JP6432840B2 - Cleaning device and image forming apparatus - Google Patents

Description

  The present invention relates to a cleaning device and an image forming apparatus.

  2. Description of the Related Art Image forming apparatuses such as printers, facsimile machines, and copiers include a cleaning member in a casing, and a cleaning device that removes transfer residual toner on an image carrier by the cleaning member. The toner removed by the cleaning member falls to a conveyance path provided with a conveyance screw in the casing, and is conveyed outside the cleaning device by the conveyance screw.

  Patent Document 1 describes a cleaning device in which a loosening member is provided as a loosening means for loosening toner deposited or stuck on the lower surface of a casing, and the deposited or stuck toner is loosened and dropped onto a conveying screw. This loosening member has a rectangular shape, and has a so-called comb-tooth shape with free ends provided with a plurality of strips at equal intervals in the axial direction of the conveying screw. The fixed end of the loosening member is fixed to the side wall of the casing so that the free end side comes into contact with the spiral blade of the conveying screw.

  When the transport screw is rotationally driven, the spiral blade portion of the transport screw hits the strip on the free end side of the loosening member from the radial direction of the transport screw. Further, when the conveying screw is rotationally driven, the blade portion lifts the strip in the radial direction. As a result, the tips of the strips slide on the lower surface of the casing in the radial direction to loosen the toner accumulated on the lower surface of the casing or the adhered toner. Further, when the conveying screw is rotated, the blade portion is separated from the strip. Then, due to the restoring force of the loosening member, the strip moves in the opposite direction to that described above, and the toner deposited on the lower surface of the casing or the adhered toner is further loosened. The loosened toner falls on the transport screw and is transported out of the cleaning device by the transport screw.

  In the configuration described in Patent Document 1, there is a problem that the amount of rocking of the strip of the loosening member is small, and the toner accumulated on the lower surface of the casing and the toner adhered thereto cannot be sufficiently loosened. Further, if the swinging amount of the loosening member is to be increased, it is necessary to increase the diameter of the blade portion of the conveying screw, leading to an increase in the size of the apparatus.

  Therefore, the present applicant has developed a cleaning device provided with a loosening plate that swings in the axial direction of the conveying screw in conjunction with the driving of the conveying screw. The loosening plate has a plate-like portion having a plurality of holes, and a contact portion that extends from the plate-like portion in the plate-like portion thickness direction and comes into contact with the blades of the conveying screw. This contact portion is pushed in by the blades of the screw, and the loosening plate moves in the waste toner conveyance direction of the conveyance screw. The plate-like portion of the loosening plate is urged in the direction opposite to the waste toner conveyance direction of the conveyance screw by a spring as an urging means, and when it moves in the waste toner conveyance direction for a predetermined distance by the blade of the conveyance screw, it contacts The part moves away from the blade and moves in the direction opposite to the waste toner conveying direction by the biasing force of the spring. As a result, the loosening plate swings in the axial direction of the transport screw.

  In the developed cleaning device, the amount of swinging of the unwinding plate can be adjusted by adjusting the timing at which the contact portion separates from the blades of the conveying screw, and the unwinding means can be swung greatly. Further, by greatly tilting the blades of the conveying screw, the amount of movement of the unwinding plate per rotation of the conveying screw can be increased, and the unwinding plate can be greatly swung with a small amount of rotation. In this way, by configuring the unwinding plate to swing in the axial direction of the transport member, the unwinding plate can be swung greatly without increasing the transport member in the radial direction. Therefore, the toner on the inner wall of the casing can be loosened well without increasing the size of the apparatus.

  However, in the cleaning device under development, when the loosening plate is moving in the waste toner transport direction, the plate-like portion is pushed upstream by the spring in the toner transport direction, and the contact portion is the toner by the blade of the transport screw. It is pushed downstream in the transport direction. As a result, the contact portion tries to bend to the downstream side in the toner transport direction with the corner between the downstream end of the contact portion in the toner transport direction and the plate portion as a fulcrum, and stress is applied around the corner portion of the plate portion. Concentrated part occurs. Then, due to fatigue due to use over time, there was a risk that the stress concentration portion of the plate-like portion would crack and eventually the loosening plate would break.

  In order to solve the above problems, the present invention provides a cleaning member that removes toner on a member to be cleaned, a casing that houses the cleaning member, and a conveying member that conveys toner removed by the cleaning member to the outside of the casing. And a loosening means for loosening the toner adhering to the inner wall of the casing, wherein the loosening means includes a plate-like portion provided along the inner wall of the casing, and the conveyance of the plate-like portion. An urging means for urging the member in a direction opposite to the toner conveying direction; and an abutting portion extending from the plate-like portion and abutting on the conveying member, wherein the abutting portion contacts the conveying member. When the plate-like portion is moved by a predetermined distance in the toner transport direction by the transport member, the biasing means moves in the direction opposite to the toner transport direction and is moved by the transport member. The loosening means is configured to return to the start position, and a cross section parallel to both the extending direction of the abutting portion from the plate-like portion and the toner conveying direction is directed toward the toner conveying direction from the abutting portion. Thus, a shape change suppressing portion having a shape that gradually shortens the length in the extending direction is provided.

  According to the present invention, it is possible to suppress breakage of the loosening means.

1 is a schematic configuration diagram showing an overall configuration of a copier according to an embodiment. FIG. 3 is an enlarged schematic configuration diagram in the vicinity of a secondary transfer belt showing a gradation pattern and an optical sensor. The enlarged block diagram which expands and shows a belt cleaning apparatus and its periphery. The graph which shows the relationship between the voltage applied to a post-cleaning roller, and the number of spots-like image generation. The graph which shows the relationship between the number of the spot-like image generation | occurrence | production in a normal temperature and normal humidity environment, and a low temperature and low humidity environment, and the applied voltage to a post cleaning roller. The schematic block diagram of the conventional 1st cleaning unit. Sectional drawing of the 1st cleaning unit of this embodiment. The top view of the 1st cleaning unit of the state which removed the 1st cleaning brush roller and the 1st collection roller. The figure which shows the relationship between the guide hole of a loosening board, and a guide protrusion. The expansion block diagram near the one end part of a loosening board. The figure which shows the state from which the end of a loosening board leaves | separates from the blade | wing part of a 1st conveyance screw. Schematic which looked at the contact part periphery of a loosening board from the radial direction. The figure which shows the modification of a reinforcement part. FIG. 10 is a schematic perspective view showing a characteristic part of Modification 1; The figure which shows the state which the one end part of the unraveling board contacted the buffer member. FIG. 10 is a schematic perspective view showing a characteristic part of Modification 2. (A) is a perspective view which shows the contact part periphery of the unwinding board of the modification 2, (b) is a figure explaining the stress concentration location of the unraveling board of the modification 2. FIG. The perspective view which shows the loosening board of the modification 2 which reinforced the periphery of the contact part. The principal part expansion perspective view of the 1st cleaning unit using the loosening board of FIG. The figure explaining the movement of the loosening board of FIG. FIG. 10 is a schematic perspective view showing a characteristic part of Modification 3.

FIG. 1 is a schematic configuration diagram illustrating an overall configuration of a copying machine 1 according to the embodiment.
The copying machine 1 has a tandem configuration in which a plurality of photoreceptors 3 (Y, C, M, B) serving as latent image carriers that carry color toner images corresponding to color separation are juxtaposed. The toner images formed on the respective photoreceptors 3 (Y, C, M, B) are superimposed and transferred (primary transfer) so as to overlap each other on an intermediate transfer belt 2 as an intermediate transfer member that is an image carrier. The superimposed toner image is collectively transferred (secondary transfer) to a recording sheet as a recording material. In this way, the copying machine 1 can form a multi-color image on the recording paper.

  In FIG. 1, a copying machine 1 serving as an image forming apparatus has an image forming unit 1A positioned at the center in the vertical direction, a sheet feeding unit 1B below it, and a document reading unit 1C above the image forming unit 1A. , Each is arranged.

  An intermediate transfer belt 2 having a horizontally extending surface is disposed in the image forming unit 1A. In the image forming unit 1A, four photosensitive members 3 (Y, C, M, B) carrying toner images of complementary colors (yellow, magenta, cyan, black) are extended on the intermediate transfer belt 2. It is juxtaposed along the surface. In the following description, in the case of content common to all colors, M, C, Y, and B that are color-coded codes are omitted as appropriate.

  Each photoconductor 3 (Y, C, M, B) is composed of a drum that can rotate in the same direction (counterclockwise in FIG. 1). Around the periphery, a charging device 4, a writing device 5, a developing device 6, a primary transfer device, and a cleaning device 8 that perform image forming processing in a rotating process are arranged to form an image forming unit 66. In FIG. 1, for convenience, the reference numerals of the respective devices are assigned to the black photoconductor 3 </ b> B.

  To the intermediate transfer belt 2, toner images on the photoreceptors 3 (Y, C, M, and B) are sequentially transferred by a primary transfer device. The intermediate transfer belt 2 is wound around a plurality of belt stretching rollers (2A to 2D) and driven to rotate. As a belt stretching roller different from the two belt stretching rollers (2A, 2B) constituting the stretched surface, a bias having the same polarity as the toner is opposed to the secondary transfer device 9 with the intermediate transfer belt 2 interposed therebetween. Is provided with a secondary rolling opposing roller 2C. Furthermore, as another belt stretching roller, a tension roller 2D is provided.

  The transfer residual toner remaining on the intermediate transfer belt 2 after the secondary transfer is removed by the belt cleaning device 10. The belt cleaning device 10 is an electrostatic cleaning system, and applies a bias to a cleaning roller or a cleaning brush, and electrostatically adsorbs the transfer residual toner attached on the intermediate transfer belt 2 to perform cleaning.

The secondary transfer device 9 includes a secondary transfer belt 9C, and the secondary transfer belt 9C is wound around four secondary transfer belt support rollers (9D, 9E, 9F, 9G). Then, one of the four secondary transfer belt support rollers is rotationally driven as a drive roller, so that the secondary transfer belt 9C rotates counterclockwise in FIG.
In the copier 1 of the embodiment shown in FIG. 1, a conveyance belt 91 is provided between the secondary transfer belt 9 </ b> C and the fixing device 11. The conveyor belt 91 is wound around a conveyor belt drive roller 91A and a conveyor belt driven roller 91B, and rotates in the counterclockwise direction in FIG. 1 when the conveyor belt drive roller 91 is rotationally driven.

  The optical sensor unit 300 is disposed at a position facing the surface of the secondary transfer belt 9C on the downstream side in the surface movement direction of the secondary transfer belt 9C with respect to the secondary transfer portion where the secondary transfer belt 9C faces the intermediate transfer belt 2. doing. Further, a secondary transfer belt cleaning device 90 for removing foreign matters on the surface of the secondary transfer belt 9C is provided on the downstream side of the surface of the secondary transfer belt 9C with respect to the position where the optical sensor unit 300 faces.

  One of the four secondary transfer belt support rollers is applied with a secondary transfer bias having the same polarity as the toner on the belt, with the secondary transfer belt 9C and the intermediate transfer belt 2 sandwiched between the secondary transfer portions. This is a secondary transfer roller 9D facing the next transfer counter roller 2C. A support roller 9E disposed on the left side of the drawing with respect to the secondary transfer roller 9D receives the recording paper carried on the surface of the secondary transfer belt 9C by the conveyance belt 91 after passing through the secondary transfer portion. This is a separation roller 9E that stretches the secondary transfer belt 9C at the sheet separation portion that is passed. The support roller 9F disposed below the separation roller 9E is a sensor facing roller 9F that stretches the secondary transfer belt 9C at a detection position where the secondary transfer belt 9C faces the optical sensor unit 300. Further, a support roller disposed on the right side of the sensor facing roller 9F in the drawing is a secondary transfer belt cleaning facing roller 9G that stretches the secondary transfer belt 9C at a position where the cleaning blade of the secondary transfer belt cleaning device 90 contacts. It is.

