Image forming apparatus

Abstract

To provide an image forming device capable of reducing the leak of a developer to the outside along with the rotation of an agitation member in a structure in which the agitation member is disposed near a blade member and a sheet member.SOLUTION: A sheet part of an agitation member disposed near a blade member is in contact with a second side face of the blade member that is opposite a first side face which is in contact with an image carrier. When a position at a most upstream end on the second side face and an axis position of a shank of the agitation member are linked with a first imaginary line in a rotation direction of the image carrier, a second imaginary line that perpendicularly intersects the first imaginary line and passes through the position of the most upstream end of the second side face is located so that a free end of a sheet member for leakage suppression can become closer to a free end of the blade member than an intersection position that interests an outer circumferential surface of the image carrier.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to an image forming apparatus. In particular, it relates to an image forming apparatus using an electrophotographic method.

Background Art

[0002] Conventionally, as an image forming apparatus using an electrophotographic method, a configuration having a belt constituting an intermediate transfer body and a cleaning unit that performs a cleaning operation on the belt is known (see Patent Document 1).

[0003] Specifically, in Patent Document 1, the cleaning unit includes a blade member that abuts on the belt and collects toner, a sheet member that prevents toner leakage to the outside from the unit frame, and a rotatable stirring member disposed in the vicinity of the blade member and the sheet member.

[0004] Further, the free end of the blade member that abuts on the belt extends to the upstream side in the rotation direction of the belt. On the other hand, the sheet member is disposed so as to be located on the upstream side of the blade member in the rotation direction of the belt. The free end of the sheet member that contacts the belt extends to the downstream side in the rotation direction of the belt, and a "nip portion" is formed between the sheet member and the belt.

[0005] On the other hand, the stirring member includes a rotating shaft portion and a sheet portion fixed to the shaft portion, and the free end of the sheet portion can contact the blade member on the side opposite to the belt side. Therefore, when the stirring member rotates, the free end of the sheet portion rubs against the blade member.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the configuration of Patent Document 1, when the stirring member rotates, the sheet portion elastically deforms due to contact with the blade member, repeatedly knocking the toner down from above the blade member. When the elastically deformed sheet portion returns to its original state, a force may be generated that pushes the toner towards the sheet member. In this case, the pushed-out toner may pass through the "nip portion" between the sheet member and the belt and leak out.

[0008] In view of the above problems, the present invention aims to provide an image forming apparatus in which a stirring member is arranged near a blade member and a sheet member, and which can reduce the leakage of developer to the outside as the stirring member rotates. [Means for solving the problem]

[0009] The image forming apparatus of the present invention is A rotatable image carrier that holds the developer image, In the rotational direction of the image carrier, the free end that contacts the image carrier extends upstream, and the blade member collects the developer on the image carrier. A sheet member is located upstream of the blade member in the rotational direction of the image carrier, and its free end extends downstream and contacts the image carrier. An image forming apparatus having a stirring member having a shaft portion that rotates in the same rotational direction as the image carrier and an elastically deformable sheet portion attached to the shaft portion that rotates together with the shaft portion, The sheet portion is in contact with the second side surface of the blade member, which is opposite to the first side surface that is in contact with the image carrier. When viewed along the rotation axis direction of the shaft portion, in the rotation direction of the image carrier, when the position of the upstream end of the second side surface and the axial position of the shaft portion are connected by a first imaginary line, The free end of the sheet member is positioned such that a second imaginary line, which is perpendicular to the first imaginary line and passes through the position of the most upstream end of the second side surface, is closer to the free end of the blade member than the intersection point where the second imaginary line intersects the outer circumferential surface of the image carrier. [Effects of the Invention]

[0010] According to the image forming apparatus of the present invention, in a configuration in which a stirring member is arranged near the blade member and the sheet member, the leakage of developer to the outside can be reduced as the stirring member rotates. [Brief explanation of the drawing]

[0011] [Figure 1] Conceptual diagram of the entire image forming apparatus according to Embodiment 1 of the present invention. [Figure 2] (A) is a conceptual diagram showing the mounting conditions for the cleaning blade of the cleaning unit in Example 1; (B) is a conceptual diagram showing the state with the cleaning blade mounted. [Figure 3] (A) is a cross-sectional conceptual diagram of the cleaning unit in Example 1; (B) is an enlarged conceptual diagram of the main part of the cleaning unit. [Figure 4] Conceptual diagram showing the toner state when the toner is recovered by the cleaning blade in Example 1. [Figure 5] (A, B) Conceptual diagram showing the toner transport state as the stirring member rotates in Example 1. [Figure 6] Conceptual diagram showing the toner recovery process by the cleaning unit in Comparative Example 1 of Example 1. [Figure 7] Conceptual diagram showing how the stirring member of the cleaning unit in Comparative Example 1 pushes the toner toward the squeegee sheet. [Figure 8] A conceptual diagram showing how toner extruded by the stirring member of the cleaning unit in Comparative Example 1 leaks out from the nip portion of the squeegee sheet and belt. [Figure 9]Conceptual diagram showing the positional relationship among the cleaning blade, the stirring member, and the squeegee sheet in Example 1, and the state when the stirring member is released (restored) from the rubbing state (elastic deformation state) with the cleaning blade [Figure 10] Conceptual diagram showing the positional relationship among the cleaning blade, the stirring member, and the squeegee sheet in Comparative Example 1 [Figure 11] Conceptual diagram showing the positional relationship among the cleaning blade, the stirring member, and the squeegee sheet in Example 1 [Figure 12] Conceptual diagram showing the tip position of the squeegee sheet in the first modification of Example 1 [Figure 13] Conceptual diagram showing the tip position of the squeegee sheet in Comparative Example 2 of Example 1 [Figure 14] Conceptual diagram showing an example of the attachment conditions of the cleaning blade in Example 1 [Figure 15] Conceptual diagram showing another example of the attachment conditions of the cleaning blade in Example 1 [Figure 16] Conceptual diagram of the main parts of the cleaning unit and the belt of the image forming apparatus according to Example 2 of the present invention [Figure 17] Conceptual diagram showing the rotation axis attachment region of the stirring member in Example 2 [Figure 18] Cross-sectional conceptual diagram of the cleaning unit in the first modification of Example 2 [Figure 19] Cross-sectional conceptual diagram of the cleaning unit in the second modification of Example 2

Embodiments for Carrying Out the Invention

[0012] (Example 1) Hereinafter, Example 1 of the present invention will be described with reference to FIGS. 1 to 16

[0013] Note that the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following examples can be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Unless otherwise specified, the scope of the present invention is not limited to the following examples

[0014] Figure 1 is a conceptual diagram of the entire image forming apparatus 100 according to Embodiment 1 of the present invention.

[0015] In this embodiment, the image forming apparatus 100 is a so-called tandem type image forming apparatus, which has multiple image forming sections a to d. The first image forming section a uses yellow (Y) toner, the second image forming section b uses magenta (M) toner, the third image forming section c uses cyan (C) toner, and the fourth image forming section d uses black (Bk) toner to form an image.

[0016] These four image forming units are arranged in a line at regular intervals, and the configuration of each image forming unit is substantially the same except for the color of the toner it contains. The image forming apparatus 100 of this embodiment will be described below using the first image forming unit a as an example.

[0017] The photosensitive drum 1a, which serves as the image carrier, is made of multiple layers of functional organic material laminated on a metal cylinder. These layers consist of a carrier generation layer that generates electric charge upon exposure to light, and a charge transport layer that transports the generated charge. The outermost layer has low electrical conductivity and is almost insulating. The photosensitive drum 1a rotates at a predetermined peripheral speed in the direction of the arrow R1 shown in the diagram, receiving a driving force from a drive source (not shown).

[0018] The charging roller 2a, acting as a charging member, contacts the photosensitive drum 1a and, as the photosensitive drum 1a rotates in the direction of the arrow R1 shown in the figure, uniformly charges the surface of the photosensitive drum 1a while rotating in response to the rotation of the photosensitive drum 1a. The charging roller 2a is charged by a DC voltage applied from the charging power supply 20a, and the photosensitive drum 1a is charged by discharge generated in the minute air gaps upstream and downstream of the charging portion where the charging roller 2a and the photosensitive drum 1a contact.

