JP5870911B2 - Image forming unit and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming unit used in an image forming apparatus such as a copying machine, an electrophotographic printer, a facsimile machine, and an MFP.

  In a conventional charging system for an image forming unit using an electrophotographic system, a contact roller charging system in which a roller-shaped charging member is brought into contact with the surface of a photosensitive drum on which an electrostatic latent image is formed to charge the surface. Has been used.

  In the contact roller charging method, the surface of the photosensitive drum is charged by bringing the charging roller into contact with the photosensitive drum with a predetermined pressure. However, for example, when a foreign substance such as toner adheres to the surface of the charging roller, there is a problem that charging unevenness occurs and an image defect occurs.

  In order to solve such a problem, for example, Patent Document 1 describes a technique for cleaning the surface of a charging roller by rotating a cleaning roller having a porous sponge member disposed on the outer periphery while contacting the charging roller. Has been.

JP 2010-54796 A

  However, in the conventional method for cleaning the surface of the charging roller using the cleaning roller, due to variations in the outer peripheral diameter of the sponge member of the cleaning roller, variations in material hardness, variations in the size of the frame that supports the cleaning roller, etc. Because the amount of crushing (nip amount) of the cleaning roller varies, there may be variations in the collection of foreign matter on the surface of the charging roller, and the cleaning performance may not be maintained throughout the life of the device due to large friction of the sponge member. Has occurred, causing image defects.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a predetermined cleaning roller with respect to the charging roller even if there are variations in the material characteristics of the cleaning roller, variations in the dimensions of each component, and the like. An object of the present invention is to provide an image forming unit and an image forming apparatus capable of securing a crushing amount and preventing occurrence of charging unevenness by realizing good cleaning.

  In order to solve the above problems, an image forming unit according to the present invention includes an image carrier that carries an electrostatic latent image, a charging member that charges the surface of the image carrier, and a cleaning member that cleans the charging member. And an adjustment member that adjusts the distance between the shaft of the charging member and the cleaning member, the adjustment member rotates about the shaft member of the cleaning member, and a plurality of recessed surfaces are formed on an outer peripheral surface thereof, The space between the shafts is adjusted by bringing the hollow surface into contact with the shaft member of the charging member.

  An image forming apparatus according to the present invention includes an image carrier that carries an electrostatic latent image, a charging member that charges the surface of the image carrier, a cleaning member that cleans the charging member, and the charging member. An adjusting member that adjusts the distance between the cleaning member and the cleaning member; and a developing unit that supplies a developer to the electrostatic latent image carried on the image carrier and develops the developer image. The cleaning member rotates about the shaft member, and a plurality of recessed surfaces are formed on the outer peripheral surface thereof, and the space between the shafts is adjusted by bringing the recessed surfaces into contact with the shaft member of the charging member. .

  According to the present invention, it is possible to secure a predetermined crushing amount of the cleaning roller with respect to the charging roller even if there are variations in the material characteristics of the cleaning roller, dimensional variations in each component, etc. An image forming unit and an image forming apparatus capable of preventing the occurrence of charging unevenness can be provided.

1 is an overall configuration diagram illustrating an overall configuration of an image forming apparatus. It is sectional drawing which shows the main members of an image forming unit. It is a perspective view which shows the structure of a charging device. It is a perspective view which shows the roller edge part of a charging device. It is a disassembled perspective view which shows the roller edge part of a charging device. It is sectional drawing which shows a charging device. It is a figure explaining the adjustment method of the center distance between the shaft member of a charging roller, and the shaft member of a sponge roller. It is a perspective view which shows the roller edge part of a charging device. It is a perspective view of an adjustment member between axes. It is an end perspective view of the image forming unit housing.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

[First Embodiment]
FIG. 1 is an overall structural diagram illustrating the overall configuration of an image forming apparatus 101 according to the first embodiment. An image forming apparatus 101 according to the present embodiment is an image forming apparatus capable of forming an image on a recording medium P by an electrophotographic method. The image forming apparatus 101 that realizes such a function is along a medium transport path S formed in a substantially S shape starting from the paper feed cassette 107 and ending with the discharge roller 112 via the transport roller 109. Image forming units 121, 122, 123, and 124 corresponding to image formation of toner colors (black (K), yellow (Y), magenta (M), and cyan (C)) as a developer, transfer unit 110, and fixing A unit 111 and the like are provided.