  The secondary transfer belt 9C used in the embodiment is a single-layer belt. Specific examples include carbon dispersion in materials such as PI (polyimide), PAI (polyamideimide), PC (polycarbonate), ETFE (ethylene-tetrafluoroethylene), PVDF (polyvinylidene fluoride), and PPS (polyphenylene sulfide). Alternatively, a medium resistance resin single layer whose resistance is adjusted by blending an ionic conductive agent can be used. Further, a belt having a surface layer slightly higher in resistance than the volume resistivity of the belt layer itself may be provided only on the surface side of the secondary transfer belt 9C having a single layer structure. In this case, the surface layer thickness is preferably about 1 to 10 [μm].

  In the copying machine 1 of the embodiment, one of the four secondary transfer belt support rollers is rotationally driven as a drive roller, so that the secondary transfer belt 9C is in the middle of the secondary transfer portion that contacts the intermediate transfer belt 2. The surface moves in the same direction as the transfer belt 2. Although depending on the bias characteristics of the primary transfer device, the secondary transfer roller 9D may be provided with a charging characteristic to electrostatically attract the recording paper. The secondary transfer device 9 transfers the superimposed toner image or the single color toner image on the intermediate transfer belt 2 to the recording sheet in the process of conveying the recording sheet by the secondary transfer belt 9C.

The secondary transfer device 9 is fed with recording paper from the paper feed unit 1B. The paper feed unit 1B includes a plurality of paper feed cassettes 1B1 and a plurality of transport rollers 1B2 arranged in a transport path for recording paper fed from the paper feed cassette 1B1. Further, the wall surface of the image forming unit 1A is provided with a manual feed tray 1A1 that can be raised and lowered and a feeding roller 1A2.
In the middle of the recording paper conveyance path from the paper feed cassette 1B1 to the registration roller 1B3, the recording paper conveyance path fed out from the manual feed tray 1A1 joins. The registration timing of the recording paper fed from any of the conveyance paths is set by a registration roller 1B3 located upstream of the secondary transfer unit in the paper conveyance direction.

  In the writing device 5, writing light is controlled by image information obtained by scanning a document on the document table 1C1 in the document reading unit 1C or image information output from a computer. An electrostatic latent image is formed on the photoreceptor 3 (Y, C, M, B) according to image information.

  The document reading unit 1C is provided with a scanner 1C2 that exposes and scans the document on the document table 1C1, and an automatic document feeder 1C3 is disposed on the upper surface of the document table 1C1. The automatic document feeder 1C3 has a configuration capable of reversing the document fed on the document table 1C1, and can perform scanning on both sides of the document.

  The electrostatic latent image formed on the photoreceptor 3 (Y, C, M, B) by the writing device 5 is developed by the developing device 6 (in FIG. 1, for convenience, indicated by reference numeral 6B). The developed image is primarily transferred to the intermediate transfer belt 2. When the toner images for each color are superimposed and transferred onto the intermediate transfer belt 2, the secondary transfer device 9 performs secondary transfer on the recording paper at once.

  The unfixed image carried on the surface of the recording paper that has been secondarily transferred is fixed by the fixing device 11. The fixing device 11 has a belt fixing structure including a fixing belt heated by a heating roller, and a pressure roller facing and abutting the fixing belt. By providing a contact area between the fixing belt and the pressure roller, that is, a nip area, a heating area for the recording paper can be expanded as compared with the fixing structure of another roller type. The recording paper that has passed through the fixing device 11 is switched in its transport direction by a transport path switching claw 12 disposed behind the fixing device 11, and is discharged again 1A3 or is reversed and registered again 1B3. It is sent toward.

In the copying machine 1 shown in FIG. 1, a primary transfer device as a transfer means uses a primary transfer roller 7 (Y, C, M, B) to which a positive polarity transfer bias is applied. The primary transfer roller 7 (Y, C, M, B) is pressed by a predetermined pressure against the photoreceptor 3 via the intermediate transfer belt 2 by a bearing and an elastic body such as a compression spring.
Further, the primary transfer roller 7 (Y, C, M, B) has an intermediate transfer belt of about 1 to 2 [mm] with respect to a position opposed to the center position of the photoreceptor 3 (Y, C, M, B). It rotates in conjunction with the intermediate transfer belt 2 at a position offset downstream in the surface movement direction. This is to prevent pre-transfer that starts transfer by a transfer bias before the normal transfer position and generates an abnormal image such as an image flow.

The primary transfer roller 7 (Y, C, M, B) is configured in such a form that a rubber material having a medium resistance electric characteristic is wound around a metal core. In the embodiment, it is made of a foamed rubber having a medium resistance, and its volume resistivity is in the range of 10 ⁶ to 10 ¹⁰ [Ω · cm], preferably 10 ⁷ to 10 ⁹ [Ω · cm]. The material is not limited to foam rubber, and medium resistance solid rubber can be used as well.

  A primary transfer voltage having a positive polarity is applied to the primary transfer roller 7 (Y, C, M, B) by a constant current controlled power source, and the current set value (set value of the primary transfer current) is approximately 10. It is controlled in the range of ˜40 [μA]. In this way, by applying the primary transfer voltage to the primary transfer roller 7 (Y, C, M, B), the primary transfer between each photoreceptor 3 (Y, C, M, B) and the intermediate transfer belt 2 is performed. A primary transfer electric field is formed in the part. This primary transfer electric field is a primary transfer electric field in a direction in which the toner (negative polarity) on each photoconductor 3 (Y, C, M, B) is drawn toward the intermediate transfer belt 2 side.

  On the other hand, a secondary transfer voltage having a negative polarity is applied to the secondary transfer facing roller 2C by a constant current controlled power source. Thus, in the configuration in which the secondary transfer voltage is applied to the secondary transfer opposing roller 2C, the drive roller 9D is electrically grounded. By facing the drive roller 9D connected to the ground, a secondary transfer electric field is formed in the secondary transfer portion in the direction in which the toner (negative polarity) on the intermediate transfer belt 2 is pushed out to the recording paper side.

  The intermediate transfer belt 2 used in this embodiment is provided with an elastic layer of 100 to 500 [μm] on a 50 to 100 [μm] base layer, and further includes an elastic intermediate transfer constituted by a three-layer belt having a surface layer. It is a belt. Specific examples of the base layer include carbon dispersion in materials such as PI (polyimide), PAI (polyamideimide), PC (polycarbonate), ETFE (ethylene-tetrafluoroethylene), PVDF (polyvinylidene fluoride), and PPS (polyphenylene sulfide). Alternatively, there is one constituted by a medium resistance resin whose resistance is adjusted by blending an ionic conductive agent. Specific examples of the elastic layer include a rubber material such as urethane, NBR, CR, and the like, which includes a material whose resistance is adjusted by carbon dispersion or ionic conductive agent blending. As a specific example of the surface layer, the surface of the elastic layer is coated with a fluorine rubber or resin having a thickness of about 1 to 10 [μm] (or a hybrid material thereof). is there.

The intermediate transfer belt 2 has a volume resistivity in the range of 10 ⁶ to 10 ¹⁰ [Ω · cm], preferably 10 ⁸ to 10 ¹⁰ [Ω · cm]. The surface resistivity is in the range of 10 ⁶ to 10 ¹² [Ω / □], preferably 10 ⁸ to 10 ¹² [Ω / □]. Further, the Young's modulus (longitudinal elastic modulus) of the base layer is desirably 3000 [Mpa] or more, and sufficient mechanical strength is required to withstand elongation, bending, wrinkling, and undulation by driving. By using the elastic intermediate transfer belt 2 having such elasticity, the recording paper such as a paper having a low density of paper fibers or a recording paper such as a so-called embossed paper having an unevenness of 20 to 30 [μm] on the surface. The elastic layer follows the concave portion. For this reason, a solid filling improvement effect that the toner transfer property to the concave portion of the recording paper is improved is known.

  In this copying machine, the contact state between the photosensitive member 3 and the intermediate transfer belt 2 is different between a monochrome mode for forming a monochrome image and a color mode for forming a color image.

  Specifically, among the four primary transfer rollers 7 (Y, C, M, B) in the transfer unit, the black primary transfer roller 7B is supported by a dedicated bracket separately from the other primary transfer rollers. doing.

  The three primary transfer rollers 7 (Y, C, M) for Y, M, and C are supported by a common moving bracket. This moving bracket is moved in a direction approaching the photoreceptor 3 (Y, C, M) for Y, M, and C and a direction away from the photoreceptor 3 (Y, C, M) by driving the solenoid. It is possible.

  When the moving bracket is moved away from the photoreceptor 3 (Y, C, M), the stretching posture of the intermediate transfer belt 2 changes, and the intermediate transfer belt 2 has three photoreceptors for Y, C, and M. 3 (Y, C, M).

  However, the B photoconductor 3B and the intermediate transfer belt 2 remain in contact with each other. In the monochrome mode, the image forming operation is performed in a state where only the B photoconductor 3B is in contact with the intermediate transfer belt 2 in this manner.

  When the moving bracket described above is moved in a direction approaching the three photoconductors 3 (Y, C, M), the stretching posture of the intermediate transfer belt 2 changes, and the three photoconductors 3 (Y, C, The intermediate transfer belt 2 that has been separated from M) contacts these three photosensitive members 3 (Y, C, M).

  At this time, the B photoconductor 3B and the intermediate transfer belt 2 remain in contact with each other. In the color mode, the image forming operation is performed in a state where all of the four photoconductors 3 (Y, C, M, and B) are in contact with the intermediate transfer belt 2 as described above.

  In such a configuration, the moving bracket, the solenoid described above, and the like function as contact / separation means for contacting / separating the photoreceptor 3 and the intermediate transfer belt 2.

  For the photoreceptor 3 (Y, C, M, B) after the Y, C, M, B toner images are primarily transferred to the intermediate transfer belt 2, the transfer residual toner is cleaned by a drum cleaning device. Then, after neutralizing with a static elimination lamp, it is charged uniformly with a charging device to prepare for the next image formation.

  Further, the intermediate transfer belt 2 after the primary transfer to the recording paper P is subjected to a cleaning process for residual toner by the belt cleaning device 10.

  In the copying machine 1 of the present embodiment, image adjustment control is performed at a predetermined timing. In the image quality adjustment control, a toner pattern is created, and image density control and positional deviation control are performed based on the result of detecting the image density and image forming position of the toner pattern. In the image density control, for example, a toner adhesion amount (image density) of a density control pattern (tone pattern) obtained by developing a predetermined pattern latent image is detected. Then, in accordance with the detection result of the toner adhesion amount, set values such as the toner concentration in the developer in the developing device, the writing conditions (exposure power, etc.) of the writing device 5, the charging bias and the developing bias are changed. In the positional deviation control, for example, the latent image writing timing of each color toner image is adjusted by the detection timing of the positional deviation control pattern (chevron patch).

  Such toner pattern detection locations for the density control pattern include, for example, on the photoreceptor between the development area and the primary transfer portion, or on the intermediate transfer belt after the primary transfer. . However, when the diameter of the photoconductor is small, it is difficult to detect on the photoconductor due to the installation space of the image density detection sensor. Therefore, it is detected on the intermediate transfer belt or the secondary transfer belt. Is preferred. On the other hand, regarding the misregistration control pattern, it is necessary to observe the misregistration between the color toner images due to the variation in the distance between the photoconductors or the misregistration due to the writing timing of each color latent image. For this reason, detection on the surface moving body carrying the toner image after the intermediate transfer belt is essential. In the embodiment, both the density control pattern and the positional deviation control pattern are detected on the secondary transfer belt 9C.

  Conventionally, many medium- and low-speed image forming apparatuses have a secondary transfer member that forms a secondary transfer electric field between the secondary transfer counter roller 2C and the intermediate transfer belt 2 at the secondary transfer unit. In general, a roller-shaped member having a small diameter is used instead of a belt-shaped member. In the configuration used for such a roller-shaped member secondary transfer member, it is difficult to detect the image quality adjustment pattern on the surface of the secondary transfer member. On the other hand, in the present embodiment, as shown in FIG. 1, since the secondary transfer belt 9C is provided as the secondary transfer member, it is possible to detect the image quality adjustment pattern on the surface of the secondary transfer member.

  Further, the secondary transfer member is not limited to a belt shape, and may be configured to use a roller having a large diameter. However, in the roller shape, since the detection position of the optical sensor unit 300 is curved, it is necessary to increase the diameter of the roller, which is disadvantageous in terms of space saving. On the other hand, by using a belt shape like the secondary transfer belt 9C, the degree of freedom can be improved by the layout configuration. In addition, since the belt-like shape is relatively easy to have a configuration in which the detection position of the optical sensor 300 is a flat surface, detection accuracy can be improved.