[0019] The developing means 8a includes a developing roller 4a as a developing element and a developer application blade 7a, and contains yellow toner. The developing roller 4a is connected to the developing power supply 21a. The cleaning means 3a includes a cleaning blade that contacts the photosensitive drum 1a and a waste toner box that contains toner and other materials removed from the photosensitive drum 1a by the cleaning blade, and recovers toner remaining on the photosensitive drum 1a.

[0020] The exposure means 11a consists of a scanner unit that scans laser light using a multifaceted mirror, and irradiates the photosensitive drum 1a with a scanning beam 12a modulated based on the image signal. The photosensitive drum 1a, charging roller 2a, cleaning means 3a, and developing means 8a are configured as a detachable, integrated process cartridge 9a for the image forming apparatus 100.

[0021] The intermediate transfer belt 13 (image carrier) is a rotatable endless belt that carries the toner image (developer). The intermediate belt 13 is tensioned by three rollers: a secondary transfer opposing roller 15 (hereinafter referred to as the opposing roller 15), a tension roller 14, and an auxiliary roller 19, which serve as tensioning members. The tension roller 14 is biased by a spring (not shown) to maintain an appropriate tension force on the intermediate transfer belt 13.

[0022] The opposing roller 15 rotates in the direction of arrow R2 in the diagram, receiving a driving force from a drive source (not shown), and the intermediate transfer belt 13 moves in the direction of arrow AA (the direction of rotation and surface movement of the belt) in conjunction with the rotation of the opposing roller 15. The intermediate transfer belt 13 can move in the forward direction relative to the photosensitive drums 1a to 1d at approximately the same speed.

[0023] The auxiliary roller 19, tension roller 14, and opposing roller 15 are electrically grounded. The opposing roller 15 is a roller with an outer diameter of 24.0 mm, formed by covering an aluminum core with EPDM rubber with a wall thickness of 0.5 mm, and has an electrical resistance of approximately 1 × 10⁻¹⁰. 5Carbon is dispersed as a conductive agent in the EPDM rubber so that it forms an Ω shape.

[0024] The primary transfer roller 10a is positioned opposite the photosensitive drum 1a via the intermediate transfer belt 13, and contacts the inner circumferential surface of the intermediate transfer belt 13, rotating in conjunction with the movement of the intermediate transfer belt 13.

[0025] The secondary transfer roller 25 is positioned opposite the opposing roller 15 via the intermediate transfer belt 13 and is in contact with the outer circumferential surface 13U of the intermediate transfer belt 13. The secondary transfer roller 25 is also connected to the secondary transfer power supply 26.

[0026] Next, the image forming operation of the image forming apparatus 100 of the present invention will be described.

[0027] When a control means (not shown), such as a controller, receives an image signal, the image forming operation is initiated, and the photosensitive drums 1a to 1d and the opposing rollers 15, etc., begin to rotate at a predetermined peripheral speed (process speed) due to the driving force from a drive source (not shown). In this embodiment, the process speed is 200 mm / s.

[0028] The photosensitive drum 1a is uniformly charged by a charging roller 2a to which a voltage of the same polarity as the normal charging polarity (negative polarity in this embodiment) of the toner is applied from a charging power supply 20a. Subsequently, an electrostatic latent image according to the image information is formed when the drum is irradiated with a scanning beam 12a from the exposure means 11a.

[0029] The toner contained in the developing unit 8a is negatively charged by the developer application blade 7a and applied to the developing roller 4a. Then, by applying a predetermined voltage from the developing power supply 21a to the developing roller 4a, the electrostatic latent image is developed by the toner in the developing section where the developing roller 4a and the photosensitive drum 1a come into contact, and a toner image corresponding to the yellow image component is formed on the photosensitive drum 1a.

[0030] Subsequently, the yellow toner image supported on the photosensitive drum 1a reaches the primary transfer section N1a, where the photosensitive drum 1a and the intermediate transfer belt 13 come into contact, as the photosensitive drum 1a rotates. Then, by applying a positive voltage from the primary transfer power supply 22a to the primary transfer roller 10a, the yellow toner image is transferred from the photosensitive drum 1a to the intermediate transfer belt 13 in the primary transfer section N1a.

[0031] Similarly, the second, third, and fourth image forming units b, c, and d form images of the second color magenta toner, the third color cyan toner, and the fourth color black toner, which are then sequentially superimposed onto the intermediate transfer belt 13 for primary transfer.

[0032] As a result, four toner images corresponding to the target color image are formed on the intermediate transfer belt 13.

[0033] Subsequently, the four toner images supported on the intermediate transfer belt 13 are transferred in one go to the surface of a transfer material P, such as paper or an OHP sheet, as they pass through the secondary transfer section N2 formed by the contact between the secondary transfer roller 25 and the intermediate transfer belt 13. At this time, a positive voltage is applied from the secondary transfer power supply 26 to the secondary transfer roller 25, thereby transferring the toner image from the intermediate transfer belt 13 to the transfer material P in the secondary transfer section N2.

[0034] The transfer material P is housed in a paper feed cassette 16 and is fed from the paper feed cassette 16 to the transport roller 18 by a paper feed roller 17, and then transported to the secondary transfer section N2 by the transport roller 18. In the secondary transfer section N2, the transfer material P onto which the four-color toner image has been transferred is heated and pressurized in a fixing means 50, causing the four colors of toner to melt and mix and be fixed to the transfer material P. After that, the transfer material P is discharged from the image forming apparatus 100 and loaded onto the output tray 52, which serves as a stacking section.

[0035] Through the above steps, a full-color print image is formed.

[0036] Furthermore, any remaining toner on the intermediate transfer belt 13 after secondary transfer is removed from the surface of the intermediate transfer belt 13 by a belt cleaning means 30 (recovery means) provided opposite the opposing roller 15 via the intermediate transfer belt 13. As will be described later, the belt cleaning means 30 has a cleaning blade 31 (blade member) that contacts the outer circumferential surface 13U of the intermediate transfer belt 13 at a position opposite the opposing roller 15.

[0037] Furthermore, the cleaning blade 31 has a free end 31b that contacts the belt in the rotation direction AA of the intermediate belt, and it is designed to collect toner from the belt.

[0038] The image forming apparatus 100 in this embodiment is provided with a control board (not shown) on which electrical circuits for controlling the operation of each part of the image forming apparatus are mounted.

[0039] The control board is equipped with a CPU (not shown) as a control means and a memory (not shown) as a storage means for various control information. The CPU performs control related to the transport of the transfer material P, control related to the driving of the intermediate transfer belt 13 and the process cartridge 9, control related to image formation, and control related to fault detection.

[0040] Next, the configuration of the intermediate transfer belt 13 in this embodiment will be described.

[0041] The intermediate transfer belt 13 is an endless belt member (or film-like member) consisting of two layers: a base layer 41 and a surface layer 40, and the circumference of the intermediate transfer belt 13 is 700 mm. Here, the base layer is defined as the thickest layer among the layers constituting the intermediate transfer belt 13 in the thickness direction of the intermediate transfer belt 13.

[0042] In this embodiment, the base layer 41 is a layer with a thickness of 70 μm. The surface layer 40 is formed on the outer circumferential surface side of the intermediate transfer belt 13 and is a layer with a thickness of 3 μm.

[0043] (Cleaning unit) Next, the configuration of the belt cleaning means 30 (cleaning unit), which is a feature of this embodiment, will be described.

[0044] Figure 2(A) is a conceptual diagram showing the mounting conditions for the cleaning blade of the cleaning unit in Example 1. Figure 2(B) is a conceptual diagram showing the state with the cleaning blade installed.

[0045] Specifically, Figure 2(A) conceptually shows the mounting position of the cleaning blade 31 when the cleaning blade 31, which will be described later, is not elastically deformed.

[0046] As shown in Figure 1(A), the belt cleaning means 30 includes a cleaning container 32 and a cleaning action part 33 provided in the cleaning container 32.

[0047] The cleaning container 32 is configured as part of the frame of an intermediate transfer unit (not shown) which has an intermediate transfer belt 13, etc.

[0048] The cleaning unit 33 includes a cleaning blade 31 (blade member) as a cleaning member and a support member 34 that supports the cleaning blade 31.

