JP2015230474A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device that supplies an appropriate amount of toner to an abutting part of a cleaning blade cleaning a moving body and the moving body, and can sufficiently reduce friction of the abutting part.SOLUTION: An image formation device 10 comprises: a first image carrier 22c; a second image carrier 22d; a movable moving body 30; a cleaning blade 35; and a control unit 100, in which the second image carrier 22d is configured to be locate on a downstream side of the first image carrier 22c in a movement direction of the moving body 30. The control unit 100 is configured to: cause the first image carrier 22c to form a prescribed toner image, and statically transfer the formed prescribed toner image transferred to the moving body 30 to the moving body 30; cause the second image carrier 22d to statically recover one part of toner of the formed prescribed toner image; and cause a movement of the moving body 30 to execute a toner supply operation of supplying toner of the prescribed toner image not recovered by the second image carrier 22d and left behind in the moving body 30 to an abutting part B of the cleaning blade 35 and the moving body 30.

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, or a facsimile apparatus using an electrophotographic system or an electrostatic recording system.

  2. Description of the Related Art Conventionally, for example, in an electrophotographic image forming apparatus, a cleaning blade method has been widely used as a method for removing deposits such as transfer residual toner from a moving body such as an intermediate transfer member or a recording material carrier. In this method, for example, a cleaning blade made of urethane rubber or the like is brought into contact with an intermediate transfer belt serving as an intermediate transfer member, so that deposits such as transfer residual toner are physically scraped from the surface of the moving intermediate transfer belt. take.

  In the cleaning blade method, residual toner or the like is stably present in the contact portion between the cleaning blade and the intermediate transfer belt (hereinafter also simply referred to as “blade contact portion”), thereby reducing friction and stability. Cleaning performance is realized.

  However, due to the friction between the intermediate transfer belt and the cleaning blade, the tip of the cleaning blade may be chipped to cause a cleaning failure, or the cleaning blade may be turned over or abnormal noise may be generated. . For example, this is the case. The first is a case where the friction of the blade contact portion becomes larger than that in the normal environment such as in a high temperature and high humidity environment. The second case is a case where image formation with a low printing rate is continuously performed and the toner interposed in the blade contact portion is exhausted. Third, in the first place, a new belt unit in which toner is not present at the blade contact portion is used.

  In order to solve this problem, it is possible to reduce the friction of the blade contact portion by forming a toner image of a predetermined pattern on the intermediate transfer belt by the image forming means and periodically feeding the toner to the blade contact portion. It has been proposed (Patent Document 1).

JP 2007-25244 A

  However, the cleaning performance is unstable under a situation where the friction between the intermediate transfer belt and the cleaning blade is increased. For this reason, if a large amount of toner such as a solid image is sent all at once to the blade contact portion, some toner may slip through the blade contact portion.

  On the other hand, in order to suppress such toner slipping, it is conceivable to form an image with a low density so as to reduce the amount of toner sent to the blade contact portion. However, for example, when a low-density image is formed using a halftone screen, the following problem may occur.

  FIG. 10A shows an enlarged toner image when an image using a halftone screen formed on a photoconductor is primarily transferred to an intermediate transfer belt. In a low density image using a halftone screen, a portion where toner is present and a portion where toner is not present are bipolar. For example, a schematic diagram of the A-A ′ cross section in FIG. 10A is as shown in FIG.

  When the toner image having such a pattern is used for reducing the friction of the blade contact portion, the toner supply to the blade contact portion becomes intermittent. For this reason, the tip of the cleaning blade may be chipped while a portion to which toner is not transferred passes through the blade contact portion. Even in the case of an image using a halftone screen, the above-described phenomenon is less likely to occur if the interval between toners entering the blade contact portion is sufficiently small. However, conditions can change due to various factors such as the material of the cleaning blade and the intermediate transfer belt, the properties of the toner, etc., so that the toner can be supplied sufficiently while suppressing the above-mentioned phenomenon by simply setting the interval. Is difficult. Therefore, a new method for supplying an appropriate amount of toner to the blade contact portion is desired.