Next, the toner pattern transferred to the secondary transfer belt 9C will be described in detail.
FIG. 2 is an enlarged schematic configuration diagram in the vicinity of the secondary transfer belt showing the gradation pattern and the optical sensor.
As shown in FIG. 2, the optical sensor unit 300 includes a Y optical sensor 300Y, a C optical sensor 300C, an M optical sensor 300M, and a B optical sensor 300B arranged in the width direction of the secondary transfer belt 9C.

  Each of these sensors is a reflection type photosensor, and the light emitted from the light emitting element is reflected by the toner image on the front surface of the secondary transfer belt 9C or the belt, and the amount of reflected light is detected by the light receiving element. The control unit 200 (see FIG. 1) detects the toner image on the secondary transfer belt 9C based on the output voltage values from these sensors, and detects the image density (toner adhesion amount per unit area). Can be.

  In this printer, image density control for optimizing the image density of each color is executed when the power is turned on or every time a predetermined number of prints are performed. In the image density control, first, as shown in FIG. 2, each color gradation pattern Sb, Sm, Sc, Sy as a density control pattern is converted into each optical sensor 300 (Y, C, M) on the secondary transfer belt 9C. , B) is automatically formed at a position facing. The gradation pattern of each color is composed of 10 toner patches having an area of 2 [cm] × 2 [cm] having different image densities.

  The charging potential of the photoreceptor 3 (Y, C, M, B) when creating the gradation patterns Sb, Sm, Sc, Sy of each color is different from the uniform drum charging potential in the printing process, and the value is Increase gradually. Then, while forming a plurality of patch electrostatic latent images for forming a gradation pattern image on the photoconductor 3 (Y, C, M, B) by scanning with a laser beam, they are Y, C, M, Development is performed by a developing device for B. During this development, the value of the developing bias applied to the developing roller is gradually increased.

By such development, gradation pattern images of Y, C, M, and B are formed on the photoreceptor 3 (Y, C, M, and B). These are primarily transferred so as to be arranged at a predetermined interval in the main scanning direction of the secondary transfer belt 9C. At this time, the toner adhesion amount of the toner patch in the gradation pattern of each color is about 0.1 [mg / cm ² ] at the minimum and 0.55 [mg / cm ² ] at the maximum, and the toner Q / d distribution When measured, it is almost aligned with the regular charging polarity. The normal charging polarity here refers to the charging polarity of the toner in the developer in the developing device. Although it is negative in the present embodiment, it may be positive depending on the image forming apparatus.

  Each toner pattern (Sb, Sm, Sc, Sy) formed on the secondary transfer belt 9C passes through a position facing the optical sensor unit 300 as the secondary transfer belt 9C moves endlessly. At this time, each color optical sensor 300 (Y, C, M, B) receives an amount of light corresponding to the toner adhesion amount per unit area with respect to the toner patch of each gradation pattern.

  Next, the adhesion amount of each color toner pattern in each toner patch is calculated from the output voltage of the optical sensor 300 (Y, C, M, B) when each color toner patch is detected and the adhesion amount conversion algorithm. Image forming conditions are adjusted based on the calculated adhesion amount.

  Specifically, a function (y = ax + b) indicating a straight line graph is calculated by regression analysis based on the result of detecting the toner adhesion amount on the toner patch and the development potential when each toner patch is imaged. Then, an appropriate development bias value is calculated by substituting the target value of the image density into this function, and the development bias values for Y, C, M, and B are specified.

  The memory stores an image forming condition data table in which several tens of development bias values and appropriate drum charging potentials individually corresponding to the values are associated in advance. For each of the image forming units 66Y, 66C, 66M, and B, a developing bias value closest to the specified developing bias value is selected from the image forming condition table, and the drum charging potential associated therewith is specified.

In recent years, it has become difficult to ensure the cleaning performance of the belt cleaning device 10 in a combination of a small particle size polymerized toner and an elastic intermediate transfer belt used for improving image quality.
Conventionally, each color gradation pattern, chevron patch, and toner consumption pattern formed on the intermediate transfer belt 2 are collected by the belt cleaning device 10. At this time, the belt cleaning device 10 must remove a large amount of toner of the untransferred toner image such as each color gradation pattern, chevron patch, and toner consumption pattern from the intermediate transfer belt 2.

  However, in the configuration of this embodiment in which a small particle size polymerized toner and an elastic intermediate transfer belt are combined, a cleaning device including a polarity control unit and a brush roller, and two brush rollers for removing positive and negative toners, respectively. In the cleaning device provided with the toner image, the untransferred toner image could not be removed at once. In such a case, the toner on the intermediate transfer belt 2 that could not be cleaned may be transferred onto the recording paper during the next printing operation, resulting in an abnormal image.

Therefore, in this copying machine 1, toner patterns such as each color gradation pattern, chevron patch, and toner consumption pattern are transferred to the secondary transfer belt 9C and removed by the secondary transfer belt cleaning device 90. As a result, only the secondary transfer residual toner is input to the belt cleaning device 10, and the amount of toner input to the belt cleaning device 10 can be reduced. Thereby, it is possible to suppress the occurrence of defective cleaning in the belt cleaning device 10, and it is possible to suppress the occurrence of an abnormal image.
On the other hand, since the secondary transfer belt 9C is a belt without an elastic layer, it is easy to ensure cleaning properties. Accordingly, the toner pattern such as the toner consumption pattern transferred to the secondary transfer belt 9C can be satisfactorily removed by the secondary transfer belt cleaning device 90.

Next, the belt cleaning apparatus 10 of this embodiment will be described.
FIG. 3 is an enlarged configuration diagram showing the belt cleaning device 10 of the copying machine 1 and its surroundings in an enlarged manner.
In the figure, the belt cleaning device 10 includes a first cleaning unit 100a and a second cleaning unit 100b adjacent to the first cleaning unit 100a on the downstream side in the belt moving direction. The post cleaning unit 100c is also adjacent to the second cleaning unit 100b on the downstream side in the belt movement direction.

  In the first casing 120a of the first cleaning unit 100a, a first cleaning brush roller 101 serving as a cleaning member that removes transfer residual toner from the surface of the intermediate transfer belt 2 is disposed. Further, the first collection roller 102 which is a collection member that rotates while contacting the first cleaning brush roller 101 to collect the transfer residual toner from the brush roller, and the first transfer roller scrapes the transfer residual toner from the surface of the first collection roller 102. A scraping blade 103 and the like are also provided. The first casing 120a is also provided with a first conveying screw 110a that discharges the transfer residual toner scraped off from the first recovery roller 102 to the outside of the first casing 120a. Further, the first casing 120a is provided with an inlet seal 111a and an outlet seal 112a that are in contact with the intermediate transfer belt 2 and prevent the toner in the first casing from scattering outside the first casing. Yes.

  Most of the secondary transfer residual toner that has not been completely transferred by the secondary transfer belt 9C (about 80% of the transfer residual toner) is reversely charged toner that is charged with a polarity opposite to the normal charge polarity (negative polarity). Therefore, in the present embodiment, a voltage having a normal charging polarity (negative polarity) is applied to the first cleaning brush roller 101 to electrostatically remove the positive polarity toner on the intermediate transfer belt 2. In addition, a negative voltage greater than that of the first cleaning brush roller 101 is applied to the first recovery roller 102. In the belt cleaning device 10, the voltage applied to the first cleaning brush roller 101 is set so that most of the secondary transfer residual toner image is removed by the first cleaning brush roller 101. However, at this time, there is a toner in which the toner receives a negative charge from the first cleaning brush roller 101 and becomes normal polarity (negative polarity).

  In the second casing 120b of the second cleaning unit 100b, similarly to the first cleaning unit 100a, the second cleaning brush roller 104, the second recovery roller 105, the second scraping blade 106, and the second conveying screw 110b, which are cleaning members. An inlet seal 111b and an outlet seal 112b are provided.

  The second cleaning unit 100b receives the secondary transfer residual toner charged to the normal charging polarity (negative polarity) that cannot be removed by the first cleaning unit 100a and the negative charge from the first cleaning brush roller 101, and receives the normal polarity (negative polarity). ) Is removed. Therefore, a voltage having a polarity (positive polarity) opposite to the normal charging polarity of the toner is applied to the second cleaning brush roller 104 to electrostatically remove the negative polarity toner on the intermediate transfer belt 2. Further, a negative voltage greater than that of the second cleaning brush roller 104 is applied to the second recovery roller 105.

  The two cleaning brush rollers (101, 104) include a metal rotary shaft member that is rotatably supported, and a brush portion that includes a plurality of raised brushes erected on the peripheral surface thereof. The outer diameter is φ15 to 16 [mm]. The raised nail has a two-layer core-sheath structure in which the inside is made of a conductive material such as conductive carbon and the surface portion is made of an insulating material such as polyester. As a result, the core has substantially the same potential as the cleaning bias applied to the cleaning brush rollers (101, 104), and the toner can be electrostatically attracted to the raised surface. As a result, the toner on the intermediate transfer belt 2 is captured by the raised brushes of the cleaning brush rollers (101, 104).

  In addition, you may comprise the raising | fluff of cleaning brush roller (101,104) only with a conductive fiber instead of the core-sheath structure of a two-layer structure. Moreover, you may make it the so-called oblique hair planted in the attitude | position inclined with respect to the normal line direction of a rotating shaft member. Further, the raising of the second cleaning brush roller 104 to which a negative cleaning bias is applied may have a core-sheath structure, and the raising of the first cleaning brush roller 101 may be composed of only conductive fibers. By forming the raised portions of the first cleaning brush roller 101 to which the negative cleaning bias is applied only with conductive fibers, it is possible to easily generate charge injection from the first cleaning brush roller 101 to the toner. Therefore, the first cleaning brush roller 101 can satisfactorily align the toner on the intermediate transfer belt 2 with negative polarity. On the other hand, the brushing of the second cleaning brush roller 104 has a core-sheath structure, so that charge injection into the toner can be suppressed, and the toner on the intermediate transfer belt 2 is suppressed from being positively charged. As a result, the second cleaning brush roller 104 can suppress the generation of toner that cannot be removed electrostatically.

  Further, the two cleaning brush rollers (101, 104) are bited into the intermediate transfer belt 2 by a biting amount of 1 [mm]. Then, the brush roller is rotationally driven by the driving means so as to move the raising at the contact position in a direction (counter direction) opposite to the moving direction of the intermediate transfer belt 2. By rotating the raised hair so as to move in the counter direction at the contact position, the linear velocity difference between the cleaning brush roller and the intermediate transfer belt 2 can be increased. As a result, the probability of contact with the raised hair before a portion of the intermediate transfer belt 2 passes through the contact range with the cleaning brush roller increases, and the toner can be removed from the intermediate transfer belt 2 satisfactorily.

  The cleaning brush rollers 101 and 104 are disposed to face the cleaning facing rollers 13 and 14 with the intermediate transfer belt 2 interposed therebetween. The cleaning counter rollers 13 and 14 are also conductive and are grounded to form a cleaning electric field between the cleaning brush rollers 101 and 104, respectively.

  As the two collection rollers (102, 105), both are made of SUS (stainless steel) rollers. The collection rollers (102, 105) may be made of any material as long as the following functions can be exhibited. That is, this function is to transfer the toner adhering to the cleaning brush rollers (101, 104) from the cleaning brush roller to the collecting roller by a potential gradient between the raised brush and the collecting roller. For example, as a collection roller, a conductive cored bar is covered with a high resistance elastic tube of several [μm] to 100 [μm] or is coated with an insulating coating so that the roller resistance is logR = 12 to 14 [Ω · cm]. You may use what you did. By using a SUS roller as the collection roller, there is an advantage that the cost can be reduced, the applied voltage can be kept low, and the power can be saved. On the other hand, by setting the roller resistance to logR = 12 to 14 [Ω · cm], charge injection into the toner during collection to the collection roller is suppressed, and the toner has the same polarity as the applied voltage of the collection roller. In addition, it is possible to suppress a decrease in the toner recovery rate.