[0049] In this embodiment, the cleaning blade 31 is an elastic blade made of urethane rubber (polyurethane), which is an elastic material, and is supported by being bonded to a support member 34 made of sheet metal using plated steel plate as the material.

[0050] Furthermore, the cleaning blade 31 is a long, plate-like member in the width direction of the intermediate transfer belt 13 (the longitudinal direction of the cleaning blade 31) that intersects with the movement direction arrow AA of the intermediate transfer belt 13 (hereinafter referred to as the belt transport direction).

[0051] Furthermore, with respect to the shorter direction, the cleaning blade 31 has its free end 31b and the end 31c of the first side surface 31e of the cleaning blade 31 on the side facing the intermediate transfer belt 13 in contact with the intermediate transfer belt 13. The second side surface 31f of the cleaning blade 31 on the side opposite to the intermediate transfer belt 13 is fixed to the support member 34 by being bonded.

[0052] In this embodiment, the length of the cleaning blade 31 in the longitudinal direction is 240 mm, the thickness is 2 mm, and the hardness of the cleaning blade 31 is 77 degrees according to the JIS K 6253 standard.

[0053] The cleaning unit 33 is configured to swing relative to the surface of the intermediate transfer belt 13. Specifically, the support member 34 is supported so as to swing relative to the surface of the intermediate transfer belt 13 via a pivot shaft 35 fixed to the cleaning container 32. The support member 34 is pressurized by a pressure spring 36, which is a biasing means provided in the cleaning container 32, causing the cleaning unit 33 to move around the pivot shaft 35, and the cleaning blade 31 to bias (press) against the intermediate transfer belt 13.

[0054] Opposite the cleaning blade 31, an opposing roller 15 is positioned on the inner circumference side of the intermediate transfer belt 13. The cleaning blade 31 is in contact with the surface of the intermediate transfer belt 13 in a counter-direction with respect to the belt transport direction, at a position opposite to the opposing roller 15. That is, the cleaning blade 31 is in contact with the surface of the intermediate transfer belt 13 such that its free end 31b in its short direction faces upstream with respect to the belt transport direction.

[0055] As shown in Figure 2(B), a blade nip portion 37 is formed between the cleaning blade 31 and the intermediate transfer belt 13. At the blade nip portion 37, the cleaning blade 31 scrapes off the remaining toner from the surface of the moving intermediate transfer belt 13 and collects it in the cleaning container 32.

[0056] In this embodiment, as shown in Figure 2(B), the portion of the free end 31b that contacts the intermediate transfer belt 13 is designated as the "blade contact end 31c," and the portion on the opposite side in the thickness direction that does not contact the free end 31b is designated as the "blade non-contact end 31d." Similarly, the surface of the cleaning blade 31 that contacts the intermediate transfer belt is designated as the first side surface 31e, and the surface on the opposite side in the thickness direction is designated as the second side surface 31f. That is, the "non-contact end 31" is the upstream end of the second side surface 31f in the belt rotation direction AA.

[0057] Furthermore, in this embodiment, the mounting position of the cleaning blade 31 is set as follows.

[0058] As shown in Figure 2(A), the cleaning blade 31 is attached to the frame with a set angle θ of 22°, an intrusion amount δ of 1.3 mm, and a contact pressure of 0.6 N / cm.

[0059] Here, the set angle θ is the angle between the tangent C1 of the opposing roller 15 at the intersection P0 (position corresponding to 31c) of the intermediate transfer belt 13 and the cleaning blade 31 (the end face on the free end side of the cleaning blade 31) and the cleaning blade 31 (one surface approximately perpendicular to the thickness direction). The penetration amount δ is the length in the thickness direction over which the cleaning blade 31 overlaps the opposing roller 15. The contact pressure is defined as the pressing force from the cleaning blade 31 at the blade nip portion 37 (linear pressure in the longitudinal direction) and is measured using a film-type pressure measurement system (product name: PINCH, manufactured by Nitta Corporation).

[0060] Generally, the frictional resistance when the urethane rubber (blade) and synthetic resin (belt) rub against each other is high, making it easy for the cleaning blade 31 to "initially curl" when it comes into contact with the belt. Therefore, an initial lubricant such as graphite fluoride can be applied to the free end 31b of the cleaning blade 31 in advance.

[0061] Furthermore, the materials of the intermediate transfer belt 13 can be appropriately selected, and the rubber hardness of the cleaning blade 31 is preferably in the range of 70 degrees or more and 80 degrees or less according to the JIS K 6253 standard. In addition, the contact pressure of the cleaning blade 31 is preferably in the range of 0.4 N / cm or more and 0.8 N / cm or less.

[0062] (Squeezable sheet) Next, the configuration of the cleaning means other than the cleaning blade 31 will be explained using Figure 3.

[0063] Figure 3(A) is a conceptual cross-sectional view of the cleaning unit in Example 1. Figure 3(B) is an enlarged conceptual view of the main part of the cleaning unit.

[0064] Figure 3(A) shows the entire cleaning unit, including parts other than the cleaning blade 31. Figure 3(B) shows the configuration around the squeegee sheet.

[0065] In this embodiment, a squeegee sheet 60 (sheet member) is installed on the side of the cleaning container 32 facing the cleaning blade 31 to prevent toner collected by the cleaning blade 31 from leaking out of the cleaner container 32.

[0066] Furthermore, the squeegee sheet 60 is positioned upstream of the cleaning blade 31 in the rotation direction AA of the intermediate transfer belt 13, and its free end 61 extends downstream and is in contact with the intermediate transfer belt 13.

[0067] Specifically, the scraping sheet 60 is made of Mylar sheet and is attached to the cleaning container 32 using double-sided tape, with one end fixed in place. The other end of the scraping sheet, which is not fixed, is the free end 61.

[0068] Furthermore, the squeezing sheet 60 contacts the intermediate transfer belt 13 at its free end to form a squeezing sheet contact nip 62. The end face (edge ​​portion) of the free end 61 of the squeezing sheet may also contact the intermediate transfer belt to form a squeezing sheet contact nip 62. However, it is not necessary for the end face (edge ​​portion) of the free end 61 of the squeezing sheet to contact the belt; the squeezing sheet contact nip 62 may be formed on the side surface near the end face of the free end 61 of the squeezing sheet.

[0069] Furthermore, in this embodiment, the squeegee contact nip 62 is in contact with the intermediate transfer belt 13 over a wider area than the longitudinal area of ​​the cleaning blade 31 with respect to the direction of the rotation axis (width direction perpendicular to the rotation direction).

[0070] Furthermore, the free end 61 of the squeeze sheet extends in the direction of rotation downstream of the intermediate transfer belt 13.

[0071] In this embodiment, the squeegee sheet 60 is a Mylar sheet with a thickness of 50 μm, a length of 250 mm, and a free length of 5 mm. The squeegee sheet 60 is in light contact with the intermediate transfer belt 13, and the squeegee sheet contact nip 62 rubs against the intermediate transfer belt 13. This fills the gap between the cleaner container 32 and the intermediate transfer belt 13, thereby suppressing toner leakage from the container (frame).

[0072] The toner collected by the cleaning blade 31 is sent to the (waste) toner storage unit (not shown), which will be described later.

[0073] Next, the configuration for supplying toner from the cleaning container in this embodiment will be explained using Figures 3 and 4.

[0074] Figure 4 is a conceptual diagram showing the toner state when the toner is recovered by the cleaning blade in Example 1.

[0075] As shown in Figure 4, in this embodiment, the cleaning blade 31 is installed above the intermediate transfer belt 13, so toner accumulates on top of the cleaning blade 31. If too much toner accumulates in this area, the pressure on the cleaning blade 31 increases, causing cleaning failures such as toner slipping through the cleaning blade 31 or toner particles agglomerating together. In this embodiment, a transport configuration is provided that transports toner near the cleaning blade 31 so that toner does not easily accumulate near the cleaning blade 31 (in front and above).

[0076] (Agitation component) Next, the transport configuration of this embodiment (including the "stirring member 70") will be explained using Figure 3.

[0077] The transport configuration of this embodiment can be divided into two parts. First, the first part is a mechanism that sends toner to the second part so that toner does not accumulate in front of or above the cleaning blade 31. The second part is a mechanism that sends the toner sent from the first part to a (waste) toner storage section (not shown) located on the outside of the cleaning container.

