material in which a material that conducts electricity using electrons and / or ions as a charge carrier, such as carbon black or an ionic conductive agent blended in a matrix material, is used. it can. The elastic material may be a foam.

  The surface layer constituting the charging layer 14B is formed for the purpose of preventing contamination by foreign matters such as toner, and the surface layer material may be any of resin, rubber, etc. It is not limited. Polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene And ethylene vinyl acetate copolymer.

  The surface layer can contain a conductive material to adjust the resistance value. The conductive material preferably has a particle size of 3 μm or less.

  In addition, as a conductive agent for the purpose of adjusting the resistance value, it electrically conducts electrons and / or ions as charge carriers, such as carbon black, conductive metal oxide particles, or ionic conductive agent blended in the matrix material. What disperse | distributed material etc. can be used.

  The conductive metal oxide particles, which are conductive particles for adjusting the resistance value, are conductive particles such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, and ITO. Any conductive agent using electrons as charge carriers can be used without any particular limitation. These may be used alone or in combination of two or more. Any particle size may be used as long as the present invention is not inhibited. From the viewpoint of resistance value adjustment and strength, tin oxide, antimony-doped tin oxide, and anatase-type titanium oxide are preferable. Tin oxide and antimony-doped tin oxide are preferred.

  By performing resistance control with such a conductive material, the resistance value of the surface layer does not change depending on environmental conditions, and stable characteristics can be obtained.

  Further, a fluorine-based or silicone-based resin is used for the surface layer. In particular, it is preferably composed of a fluorine-modified acrylate polymer. Further, fine particles may be added to the surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the adhesion of foreign matter to the charging roll 14. In addition, insulating particles such as alumina and silica are added to give unevenness to the surface of the charging roll 14, thereby reducing the burden at the time of rubbing against the photosensitive drum 12, and the charging roll 14 and the photosensitive drum. It is also possible to improve the mutual wear resistance.

  Next, a structure for attaching the photosensitive drum 12 to the image forming unit 52 will be described in detail.

  As shown in FIGS. 4 and 5, a rail 124 is attached to the frame 53 of the image forming unit 52 (see FIG. 1) in parallel with the axis of the photosensitive drum 12. Engaging portions (not shown) of support members 112 disposed at both ends of the photosensitive drum 12 are engaged with the rail 124. Thus, the photosensitive drum 12 can be slid along the rail 124 to the left and right in the drawing.

  The support member 112 closes the opening of the substantially U-shaped receiving portion 114 that supports the outer peripheral surface of the bearing 106 provided at both ends of the photosensitive drum 12 and the receiving portion 114, and between the receiving portion 114. And a lid 116 that sandwiches the bearing 106. Thus, the photosensitive drum 12 is rotatably supported by the support member 112 at both ends via the bearing 106.

  A power supply device 110 is attached to one end (right side in the drawing) of the photosensitive drum 12. The power supply device 110 is charged by applying a voltage to the charging roll 14. A gear 108 is provided at the other end (left side in the figure) of the photosensitive drum 12. The gear 108 is meshed with a gear provided on a shaft of a drive motor (not shown) provided in the main body of the image forming apparatus 10 (see FIG. 1). As a result, the rotational force of the drive motor is transmitted to the photosensitive drum 12 via the gear 108.

  On the other hand, a plate-shaped plate piece 119 is integrally provided on the lower surface of the receiving portion 114 of the support member 112. A substantially U-shaped groove 121 is formed near the lower end of the plate piece 119. A convex piece 128 provided on the housing 118 described later is engaged with the groove 121.

  With the above configuration, when the photosensitive drum 12 is replaced, the upper cover 54 of the image forming apparatus 10 is opened as shown in FIG. 2, and the image forming unit is opened as shown in FIGS. 52 is removed from the image forming apparatus 10 main body. Then, as shown in FIGS. 5 and 7C, the photosensitive drum 12 is pulled out in the right direction in the figure and removed from the image forming unit 52.

  Next, the attachment structure of the charging roll 14 and the cleaning roll 102 will be described.

  As shown in FIG. 6, the charging roll 14 and the cleaning roll 102 are accommodated in a substantially rectangular box-shaped housing 118. The housing 118 has a two-stage structure including a large accommodating portion 120 and a small accommodating portion 122 that is provided below the large accommodating portion 120 and is slightly smaller than the large accommodating portion 120. The large accommodating portion 120 and the small accommodating portion 122 are fitted and positioned in a step portion 123 formed on the main body frame.

  The charging roll 14 is accommodated in the large accommodating portion 120. Plate-like support pieces 127 are erected on both sides in the longitudinal direction of the overhanging portion 120 </ b> A of the large accommodating portion 120. An arcuate cutout 125 is formed in the support piece 127, and the shaft 14A of the charging roll 14 is rotatably supported.