  The paper feed cassette 107 stores the recording medium P in an accumulated state, and is detachably attached to the lower part of the image forming apparatus 101. The paper feeding unit 108 having a paper feeding means such as a hopping roller provided at the upper part of the paper feeding cassette 107 takes out the recording medium P stored in the paper feeding cassette 107 one by one from the top to convey the medium. It goes out to the route S.

  The transport roller 109 corrects the skew of the recording medium P fed from the paper supply unit 108 and transports the recording medium P to the transfer unit 110.

  The transfer unit 110 includes a transfer belt 1101, a drive roller 1102, a tension roller 1103, and transfer rollers 11041, 11042, 11043, and 11044. The transfer belt 1101 is an endless belt member that electrostatically attracts and conveys the recording medium P, and a tension roller 1103 supported by a spring (not shown) to keep the tension of the transfer belt 1101 constant, and the tension The roller 1103 is arranged in a pair and is stretched by a drive roller 1102 that rotates by driving of a drive motor (not shown). The transfer rollers 11041, 11042, 11043, and 11044 are formed of conductive rubber or the like, and are disposed so as to face and contact a photosensitive drum as an image carrier included in each image forming unit. The transfer rollers 11041, 11042, 11043, and 11044 transfer a toner image developed on the surface of the photosensitive drum to the recording medium P by a bias voltage applied from a transfer power source (not shown) and having a polarity opposite to that of the toner.

  The fixing unit 111 is disposed on the downstream side of the medium transport path S after the image forming units 121, 122, 123, and 124, and includes a heat roller 1111, a backup roller 1112, a temperature sensor (not shown), and the like. The heat roller 1111 is formed, for example, by covering a hollow cylindrical metal core made of aluminum or the like with a heat-resistant elastic layer of silicone rubber and coating a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) tube thereon. Is formed by. In the core bar, for example, a heater such as a halogen lamp is provided. The backup roller 1112 has, for example, a configuration in which a core metal made of aluminum or the like is coated with a heat-resistant elastic layer of silicone rubber and PFA is coated thereon, so that a pressure contact portion is formed between the backup roller 1112 and the heat roller 1111. Has been placed. The heat roller 1111 and the backup roller 1112 rotate based on control of a fixing control unit (not shown). A temperature sensor (not shown) is means for detecting the surface temperature of the heat roller 1111 and is disposed in the vicinity of the heat roller 1111 in a non-contact manner. The surface temperature of the heat roller 1111 is maintained at a predetermined temperature by controlling the heater based on the detection result of the surface temperature of the heat roller 1111 detected by a temperature sensor (not shown). The recording medium P to which the toner image formed in the image forming units 121, 122, 123, 124 is transferred passes through a pressure contact portion formed by a heat roller 1111 and a backup roller 1112 maintained at a predetermined temperature. Then, heat and pressure are applied to the toner on the recording medium P, the toner is melted, and the toner image is fixed.

  The discharge roller 112 sandwiches and conveys the recording medium P that has passed through the fixing unit 111, and discharges the recording medium P to a discharge stacker 113 that is formed using the outer casing of the image forming apparatus 101.

  The image forming units 121, 122, 123, and 124 are configured to be detachable from the image forming apparatus 101 from the upstream side of the medium conveyance path S. The image forming units 121, 122, 123, and 124 include photosensitive drums 511, 512, 513, and 514 that can carry an electrostatic latent image based on the irradiation light emitted from each exposure device 141, 142, 143, and 144. The electrostatic latent images corresponding to the respective toner colors formed on the respective photosensitive drums 511, 512, 513, and 514 are developed by the toner supplied from the respective toner containers 131, 132, 133, and 134, and the transfer unit 110 is developed. Is transferred onto the recording medium P. The configuration of the image forming units 121, 122, 123, and 124 will be described in detail later.

  The exposure apparatuses 141, 142, 143, and 144 are LED heads having LED (Light Emitting Diode) light emitting elements and a lens array. Each of the exposure apparatuses 141, 142, 143, and 144 is irradiated with light emitted when the LED light emitting element is turned on based on control by an exposure control unit (not shown) on the surface of the photosensitive drum included in each image forming unit. It arrange | positions so that it may become a position to form an image.