[0078] First, let me explain the first part of the transport configuration.

[0079] To prevent the toner collected by the cleaning blade 31 from accumulating and forming a packing, the first part of the transport configuration consists of an agitation member 70.

[0080] The stirring member 70 has a rotating shaft 71 that rotates in the same rotational direction R3 (=R2) as the intermediate transfer belt, and an elastically deformable stirring sheet 72 that is attached to the rotating shaft and rotates together with the rotating shaft. The stirring sheet 72 is in contact with the second side surface 31f of the cleaning blade 31, which is opposite to the first side surface 31e that is in contact with the intermediate transfer belt.

[0081] Specifically, the stirring member 70 consists of a rotating shaft 71 (shaft portion) that is linked to the drive, and a stirring sheet 72 (sheet portion) that is fixed to the rotating shaft 71.

[0082] The stirring sheet 72 is fixed by attaching one end of it to one side of the rotating shaft 71 with double-sided tape. That is, one end of the stirring sheet 72 is fixed to the rotating shaft 71 with double-sided tape, and the other end becomes a free end 73 (sometimes referred to as the free end 73 of the stirring member).

[0083] Furthermore, the direction in which the double-sided tape is attached to the rotating shaft 71 is such that the free end extends in a direction in which the double-sided tape is pressed against the shaft when a force is applied from upstream to downstream in the rotational direction of the rotating shaft 71. This is because the stirring member 70 receives a force (reaction force) from the toner in order to transport the toner, and this makes it less likely for the double-sided tape to peel off at this time. In addition, the stirring member 70 is linked to the drive of the process means, and in this embodiment, it rotates at a speed of 3 revolutions per second.

[0084] Furthermore, the stirring member 70 does not need to be wider than the longitudinal length of the cleaning blade 31; it only needs to be wider than the printing area corresponding to the supply area of ​​residual toner generated during normal printing. For this reason, the rotating shaft 71 is a rectangular parallelepiped member with a cross section perpendicular to the shaft, measuring 2 mm on each side, and with a length of 225 mm, which is longer than the printing area and the stirring sheet 72 described later.

[0085] In this embodiment, the stirring sheet 72 is made of Mylar sheet and has a width of 220 mm, which is wider than the printable area width of letter-size paper. The free length from the rotating shaft 71 is 4 mm so that the stirring sheet 72 is long enough to come into contact with the cleaning blade 31.

[0086] The reason for bringing the agitation sheet 72 into contact with the cleaning blade 31 is to efficiently transport the toner that accumulates on the top of the cleaning blade 31 and to suppress toner buildup. This effectively suppresses the increase in pressure on the cleaning blade 31 caused by toner buildup.

[0087] Furthermore, the rotation direction of the stirring member 70 is the same as that of the intermediate transfer belt 13, and near the cleaning blade 31, the free end 73 of the stirring member 70 moves in the opposite direction to the surface movement direction of the intermediate transfer belt 13.

[0088] This is because, if the stirring member 70 and the intermediate transfer belt 13 were to rotate in opposite directions, the stirring member 70 would be directed to carry the toner from the free end to the fixed end of the cleaning blade 31 near the cleaning blade 31. In this case, there is a risk that the free end 31b of the cleaning blade 31, which constitutes the collection surface for collecting remaining toner, will come into contact with the free end 73 of the stirring member. Consequently, cleaning defects are likely to occur due to the impact caused by contact between the toner carried by the stirring member 70 or the free end of the stirring member 70 and the cleaning blade 31. Therefore, in this embodiment, the rotation direction of the stirring member 70 and the rotation direction of the intermediate transfer belt 13 are set to the same direction.

[0089] Furthermore, the stirring member 70 sends the toner accumulated above the squeegee sheet 60 and cleaning blade 13 to a second part of the transport configuration (not shown) to prevent it from accumulating in amounts exceeding a predetermined quantity.

[0090] The transport of toner from the first part (transport member 70) of the transport configuration to the second part will be explained below using Figure 5.

[0091] Figure 5(A, B) is a conceptual diagram showing the toner transport state as the stirring member rotates in Example 1.

[0092] Specifically, Figure 5A shows the stirring member 70 lifting the toner upwards. At this time, as shown in Figure 5(A), it is preferable that the stirring member 70 be configured to be able to rub against the inner circumferential surface of the cleaning container 32. In this embodiment, the distance from the center of the rotation axis to the inner wall surface of the cleaner container 32 is 5 mm, and the free length of the stirring sheet 72 is set so that the distance from the center of rotation to the tip of the stirring sheet 72 is greater than 5 mm.

[0093] Figure 5(B) shows the state immediately after the stirring member is released from contact (flexural deformation) with the inner wall surface (elastic recovery). As shown in Figure 5(B), the toner lifted up by the stirring member 70 is ejected by the restorative force when the stirring member 70 is released from contact with the inner wall surface of the cleaner container 32.

[0094] The toner that is ejected is sent by the second part of the transport configuration to the (waste) toner storage section (not shown) on the outside of the cleaner container 32.

[0095] The second part of the transport configuration consists of a screw member 75. As shown in Figure 5B, the screw member 75 is positioned so that toner is delivered when the stirring member 70 is released.

[0096] The helical screw member 75 also rotates in conjunction with the drive of the process means. The screw member 75 also transports the toner sent from the stirring member 70 to one end of the intermediate transfer belt 13 in the direction of its rotation axis.

[0097] In this embodiment, the screw member 75 transports the toner in the depth direction shown in Figure 3, and carries it to the outside of the cleaner container 32. From there, a different transport member (not shown) is used to send the toner to the waste toner storage section (not shown).

[0098] With the transport configuration described above, the toner collected by the cleaning blade 31 is transported from the cleaning container 32 to the outside and sent to the waste toner storage section (not shown).

[0099] In this way, it is possible to prevent toner inside the cleaner container 32 from accumulating too much near the free end (upper part) of the cleaning blade 31.

[0100] Next, we will describe "Comparative Example 1" using Figures 6 to 8 for comparison with Example 1.

[0101] Figure 6 is a conceptual diagram showing the toner recovery process by the cleaning unit in Comparative Example 1 of Example 1.

[0102] Specifically, Figure 6 shows the toner recovery process using the squeegee sheet 60 and cleaning blade 31 in Comparative Example 1.

[0103] Similar to Example 1 described above, Comparative Example 1 also has a squeegee sheet 60 installed to suppress toner leakage from the cleaner container 32. As shown in Figure 6, the squeegee sheet 60 is installed in such a way that its free end 61 faces the cleaning blade 31.

[0104] Figure 7 is a conceptual diagram showing the cleaning unit in Comparative Example 1 as the agitator pushes the toner toward the squeegee sheet. Figure 8 is a conceptual diagram showing the cleaning unit in Comparative Example 1 as the toner pushed out by the agitator leaks out from the squeegee sheet and the nip portion of the belt.

[0105] Specifically, Figure 7 shows how the toner on the cleaning blade 31 is being transported by the stirring member 70. Figure 8 shows the toner falling after some time has passed since the state shown in Figure 7, having slipped through the squeegee sheet 60.

[0106] As shown in Figure 7, in Comparative Example 1, the agitator 70 transports the toner while in contact with the cleaning blade 31. When the free end 73 of the agitator 70 leaves the cleaning blade 31, the force of the agitator 70 being released causes it to flick away the toner.

[0107] In particular, when the stirring member 70 moves away from the free end of the cleaning blade 31, it forcefully ejects the toner from the non-contact end 31d of the blade towards the squeegee sheet 60. Specifically, as shown in Figure 7, when the rotating stirring member 70 moves away from the non-contact end 31 of the blade, the toner is pushed in the direction F1 (arrow direction).

[0108] At this time, since the free end 61 of the squeegee sheet is facing the direction F1 in which the toner flows, a force is generated that pushes the toner outward from the free end 61 of the squeegee sheet, as shown in Figure 8. As a result, there was a possibility that toner would leak from the free end 61 of the squeegee sheet.

[0109] Furthermore, if toner leaks from the squeegee sheet 60 of the cleaner container 32 to the outside, the toner may splatter onto the secondary transfer section, potentially contaminating the secondary transfer roller 25 or adhering to the transfer material P passing through the secondary transfer section, which could lead to image defects.