  In the above, the conventional problem has been described by taking the case where the moving body is an intermediate transfer body as an example, but the same problem may occur when the moving body is a recording material carrier.

  Therefore, an object of the present invention is to form an image by which an appropriate amount of toner is supplied to the contact portion between the cleaning blade for cleaning the moving body and the moving body, and the friction at the corresponding contact portion can be sufficiently reduced. Is to provide a device.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the main configuration of the present invention is that a first image carrier that carries a toner image, a second image carrier that carries a toner image, and a toner from the first and second image carriers. A movable body that conveys a recording material on which toner is transferred or toner is transferred from the first and second image carriers, and a cleaning that contacts the movable body and removes toner from the movable body A blade, and a control unit, wherein the second image carrier is positioned downstream of the first image carrier in the moving direction of the movable body. A predetermined toner image is formed on the first image carrier, and the predetermined toner image formed on the first image carrier is electrostatically transferred to the moving body and transferred to the moving body. Part of the toner of the predetermined toner image is electrostatically collected on the second image carrier. And supplying the toner of the predetermined toner image remaining on the moving body without being collected by the second image carrier to the contact portion between the cleaning blade and the moving body by the movement of the moving body An image forming apparatus that performs a supply operation.

  Another main configuration of the present invention is a movable movable body constituting an image carrier that carries a toner image and an intermediate transfer member for transferring toner transferred from the image carrier to a recording material. An image forming apparatus including: a transfer member that transfers toner from the moving body to a recording material; a cleaning blade that contacts the moving body and removes toner from the moving body; and a control unit. Forming a predetermined toner image on the image carrier, electrostatically transferring the predetermined toner image formed on the image carrier to the moving body, and transferring the predetermined toner image transferred to the moving body. A part of the toner of the toner image is electrostatically collected by the transfer member, and the toner of the predetermined toner image remaining on the moving body without being collected by the transfer member is moved by the movement of the moving body. And the above An image forming apparatus, characterized in that to perform the toner supply operation for supplying the contact portion between the body.

  According to the present invention, it is possible to supply an appropriate amount of toner to the contact portion between the cleaning blade for cleaning the moving body and the moving body, and to sufficiently reduce the friction at the contact portion.

1 is a schematic cross-sectional view of an image forming apparatus. It is a typical sectional view of a belt cleaning device. 3 is a control block diagram of a main part of the image forming apparatus. FIG. FIG. 6 is a schematic diagram around an intermediate transfer belt for explaining a toner supply operation. FIG. 4 is a schematic cross-sectional view of a toner image on an intermediate transfer belt that enters a blade contact portion. FIG. 6 is an enlarged view of a residual toner image on an intermediate transfer belt supplied to a blade contact portion by a toner supply operation. FIG. 10 is a control block diagram of a main part of another example of the image forming apparatus. FIG. 10 is a flowchart until execution of a toner supply operation in another example of the image forming apparatus. FIG. 10 is a schematic diagram around an intermediate transfer belt for explaining a toner supply operation in another example of the image forming apparatus. FIG. 4 is an enlarged view and a schematic cross-sectional view of an image using a halftone screen on an intermediate transfer belt.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
1. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 according to the present exemplary embodiment is a laser beam printer that employs an intermediate transfer method and a tandem method (four drum system) capable of forming a full-color image using an electrophotographic method.

  The image forming apparatus 10 includes first, second, third, and fourth stations Sa, Sb, Sc, and Sd as a plurality of stations (image forming units). Each station Sa, Sb, Sc, Sd forms an image of each color of yellow (Y) magenta (M), cyan (C), and black (Bk).

  In this embodiment, the basic configurations and operations of the stations Sa, Sb, Sc, and Sd are substantially the same except that the color of the toner used is different. Therefore, hereinafter, unless there is a particular need to distinguish, elements a, b, c, d at the end of the reference numerals indicating any color element will be omitted, and the elements will be described collectively.