  Next, the configuration of the image forming units 121, 122, 123, and 124 will be described. FIG. 2 is a cross-sectional view showing main members of the image forming units 121, 122, 123, and 124. As shown in FIG. 1, the image forming units 121, 122, 123, and 124 differ only in the toner stored in the toner containers 131, 132, 133, and 134, and the other configurations are the same. Therefore, in the following description, the image forming unit 121 that forms a black image will be described as an example.

  The image forming unit 121 includes a photosensitive drum 511, a charging device 52 for charging the photosensitive drum 511, and an electrostatic latent image recorded on the photosensitive drum 511 by exposure performed from the exposure device 141 based on print data. The toner 54 is supplied to the developing roller 53, the developing roller 53 for developing the toner image, the developing blade 55 that is in contact with the developing roller 53 and forming a toner layer on the surface of the developing roller 53, and the toner 54 on the developing roller 53. A supply roller 56 to be supplied and a cleaning blade 57 for removing residual toner on the photosensitive drum 511 are provided.

  The photosensitive drum 511 includes a conductive support and a photoconductive layer. For example, a charge generation layer as a photoconductive layer and a charge transport layer are sequentially formed on a metal hollow tube such as aluminum as a conductive support. This is a negatively charged laminated type photosensitive drum constructed by being laminated. For example, the outer diameter of the photosensitive drum 511 can be set to Φ30 mm, and an electrostatic latent image based on the irradiation light irradiated from the exposure device 141 is formed.

  The charging device 52 includes a charging roller 1 as a charging member that directly charges the surface of the photosensitive drum 511. For example, the outer diameter of the charging roller 1 can be set to Φ12 mm, and is brought into contact with the photosensitive drum 511 with a predetermined pressure by a biasing force from a biasing member described later. The charging roller 1 uniformly charges the surface of the photosensitive drum 511 based on a bias voltage having the same polarity as that of the toner applied from a charging roller power source (not shown). Other main members constituting the charging device 52 will be described later.

  The developing roller 53 as a developing means has urethane rubber in which carbon black is dispersed on the outer periphery of a metal shaft such as stainless steel, and the surface thereof is subjected to isocyanate treatment. For example, the outer diameter of the developing roller 53 can be Φ19.6 mm, and is arranged in contact with the surface of the photosensitive drum 511, and rotates while rotating to an electrostatic latent image formed on the photosensitive drum 511. The toner image is developed by adhering. The developing roller 53 is applied with a bias voltage having the same polarity as that of the toner or a reverse polarity from a developing roller power source (not shown).

  As the toner 54, for example, a one-component non-magnetic material prepared by a pulverization method can be used. In order to adjust fluidity and charging characteristics, the toner 54 has a size of several to several tens of nanometers called an external additive (not shown). Fine particles made of silica, titanium oxide or the like are added. Further, the amount of the external additive added and the colorant for coloring vary from toner to toner.

  The developing blade 55 as the developer layer regulating means is a plate-like member configured by bending a metal plate having a thickness of 0.08 mm such as stainless steel, and one end thereof is a predetermined position on the surface of the developing roller 53. It arrange | positions so that it may contact | abut. The developing blade 55 regulates the layer thickness of the toner supplied from the supply roller 56.

  The supply roller 56 as a developer supply means has a semiconductive foamed silicone sponge layer disposed on the outer periphery of a metal shaft such as stainless steel. For example, the outer diameter of the supply roller 56 can be Φ15.5 mm, and is arranged in contact with the surface of the developing roller 53 to supply the toner supplied from the toner container 131 to the developing roller 53 while rotating. To do. The supply roller 56 is applied with a bias voltage having the same polarity as that of the toner or a reverse polarity from a power supply for supply roller (not shown).

  The cleaning blade 57 as an image carrier cleaning member has a blade member made of, for example, a rubber member made of urethane, and one end thereof is disposed so as to contact at a predetermined position on the surface of the photosensitive drum 511. The cleaning blade 57 cleans the surface of the photosensitive drum 511 by scraping off the toner 54 remaining on the surface of the photosensitive drum 511.

  Next, the charging device 52 will be described with reference to FIGS. 3, 4, 5, and 6. 3 is a perspective view showing a configuration of the charging device 52 according to the present embodiment, FIG. 4 is a perspective view showing a roller end portion of the charging device 52, and FIG. 5 is an exploded view showing a roller end portion of the charging device 52. FIG. 6 is a perspective view, and FIG. 6 is a cross-sectional view showing the charging device 52.