[0110] Here, the phenomenon of toner leaking out of the squeegee sheet 60 of the cleaner container 32 is called "toner dripping."

[0111] This invention focuses on the arrangement of the squeezing sheet 60 and conducts detailed studies to suppress "toner dripping" caused by toner leakage.

[0112] Specifically, the present invention reduces the amount of toner that leaks from the squeegee sheet 60 by making it less likely for the free end 61 of the squeegee sheet to receive the force that the stirring member 70 exerts toner, thereby suppressing image defects caused by toner dripping.

[0113] First, using Figure 9, we will explain the direction of the force and the flow of the toner when the stirring member 70 of Embodiment 1 of the present invention pushes out the toner.

[0114] Figure 9 is a conceptual diagram showing the positional relationship between the cleaning blade, the stirring member, and the squeegee sheet in Example 1, and the state when the stirring member is released (recovered) from the frictional state (elastic deformation state) with the cleaning blade.

[0115] Figure 9 shows minute variations in the timing of when the free end 73 of the stirring member separates from the cleaning blade 31.

[0116] As shown in Figure 9, the stirring member 70 rotates around the rotation center K (axis position) as its axis of rotation. The pushing force (toner flow) along direction K is greatest when the free end 73 of the stirring member separates from (is released from) the non-contact end 31d of the cleaning blade 31.

[0117] Figure 9 shows the state of the stirring member's free end 73 "just before" and "just after" separating from the blade's non-contact end 31d. The solid line shows the free end 73 of the stirring member "just before," and the dotted line shows it "just after."

[0118] The direction (K) in which the free end 73 of the stirring member moves from "immediately before" to "immediately after" is the tangential direction to the non-contact end 31d due to the rotational motion. That is, the direction in which the free end 73 of the stirring member moves due to the rotational motion is along a second virtual line B that is perpendicular to the first virtual line A connecting the rotation center K and the non-contact end 31d of the blade and passes through the non-contact end 31d.

[0119] Therefore, when the free end 73 of the stirring member separates from the non-contact end 31d of the blade, the direction of the force pushing out the toner will be along the imaginary line B.

[0120] Next, we will explain the difference between the configuration of Example 1 shown in Figure 9 and Comparative Example 1 shown in Figure 10.

[0121] Figure 10 is a conceptual diagram showing the positional relationship between the cleaning blade, the stirring member, and the squeegee sheet in Comparative Example 1 of Example 1.

[0122] As can be seen from the comparison between Figure 9 and Figure 10, in Embodiment 1, the free end 61 of the squeegee sheet is positioned closer to the cleaning blade 31 than the intersection point P1 (intersection position) of the imaginary line B and the belt. In other words, in Embodiment 1, in the direction of belt movement, the free end 61 of the squeegee sheet is located between the intersection point P1 and the free end of the cleaning blade 31.

[0123] On the other hand, in Comparative Example 1, the free end 61 of the squeegee sheet is further from the cleaning blade 31 than the intersection P1. In other words, in the direction of belt movement, the intersection P1 is located between the free end 61 of the squeegee sheet and the free end of the cleaning blade 31.

[0124] In other words, if the free end 61 of the squeegee sheet is far from the cleaning blade 31 with respect to the intersection P1 of the virtual line B, the force exerted by the stirring member 70 to push out the toner is more likely to act on the free end 61 of the squeegee sheet.

[0125] Therefore, in Comparative Example 1, the free end 61 of the squeegee sheet is subjected to a force that pushes out the toner, resulting in the phenomenon of toner dripping.

[0126] In this embodiment, compared to Comparative Example 1, the arrangement of the scrubbing sheet was devised to suppress toner dripping due to the force in the extrusion direction. Specifically, toner dripping occurs when the force that pushes out the toner by the stirring member 70 is applied to the free end 61 of the scrubbing sheet. Therefore, in this embodiment, the configuration makes it difficult for the force that pushes out the toner to be applied to the free end 61 of the scrubbing sheet. The free end 61 of the scrubbing sheet is placed between the intersection P1 and the free end of the cleaning blade 31 so that the force that pushes out the toner by the stirring member 70 is not directly applied to it.

[0127] Next, the "positional relationship between the cleaning blade, the stirring member, and the skiving sheet," which is a characteristic of this embodiment, will be explained using Figures 9 and 11.

[0128] Figure 11 is a conceptual diagram showing the positional relationship between the cleaning blade, the stirring member, and the skimmer sheet in Example 1. In particular, Figure 11 shows the distance (W2) between the free end of the skimmer sheet and the free end of the cleaning blade.

[0129] First, as shown in Figure 9, the force acting on the toner can be determined by drawing a virtual line B perpendicular to the virtual line A (a line perpendicular to virtual line A) with respect to the virtual line A connecting the rotation center K and the non-contact end 31d of the blade, and passing through the non-contact end 31d of the blade.

[0130] When the free end 61 of the squeegee sheet is brought closer to the cleaning blade 31 than the intersection point P1 of the virtual line B and the intermediate transfer belt 13, the cleaning blade 31 (thickness W1) acts as a wall when the toner is pushed out by the stirring member.

[0131] Therefore, when the free end 61 of the squeegee sheet is closer to the cleaning blade 31 than the intersection point P1 (see Figure 11), the force exerted by the stirring member 70 to push out the toner is reduced on the free end 61 of the squeegee sheet.

[0132] Therefore, in this embodiment, the free end 61 of the squeegee sheet is positioned closer to the cleaning blade 31 than the intersection point P1 of the imaginary line B and the intermediate transfer belt 13.

[0133] Furthermore, as shown in the first modified example of Embodiment 1 described later, when the component is positioned closer to the cleaning blade 31 than to intersection P1, it can also be positioned between intersection P1 and the free end of the cleaning blade so that it is closer to the cleaning blade than to intersection P1.

[0134] Furthermore, if the free end 61 of the squeegee sheet is too close to the cleaning blade 31 and comes into contact with the cleaning blade 31, cleaning failures or toner dripping may occur (see Comparative Example 2 described later). Therefore, in this embodiment, the squeegee sheet 60 is positioned upstream of the cleaning blade 31 in the direction of belt movement, so that the squeegee sheet 60 and the cleaning blade do not come into contact.

[0135] From the viewpoint of further suppressing the occurrence of image defects, it is preferable that the distance (W2) between the free end 61 of the squeegee sheet and the cleaning blade 31 be, for example, 50 times or more the toner size (average particle size K1) (W2 ≥ 50 × K1). More preferably, the distance (W2) should be 70 times or more the toner size.

[0136] For example, in Example 1, the toner size (average particle size) is 7 μm. Therefore, the distance (W2) between the cleaning blade and the free end 61 of the squeegee sheet can be set to 0.35 mm or more. More preferably, the distance (W2) is set to 0.49 mm or more.

[0137] Next, the first modified example of Example 1 (Experimental Example 1 and Experimental Example 2) will be described using Figure 12. Furthermore, Comparative Example 2 to Example 1 and the first modified example will be described using Figure 13.

[0138] Figure 12 is a conceptual diagram showing the tip position of the squeezing sheet in the first modified example of Example 1.

[0139] Figure 13 is a conceptual diagram showing the tip position of the squeezing sheet in Comparative Example 2 (compared to the first modified example) of Example 1.

[0140] As mentioned above, if the force of the stirring member 70 pushing out the toner brings the free end 61 of the squeegee sheet closer to the cleaning blade 31 than the intersection point P1 of the imaginary line B, the force of the stirring member 70 pushing out the toner can be reduced at the free end 61 of the squeegee sheet.

[0141] However, as shown in Figure 13, in Comparative Example 2, when the free end 61 of the squeegee sheet and the cleaning blade 31 are close enough to come into contact, the squeegee sheet 60 obstructs the toner collected by the cleaning blade 31, making it difficult for the toner to be sent into the cleaner container 32.

[0142] Therefore, as shown in Figure 13, toner may tend to accumulate in the area in front of the squeegee sheet 60 and the cleaning blade 31. In this case, there is a possibility of cleaning failure by the cleaning blade 31. Furthermore, the toner may lift the squeegee sheet 60, increasing the likelihood of toner dripping.