  The station S includes a photosensitive drum 22 that is a drum-type (cylindrical) electrophotographic photosensitive member (photosensitive member) as an image carrier that supports a toner image. The photosensitive drum 22 is rotationally driven in the direction of arrow D2 in the figure. The following units are arranged around the photosensitive drum 22 in order along the rotation direction. First, a charging roller 23 that is a roller-shaped charging member as a charging unit is disposed. Next, an exposure apparatus (laser scanner unit) 20 as an exposure unit is arranged. Next, a developing device 25 as a developing unit is arranged. Next, a primary transfer roller 26 which is a roller-shaped primary transfer member as a primary transfer unit is disposed. Next, a drum cleaning device 28 is disposed as an image carrier cleaning means for cleaning the image carrier.

  Further, the image forming apparatus 10 includes an intermediate transfer composed of an endless belt as an intermediate transfer member so as to contact all of the photosensitive drums 22a, 22b, 22c, and 22d of the stations Sa, Sb, Sc, and Sd. A belt 30 is disposed. The intermediate transfer belt 30 is an example of a movable movable body to which toner is transferred from an image carrier. The intermediate transfer belt 30 is wound (stretched) in a state where a predetermined tension is applied to a tension roller 31, a driving roller 32, and a secondary transfer counter roller 33 as a plurality of stretching rollers. The intermediate transfer belt 30 rotates (circulates) in the direction of arrow D1 in the drawing when the driving roller 32 is driven to rotate. On the inner peripheral surface (back surface) side of the intermediate transfer belt 30, the above-described primary transfer rollers 26 are disposed at positions facing the respective photosensitive drums 22. The primary transfer roller 26 is urged (pressed) to the photosensitive drum 22 with a predetermined pressure via the intermediate transfer belt 30, and a primary transfer portion (primary transfer portion) where the intermediate transfer belt 30 and the photosensitive drum 22 come into contact with each other. Transfer nip) N1 is formed. Further, on the outer peripheral surface (front surface) side of the intermediate transfer belt 30, a secondary transfer roller 27 that is a roller-like secondary transfer member as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 33. Has been. The secondary transfer roller 27 is biased (pressed) to the secondary transfer counter roller 33 via the intermediate transfer belt 30 with a predetermined pressure, and the secondary transfer roller 30 and the secondary transfer roller 27 are in contact with each other. A transfer portion (secondary transfer nip) N2 is formed. A belt cleaning device 34 as an intermediate transfer member cleaning unit for cleaning the intermediate transfer member is disposed at a position facing the tension roller 31 on the outer peripheral surface side of the intermediate transfer belt 30. In this embodiment, the intermediate transfer belt 30 supported by the stretching rollers 31, 32, 33, the belt cleaning device 34, and each primary transfer roller 26 are integrally unitized to form an image forming apparatus 100. A belt unit 39 that can be attached to and detached from the apparatus main body is configured. The belt unit 39 is replaced with a new one when the intermediate transfer belt 30 reaches the end of its life.

  In the image forming process, the recording material P fed out from the cassette 12 by the pickup roller 13 is first transported at a position where the front ends slightly pass through the pair of transport rollers 64 and 65 after the front end position is detected by the registration sensor 14. Stopped.

  On the other hand, an exposure apparatus 20 including a reflection mirror and a laser diode (light emitting element) irradiates a rotationally driven photosensitive drum 22 with a laser beam 21 according to image information of component colors corresponding to each station S. . At this time, the photosensitive drum 22 is charged in advance by the charging roller 23. A voltage of, for example, -1200 V is applied to the charging roller 23 as a charging bias (charging voltage), whereby the surface of the photosensitive drum 22 is charged to, for example, -700 V. By irradiating the charged surface of the photosensitive drum 22 with the laser light 21, an electrostatic latent image (electrostatic latent image) is formed on the photosensitive drum 22. At this time, the potential of the portion of the photosensitive drum 22 irradiated with the laser light 21 is, for example, −100V.

  The electrostatic latent image formed on the photosensitive drum 22 is developed (visualized) by the developing device 25 using toner as a developer. For example, a voltage of −350 V is applied as a developing bias (developing voltage) to the developing sleeve 24 as a developer carrying member in the developing device 25. As a result, toner is supplied to the electrostatic latent image exposure portion of the photosensitive drum 22 to form a toner image on the photosensitive drum 22. In this embodiment, the charging polarity (normal charging polarity) of the toner during development is negative. In this way, the developing device 25 is charged with the charged polarity of the photosensitive drum 22 (in this embodiment, the negative polarity) on the exposed portion of the photosensitive drum 22 where the absolute value of the potential is reduced by exposure after being uniformly charged. The toner image is formed by reversal development in which a toner charged with the same polarity as that of the toner is attached.