  In FIG. 3, the two-transfer residual toner on the intermediate transfer belt moves to the position of the first cleaning brush roller 101 over the contact portion between the first inlet seal 111 a and the belt as the intermediate transfer belt 2 moves. Is done. A cleaning bias having a normal charging polarity (negative polarity) of toner is applied to the first cleaning brush roller 101. The positively charged toner on the intermediate transfer belt 2 is electrostatically applied to the brush of the first cleaning brush roller 101 by the electric field formed by the potential difference between the intermediate transfer belt 2 and the surface potential of the first cleaning brush roller 101. Adsorb. At this time, a negative charge is received from the brush by charge injection or discharge, and a part of the toner is charged with normal polarity (negative polarity) and remains on the belt.

  The positive toner transferred to the first cleaning brush roller 101 is transferred to a contact position with the first recovery roller 102 to which a negative recovery bias having a larger absolute value than the first cleaning brush roller 101 is applied. . Then, due to the electric field formed by the potential difference between the surface potential of the first cleaning brush roller 101 and the surface potential of the first recovery roller 102, the transfer residual toner in the brush of the first cleaning brush roller 101 is transferred onto the first recovery roller 102. Is electrostatically transferred to. Then, after being scraped off from the surface of the first recovery roller 102 by the first scraping blade 103, the first cleaning screw 100a transports the toner from the first cleaning unit 100a to the toner reservoir.

  The secondary transfer residual toner on the intermediate transfer belt 2 that could not be removed by the first cleaning brush roller 101 is transferred to a contact position with the second cleaning brush roller 104. The second cleaning brush roller 104 is applied with a voltage having a polarity opposite to the normal charging polarity (positive polarity) of the toner, and an electric field formed by a potential difference between the intermediate transfer belt 2 and the surface potential of the second cleaning brush roller 104. Thus, the negatively charged toner on the intermediate transfer belt 2 is electrostatically attracted and moved to the second cleaning brush roller 104. Thereafter, after electrostatic transfer to the second recovery roller 105, the second scraping blade 106 scrapes off the second recovery roller 105, and then from the second cleaning unit 100 b to the toner storage unit by the second transport screw 110 b. It is conveyed to.

  In the present embodiment, most of the secondary transfer residual toner can be cleaned by the first cleaning unit 100a and the second cleaning unit 100b. However, in the case of the belt cleaning apparatus 10 including only the first cleaning unit 100a that electrostatically removes the positive polarity toner and the second cleaning unit 100b that electrostatically removes the negative polarity toner, sometimes the cleaning seems to be poor. A spot-like abnormal image may occur. In particular, among the plurality of image forming units 66, a noticeable spot-like abnormal image occurred in the Y color solid image formed by the Y color image forming unit 66 arranged at the most upstream in the moving direction of the intermediate transfer belt 2.

  As a result of diligent research on the above-mentioned spot-like abnormal image, the present applicants sometimes have toner that reattaches to the intermediate transfer belt 2 from each cleaning brush roller (101, 104) (hereinafter referred to as reattachment toner). It was found that the reattached toner appeared as a spot-like abnormal image.

  Therefore, in the belt cleaning device 10 of the present embodiment, the reattached toner that has reattached to the intermediate transfer belt 2 from the cleaning brush rollers (101, 104) on the downstream side in the moving direction of the intermediate transfer belt 2 of the second cleaning unit 100b. A post-cleaning unit 100c is provided for removing water.

  The post cleaning unit 100c is a post cleaning roller 107 made of a conductive sponge that removes the reattached toner on the intermediate transfer belt 2, and a recovery member that rotates while contacting the post cleaning roller 107 and collects toner from the post cleaning roller. A post collection roller 108, a post scraping blade 109 for scraping off transfer residual toner from the surface of the post collection roller 108, and the like are provided. The post cleaning roller 107, the post collection roller 108, and the post scraping blade 109 are disposed in the post casing 120c. In the post casing 120c, a post transport screw 110c and the like for discharging the toner scraped off from the post collection roller 108 to the outside of the post casing 120c are also provided. Further, the post casing 120c is provided with an inlet seal 111c and an outlet seal 112c that are in contact with the intermediate transfer belt 2 and prevent the toner in the post casing from scattering outside the post casing.

  A positive voltage much larger than the absolute value of the voltage applied to each of the cleaning brush rollers 101 and 104 is applied to the post cleaning roller 107. A positive voltage greater than that of the post cleaning roller 107 is applied to the post collection roller 108. Further, the post cleaning roller 107 is disposed to face the cleaning facing roller 15 with the intermediate transfer belt 2 interposed therebetween. The cleaning counter roller 15 is conductive, and is grounded to form a cleaning electric field with the post cleaning roller 107.

FIG. 4 is a graph showing the relationship between the voltage applied to the post-cleaning roller 107 and the number of spot-like images generated. The number of occurrences on the vertical axis in FIG. 4 indicates that 50 solid images of M color, C color, and B color are each output continuously, then 50 Y color solid images are output, and the output Y color solid image is output. This is the number of sheets that have been visually confirmed and a stain-like abnormal image has been confirmed.
As shown in FIG. 4, it can be seen that the number of occurrences of spot-like abnormal images decreases as the voltage applied to the post cleaning roller 107 is increased. In particular, when the post cleaning roller 107 is a conductive sponge roller and the applied voltage is increased, the number of occurrences of spot-like abnormal images can be reduced to zero. In the above description, the cleaning property and the toner re-adhesion property of the re-adhering toner of the post-cleaning unit 100c are evaluated by the number of the spot-like images generated.

  How much bias is sufficient depends on the intended user and system of the machine. It also depends on the environment. In this embodiment, as shown in FIG. 5, in a low temperature and low humidity environment, the current setting value 20 [μA] of the second cleaning brush roller 104 and the current setting value −30 [μA] of the first cleaning brush roller 101 are used. Yes, at that time, the number of occurrences of spot-like abnormal images could be reduced to 0 with the current setting value 55 [μA] of the post-cleaning roller 107. At this time, the absolute value | 30 | [μA] of the current setting value used by the brush is the absolute value | 55 | [μA] of the current setting value of the post cleaning roller 107, and the current setting of the post cleaning roller 107 When the value was 1.8 times or more than the current setting value of the brush, the number of occurrences of spot-like abnormal images was reduced to zero. The current value here is a current flowing from the cleaning brush roller or the post cleaning roller to the intermediate transfer belt.

  Furthermore, in a normal temperature environment, the current setting value of the second cleaning brush roller 104 is 10 [μA], and the current setting value of the first cleaning brush roller 101 is −30 [μA]. At this time, the current setting value of the post-cleaning roller 107 is 100 [μA], and the number of occurrences of spot-like abnormal images is reduced to 0. 3 times or more by the absolute value of the brush current setting value. I was able to.

  Further, when further examined including the high humidity environment, the absolute value of the current setting value of the post cleaning roller 107 is set to 10 times or more or 30 times or more the absolute value of the current setting value of the brush. The number of spot-like abnormal images generated was reduced to zero. Thus, the higher the humidity is, the higher the cleaning bias current value to the post cleaning roller 107 required for suppressing abnormal images due to reattached toner is required.

  As described above, the absolute value of the current value of the post cleaning roller 107 is set to at least twice the absolute value of the current value of the cleaning brush rollers 101 and 104. Further, the current setting value of the post cleaning roller 107 is varied under each environment. Specifically, a temperature / humidity sensor is provided in the apparatus, and the current setting value of the post cleaning roller 107 is changed based on the detection result of the temperature / humidity sensor.

  The post cleaning roller 107 includes a metal rotating shaft member that is rotatably supported and a conductive sponge roller portion that covers the peripheral surface of the rotating shaft member, and has an outer diameter of 15 to 16 mm. The post collection roller 108 has the same configuration as the first and second collection rollers 102 and 105.

  Further, as shown in FIG. 4, in the case of the brush roller, the number of occurrences of spot-like abnormal images can be reduced by increasing the bias, but the number of occurrences cannot be reduced to zero. On the other hand, in the case of the conductive sponge roller, by increasing the bias, the number of occurrences of spot-like abnormal images could be reduced to zero. In the case of the brush roller, the toner adsorbed to the brush may move to the base of the brush, and thus the toner that has moved to the base of the brush is not collected by the collecting roller but remains on the brush. It is considered that the toner remaining on the brush reattaches to the intermediate transfer belt 2 at some point. Therefore, in the case of the brush roller, it is considered that the reattached toner that was removed by itself reattached to the intermediate transfer belt 2 again, and the spot-like image could not be reduced to zero.

  On the other hand, in the conductive sponge roller, the toner adsorbed on the sponge roller stays near the surface of the sponge roller. Therefore, it is considered that there is hardly any toner that is well collected by the collecting roller and that remains without being collected. As a result, it is considered that the toner reattached to the intermediate transfer belt 2 from the sponge roller is not generated, and the occurrence of a spot-like image can be reduced to zero.

  In this embodiment, a sponge roller is used as the post cleaning roller 107, but a rubber roller, a metal roller, or the like may be used. The post cleaning roller 107 can also prevent the toner from being held in the rubber roller or metal roller. As a result, the reattachment toner removed by the post cleaning roller 107 can be prevented from adhering to the intermediate transfer belt 2 again from the post cleaning roller, and the number of occurrences of spot-like abnormal images can be reduced to zero. .

  In this embodiment, the polarity of the voltage applied to the post cleaning roller 107 is positive. Thereby, the polarity of the voltage applied to the post cleaning roller 107 and the polarity of the voltage applied to the second cleaning brush roller 104 can be made the same polarity. as a result. The potential difference between the second cleaning brush roller 104 and the post cleaning roller 107 is smaller than when the polarity of the voltage applied to the second cleaning brush roller 104 and the polarity of the voltage applied to the post cleaning roller 107 are different from each other. can do. Therefore, voltage leakage between the second cleaning brush roller 104 and the post cleaning roller 107 can be suppressed. Further, by setting the polarity of the voltage applied to the post cleaning roller 107 to a positive polarity, it is possible to remove a slight amount of negative polarity toner that could not be removed by the second cleaning brush roller 104.

  The post collection roller 108 is a stainless steel (SUS) roller, like the first and second collection rollers 102 and 105, and can adopt the same configuration as the first and second collection rollers 102 and 105. Of course, the post recovery roller 108 may be made of any material as long as it can perform the function of transferring the toner adhering to the post cleaning roller 107 from the roller to the recovery roller by the potential gradient with the post recovery roller 108. . The post recovery roller 108 is also covered with a high resistance elastic tube of several [μm] to 100 [μm] on the conductive mandrel, or further coated with an insulating coating so that the roller resistance is logR = 12 to 14 [Ω · cm You may use what was set to].

  As described above, the post-cleaning roller 107 is transported with the re-attached toner that has re-attached to the intermediate transfer belt 2 from the second cleaning brush roller 104 and a very small amount of negative-polarity toner that could not be removed by the second cleaning brush roller. Is done. A very small amount of negative polarity toner and re-adhering toner transferred to the post cleaning roller 107 are electrostatically attached to the post cleaning roller 107 to which a voltage having a polarity opposite to the normal charging polarity of the toner is applied. Then, the toner is recovered by the post recovery roller 108 and scraped off from the post recovery roller 108 by the post toner scraping blade 109. After being scraped off from the post collection roller 108 by the post scraping blade 109, it is transported from the post cleaning unit 100c to the toner reservoir by the post transport screw 110c.

  The conditions of the cleaning brush rollers 101 and 104 are as follows.

Brush material: conductive polyester (the first brush has a structure with a conductive material on the fiber surface, the second brush has conductive carbon inside the fiber, and the fiber surface has a polyester, so-called core-sheath structure. (Available at brush manufacturers such as Toei Sangyo Co., Ltd.)
Brush resistance: 10 ⁶ to 10 ⁸ [Ω]
・ Brush flocking density: 60,000 to 150,000 [lines / inch ² ]
・ Brush fiber diameter: about 25 to 35 [μm]
-Brush tipping treatment: None-Brush diameter φ: 14-20 [mm]
-Brush fiber biting amount into the intermediate transfer belt 2: 1 to 1.5 [mm]

The conditions of the post cleaning roller 107 are as follows.
・ Cleaning roller material: Conductive polyurethane (manufactured by Yamauchi Co., Ltd.)
・ Diameter φ: 14-20 [mm]
・ Resistance: 10 ^{7.25 ± 0.25} [Ω]
・ Hardness: Asuka C35 degrees ・ Intermediate transfer belt biting amount: 0.05 [mm] to 0.4 [mm]

  The voltage applied to the first cleaning brush roller is set such that when the secondary transfer residual toner is input to the intermediate transfer belt 2, the reverse polarity charged toner is eliminated. Specifically, the toner after passing through the first brush is sucked into the air by an experiment and is measured by placing it in a Faraday cage or the like, or the toner adhesion after cleaning is determined.