[0143] Furthermore, toner dripping is less likely to occur if the toner collected by the cleaning blade 31 can pass through the gap between the squeegee sheet 60 and the cleaning blade 31. In other words, as shown in the first modified example of the present invention in Figure 12, the toner dripping phenomenon can be suppressed if there is an appropriate gap (distance W2).

[0144] As shown in Comparative Example 2 in Figure 13, in a configuration where the gap is close to zero (narrow), if a large amount of toner is collected at once during recovery, the toner particles are more likely to collide with each other and have difficulty passing through the gap.

[0145] In this embodiment, the gap between the squeegee sheet 60 and the cleaning blade 31 is greater than "0" (the free end of the squeegee sheet 160 is located upstream of the free end of the cleaning blade 31), thereby suppressing the toner dripping problem.

[0146] In particular, setting the gap (distance W2) to 50 times or more the toner size (average particle size of toner particles) yields a more significant effect on the problems described above. In other words, if the average particle size of toner particles is K1, the configuration can satisfy the relationship W2 ≥ 50 × K1.

[0147] Thus, from the standpoint of further suppressing toner leakage, it is preferable to separate the squeegee sheet and the cleaning blade beyond a predetermined gap.

[0148] Thus, in this embodiment, when viewed along the rotation axis direction of the rotating shaft 71, a first virtual line A can be defined as a virtual line connecting the position of the upstream end (31d) of the second side surface 31f and the axial position K of the rotating shaft 71 in the rotation direction R2(AA) of the intermediate transfer belt. A second virtual line B can be defined as a virtual line perpendicular to the first virtual line A and passing through the position of the upstream end (31d) of the second side surface 31f. The free end 61 of the squeegee sheet 60 is positioned so that it is closer to the free end 31b of the cleaning blade 31 than to the intersection point P1 where the second virtual line B intersects the outer circumferential surface 13U of the intermediate transfer belt 13.

[0149] This makes it less likely for the free end 61 of the squeegee sheet to be subjected to the force of the stirring member 70 pushing out the toner, thereby suppressing the occurrence of toner dripping from the squeegee sheet 60.

[0150] In particular, the free end of the scrubbing sheet can be positioned so that it is away from the cleaning blade 31 at a distance W2 of 50 times the toner size. This makes it less likely for the free end 61 of the scrubbing sheet to be subjected to the force of the stirring member 70 pushing out the toner, and also further suppresses the occurrence of toner dripping from the scrubbing sheet 60.

[0151] Furthermore, in this embodiment, the cleaning blade 31 has a thickness W1 (in this embodiment, the thickness (W1) is 2 mm) at the free end 31b from the blade contact end 31c to the blade non-contact end 31d, which acts as a wall for the stirring member 70.

[0152] Therefore, the stirring member has difficulty reaching the area near the cleaning blade. It can also be said that the stirring member 70 has difficulty reaching the area within the thickness of the cleaning blade 31. Accordingly, the distance between the squeegee sheet and the cleaning blade can be set to be less than or equal to the thickness of the cleaning blade 31.

[0153] In other words, if W1 is the thickness between the first side surface 31e and the second side surface 31f of the cleaning blade 31, and W2 is the distance between the free end 61 of the squeegee sheet and the free end 31b of the cleaning blade, then the configuration can satisfy the relationship W1 ≥ W2.

[0154] Thus, in order to further suppress image defects, it is desirable to set the distance W2 between the cleaning blade and the squeegee sheet to a distance of 50 times or more the toner size, and less than or equal to the thickness W1 of the cleaning blade.

[0155] Furthermore, as shown in Figure 9, in this embodiment, the axial position K of the rotation axis 71 can be configured so that, in the orientation during use, the axial position K is above the position (31d) of the uppermost end of the second side surface 31f in the direction of gravity G. That is, in the configuration shown in Figure 9, the toner is pushed out by the stirring member 70 from above in the direction of gravity G, so the risk of image defects is considered to be higher compared to the case where there is no (or little) force from above in the direction of gravity G. In this embodiment, even with the configuration shown in Figure 9, the risk of image defects can be sufficiently reduced by arranging the free end 61 of the squeegee sheet to be closer to the free end 31b of the cleaning blade than to the intersection P1.

[0156] Furthermore, as shown in Figure 9, in this embodiment, when viewed along the rotation axis direction of the rotation axis 71, the axial position K of the rotation axis 71 can be configured to be on the same side as the squeegee sheet 60 with respect to the perpendicular line G1 that passes through the position (31c) of the most upstream end of the first side surface 31e. That is, in the configuration shown in Figure 9, the force of the stirring member 70 that pushes out the toner is directed towards the squeegee sheet 60 side rather than the free end 31b side of the cleaning blade, so it is thought that the risk of toner leakage will be higher compared to when it is not directed in this way. In this embodiment, even with the configuration shown in Figure 9, the risk of toner leakage can be sufficiently reduced by arranging the free end 61 of the squeegee sheet to be closer to the free end 31b of the cleaning blade than to the intersection P1.

[0157] Furthermore, as shown in Figure 9, in this embodiment, when viewed along the rotation axis direction of the rotation axis 71 in the orientation used, the shortest distance between the axial position K of the rotation axis 71 and the free end 61 of the squeezing sheet 60 can be defined as W3. The distance between the axial position K of the rotation axis 71 and the position of the upstream end (31c) of the first side surface 31e can be defined as W4, and the distance between the axial position K of the rotation axis 71 and the position of the upstream end (31d) of the second side surface 31f can be defined as W5. In this case, the configuration can satisfy the relationship W4 > W3 > W5.

[0158] Next, the effects of Example 1 and the first modified example will be explained in more detail by comparing them with Comparative Examples 1 and 2.

[0159] In each embodiment, modification, and comparative example of the present invention, the distance PS between "intersection P1" and "cleaning blade 31" is set to 3.5 mm.

[0160] In Comparative Example 1 shown in Figure 10, the free end 61 of the squeegee sheet is positioned further from the cleaning blade 31 than the intersection point P1 of the imaginary line B passing through the non-contact end 31d of the blade (distance W2 = 4 mm). In Comparative Example 2 shown in Figure 13, the free end 61 of the squeegee sheet and the cleaning blade 31 are in contact (distance W2 = 0).

[0161] On the other hand, in Example 1 shown in Figure 11, the free end 61 of the squeegee sheet is positioned closer to the cleaning blade 31 than the intersection P1 (Example 1, distance W2 = 2 mm). In Experiment Example 1 of the first modification (of Example 1) shown in Figure 12, the distance (W2) between the free end 61 of the squeegee sheet and the cleaning blade 31 is 0.2 mm. In Experiment Example 2 of the first modification, the distance W2 is 0.4 mm.

[0162] Compared to Comparative Examples 1 and 2, it can be seen that the toner dripping phenomenon was effectively suppressed in Example 1 and the first modified example. Table 1 shows the evaluation results.

[0163] [Table 1]

[0164] <Table 1: Relationship between the distance of the cleaning blade on the squeegee and toner dripping> ◎: No leaks were detected at all. ○: Almost no leaks were observed. △: Only minor leaks have been observed. ×: Significant leakage has been confirmed. (Cleaning blade mounting angle) Next, the mounting angle of the cleaning blade 31 in Example 1 will be explained using Figures 14 and 15.

[0165] Figure 14 shows an example of the mounting conditions for the cleaning blade in Example 1, and Figure 15 is a conceptual diagram showing another example of the mounting conditions for the cleaning blade.

[0166] As shown in Figure 14 or Figure 15, the installation angle of the cleaning blade 31 can be arbitrarily set between -45° (see Figure 14) and +45° (see Figure 15) relative to the horizontal direction in the operating position. That is, when the installation angle is between -45° and +45°, the collected toner will accumulate on the top of the cleaning blade.

[0167] In other words, in this embodiment, when viewed along the rotation axis direction of the rotating shaft 71, the intermediate transfer belt 13 is in contact with the upstream end 31c of the first side surface 31e of the cleaning blade 31 in the rotation direction (R2, AA) of the intermediate transfer belt. The angle AG between the tangent C1 of the intermediate transfer belt 13 and the horizontal line H1 at the contact point (31c) between the upstream end 31c of the first side surface 31e and the intermediate transfer belt 13 can be configured to be within 45°.