  Further, the bottom surface 122A of the small accommodating portion 122 has an arc shape, and the cleaning roll 102 is accommodated therein. On both sides of the bottom surface 122A in the longitudinal direction, plate-like support pieces 126 are erected. Similarly to the support piece 127, the support piece 126 is formed with an arc-shaped notch, and the shaft 102A of the cleaning roll 102 is rotatably supported.

  On both side walls 120 </ b> B of the large accommodating portion 120, rectangular convex pieces 128 project. The convex piece 128 is adapted to be engaged with a U-shaped groove 121 (see FIG. 5) formed in the support member 112 of the photosensitive drum 12. By engaging the convex piece 128 with the groove 121 of the support member 112, the photosensitive drum 12 and the charging roll 14 are positioned.

  That is, when the image forming unit 52 is mounted in the image forming apparatus 10, the groove 121 formed in the support member 112 is engaged with the convex piece 128 provided in the housing 118. Accordingly, the image forming unit 52 is mounted in the image forming apparatus 10 in a state where the photosensitive drum 12 is positioned with respect to the charging roll 14.

  With such a configuration, when replacing the charging roll 14 and the cleaning roll 102, first, as shown in FIG. 2, the upper cover 54 of the image forming apparatus 10 is opened, and the image forming unit 52 is mounted on the main body of the image forming apparatus 10. Remove from inside. Then, the housing 118 is pulled up and removed from the image forming apparatus 10, and the charging roll 14 and the cleaning roll 102 are exchanged outside the apparatus.

  As a result, as shown in FIGS. 7 and 8, even when the image forming unit 52 is taken out from the main body of the image forming apparatus 10 when the photosensitive drum 12 is replaced, the charging roll 14 and the cleaning roll 102 are not affected by the image forming unit. 52 is not taken out from the main body of the image forming apparatus 10 together with the main body 52 but remains in the main body of the image forming apparatus 10, so that the charging roll 14 and the cleaning roll 102 are matched with the photosensitive drum 12 having a shorter life than the charging roll and the cleaning roll 102. Will never be replaced. Therefore, the charging roll 14 and the cleaning roll 102 can be used until the end of their lifetime.

  Further, the charging roll 14 and the cleaning roll 102 are supported in a housing 118 provided separately from the frame 53 of the image forming unit 52 on which the photosensitive drum 12 is supported. 14 and the cleaning roll 102 are not included. Therefore, the image forming unit 52 is downsized and configured at low cost.

  Further, when the charging roll 14 or the cleaning roll 102 is accommodated in the box-shaped housing 118, the surface of the charging roll 14 removed by the cleaning roll 102 can be received by the housing 118. There is no fear of getting dirty.

  The replacement timing of the charging roll 14 and the cleaning roll 102 is determined according to various process conditions. In this embodiment, the replacement timing of the charging roll 14 and the cleaning roll 102 is determined according to the following process conditions. When it is time to replace the charging roll 14 and the cleaning roll 102, the display panel 11 prompts the user to replace the charging roll 14 and the cleaning roll 102.

  For example, the image density is calculated from the image information, and the image density is accumulated by a control unit (not shown) built in the main body of the image forming apparatus 10. When the accumulated image density exceeds a predetermined value, the charging roll 14 and the cleaning roll 102 are replaced.

  Further, the control unit counts the time when the voltage is applied to the charging roll 14 from the power supply device 110 that applies the voltage to the charging roll 14. When the cumulative voltage application time of the power supply device 110 exceeds a predetermined value, the charging roll 14 and the cleaning roll 102 are replaced.

  Further, the number of rotations of the photosensitive drum 12, the number of rotations of the developing unit 18, the exposure time of the exposure device 16, and the number of recording sheets 24 on which images are recorded are counted, and when these accumulated values exceed a predetermined value, The charging roll 14 and the cleaning roll 102 are exchanged.

  Further, the temperature and humidity meter is used to detect the environment (temperature, humidity) in which the image forming apparatus 10 is installed, and the replacement timing of the charging roll 14 and the cleaning roll 102 is also determined from the image forming speed. The

  In this embodiment, the upper cover 54 of the image forming apparatus 10 is opened and the housing 118 containing the charging roll 14 and the cleaning roll 102 is taken out from the main body of the image forming apparatus 10. The charging roll 14 and the cleaning roll 102 may be taken out from the main body of the image forming apparatus 10 by opening the side cover and pulling out the housing 118 to the side of the image forming apparatus 10 (toward the front in FIG. 1). .

  Next, an image forming apparatus according to a second embodiment of the present invention will be described. In addition, the description about the part similar to 1st Embodiment is omitted.

  As shown in FIGS. 9 and 10, the support member 112 that supports the photosensitive drum 12 is integrally provided with a plate-shaped plate piece 151, and a charging roll 154 is rotatable on the plate piece 151. It is supported by. Further, a substantially U-shaped groove 152 is formed near the lower end of the plate piece 151. A convex piece 160 provided in a housing 158 described later is engaged with the groove 152.