  As described above, the charging device 52 includes the charging roller 1 that directly charges the photosensitive drum 511. The charging roller 1 is in contact with the outer peripheral surface of the photosensitive drum 511 with a predetermined pressure contact force. As the photosensitive drum 511 rotates in the direction of arrow A in FIG. 4, the frictional resistance of the contact surface causes arrow B in FIG. Rotate following direction. Such a charging roller 1 has a configuration in which a shaft member 1b made of metal such as stainless steel is used as a core, and a rubber member 1a such as semiconductive epichlorohydrin rubber is coated on the outer periphery thereof.

  The charging roller 1 is rotatably supported by a pair of bearing members 7 supported by a pair of frames 5 and 6 disposed on the outer side in the rotation axis direction of the photosensitive drum, and is disposed in contact with the bearing member and the frame. The urging force of the urging member 3 thus made contacts the photosensitive drum 511 with a predetermined pressure contact force. Although only one urging member 3 and bearing member 7 are shown in the figure, they are also arranged so as to be the target at the opposite end of the one end shown in the figure. In this way, the charging roller 1 rotates at a constant speed with the photosensitive drum 511 by frictional resistance on the contact surface while contacting the surface of the photosensitive drum 511 with a predetermined pressure contact force, and is applied from a charging roller power supply (not shown). A predetermined potential is charged on the outer peripheral surface of the photosensitive drum 511 by the bias voltage thus applied.

  The charging roller 1 is provided with a cleaning roller 2 as a cleaning member that contacts the outer peripheral surface of the charging roller 1 with a predetermined pressure contact force. As the charging roller 1 rotates in the direction of arrow B in FIG. 4, the cleaning roller 2 is driven to rotate in the direction of arrow C in FIG. 4 due to frictional resistance on the contact surface, thereby cleaning the outer peripheral surface of the charging roller 1. . The cleaning roller 2 has a structure in which a shaft member 2b formed of a metal such as stainless steel is used as a core, and an outer periphery of the cleaning roller 2 is covered with a sponge member 2a such as open-cell foamed polyurethane.

  In addition, inter-axis adjusting members 10 and 11 as adjusting members that are rotatably fitted to the shaft member 2b are disposed at both ends of the shaft member 2b of the cleaning roller 2. A boss portion 10-a coaxial with the shaft member 2b is formed on the outer side in the roller rotation axis direction of the inter-axis adjusting members 10, 11. The bearing member 12 that is rotatably fitted to the boss portion 10-a is supported by the frames 5 and 6 so as to be slidable. The urging member 13 in contact with the bearing member 12 and the frame 5 urges the cleaning roller 2 toward the charging roller 1 via the inter-axis adjusting member 10, so that the cleaning roller 2 comes into contact with the charging roller 1. Yes.

  The inter-axis adjusting member 10 is formed with a disc-shaped spacer portion 14 that is coaxial with the shaft member 2b and has a plurality of recessed surfaces on the outer periphery. The shape of the recessed surface is formed so as to correspond to the outer peripheral shape of the shaft member 1b of the charging roller 1, and one recessed surface is a biasing member on the surface of the shaft member 1b of the charging roller 1 among the plurality of recessed surfaces. The contact is made by 13 urging forces. By this contact, the cleaning roller 2 is supported while maintaining a predetermined distance from the charging roller 1, and as a result, the sponge member 2 a comes into contact with the rubber member 1 a that is the outer peripheral surface of the charging roller 1 with a predetermined crushing amount.

  As described above, the cleaning roller 2 receives the urging force from the urging member 13 in the direction of the charging roller 1 with respect to the charging roller 1 that is in contact with the photosensitive drum 511 with a predetermined pressure contact force. The charging roller 1 is brought into contact with the inner wall of the central hole and the recessed surface of the spacer portion 14 in a state where the distance is supported. The charging roller 1 rotates while being supported by the bearing member 7, and the cleaning roller 2 is supported and rotated at the center hole of the inter-axis adjusting member 10 fitted to the bearing member 12.