[0168] In this configuration, the agitator 70 is positioned near the cleaning blade, allowing the toner to be transported in the longitudinal direction. That is, by using the agitator 70, the accumulation of toner on the cleaning blade 31 is suppressed. This prevents the pressure on the cleaning blade 31 (relative to the belt located below) from becoming too high, thereby improving the cleaning performance of the cleaning blade 31.

[0169] Furthermore, even in the case of the leaning blade 31 configuration shown in Figure 14 or Figure 15, the position of the free end 61 of the squeegee sheet can be set in the same way as in Embodiment 1 shown in Figure 3.

[0170] In the embodiment 1 shown in Figure 3, the rotation axis 71 of the stirring member 70 is located "above and to the left" of the blade non-contact end 31d. In addition to the example shown in Figure 3, any position that allows for the removal of toner from the cleaning blade 31 is acceptable.

[0171] (Example 2) Next, Embodiment 2 of the present invention will be described with reference to Figure 16.

[0172] Figure 16 is a conceptual diagram of the main parts of the cleaning unit and belt of the image forming apparatus according to Embodiment 2 of the present invention.

[0173] As shown in Figure 16, the cleaning blade 31 has a thickness W1 equal to the free end 31b from the blade contact end 31c to the blade non-contact end 31d, which acts as a barrier for the stirring member 70. Therefore, the stirring member has difficulty reaching the area near the cleaning blade. Thus, it can be said that the stirring member 70 has difficulty reaching the area within the thickness of the cleaning blade 31.

[0174] As shown in Figure 16, in Example 2, the distance between the squeegee sheet and the cleaning blade can be less than or equal to the thickness of the cleaning blade 31.

[0175] In other words, if W1 is the thickness between the first side surface 31e and the second side surface 31f of the cleaning blade 31, and W2 is the distance between the free end 61 of the squeegee sheet 60 and the free end 31b of the cleaning blade 31, then the configuration satisfies the relationship W1 ≥ W2.

[0176] Furthermore, similar to Example 1, in order to further suppress image defects, it is desirable in Example 2 as well to set the distance W2 between the cleaning blade and the squeegee sheet to a distance of 50 times or more the toner size and less than or equal to the thickness W1 of the cleaning blade.

[0177] In other words, the image forming apparatus 100 of Example 2 includes an intermediate transfer belt 13, a cleaning blade 31, a squeegee sheet 60, and a stirring member 70.

[0178] The intermediate transfer belt is a rotatable, continuously rotating belt that carries the toner image.

[0179] The cleaning blade has a free end 31b that contacts the intermediate transfer belt in the direction of rotation of the intermediate transfer belt, extending upstream, and it collects toner from the intermediate transfer belt.

[0180] The squeegee sheet is positioned upstream of the cleaning blade 31 in the rotational direction R2(AA) of the intermediate transfer belt, and its free end 61 extends downstream and contacts the intermediate transfer belt.

[0181] The stirring member has a rotating shaft 71 that rotates in the same rotational direction R3 (=R2) as the intermediate transfer belt, and an elastically deformable stirring sheet 72 that is attached to the rotating shaft and rotates together with the rotating shaft. The stirring sheet 72 is in contact with the second side surface 31f of the cleaning blade 31, which is opposite to the first side surface 31e that is in contact with the intermediate transfer belt. The stirring sheet 72 is also able to contact the upstream end 31d of the second side surface 31f in the rotational direction R2 (AA) of the intermediate transfer belt.

[0182] The cleaning blade 31 is configured such that, when W1 is the thickness between the first side surface 31e and the second side surface 31f, and W2 is the distance between the free end 61 of the squeegee sheet and the free end 31b of the cleaning blade 31, the relationship W1 ≥ W2 is satisfied.

[0183] Example 2 achieves the same effect as Example 1. Specifically, in a configuration in which an agitator is placed near the cleaning blade and the squeegee, the leakage of toner to the outside can be reduced as the agitator rotates.

[0184] In Embodiment 2 shown in Figure 16, the rotation axis 71 of the stirring member 70 is located "above and to the left" of the blade non-contact end 31d. In addition to the example shown in Figure 16, any position that allows for the removal of toner from the cleaning blade 31 is acceptable.

[0185] In other words, any configuration that performs contact scraping on the upper part of the cleaning blade 31 is acceptable. Specifically, in Embodiment 2, the rotating shaft 71 can be positioned in the region shown in Figure 17. Figure 17 is a conceptual diagram showing the region where the rotating shaft of the stirring member can be attached in Embodiment 2. Figures 18 and 19 are conceptual cross-sectional diagrams of the cleaning unit in the first and second modified examples of Embodiment 2, respectively.

[0186] More specifically, Figure 17 shows possible positions for the rotation axis 71. On the other hand, Figure 18 or Figure 19 shows the position of the rotation axis 71.

[0187] First, as shown in Figure 17, in the operating position, "C" is a virtual line (third virtual line) that is parallel to the tangent (C1) of the intermediate transfer belt 13 at the contact end 31c (contact position) of the intermediate transfer belt 13 and passes through the non-contact end 31d of the blade.

[0188] Then, let's define "D" as a virtual line (fourth virtual line) that extends along the plane direction of the surface of the support member 34 to which the second side surface 31f of the cleaning blade 31 is fixed, and that passes through the contact point between the fixed end 31a of the cleaning blade 31 and the support member 34.

[0189] In this case, the rotation axis 71 can be positioned in the region opposite to the belt side with respect to the virtual lines "C" and "D".

[0190] In other words, when viewed in the direction of the rotation axis of the rotation axis 71, a third imaginary line C can be defined as an imaginary line that is parallel to the tangent of the intermediate transfer belt at the contact point between the cleaning blade and the intermediate transfer belt, and that passes through the upstream end 31d of the second side surface 31f. A fourth imaginary line D can be defined as an imaginary line that extends along the plane direction of the surface to which the second side surface 31f of the support member 34 that supports the cleaning blade 31 is fixed, and that passes through the contact point between the fixed end 31a of the cleaning blade 31 and the support member 34. The rotation axis 71 can be positioned in the region opposite to the intermediate transfer belt side with respect to the third and fourth imaginary lines.

[0191] In other words, as shown in Figures 18 and 19, when the rotation axis 71 of the stirring member 70 is positioned within the "rotation axis possible region," it becomes easier to realize a configuration in which the free end 73 of the stirring member 70 rotates while rubbing against the second side surface 31f of the cleaning blade 31. This allows for efficient toner transport and increases the design flexibility of the stirring member.

[0192] As shown in Figure 18, in the first modified example of Embodiment 2, when viewed along the rotation axis direction of the rotation axis 71 in the orientation used, a perpendicular line (G1) can be set that passes through the position (31c) of the most upstream end of the first side surface (31e). Then, the axial center position (K) of the rotation axis 71 can be configured to be on the same side as the squeezing sheet 60 with respect to the perpendicular line (G1).

[0193] On the other hand, as shown in Figure 19, in the second modified example of Embodiment 2, when viewed along the rotation axis direction of the rotation axis 71 in the orientation used, a perpendicular line (G1) can be set that passes through the position (31c) of the upstream end of the first side surface (31e). The axial center position (K) of the rotation axis 71 may be configured to be on the opposite side of the squeezing sheet 60 with respect to the perpendicular line (G1).

[0194] As mentioned above, when the stirring member 70 rubs against the second side surface 31f of the cleaning blade 31 and separates from the non-contact end 31d of the blade during rotation, toner may be pushed out. In this implementation, by positioning the rotating shaft 71 in the "rotating shaft possible region," even when the scrubbing sheet rubs against the second side surface 31f of the cleaning blade 31, the flow of toner pushed out by the stirring member toward the free end 61 of the scrubbing sheet can be reduced. As a result, toner leakage can be suppressed.

[0195] The present invention can be summarized as follows.