  The second cleaning brush roller 104 is set so that the toner on the intermediate transfer belt 2 can be cleaned. Further, the brush flocking density, brush resistance, fiber diameter, applied voltage, fiber type, and brush fiber biting amount can be optimized by the system, and thus are not limited thereto. Examples of the types of fibers that can be used include nylon, acrylic, and polyester.

  The conditions of each collection roller 102, 105, 108 are as follows.

・ Recovery roller core material: SUS303
-Brush fiber biting amount into the collection roller: 1 to 1.5 [mm]
Roller bite amount is 0.5mm

  The collection roller material, brush fiber entrapment amount, and applied voltage can be optimized by the system, and are not limited thereto.

  The conditions of each scraping blade 103, 106, 109 are as follows.

・ Recovery roller core material: SUS304
・ Blade contact angle: 20 [°]
・ Blade thickness: 0.1 [mm]
・ Amount of blade biting into the collection roller: 0.5 to 1.5 [mm]

  The blade contact angle, the blade thickness, and the amount of biting into the collection roller can be optimized by the system, and are not limited thereto.

  In the belt cleaning device 10, a voltage is applied to each of the collection rollers 102, 105, 108, each of the cleaning brush rollers 101, 104, and the post cleaning roller 107, but a configuration in which a voltage is applied only to the collection roller may be used.

  In this case, a bias voltage somewhat lower than the bias voltage applied to the recovery roller is caused by a potential drop due to the resistance of the cleaning brush rollers 101 and 104 and the post cleaning roller 107 via the contact portion with the recovery roller. The cleaning rubbing rollers 101 and 104 and the post cleaning roller 107 are applied. Thereby, a potential difference is formed between the collection roller and the cleaning brush roller and between the post cleaning roller and the post collection roller, and the toner can be electrostatically moved to the collection roller in a potential gradient toward the collection roller. .

  The cleaning current that provides the best cleaning is a target current that flows through the contact points between the cleaning brush rollers 101 and 104 and the post cleaning roller 107 and the intermediate transfer belt 2. Table 1 shows an example of the target current value. In Table 1, 1st means the first cleaning brush rollers 101, 2 nd are the second cleaning brush rollers 104, 3 rd are the post cleaning rollers 107. In the present embodiment, the first cleaning brush roller 101 is set to a constant voltage. This is a reason for current control, and current setting is desirable. () Is a reference value.

  The process linear velocity in the embodiment is 350 [mm / s]. Of course, it is possible to cope with a process linear velocity of 100 to 800 [mm / s].

  The target current may be a value proportional to the linear velocity. For example, when the process linear velocity is 175 [mm / s] which is half of 350 [mm / s], the target current value may be half of the process linear velocity 350 [mm / s]. In addition, when the process linear velocity is 700 [mm / s], which is twice the 350 [mm / s], the target current value may be set twice the process linear velocity 350 [mm / s].

Further, it is more preferable that the flocking density of the second cleaning brush roller 104 is smaller than that of the first cleaning brush roller 101 to be 15,000 to 20,000 [lines / inch ² ].

Next, features of the present embodiment will be described.
FIG. 6 is a schematic configuration diagram of a conventional first cleaning unit 100a.
Part of the toner adhering to the first cleaning brush roller 101 falls off the first cleaning brush roller 101 due to centrifugal force generated by the rotation of the first cleaning brush roller 101, brush vibration, or the like. Further, a part of the toner adhering to the first collection roller 102 also falls off due to a centrifugal force caused by the rotation of the first collection roller 102. The toner dropped from the first cleaning brush roller 101 and the first collection roller 102 falls on the lower surface 121a of the casing 120a. The dropped toner accumulates on the lower surface 121a of the casing 120a over time, and forms a toner deposit T as shown in FIG. When the toner deposit T further grows with the toner dropped on the lower surface 121a of the casing 120a, the toner deposit T finally comes into contact with the first cleaning brush roller 101. As a result, the toner in the toner deposit T adheres to the first cleaning brush roller 101, and a large amount of toner adheres to the first cleaning brush roller 101. A large amount of toner on the first cleaning brush roller 101 is not collected by the first collecting roller 102, but a part of the toner remains on the first cleaning brush roller 101 and is conveyed to a contact position with the intermediate transfer belt 2. . The toner remaining on the first cleaning brush roller 101 inhibits the toner on the intermediate transfer belt from being electrostatically attracted to the brush fiber, and the cleaning performance of the first cleaning brush roller 101 is deteriorated.
Therefore, in this embodiment, toner loosening means is provided on the lower surface 121a of the casing 120a to prevent toner from accumulating on the lower surface 121a of the casing 120a.

FIG. 7 is a cross-sectional view of the first cleaning unit 100a of this embodiment, and FIG. 8 is a plan view of the first cleaning unit 100a with the first cleaning brush roller 101 and the first recovery roller 102 removed. .
As shown in FIG. 7, a loosening plate 140 as a loosening means is provided on the lower surface of the casing of the first cleaning unit 100a of the present embodiment. The loosening plate 140 is attached to the casing lower surface 121a so as to be able to swing in parallel with the casing lower surface 121a in the axial direction of the first conveying screw of the first conveying screw 110a and the radial direction of the first conveying screw 110a.

  As shown in FIG. 8, the loosening plate 140 is provided with a plurality of holes. Four of them are guide holes 140a guided in the axial direction of the first conveying screw 110a while being supported by guide protrusions 141 provided on the casing lower surface 121a. Edges 140e of these holes including a plurality of guide holes loosen the toner accumulated on the casing lower surface 121a.

FIG. 9 is a view showing the relationship between the guide hole 140a of the loosening plate 140 and the guide protrusion 141. As shown in FIG.
As shown in FIG. 9, among the plurality of guide holes 140a, the first and third guide holes of the first conveying screw 110a on the left side in the drawing on the downstream side in the toner conveyance direction (hereinafter simply referred to as the downstream side in the toner conveyance direction). 140a is inclined such that the edge on the intermediate transfer belt side is positioned on the intermediate transfer belt side as it goes downstream in the toner conveyance direction. On the contrary, the second and fourth guide holes 140a from the downstream side in the toner conveyance direction are inclined so that the edge on the first conveyance screw side is positioned on the intermediate transfer belt side as it goes downstream. It has become.

  The first and third guide holes 140a from the downstream side have guide protrusions 141 in contact with the edge on the intermediate transfer belt side, and the second and fourth guide holes 140a are guided on the edge on the first conveying screw side. The protrusion 141 is in contact. Thus, the edges with which the guide protrusions 141 abut are different between adjacent guide holes. Accordingly, the loosening plate 140 is supported by the guide protrusion 141 without moving in the direction in which the first conveying screw 110a and the intermediate transfer belt 2 are arranged (hereinafter referred to as a radial direction) due to vibration of the apparatus or the like. In this embodiment, four guide holes 140a are provided. However, a guide hole that hits the guide projection 141 on the edge on the intermediate transfer belt side, and a guide hole that hits the edge on the first conveying screw side. If there is, the loosening plate 140 can be supported without moving the loosening plate 140 due to the vibration of the apparatus. However, in order to stably support the loosening plate 140, it is preferable to provide at least three or more guide holes so that the edges with which the guide protrusions 141 abut are different between adjacent guide holes. By doing so, the loosening plate 140 is supported in the form of three-point support, and the loosening plate 140 can be stably supported by the guide protrusions.

FIG. 10 is an enlarged configuration diagram in the vicinity of one end portion of the loosening plate 140.
As shown in FIG. 10, one end of a loosening plate 140 located on the upstream side in the toner conveyance direction of the first conveyance screw 110a (hereinafter simply referred to as the upstream side in the toner conveyance direction) has a first conveyance from the downstream side in the toner conveyance direction. An abutting portion 140c that abuts on the spiral blade portion 110a1 of the screw is provided. Further, adjacent to the contact portion 140c, a shape change suppressing portion 140d that suppresses a sudden shape change of the loosening plate 140 is provided.

  Further, a hook-shaped spring receiver 140b is provided at one end of the loosening plate 140, and one end of a spring 143 serving as a biasing means is attached to the spring receiver 140b. The other end of the spring 143 is attached to a hook-shaped spring receiver 122a provided on the lower surface of the casing. The loosening plate 140 is urged to the upstream side in the toner conveyance direction by the urging force of the spring 143, and the contact portion 140c abuts against the spiral blade portion 110a1 of the first conveyance screw.

  Moreover, the screw pitch S1 of the blade | wing part which the contact part 140c of the loosening board 140 contacts differs from the screw pitch S2 of another location. If the screw pitch S1 of the blade portion with which the contact portion 140c of the loosening plate 140 contacts is increased, the moving speed of the loosening plate 140 in the toner transport direction is increased. Therefore, the screw pitch S1 of the blade portion is a pitch at which the speed of the loosening plate 140 in the toner conveying direction becomes a speed at which the toner on the lower surface of the casing can be loosened well. On the other hand, screw pitches at other locations are pitches that can favorably convey toner.

  As shown in FIG. 10, when the first conveying screw 110a rotates in the direction of arrow Q in the drawing, the contact portion 140c of the loosening plate 140 is pushed downstream by the blade portion 110a1 of the first conveying screw. Then, the loosening plate 140 moves to the downstream side in the toner conveyance direction while being guided by the guide protrusion 141. By this movement of the loosening plate 140, the toner accumulated on the casing lower surface 121a is loosened by the edge 140e (see FIG. 8) extending in the radial direction of the hole provided in the loosening plate 140.

  Further, when the loosening plate 140 moves to the downstream side in the toner conveyance direction, the edge on the intermediate transfer belt side of the first and third guide holes from the downstream side in the toner conveyance direction shown in FIG. Lifted to the belt side. As a result, the loosening plate 140 moves not only in the toner conveyance direction but also toward the intermediate transfer belt. By the movement of the unwinding plate 140 on the intermediate transfer belt side, the loosened toner accumulated in each hole of the unraveling plate 140 is scraped off by the edge of the hole of the unraveling plate 140 on the first transfer screw side, and the first transfer It can be dropped onto the screw 110a.

  As shown in FIG. 11, when the guide protrusion 141 comes near the upstream end portion of the guide hole 140a in the toner conveyance direction, the contact portion 140c of the loosening plate is separated from the blade portion 110a1 of the first conveyance screw 110a. Then, the loosening plate 140 moves to the upstream side in the toner conveyance direction (right side in the figure) by the urging force of the spring 143. Further, when the loosening plate 140 is moved upstream in the toner conveyance direction, the edge on the first conveyance screw side of the second and fourth guide holes from the downstream side in the toner conveyance direction shown in FIG. It is pushed down to the conveying screw side. As a result, the loosening plate 140 moves toward the upstream side in the toner conveyance direction and also toward the first conveyance screw side, and the contact portion 140c moves to the initial position indicated by the alternate long and short dash line X in the drawing. Then, by the rotation of the first conveying screw, the blade portion 110a1 of the first conveying screw again abuts on the abutting portion 140c of the loosening plate 140 at the initial position, and pushes the loosening plate 140 downstream in the toner conveying direction.

  Thus, in the present embodiment, the toner accumulated on the casing lower surface 121a can be loosened by the loosening plate 140 swinging in the axial direction of the first conveyance screw, which is the toner conveyance direction of the first conveyance screw 110a. . In the present embodiment, by forming a plurality of holes in the loosening plate 140, the toner deposited on the casing lower surface 121a can be loosened well by the edges 140e extending in the radial direction of each hole. Further, the loosening plate 140 may be provided with a plurality of protrusions extending in the radial direction. Even in this configuration, when the loosening plate 140 swings in the axial direction of the first conveying screw 110a, the toner accumulated on the lower surface of the casing can be loosened by this protrusion.