  The cleaning roll 156 is housed in a substantially rectangular box-shaped housing 158 in a rotatable state.

  On both side walls 158A of the housing 158, rectangular convex pieces 160 project. This convex piece 160 is adapted to be engaged with a groove 152 formed in the plate piece 151, and the positioning of the cleaning roll 156 is achieved by engaging the convex piece 160 with the groove 152.

  With the above configuration, when the cleaning roll 156 is replaced, the upper cover 54 (see FIG. 2) of the image forming apparatus 10 is opened, and as shown in FIGS. 11 (B) and 12 (B), the image forming unit. 162 is removed from the image forming apparatus 10 main body. Then, as shown in FIGS. 10 and 11C, the photosensitive drum 12 is pulled out in the right direction in the figure and removed from the image forming unit 162. At this time, the charging roll 154 is also pulled out together with the photosensitive drum 12 and is removed from the image forming unit 162.

  Then, the housing 158 is pulled up and removed from the image forming apparatus 10, and the cleaning roll 156 is exchanged outside the apparatus.

  Accordingly, as shown in FIG. 12B, even when the image forming unit 162 is taken out from the main body of the image forming apparatus 10 when the photosensitive drum 12 is exchanged, the cleaning roll 156 can be used together with the image forming unit 162 to perform image processing. Since it remains in the main body of the image forming apparatus 10 without being taken out from the main body of the forming apparatus 10, the cleaning roll 156 is not replaced according to the photosensitive drum 12 having a shorter life than the cleaning roll 156. Therefore, the cleaning roll 156 can be used for the lifetime.

  The cleaning roll 156 is supported in the housing 158 provided separately from the frame 53 of the image forming unit 162 on which the photosensitive drum 12 and the charging roll 154 are supported. Is not included. Therefore, the image forming unit 52 is downsized and configured at low cost.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic view showing an upper body obtained by taking out an image forming unit including a photosensitive drum from the image forming apparatus. FIG. 3 is an enlarged view showing a configuration of a photosensitive drum, a charging roll, and a cleaning roll mounted on the image forming apparatus. FIG. 4 is a perspective view showing a mounting structure of a photosensitive drum, a charging roll, and a cleaning roll. FIG. 4 is a perspective view showing a mounting structure of a photosensitive drum, a charging roll, and a cleaning roll. It is a figure which shows the attachment structure of a charging roll and a cleaning roll, (A) is a disassembled perspective view, (B) is a partial side view. FIG. 4 is a side view showing the positional relationship between the image forming unit, the charging roll, and the cleaning roll, (A) is a view showing a state in which the image forming unit is mounted in the image forming apparatus, and (B) is a view from the image forming apparatus. It is a figure which shows the state which took out the image forming unit, and (C) is a figure which shows a mode that a photosensitive drum is removed from an image forming unit. FIG. 3 is a side view from the axial direction showing the positional relationship between the image forming unit, the charging roll, and the cleaning roll, (A) is a view showing a state where the image forming unit is mounted in the image forming apparatus, and (B) is a view. FIG. 3 is a diagram illustrating a state where an image forming unit is taken out from the image forming apparatus. FIG. 5 is a perspective view showing a mounting structure of a photosensitive drum, a charging roll, and a cleaning roll mounted on an image forming apparatus according to a second embodiment of the present invention. FIG. 4 is a perspective view showing a mounting structure of a photosensitive drum, a charging roll, and a cleaning roll. FIG. 4 is a side view showing the positional relationship between the image forming unit, the charging roll, and the cleaning roll, (A) is a view showing a state in which the image forming unit is mounted in the image forming apparatus, and (B) is a view from the image forming apparatus. It is a figure which shows the state which took out the image forming unit, and (C) is a figure which shows a mode that a photosensitive drum is removed from an image forming unit. FIG. 3 is a side view from the axial direction showing the positional relationship between the image forming unit, the charging roll, and the cleaning roll, (A) is a view showing a state where the image forming unit is mounted in the image forming apparatus, and (B) is a view. FIG. 3 is a diagram illustrating a state where an image forming unit is taken out from the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum (Image carrier)
14 Charging roll 53 Frame (first holding means)
102 Cleaning roll (cleaning member)
118 Housing (second holding means)
154 Charging roll 156 Cleaning roll (cleaning member)
158 Housing (second holding means)

Claims (4)

An image carrier that carries an image, a charging roll that charges the image carrier, and a cleaning member that contacts the charging roll and cleans the charging roll,
A first holding means which is detachably provided in the apparatus main body and holds the image carrier;
A second holding unit that is provided in the apparatus main body separately from the first holding unit and holds the charging roll and / or the cleaning member;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the second holding unit is detachable from the apparatus main body.   The image forming apparatus according to claim 1, wherein the second holding unit is a housing that accommodates the charging roll and / or the cleaning member.   The image forming apparatus according to claim 1, wherein the charging roll and / or the cleaning member are replaced based on a process condition.

Images