[0196] (1) The image forming apparatus of the present invention is A rotatable image carrier (13) that holds the developer image, In the rotational direction (AA) of the image carrier, the free end (31b) that contacts the image carrier extends upstream, and the blade member (31) collects the developer on the image carrier. In the rotational direction of the image carrier, the sheet member (60) is located upstream of the blade member (31), and its free end (61) extends downstream and contacts the image carrier. The device includes a stirring member (70) having a shaft portion (71) that rotates in the same rotational direction as the image carrier, and an elastically deformable sheet portion (72) attached to the shaft portion that rotates together with the shaft portion.

[0197] The sheet portion (72) is in contact with the second side surface (31f) of the blade member (31), which is opposite to the first side surface (31e) that is in contact with the image carrier. When viewed along the rotational axis direction of the shaft, in the rotational direction of the image carrier, when the position of the uppermost end (31d) of the second side surface (31f) and the axial position (K) of the shaft (71) are connected by the first imaginary line (A), A second imaginary line (B), which is perpendicular to the first imaginary line and passes through the position of the most upstream end of the second side surface (31f), positions the free end (61) of the sheet member closer to the free end of the blade member than the intersection point (P1) where it intersects the outer surface (13U) of the image carrier.

[0198] (2) In the image forming apparatus of the present invention, If W1 is the thickness between the first side surface (31e) and the second side surface (31f) of the blade member (31), and W2 is the distance between the free end (61) of the sheet member and the free end (31b) of the blade member, the configuration may satisfy the relationship W1 ≥ W2.

[0199] (3) Other image forming apparatuses of the present invention are A rotatable image carrier (13) that holds the developer image, In the rotational direction of the image carrier, the free end (31b) that contacts the image carrier extends upstream, and the blade member (31) collects the developer on the image carrier. In the rotational direction of the image carrier, the sheet member (60) is located upstream of the blade member (31), and its free end (61) extends downstream and contacts the image carrier. The device includes a stirring member (70) having a shaft portion (71) that rotates in the same rotational direction as the image carrier, and an elastically deformable sheet portion (72) attached to the shaft portion that rotates together with the shaft portion.

[0200] The sheet portion (72) is in contact with the second side surface (31f) of the blade member (31), which is opposite to the first side surface (31e) on the side that contacts the image carrier, and is capable of contacting the upstream end (31d) of the second side surface in the rotational direction of the image carrier. Let W1 be the thickness between the first side surface (31e) and the second side surface (31f) of the blade member (31). When the distance between the free end (61) of the sheet member and the free end (31b) of the blade member is W2, the configuration satisfies the relationship W1 ≥ W2.

[0201] (4) The image forming apparatus of the present invention may be configured such that when the average particle size of the developer is K1, the relationship W2 ≥ 50 × K1 is satisfied.

[0202] (5) In the image forming apparatus of the present invention, the axial center position (K) of the shaft portion may be configured to be above the position (31d) of the uppermost end of the second side surface (31f) in the direction of gravity (G) when in use.

[0203] (6) In the image forming apparatus of the present invention, In the orientation used, when viewed along the rotational axis direction of the shaft, the axial center position (K) of the shaft may be configured to be on the same side as the sheet member (60) with respect to a perpendicular line (G1) passing through the position (31c) of the most upstream end of the first side surface (31e).

[0204] (7) In the image forming apparatus of the present invention, When viewed along the rotation axis direction of the shaft in the position used, Let W3 be the shortest distance between the axial center position (K) of the shaft and the free end of the sheet member. When W4 is the distance between the axial center position (K) of the shaft and the position (31c) of the uppermost end of the first side surface (31e), Let W5 be the distance between the axial center position (K) of the shaft and the position (31d) of the uppermost end of the second side surface (31f). The configuration may also satisfy the relationship W4 > W3 > W5.

[0205] (8) In the image forming apparatus of the present invention, When viewed along the rotational axis direction of the shaft, in the rotational direction of the image carrier, The uppermost end (31c) of the first side surface (31e) of the blade member (31) is in contact with the image carrier (13). The angle (AG) between the tangent line (C1) of the image carrier and the horizontal line (H1) at the point of contact (31c) between the uppermost end (31c) of the first side surface (31e) and the image carrier (13) may be configured to be within 45°.

[0206] (9) In the image forming apparatus of the present invention, the image carrier (13) may be composed of an intermediate transfer belt.

[0207] (others) In the image forming apparatus of the present invention, When viewed along the rotational axis of the shaft, A third imaginary line (C) is defined as an imaginary line that is parallel to the tangent to the image carrier at the contact point between the blade member (31) and the image carrier (13), and that passes through the upstream end (31d) of the second side surface (31f). When the fourth imaginary line (D) is defined as an imaginary line that extends along the plane direction of the surface to which the second side surface (31f) of the support member (34) supporting the blade member (31) is fixed, and that passes through the contact point between the fixed end (31a) of the blade member (31) and the support member (34), The axis portion (71) may be positioned in the region opposite to the image carrier side with respect to the third and fourth virtual lines. [Explanation of symbols]

[0208] 13. Intermediate transfer belt (image carrier) Outer surface of 13U intermediate transfer belt 31 Cleaning blade (blade component) 31b Free end of the cleaning blade 31e Cleaning blade, first side 31f Cleaning blade, second side 31d Blade non-contact end (the upstream end of the second side) 60 Squeegee Sheet (Sheet Material) 61 Free end of the squeezing sheet 70 Stirring member 71. Rotating shaft (shaft part) 72. Stirring sheet (sheet portion) A First virtual line B. Second virtual line K: Axis position of the rotation axis P1 Intersection point (crossing position) AA Intermediate transfer belt surface movement direction (rotation direction R2)

Claims

1. A rotatable image carrier that holds the developer image, In the rotational direction of the image carrier, the free end that contacts the image carrier extends upstream, and the blade member collects the developer on the image carrier. A sheet member is located upstream of the blade member in the rotational direction of the image carrier, and its free end extends downstream and contacts the image carrier. An image forming apparatus having a stirring member having a shaft portion that rotates in the same rotational direction as the image carrier and an elastically deformable sheet portion attached to the shaft portion that rotates together with the shaft portion, The sheet portion is in contact with the second side surface of the blade member, which is opposite to the first side surface that is in contact with the image carrier. When viewed along the rotation axis direction of the shaft portion, in the rotation direction of the image carrier, when the position of the upstream end of the second side surface and the axial position of the shaft portion are connected by a first imaginary line, An image forming apparatus characterized in that the free end of the sheet member is positioned such that a second virtual line, which is perpendicular to the first virtual line and passes through the position of the most upstream end of the second side surface, is closer to the free end of the blade member than the intersection point where the second virtual line intersects the outer circumferential surface of the image carrier.

2. The thickness of the blade member between the first side surface and the second side surface is defined as W1. When the distance between the free end of the sheet member and the free end of the blade member is W2, The image forming apparatus according to claim 1, characterized in that it satisfies the relationship W1 ≥ W2.

3. When the average particle size of the developer is K1, The image forming apparatus according to claim 2, characterized in that it satisfies the relationship W2 ≥ 50 × K1.

4. The image forming apparatus according to any one of claims 1 to 3, characterized in that, in the orientation used, the axial center position of the shaft portion is above the position of the most upstream end of the second side surface in the direction of gravity.

5. When viewed along the rotation axis direction of the shaft portion in the orientation used, With respect to the perpendicular line passing through the position of the most upstream end of the first side surface, The image forming apparatus according to claim 4, characterized in that the axial center position of the shaft portion is on the same side as the sheet member.

6. When viewed along the rotation axis direction of the shaft portion in the orientation used, Let W3 be the shortest distance between the axial position of the shaft and the free end of the sheet member. When W4 is the distance between the axial center position of the shaft portion and the position of the most upstream end of the first side surface, Let W5 be the distance between the axial position of the shaft portion and the position of the most upstream end of the second side surface. The image forming apparatus according to claim 5, characterized in that it satisfies the relationship W4 > W3 > W5.

7. When viewed along the rotation axis direction of the aforementioned shaft portion, in the rotation direction of the image carrier, The image carrier is in contact with the upstream end of the first side surface of the blade member. The image forming apparatus according to any one of claims 1 to 6, characterized in that the angle between the tangent to the image carrier at the point of contact between the most upstream end of the first side surface and the image carrier and the horizontal line is within 45°.

8. The image forming apparatus according to any one of claims 1 to 7, characterized in that the image carrier is an intermediate transfer belt.

Images