  In the present embodiment, the loosening plate 140 is swung not only in the axial direction of the first conveying screw 110a but also in the radial direction. Thereby, the toner on the casing lower surface 121a can be assisted by the swinging of the loosening plate 140 in the radial direction to fall to the first conveying screw 110a. Thereby, it is possible to further suppress toner accumulation on the casing lower surface 121a. In this embodiment, the timing at which the contact portion 140c is separated from the blade portion 110a1 of the first conveying screw is determined by the shape of the contact portion 140c, the inclination of the edge with which the guide projection of the guide hole 140a contacts, and the like. The amount of shaking of the loosening plate 140 in the toner conveyance direction is determined. Thereby, the swinging amount of the loosening plate can be designed easily. Furthermore, the swing speed of the loosening plate 140 in the toner transport direction can be determined by the screw pitch of the transport screw. Further, as shown in FIG. 10, only the screw pitch at the location where the contact portion 140 c of the loosening plate 140 abuts may be set so that the loosening plate 140 has a desired moving speed. Therefore, the other portions can be set to a screw pitch that provides a desired toner conveyance speed.

  In the present embodiment, as shown in FIG. 11, the loosening plate 140 can be swung L [mm] in the toner conveyance direction. If the unwinding plate 140 is to be configured to move L [mm] in the radial direction by the rotation of the first transfer screw 110a, the diameter of the portion of the transfer screw where the contact portion of the unwinding plate 140 contacts is at least L. It is necessary to set to [mm], and the apparatus becomes large in the radial direction. On the other hand, in the present embodiment, the unwinding plate 140 is configured to be swung in the axial direction of the first conveying screw 110a, so that the unwinding plate 140 is swung by L [mm] without increasing the size of the apparatus. Can do. In this way, by adopting a configuration in which the loosening plate 140 is swung in the axial direction, the unwinding plate 140 can be swung greatly without increasing the size of the apparatus. Thereby, the toner deposited on the lower surface of the casing can be loosened well without increasing the size of the apparatus.

  In the present embodiment, the contact portion 140c of the loosening plate 140 is applied to the blade portion on the upstream side in the toner transport direction of the first transport screw 110a. The contact portion 140c of the loosening plate 140 may be applied to the blade portion on the downstream side in the toner transport direction of the first transport screw 110a, but in this case, the contact portion 140c is provided where there is a large amount of toner. . As a result, there is a possibility that the toner may be caught between the contact part 140c and the blade part 110a1, and the toner may be fixed to the contact part or the blade part. Therefore, it is preferable that the contact portion 140c of the loosening plate 140 is brought into contact with the blade portion on the upstream side in the toner transport direction of the transport screw with less toner. When the loosening plate 140 has a screw pitch at which the moving speed becomes a predetermined moving speed by applying the contact portion 140c of the loosening plate 140 to the blade portion on the upstream side in the toner conveying direction of the first conveying screw 110a that transports a small amount of toner. The influence of the toner conveyance speed can be minimized.

  The contact portion 140c extends from the plate-like portion 140f of the loosening plate 140 in the vertical direction. The contact portion 140c extending in the vertical direction is pushed in the toner transport direction by the blade portion 110a1 of the first transport screw 110a, and the loosening plate 140 is moved downstream in the toner transport direction. Further, the plate-like portion 140 f of the loosening plate 140 is urged upstream by the spring 143 in the toner conveyance direction. Therefore, when the loosening plate 140 is moved to the downstream side in the toner conveyance direction, the plate-like portion 140f is pushed to the upstream side in the toner conveyance direction by the urging force of the spring 143, and the contact portion 140c is the first conveyance screw 110a. Is pushed to the downstream side in the toner transport direction by the blade portion 110a1. As a result, the contact portion 140c tries to bend to the downstream side in the toner transport direction with the corner between the downstream end of the contact portion 140c in the toner transport direction and the corner of the plate portion 140f as a fulcrum. Stress concentration part occurs around the part. Then, due to fatigue due to use over time, there is a possibility that a crack occurs in the stress concentration portion of the plate-like portion 140f, and the loosening plate 140 is finally broken.

  The corners of the contact portion 140c and the plate-like portion 140f extending from the plate-like portion 140f of the loosening plate 140 are portions where the outer shape of the loosening plate 140 changes abruptly. When the contact part 140c is pushed in the toner transport direction by the blade part 110a1 of the transport screw, the corner between the downstream end in the toner transport direction of the contact part 140c whose outer shape is rapidly changing and the plate-like part 140f. Stress concentration part is generated around the part.

  Therefore, even if a rectangular reinforcing part is provided when viewed from the radial direction, the corners of the reinforcing part and the plate-like part 140f are suddenly changed in shape, and stress is concentrated at the corners, resulting in a plate-like shape. The breakage of the portion 140f cannot be prevented satisfactorily.

  For this reason, in this embodiment, the shape change suppression unit 140d in which the length in the plate thickness direction of the plate-like portion 140f is gradually shortened toward the downstream side in the toner conveyance direction is changed to the toner conveyance direction of the contact portion 140c. Adjacent to the downstream end. Thereby, it can suppress that a stress concentration part arises in the plate-shaped part 140f. The plate-like portion 140f, the contact portion 140c, and the shape change suppressing portion 140d are formed by integral molding of resin. Thereby, compared with the case where the shape change suppression part 140d is separated from the plate-like part 140f and the contact part 140c, the stress is concentrated more favorably at the corners of the contact part 140c and the plate-like part 140f. Can be suppressed.

FIG. 12 is a schematic view of the periphery of the contact portion 140c of the loosening plate 140c as seen from the radial direction.
As shown in FIG. 12, the shape change suppression unit 140d has a triangular shape when viewed from the radial direction. Thereby, the change in the shape downstream of the contact portion 140c of the loosening plate 140 in the toner conveyance direction becomes gradual, and the occurrence of a stress concentration portion in the plate-like portion 140f can be suppressed.

  Further, the shape change suppressing portion 140d is formed from the front end side with respect to the central portion A in the plate thickness direction of the plate-like portion 140f of the contact portion 140c. Thereby, it is possible to suppress stress concentration at the corners of the contact part 140c and the shape change suppressing part 140d, and cracks or the like may occur at the corners of the contact part 140c and the shape change part 140d over time. Can be suppressed.

FIG. 13 is a diagram illustrating a modification of the shape change suppression unit 140d.
As shown in FIG. 13, of the three sides of the triangular reinforcing portion 104d, the side closer to the plate-like portion 140f from the downstream end of the contact portion 140c in the toner transport direction toward the downstream side in the toner transport direction is a concave arc. It is a shape. With such a configuration, the shape change of the shape changing portion 140d on the downstream side in the toner conveyance direction can be made more gradual, and the stress concentration portion can be further suppressed from occurring in the plate-like portion 140f.

  In addition, a drive motor for driving the first conveying screw 110a is on the downstream side in the toner conveying direction (on the side opposite to the contact portion side of the loosening plate 140), and at the upstream end of the first conveying screw 110a in the toner conveying direction. When there is no particular support, the toner conveying upstream side of the first conveying screw may be tilted so as to be located slightly below the downstream side (the side away from the loosening plate 140) due to gravity. In that case, there is a possibility that the blade portion 110a1 of the conveying screw does not come into contact with the contact portion 140c of the loosening plate. Therefore, when the blade portion 110a1 is separated from the contact portion 140c and the blade portion 110a1 is not supported by the blade portion 110a1, it is preferable that the loosening plate 140 is inclined so that the contact portion 140c side is positioned on the lower side. . Specifically, the contact portion 140c side of the loosening plate 140 is made heavy, or the urging force of the spring 143 is configured to act also on the lower side (conveying screw side). Further, the guide protrusion 141 near the contact portion 140c is brought into contact with the lower edge (edge on the conveying screw side) of the guide hole 140a. As a result, even if the first conveying screw is tilted so that the upstream side of the first conveying screw is positioned on the lower side, the unwinding plate has the contact portion 140c on the lower side (conveying screw side) due to its own weight or the biasing force of the spring 143. ) And the contact state with the blade portion 110a1 is maintained. As a result, the unwinding plate 140 can be moved in the axial direction even if the first conveying screw is inclined.

  Next, a modification of this embodiment will be described.

[Modification 1]
FIG. 14 is a schematic perspective view showing a characteristic part of the first modification.
In the first modification, a buffer member 144 made of sponge or the like is provided on the casing lower surface 121a. The buffer member 144 is affixed to the casing lower surface 121a. The upper end portion of the buffer member 144 extends to the downstream side in the toner conveyance direction, and is opposed to the upstream end portion in the toner conveyance direction of the loosening plate 140 in the vertical direction. This portion serves to hold the loosening plate 140 against the casing lower surface 121a so that the loosening plate 140 does not transfer the buffering member 144 when the loosening plate 140 hits the buffering member 144.

  Depending on the configuration of the apparatus, when the unwinding plate 140 is moved to the initial position by the urging force of the spring 143, the contact portion 140c collides with the blade portion 110a1 of the first conveying screw or the toner conveying direction of the guide hole 140a. The downstream edge may collide with the guide protrusion 141 in some cases. In this case, an impact sound is generated, or the unit vibrates due to a collision and generates a vibration sound.

  On the other hand, when the buffer member 144 is provided, as shown in FIG. 15, when the upstream end of the unwinding plate 140 in the toner conveyance direction reaches the initial position indicated by the alternate long and short dash line in FIG. The portion collides with the buffer member 144. Thereby, it can suppress that an impact is absorbed by the buffer member 144 and an impact sound, a vibration sound, etc. generate | occur | produce.

  In the first modification, the buffer member 144 is provided on the casing 120a. However, the buffer member 144 may be provided on the loosening plate 140. In this case, a buffer member is provided in at least one of the locations that collide with the components (guide protrusions, blades of the conveying screw) inside the unit of the loosening plate 140. For example, when the loosening plate 140 collides with the guide protrusion, the buffer member 144 is attached to the edge of the guide hole 140a on the downstream side in the toner conveyance direction. Thereby, when the loosening plate 140 reaches the initial position, the buffer member 144 can abut against the guide protrusion 141 to absorb the impact.

[Modification 2]
FIG. 16 is a schematic perspective view showing a characteristic part of the second modification.
In the second modification, the contact portion 140c is held by a contact member 146 made of a resin having excellent slidability such as POM (polyacetal), which is a separate member from the loosening plate 140, and the contact member 146. It is comprised with the contact holder 140i. The contact member 146 is configured to be detachable from the contact holder 140i.

  When the loosening plate 140 is moved to the downstream side in the toner conveying direction by the blade portion 110a1 of the first conveying screw, it is guided by the guide protrusion 141 and moves to the intermediate transfer belt side. Therefore, since the contact part 140c rubs with the blade | wing part 110a1 of a 1st conveyance screw in a radial direction, the contact part 140c will be worn out.

On the other hand, in the modified example 2, the contact member 146 made of resin having excellent slidability comes into contact with the blade portion 110a1 of the first conveying screw. Thereby, the friction between the contact part 140c and the blade part 110a1 can be suppressed. Further, the contact holder 140j is provided with a notch 140g, and the contact member 146 is held in the notch 140g by light press fitting so that it can be easily detached from the contact holder 140j. ing. Thus, when the contact member 146 is worn, only the contact member 146 needs to be replaced, and the maintenance cost of the apparatus can be reduced as compared with the case where the entire loosening plate 140 is replaced.
Further, in the second modification, the two notches 140h are provided in the notch 140g, the contact area with the notch 140g when the contact member 146 is lightly press-fitted can be reduced, and light press-fitting is performed. Sometimes the friction force can be weakened. Thereby, the contact member 146 can be lightly press-fitted easily into the notch 140g.

  In the second modification, the contact portion 140c has a rectangular parallelepiped shape as shown in FIG. In the case of such a configuration, when the contact portion 140c is pushed downstream of the toner conveyance direction against the urging force of the spring 143 by the blades of the first conveyance screw 110a, the chain line B in FIG. As shown, stress concentrates around the corner of the contact portion 140c of the plate-like portion 140f with the downstream end in the toner conveyance direction.