  As described above, a recessed surface is formed on the outer periphery of the spacer portion 14 of the inter-axis adjusting member 10. As shown in FIG. 6, the bottoms of these hollow surfaces are set such that the distances from the center O of the central hole of the spacer portion 14 are different. The distance is the distance from the center O of the central hole of the spacer portion 14 to the outer peripheral surface of the shaft member 1b (that is, the deepest portion of the recessed surface) when the cleaning roller 2 contacts the charging roller 1 with a predetermined crushing amount. Assuming the distance (r21) to one depression surface A21, the depression surfaces having a longer distance of 0.05 mm (r22) and 0.1 mm (r23) with respect to that distance are designated as depression surface B22 and depression surface C23. . On the other hand, with respect to the distance to the depression surface A21, the depression surfaces whose distances are shortened to 0.05 mm (r24), 0.1 mm (r25), and 0.15 mm (r26) are the depression surface D24, the depression surface E25, Let it be a hollow surface F26.

  In general, the cleaning performance improves as the amount of squashing of the sponge member 2a of the cleaning roller 2 with respect to the charging roller 1 increases. However, considering the rotational load, the wear of the sponge member 2a, etc., the crushing amount is preferably about 0.4 to 0.5 mm. In the present embodiment, the inter-axis adjusting member 10 is rotated in a state where the image forming unit 121 is assembled, and the concave surfaces to be brought into contact with the shaft member 1b of the charging roller 1 are the concave surface A21, the concave surface B22, the concave surface C23, and the concave. By selecting and engaging any one of the surface D24, the recessed surface E25, and the recessed surface F26, the inter-axis distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 is arbitrarily changed. As a result, the amount of crushing of the surface of the cleaning roller 2 relative to the charging roller 1 can be changed.

  Next, a printing operation of the image forming apparatus 101 having the above configuration will be described.

  First, for example, when a control command and print data relating to printing are input from a host device (not shown) such as a personal computer, the photosensitive drum 511 starts rotating at a predetermined peripheral speed.

  At the same time, a charging roller power source (not shown) applies a predetermined bias voltage to the charging roller 1 of the charging device 52 to uniformly charge the surface of the photosensitive drum 511.

  Next, an exposure control unit (not shown) controls the exposure device 141 to irradiate light based on the input print data, and forms an electrostatic latent image on the photosensitive drum 511.

  The developing blade 55 disposed at a predetermined position on the surface of the developing roller 53 forms the toner 54 supplied from the supply roller 56 with a uniform layer thickness. Then, between the developing roller 53 and the photosensitive drum 511, the toner 54 adheres to the electrostatic latent image portion by the electric lines of force corresponding to the electrostatic latent image formed on the photosensitive drum 511, so that the toner image is formed. Developed.

  In accordance with the toner image forming operation, the paper feeding unit 108 feeds the recording medium P to the medium conveyance path S. The recording medium P fed out to the medium conveyance path S is conveyed to the transfer unit 110 while the skew feeding is corrected by the conveyance roller 109.

  A toner image is transferred onto the recording medium P by a transfer roller 11041 to which a predetermined voltage is applied by a bias voltage applied from a transfer power supply (not shown).

  Similar operations are performed in the image forming units 122, 123, and 124, and the toner images formed by the image forming units are sequentially transferred to the recording medium P. Thereafter, the recording medium P is conveyed to the fixing unit 111. Then, the toner 54 is melted by the heat applied from the heat roller 1111, and further, the toner image is fixed on the recording medium P by being pressed in a pressure contact portion formed by the heat roller 1111 and the backup roller 1112. The The recording medium P on which the toner image is fixed is discharged to the discharge stacker 113 by the discharge roller 112, and a series of printing operations is completed.

  As described above, in the present invention, the amount of crushing of the surface of the cleaning roller 2 with respect to the charging roller 1 is changed by arbitrarily changing the distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2. Can be changed. Hereinafter, an example of a method for adjusting the inter-axis distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 will be described with reference to FIG.

  In the manufacturing process of the image forming unit 121, the image forming unit 121 is operated by an inspection device (not shown) in a state where the photosensitive drum 511, the charging device 52, and the frames 5 and 6 are mounted.