  Therefore, as shown in FIG. 18, in this case, the plate-like portion 140f is provided with the shape change suppressing portion 140d so that the shape gradually changes from the contact portion 140c toward the downstream side in the toner conveyance direction. It can suppress that a stress concentration part arises.

  In the configuration shown in FIG. 17, a hole 140i is also formed in the upper part of the figure where the contact part 140c of the plate-like part 140f is formed. As a result, the rigidity of the portion of the plate-like portion 140f where the contact portion 140c is formed is low, the portion of the plate-like portion 140f where the contact portion 140c is formed is not deformed, and is surrounded by the chain line in FIG. The stress was concentrated on the part.

  Therefore, as shown in FIGS. 18 and 19, the hole portion is not provided in the portion where the contact portion 140 c of the plate-like portion 140 f is formed. Thereby, the rigidity of the part in which the contact part of the plate-shaped part 140f was formed can be improved. As a result, when the contact portion 140c is pushed by the transport screw downstream in the toner transport direction, the portion of the plate-like portion 140f where the contact portion 140c is formed is deformed, and the contact portion of the plate-like portion 140f is deformed. It is possible to suppress the stress from being concentrated in the vicinity of the corner of the toner conveyance downstream end 140c.

  In addition, by not forming a hole on the upstream side of the toner conveyance direction of the contact portion 140c in the toner conveyance direction, stress is generated near the corner of the contact portion 140c of the plate-like portion 140f with the downstream end of the toner conveyance. Concentration can be suppressed.

  Further, due to manufacturing errors of the guide protrusion 141 and the guide hole 140a, the contact portion 140c does not move away from the blades of the first conveying screw at a predetermined timing, and the loosening plate 140 moves more than necessary to the downstream side in the toner conveying direction. There was a case. In that case, the urging force of the spring 143 increases, and a large stress is applied to the plate-like portion 140f. Moreover, since the timing at which the loosening plate 140 returns to the initial position is deviated, there is an increased possibility that the contact portion 140c collides with the blade portion 110a1 of the first conveying screw. Further, as shown in the first modification, in the configuration in which the buffer member is provided, the buffer member 144 that vigorously collides with the buffer member 144 and is attached to the first casing 120a with the double-sided tape is the first casing. There is a risk of peeling off from 120a.

  For this reason, in the configuration shown in FIGS. 18 and 19, the guide holes 140 a (second and fourth guide holes from the left side in FIG. 9) in which the guide protrusions 141 come into contact with the edge on the first conveying screw side, A relief portion 140a1 that is recessed toward the first conveyance screw is formed on the upstream side in the toner conveyance direction at the edge on the first conveyance screw side. The guide hole 140a with which the guide protrusion 141 comes into contact with the edge on the first conveying screw side restricts the unwinding plate 140 from moving in a direction away from the first conveying screw. Therefore, if the accuracy of the vertical positional relationship between these guide holes and the guide protrusions is poor, the contact portion does not separate from the blades of the first conveying screw at a predetermined timing.

  However, as shown in FIGS. 18 and 19, by forming the escape portion 140a1, the unwinding plate 140 moves in a direction away from the first conveying screw at a predetermined timing, and the contact portion 140c is moved to the first position. It can be separated from the blade part 110a1 of one conveying screw. Thereby, it can suppress that a big bending stress is added by the plate-shaped part 140f and the contact part 140c. Moreover, it can suppress that the contact part 140c collides with the blade | wing part 110a1 of a 1st conveyance screw, or a buffer member peels off from a case.

  As shown in FIGS. 18 and 19, the most upstream guide hole 140a in the vicinity of the contact portion 140c in the toner transport direction is configured such that the guide projection comes into contact with the edge on the first transport screw side, and the escape portion 140a1 is formed. However, by forming the relief portion 140a1, the portion becomes thin and the rigidity becomes weak. As a result, there is a possibility that stress concentrates in the vicinity where the escape portion 140a1 is formed.

  Therefore, as shown in FIGS. 18 and 19, it is preferable that the shape change suppressing portion 140d extends to the escape portion 140a1. Thereby, escape part 140a1 can be reinforced and it can suppress that stress concentrates on escape part 140a1 vicinity. It is preferable that at least half of the escape portion 140a1 in the toner conveyance direction is reinforced by the shape change suppressing portion 140d. It is preferable that more than half of the escape portion 140a1 in the toner conveyance direction is reinforced by the shape change suppressing portion 140d, so that the escape portion 140a1 can be reinforced.

  18 and 19 may also be configured such that the contact portion 140c side of the loosening plate 140 is heavy, or the urging force of the spring 143 acts on the lower side (conveying screw side). Thus, the loosening plate is inclined so that the contact portion 140c moves downward (to the conveying screw side). As a result, as described above, even when the toner conveying upstream side of the first conveying screw is tilted so as to be located slightly below the downstream side (the side away from the loosening plate 140) due to gravity, the contact portion 140c is moved to the first conveying screw. Can contact the blades of one transport screw.

  However, if the loosening plate 140 is inclined too much, the contact portion 140c may contact the shaft portion of the first conveying screw, and the contact portion 140c may be worn. Therefore, in the configuration shown in FIGS. 18 and 19, when the loosening plate 140 is tilted, the guide protrusion 141 comes into contact with the edge on the opposite side of the first conveying screw side of the guide hole 140a in the most upstream in the toner conveying direction, and the loosening plate 140 is loosened. The plate 140 is prevented from tilting too much. In addition, a rib-shaped reinforcing portion 140k is provided near the portion where the guide projection abuts when the loosening plate 140 is tilted to reinforce that portion.

FIG. 20 is a diagram for explaining the movement of the loosening plate 140 configured as shown in FIG.
As shown in FIG. 20A, when the contact portion 140c is pushed by the blade portion 110a1 of the first conveying screw and the loosening plate 140 moves downstream in the toner conveying direction, the edge of the guide hole 140a is reached. Accordingly, the guide protrusion 141 moves relative to the guide hole 140a toward the upstream side in the toner conveyance direction.

  The loosening plate 140 moves downstream in the toner conveyance direction, and gradually moves away from the first conveyance screw due to the inclination of the edge of the guide hole 140a. Then, as shown in FIG. 20B, when the guide projection 141 reaches the escape portion 140a1, the amount of movement toward the side away from the first conveying screw increases as shown by the arrow e1 in the figure. The contact portion 140c rides on the blade portion 110a1. As a result, as shown in FIG. 20C, the contact portion 140c can ride on the blade portion 110a1 at a predetermined timing, and the unwinding plate 140 is moved upstream in the toner conveyance direction by the urging force of the spring 143. And can be moved.

  Further, when the unwinding plate moves to the upstream side in the toner transport direction, the unwinding plate 140 rotates in the direction of arrow e2 in the drawing due to the urging force of the spring 143 and the upstream side of the unwinding plate 140 in the toner transport direction becoming heavy. Then, the loosening plate 140 is inclined. Then, the guide protrusion 141 that has been in contact with the edge on the first conveying screw side of the guide hole 140a at the most upstream in the toner conveying direction moves away from the edge and moves toward the intermediate transfer belt relative to the guide hole. To do. Then, as shown in FIG. 20 (d), the guide protrusion 141 hits the edge of the guide hole 140a opposite to the first conveying screw side, and the rotation of the loosening plate in the direction of arrow e2 in the figure is restricted. As a result, as shown in FIG. 20D, the contact portion 140c can be prevented from coming into contact with the shaft portion 110a2 of the first conveying screw, and the contact portion 140c slides against the shaft portion 110a2. Wear can be suppressed.

  As shown in FIG. 20D, the guide protrusion 141 hits and the vicinity of the edge portion of the guide hole 140a that restricts the rotation of the loosening plate 140 on the side opposite to the first conveying screw side is reinforced by the reinforcing portion 140k. doing. Therefore, it can suppress that the part which the guide protrusion 141 of the edge on the opposite side to the 1st conveyance screw side of the guide hole 140a contacts is deformed to the upper side, or is damaged.

[Modification 3]
FIG. 21 is a schematic perspective view showing a characteristic part of the third modification.
In the third modification, a cam 145 is provided on the first conveying screw 110a, and the loosening plate 140 is swung in the toner conveying direction by the cam 145.
In the third modification, the contact portion 140c of the loosening plate 140 is brought into contact with an inclined surface 145a inclined with respect to the toner transport direction of the cam 145 (the rotation shaft of the first transport screw). In this case, in the contact portion 140c, the loosening plate 140 swings in the toner conveyance direction along the inclined surface 145a of the cam 145. In the above description, the loosening plate 140 returns to the initial position X at once by the urging force of the spring 143. However, in Modification 3, the loosening plate 140 is gradually moved to the upstream side in the toner conveyance direction while abutting the inclined surface 145a of the cam 145, and the loosening plate 140 slowly returns to the initial position X. Therefore, there is an advantage that no impact sound or vibration sound is generated when the loosening plate 140 returns to the initial position.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
A cleaning member such as a cleaning brush roller that removes toner on a member to be cleaned such as the intermediate transfer belt 2, a casing 120a that houses the cleaning member, a conveyance screw that conveys toner removed by the cleaning member to the outside of the casing, and the like In the cleaning apparatus, the loosening means includes a plate-like portion 140f provided along the inner wall of the casing, and a loosening means such as a loosening plate 140 for loosening toner adhering to the inner wall of the casing. An urging means such as a spring 143 that urges the plate-like portion 140f in a direction opposite to the toner conveying direction of the conveying member, and an abutting portion 140c that extends from the plate-like portion 140f and contacts the conveying member. The abutting portion 140c abuts on the conveying member and is moved forward by the conveying member. The loosening means is configured such that when the loosening means moves a predetermined distance in the toner conveyance direction, the biasing means moves in a direction opposite to the toner conveyance direction and returns to the movement start position by the conveyance member, and the contact The cross section of the portion 140c parallel to both the extending direction from the plate-like portion 140f and the toner conveying direction is such that the length in the extending direction gradually decreases from the contact portion toward the toner conveying direction. A shape change suppressing portion having a shape is provided.
The corners of the contact portion 140c and the plate-like portion 140f extending from the plate-like portion 140f of the loosening plate 140, which is the loosening means, are portions where the outer shape of the loosening means changes abruptly. When the abutting portion 140c is pushed in the toner conveying direction by a conveying member such as the conveying screw 110a, the downstream end of the abutting portion 140c in which the outer shape changes suddenly in the toner conveying direction and the plate-like portion 140f Stress concentration parts are generated around the corners.
For this reason, in aspect 1, the cross section parallel to both the extending direction and the toner conveying direction has a shape such that the length in the extending direction gradually decreases from the contact portion toward the toner conveying direction. Therefore, when the contact portion is pushed in the toner transport direction by the transport screw, it is possible to suppress the stress concentration portion from being generated in the plate-shaped portion. Thereby, it is possible to prevent the loosening means from being broken due to cracks in the plate-like portion when used over time.
Moreover, in the aspect 1, the swinging amount of the loosening means can be adjusted by adjusting the timing at which the contact portion is separated from the conveying member, and the loosening means can be swung greatly. In this way, by configuring the unwinding plate to swing in the axial direction of the transport member, the unwinding plate can be swung greatly without increasing the transport member in the radial direction. Therefore, the toner on the inner wall of the casing can be loosened well without increasing the size of the apparatus.

(Aspect 2)
In (Aspect 1), the contact portion 140c, the shape change suppressing portion 140d, and the plate-like portion 140f are integrally formed of the same material.
According to this, as described in the embodiment, it is possible to prevent the stress concentration from being generated in the plate-like portion better than in the case where they are provided separately.

(Aspect 3)
In (Aspect 1) or (Aspect 2), the cross section of the shape change suppressing portion 140d parallel to both the extending direction of the contact portion from the plate-like portion and the toner conveying direction is triangular.
According to this, as described in the embodiment, it is possible to favorably disperse the stress by the shape change suppressing portion 140d, and it is possible to suppress the occurrence of the stress concentration portion in the plate-like portion 140f.

(Aspect 4)
In (Aspect 3), of the three sides of the triangular shape change suppressing portion 140d, the side approaching the plate-like portion 140f from the toner conveyance downstream end of the contact portion 140c toward the toner conveyance downstream side has a concave shape. An arc shape was adopted.
According to this, as described with reference to FIG. 13, the stress can be effectively dispersed by the shape change suppressing portion 140 d, and the generation of the stress concentration portion in the plate-like portion 140 f is favorably suppressed. Can do.

(Aspect 5)
In any one of (Aspect 1) to (Aspect 4), the shape change suppression portion is formed from the distal end side of the center portion in the extending direction of the contact portion.
According to this, it can suppress that stress concentrates on the corner part of the contact part 140c and a shape change suppression part.

(Aspect 6)
In any one of (Aspect 1) to (Aspect 5), the contact portion 140c is provided at the upstream end of the plate-like portion 140f in the toner conveyance direction, and the plurality of holes of the plate-like portion 140f are provided. The contact portion 140f is formed on the downstream side in the toner transport direction from the central portion in the toner transport direction.
According to this, as described with reference to FIGS. 17 to 19, the periphery of the contact portion 140 c of the plate-like portion 140 f is deformed together with the contact portion 140 c, and the toner is conveyed more than the contact portion 140 c of the plate-like portion 140 f. Concentration of bending stress on the downstream side in the direction can be suppressed. As a result, damage to the plate-like portion 140f can be suppressed.

(Aspect 7)
In any one of (Aspect 1) to (Aspect 6), a plurality of guide protrusions 141 are provided on the inner wall of the casing 120a, and the plate-like portion 140f is provided corresponding to each guide protrusion 141 and is formed by the guide protrusions 141. The plurality of guide holes 140a to be guided and the edges extending in the toner conveyance direction with which the guide projections of the plurality of guide holes abut are separated from the conveyance member such as the conveyance screw as going downstream in the toner conveyance direction. The loosening means is configured to swing in the axial direction of the transport member and also in the radial direction of the transport member while the guide hole is guided by the guide projection. And at least one of the plurality of guide holes has a guide plate abutting against an edge of the guide hole on the conveying member side, and a loosening plate It is a guide hole for restricting movement in a direction away from the transport member, and the remaining guide holes are configured to contact an edge on the side opposite to the transport member, and the movement of the loosening means toward the transport member side is configured. A relief hole 140a1 which is a guide hole to be regulated and is recessed toward the conveyance member on the upstream side in the toner conveyance direction of the edge where the guide projection of the guide hole which regulates the movement of the loosening means in the direction away from the conveyance member comes into contact. Formed.
According to this, as described with reference to FIGS. 18 to 20, when the abutment portion 140 c comes into contact with a conveyance member such as a conveyance screw and the loosening means moves in the toner conveyance direction, the guide hole downstream in the conveyance direction. As it goes to, the edge that is inclined so as to be separated from the conveying member is guided by the guide projection, and the loosening means is gradually separated from the conveying member. Then, as shown in FIG. 20C, when the guide protrusion 140 reaches the escape portion 140a1 that is recessed toward the conveying member, the moving amount of the loosening means in the direction away from the conveying member increases. As a result, the contact portion 140c can be separated from the conveying member such as the conveying screw at a predetermined timing even if there is a manufacturing error or the like as compared with the case where the inclination is constant.

(Aspect 8)
In (Aspect 7), the contact portion 140c is provided at the upstream end portion of the plate-like portion 140f in the toner conveyance direction, and among the plurality of guide holes 140a, the most upstream guide hole in the toner conveyance direction is: In the guide hole in which the escape portion 140a1 is formed, the reinforcing portion 140c is provided up to the escape portion 140a1.
According to this, as described with reference to FIGS. 18 and 19, since the escape portion 140a1 is recessed, the thickness of the portion of the plate-like portion 140 where the escape portion 140a1 is formed is thin in the radial direction. The rigidity becomes weak. Therefore, by providing the reinforcing portion 140c up to the escape portion 140a1, it is possible to suppress a decrease in rigidity, and it is possible to suppress the bending stress from being concentrated near the escape portion 140a1.

(Aspect 9)
In (Aspect 8), the downstream end of the reinforcing portion 140c in the toner transport direction is located downstream of the central portion of the escape portion 140a1 in the toner transport direction.
Accordingly, the periphery of the escape portion 140a1 can be favorably reinforced with the reinforcement portion 140c.

(Aspect 10)
(Aspect 6) to (Aspect 9) In any one of the plurality of guide holes 140a, the most upstream guide hole in the toner transport direction is a guide hole that regulates the movement of the loosening means in the direction away from the transport member. The urging means such as the spring 143 also urges the unwinding means to the conveying member side, and the unwinding means moves in the direction opposite to the moving direction by the driving of the conveying member by the urging means. Then, when returning to the movement start position by the conveying member, the guide projection comes into contact with the edge of the most upstream guide hole in the toner conveying direction opposite to the conveying member side, thereby restricting the rotation of the loosening means.
According to this, as described with reference to FIGS. 18 to 20, when the loosening means such as the loosening plate 140 returns to the movement start position by the conveying member by the biasing means such as the spring 143, the contact portion 140c. It is possible to prevent the loosening means from rotating until the abutment comes into contact with a shaft portion of a conveying member such as a conveying screw. Thereby, it is possible to suppress the contact portion 140c from being worn by rubbing with the shaft portion of the transport member.

(Aspect 11)
In (Aspect 10), a reinforcing portion 140k that reinforces the portion of the edge on the opposite side to the conveying member side of the guide hole on the most upstream side in the toner conveying direction that abuts the guide protrusion 141 is provided.
According to this, as described with reference to FIGS. 18 to 20, the portion where the guide protrusion 141 on the edge opposite to the conveying member side of the guide hole at the most upstream in the toner conveying direction abuts is deformed. , And can be prevented from being damaged.

(Aspect 12)
An image carrier such as an intermediate transfer belt 2 carrying a toner image, and a toner image forming means (consisting of an image forming unit 66, a writing device 5, a primary transfer roller, etc.) for forming a toner image on the surface of the image carrier; The transfer means such as a secondary transfer device 9 for transferring the toner image formed on the surface of the image carrier to the transfer body, and the toner as the adhering matter adhering to the surface of the image carrier are scraped to remove the surface. 12. An image forming apparatus comprising a cleaning unit for cleaning, wherein the cleaning unit according to claim 1 is used as the cleaning unit.
According to this, good cleaning properties can be maintained over time, and good images can be maintained over time.

1: copier 2: intermediate transfer belt 6: developing device 9C: secondary transfer belt 10: belt cleaning device 66: image forming unit 100a: first cleaning unit 100b: second cleaning unit 100c: post cleaning unit 101: first Cleaning brush roller 102: First recovery roller 103: First scraping blade 104: Second cleaning brush roller 105: Second recovery roller 106: Second scraping blade 107: Post cleaning roller 108: Post recovery roller 109: Post scraping Take-off blade 110a: first transfer screw 110b: second transfer screw 110c: post transfer screw 111a, 111b, 111c: inlet seal 112a, 112b, 112c: outlet seal 120a: first casing 120b: second Thing 120c: Post casing 121a: Casing lower surface 130: First cleaning power supply 131: First recovery power supply 132: Second cleaning power supply 133: Second recovery power supply 134: Third cleaning power supply 135: Third recovery power supply Part 140: Relaxing plate 140a: Guide hole 140a1: Escape part 140c: Contact part 140d: Reinforcing part 140k: Reinforcing part 141: Guide protrusion 143: Spring 144: Buffer member 145: Cam 145a: Inclined surface 200: Control part 211: Base layer 212: Elastic layer 213: Surface layer 300: Optical sensor

JP 2000-181315 A

Claims (12)

A cleaning member for removing toner on the object to be cleaned;
A casing for storing the cleaning member;
A conveying member for conveying the toner removed by the cleaning member to the outside of the casing;
A cleaning device comprising a loosening means for loosening the toner adhering to the inner wall of the casing,
The loosening means extends from the plate-like portion, a plate-like portion provided along the inner wall of the casing, an urging means for urging the plate-like portion in a direction opposite to the toner conveyance direction of the conveying member, and the plate-like portion. And having a contact portion that contacts the transport member,
When the abutting portion comes into contact with the conveying member and the plate member moves by a predetermined distance in the toner conveying direction by the conveying member, the urging means moves in a direction opposite to the toner conveying direction to move the conveying member. The loosening means is configured to return to the movement start position by
The cross section of the abutting portion parallel to both the extending direction from the plate-like portion and the toner conveying direction is such that the length in the extending direction gradually decreases from the abutting portion toward the toner conveying direction. A cleaning apparatus comprising a shape change suppressing portion having a unique shape. The cleaning device according to claim 1,
The cleaning device, wherein the contact portion, the shape change suppressing portion, and the plate-like portion are integrally formed of the same material. The cleaning device according to claim 1 or 2,
The cleaning device according to claim 1, wherein a cross section of the contact portion of the shape change suppressing portion parallel to both the extending direction from the plate-like portion and the toner conveying direction is triangular. The cleaning device according to claim 3.
Of the three sides of the triangular shape change suppressing portion, the side approaching the plate-like portion as it goes from the downstream end in the toner transport direction toward the downstream side in the toner transport direction has a concave arc shape. A cleaning device characterized. The cleaning device according to claim 1,
The cleaning apparatus according to claim 1, wherein the shape change suppression portion is formed from the tip side of the contact portion in the extending direction central portion. The cleaning device according to any one of claims 1 to 5,
The contact portion is provided at the upstream end of the plate-like portion in the toner conveyance direction,
The cleaning device according to claim 1, wherein the plate-like portion has a plurality of holes formed on the downstream side in the toner transport direction from the central portion of the contact portion in the toner transport direction. The cleaning device according to any one of claims 1 to 6,
A plurality of guide protrusions on the inner wall of the casing;
The plate-like portion has a plurality of guide holes provided corresponding to the guide protrusions and guided by the guide protrusions,
An edge extending in the toner transport direction with which the guide projections of the plurality of guide holes abut is inclined so as to be separated from the transport member toward the downstream side in the toner transport direction,
The loosening means is configured to swing in the axial direction of the transport member and also in the radial direction of the transport member while the guide hole is guided by the guide protrusion.
At least one of the plurality of guide holes is a guide hole that regulates movement of the loosening plate in a direction away from the transport member by abutting the guide projection on an edge of the guide hole on the transport member side, The remaining guide holes are configured to abut against the edge opposite to the conveying member, and are guide holes that restrict movement of the loosening means toward the conveying member.
A cleaning portion characterized in that a relief portion recessed toward the conveying member is formed on the upstream side in the toner conveying direction of the edge of the guide hole for restricting the movement of the loosening means in the direction away from the conveying member. apparatus. The cleaning device according to claim 7, wherein
The contact portion is provided at the upstream end of the plate-like portion in the toner conveyance direction,
Among the plurality of guide holes, the most upstream guide hole in the toner conveying direction is a guide hole in which the escape portion is formed,
The cleaning device, wherein the shape change suppression portion extends to the escape portion. The cleaning device according to claim 8, wherein
A cleaning device, wherein a downstream end of the shape change suppressing portion in the toner transport direction is located downstream of a central portion of the escape portion in the toner transport direction. The cleaning device according to claim 7乃 Itaru 9,
Of the plurality of guide holes, the most upstream guide hole in the toner conveyance direction is a guide hole that regulates movement of the loosening means in a direction away from the conveyance member,
The urging means urges the loosening means also on the conveying member side,
When the loosening means is moved in the direction opposite to the toner conveyance direction by the biasing means and returns to the movement start position by the conveyance member, the edge of the most upstream guide hole in the toner conveyance direction opposite to the conveyance member side A cleaning device, wherein the guide projection abuts to restrict rotation of the loosening means. The cleaning device according to claim 10, wherein
A cleaning device, comprising: a reinforcing portion that reinforces a portion of the edge of the most upstream guide hole in the toner conveying direction opposite to the conveying member side that abuts the guide protrusion. An image carrier for carrying a toner image;
Toner image forming means for forming a toner image on the surface of the image carrier;
Transfer means for transferring the toner image formed on the surface of the image carrier to a transfer member;
In an image forming apparatus comprising: a cleaning unit that scrapes off the toner that is attached to the surface of the image carrier to clean the surface.
An image forming apparatus using the cleaning device according to claim 1 as the cleaning unit.

Images