  When the driving force is transmitted from the transmission device of the inspection apparatus to the photosensitive drum 511, the photosensitive drum 511 starts rotating, and the charging roller 1 and the cleaning roller 2 start driven rotation due to frictional resistance on the contact surface. . At this time, when an inspection film made of PET (Polyethylene terephthalate) is inserted into the contact surface between the charging roller 1 and the cleaning roller 2, the inspection film is drawn in the direction of arrow B in FIG. 5 due to the contact pressure and frictional resistance of both rollers. . While measuring the pulling force with the tension gauges 33 and 34, the inter-axis adjusting members 10 and 11 at both ends of the roller are rotated so as to obtain a predetermined force, and the depression surface A21, the depression surface B22, the depression surface C23, the depression Any one of the surface D24, the recessed surface E25, and the recessed surface F26 is selected. If the tension gauges 33 and 34 show a predetermined pulling force, the adjustment is completed. By adjusting the distance between the shafts, the sponge member 2a of the cleaning roller 2 comes into contact with the rubber member 1a which is the outer peripheral surface of the charging roller 1 with a predetermined crushing amount, so that good cleaning performance can be ensured. The adjustment of the inter-axis distance may be performed in the operation of the image forming apparatus 101 in addition to the adjustment by the inspection apparatus in the manufacturing process.

  As described above, according to the first embodiment, the amount of crushing of the surface of the sponge roller with respect to the charging roller can be reduced by arbitrarily changing the inter-axis distance between the shaft member of the charging roller and the shaft member of the sponge roller. Because it can be changed, even if there are variations in the material characteristics of the cleaning roller, dimensional variations in each part, etc., the predetermined crushing amount of the cleaning roller relative to the charging roller can be secured, and good cleaning can be realized Thus, the occurrence of uneven charging can be prevented.

[Second Embodiment]
The configuration of the image forming unit according to the second embodiment is substantially the same as the configuration of the image forming unit according to the first embodiment. Therefore, in the description of the second embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 8 is a perspective view showing a roller end portion of the charging device 52, FIG. 9 is a perspective view of the inter-axis adjusting member 31, and FIG. 10 is an end perspective view of the image forming unit housing 33.

  As shown in FIGS. 8 and 9, the spacer portion 14 of the inter-axis adjusting member 31 according to the present embodiment has a recessed surface 31-a, a recessed surface 31-b, a recessed surface 31-c, and a recessed surface 31-d. Is formed. In the present embodiment, the recessed surface 31-a is disposed at a distance where the interaxial distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 is a design value. The depression surface 31-b is at a position where the 0.05 mm axis distance is shorter than the depression surface 31-a, and the depression surface 31-c is 0.05 mm longer than the depression surface 31-a. The recessed surface 31-d was disposed at a position where the distance between the axes was 0.1 mm shorter than the recessed surface 31-a.

  What is necessary is just to set the difference with the magnitude | size of the dimension dispersion | variation of each component, and the characteristic of the sponge member 2b about the deviation | shift amount with respect to the hollow surface 31-a of the hollow surface 31-b and the hollow surface 31-c. Further, the recessed surface 31-d is an inter-axis distance set for the purpose of enhancing the cleaning performance, and may be set arbitrarily according to the outer diameter, thickness, and material of the sponge member 2a. In this embodiment, the cleaning performance is enhanced, but a special inter-axis distance can be set under more detailed conditions such as a printing pattern and a printing environment.

  As shown in FIG. 10, the inter-axis adjusting member 31 according to the present embodiment extends in the radial direction (right-angle direction) of the shaft member 2 b, and the tip 31-is inserted through the image forming unit housing 33. e. A through hole is formed in the image forming unit housing 33 within a range in which the lever 31-e can rotate, and the spacer portion 14 of the inter-axis adjusting member 31 is rotated from the outside of the image forming unit housing 33. As a result, the distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 can be changed.

  The method for adjusting the inter-axis distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 in the manufacturing process of the image forming unit 121 can be performed in the same manner as in the first embodiment. Explanation here is omitted.

  Next, a method for adjusting the inter-axis distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 using the lever 31-e provided in the spacer portion 14 of the inter-axis adjusting member 31. explain.

  After the sponge member 2a of the cleaning roller 2 is adjusted to a predetermined crushing amount, the inter-axis distance between the shaft member 1b of the charging roller 1 and the shaft member 2b of the cleaning roller 2 using the lever 31-e is set. In the case of adjustment, first, the user takes out the image forming unit 121 from the image forming apparatus 101. Then, the user moves the lever 31-e from the outside of the image forming unit housing 33 in the direction of arrow D in FIG. 10 to engage the shaft member 1b of the charging roller 1 with the recessed surface 31-d. The image forming unit 121 is set in the image forming apparatus 101.

  When the initial operation or the printing operation of the image forming apparatus 101 is performed, the image forming apparatus 101 operates in a state in which the amount of crushing of the surface of the cleaning roller 2 with respect to the charging roller 1 is temporarily larger than usual. Foreign matter adhering to one surface can be further removed. After that, the crushing amount of the surface of the cleaning roller 2 with respect to the charging roller 1 is returned to the original by returning the lever 31-e to the original position.

  In this way, when the foreign matter is abnormally attached to the charging roller 1 by the handling of the user or a large amount of foreign matter is attached due to the printing pattern or printing environment, the amount of crushing of the surface of the cleaning roller 2 with respect to the charging roller 1 is temporarily increased. It is possible to enhance the removal of foreign matter on the surface of the charging roller 1.

  As described above, according to the second embodiment, in addition to the effects of the first embodiment, the shaft member of the charging roller and the shaft of the sponge roller are externally provided from the outside of the image forming unit after adjustment between the axes at the time of manufacturing the image forming unit. It is possible to adjust the distance between the shafts between the members and temporarily increase the amount of crushing of the surface of the cleaning roller 2 with respect to the charging roller 1, thereby enhancing the removal of foreign matter on the surface of the charging roller. Even when the foreign matter is abnormally attached to the charging roller by handling, or a large amount of foreign matter is attached due to the printing pattern or printing environment, it is possible to prevent the occurrence of charging unevenness by realizing good cleaning.

  The present invention can be applied to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and an MFP using an image forming unit using a contact charging method.

DESCRIPTION OF SYMBOLS 1 Charging roller 1a Rubber member 1b Shaft member 2 Cleaning roller 2a Sponge member 2b Shaft member 3 Energizing members 5, 6 Frame 7 Bearing members 10, 11 Inter-shaft adjusting member 10-a Boss portion 12 Bearing member 13 Energizing member 14 Spacer Part 21 Recessed surface A
22 Recessed surface B
23 Recessed surface C
24 Recessed surface D
25 Recessed surface E
26 Recessed surface F
31 Inter-shaft adjustment member 31-a, 31-b, 31-c, 31-d Recessed surface 31-e Lever 511, 512, 513, 514 Photosensitive drum 52 Charging device 53 Developing roller 54 Toner 55 Developing blade 56 Supply roller 57 Cleaning Blade 101 Image Forming Device 107 Paper Feed Cassette 108 Paper Feeding Section 109 Transport Roller 110 Transfer Unit 1101 Transfer Belt 1102 Drive Roller 1103 Tension Rollers 11041, 11042, 11043, 11044 Transfer Roller 111 Fixing Unit 1111 Heat Roller 1112 Backup Roller 112 Discharge Roller 113 Discharge stacker 121, 122, 123, 124 Image forming unit 131, 132, 133, 134 Toner container 141, 142, 143, 144 Exposure device

Claims (6)

An image carrier for carrying an electrostatic latent image;
A charging member for charging the surface of the image carrier;
A cleaning member for cleaning the charging member;
An adjusting member that adjusts the distance between the charging member and the cleaning member;
The adjusting member rotates about the shaft member of the cleaning member, and a plurality of recessed surfaces are formed on an outer peripheral surface thereof, and the space between the shafts is adjusted by bringing the recessed surfaces into contact with the shaft member of the charging member. A featured image forming unit.   The image forming unit according to claim 1, wherein the recessed surface formed in the adjustment member forms a surface at a position where the space between the axes is reduced and enlarged.   3. The image forming unit according to claim 2, wherein the distance from the center of the shaft member of the cleaning member to the surface is different in each of the plurality of recessed surfaces.   The image forming unit according to claim 1, wherein the adjustment member can be operated from outside the image forming unit. The adjustment member includes a lever member formed to extend in the radial direction of the shaft member of the cleaning member,
5. The image forming unit according to claim 4, wherein the lever member is inserted through a hole formed in the image forming unit casing and exposed to the outside. An image carrier for carrying an electrostatic latent image;
A charging member for charging the surface of the image carrier;
A cleaning member for cleaning the charging member;
An adjustment member that adjusts the distance between the charging member and the cleaning member;
Developing means for supplying a developer to the electrostatic latent image carried on the image carrier and developing the developer image;
The adjusting member rotates about the shaft member of the cleaning member, and a plurality of recessed surfaces are formed on an outer peripheral surface thereof, and the space between the shafts is adjusted by bringing the recessed surfaces into contact with the shaft member of the charging member. An image forming apparatus.