  The toner image formed on the photosensitive drum 22 is transferred (primary transfer) to the intermediate transfer belt 30 by the action of the primary transfer roller 26 in the primary transfer portion N1. At this time, the primary transfer roller 26 is supplied with direct current having a polarity opposite to the normal charging polarity of the toner as a primary transfer bias (primary transfer voltage) from a primary transfer power source 51 (FIG. 3) as an application unit. For example, a voltage of +1000 V is applied. For example, when forming a full-color image, the toner images formed on the respective photosensitive drums 22 at the first, second, third, and fourth stations Sa, Sb, Sc, and Sd are superimposed on the intermediate transfer belt 30. Thus, the images are sequentially transferred. In this embodiment, primary transfer power supplies 51a, 51b, 51c, and 51d are provided corresponding to the stations Sa, Sb, Sc, and Sd, respectively. As a result, the polarity and value of the voltage applied to each primary transfer roller 26 at each station Sa, Sb, Sc, Sd can be controlled independently.

  Toner remaining on the photosensitive drum 22 without being transferred to the intermediate transfer belt 30 (primary transfer residual toner) is removed from the photosensitive drum 22 by the drum cleaning device 28 and collected. The drum cleaning device 28 scrapes off the primary transfer residual toner from the surface of the rotating photosensitive drum 22 by a cleaning blade as a cleaning member in contact with the photosensitive drum 22 and collects it in a waste toner container.

  The toner image transferred to the intermediate transfer belt 30 is conveyed by the intermediate transfer belt 30 to the secondary transfer portion N2. At this time, the conveyance of the recording material P toward the secondary transfer portion N2 is resumed so that the timing coincides with the toner image on the intermediate transfer belt 30. The toner image on the intermediate transfer belt 30 is transferred onto the recording material P that is nipped and conveyed by the secondary transfer roller 27 and the intermediate transfer belt 30 by the action of the secondary transfer roller 27 in the secondary transfer portion N2. (Secondary transfer). At this time, the secondary transfer roller 27 receives a direct current having a polarity opposite to the normal charging polarity of the toner as a secondary transfer bias (secondary transfer voltage) from a secondary transfer power source 52 (FIG. 3) as an application unit. A voltage is applied. For example, when a full color image is formed, a multiple toner image obtained by superimposing four color toner images on the intermediate transfer belt 30 is collectively transferred onto the recording material P.

  The recording material P onto which the toner image has been transferred is then conveyed to the fixing device 78, where it is heated and pressurized in the process of being nipped and conveyed by the fixing roller pair 76 and 77, and the toner image is heated and fixed thereon. Is done. Thereafter, the recording material P is discharged (output) to the outside (outside the apparatus) of the main body of the image forming apparatus 10.

  Toner remaining on the intermediate transfer belt 30 without being transferred to the recording material P (secondary transfer residual toner) is removed from the intermediate transfer belt 30 by the belt cleaning device 34 and collected. As will be described in detail later, the belt cleaning device 34 scrapes off the secondary transfer residual toner from the surface of the moving intermediate transfer belt 30 by a cleaning blade 35 as a cleaning member that contacts the intermediate transfer belt 30, and a waste toner container. Recover to 36.

  In the present embodiment, the secondary transfer roller 27 is between a first position (contact position) where the secondary transfer roller 27 is in contact with the intermediate transfer belt 30 and a second position (separation position) where the secondary transfer roller 27 is separated from the intermediate transfer belt 30. It is possible to move with. The image forming apparatus 10 includes a separation mechanism 29 for separating and contacting the secondary transfer roller 27 with respect to the intermediate transfer belt 30.

2. Belt Cleaning Device Next, the belt cleaning device 34 will be described. FIG. 2 is a schematic cross-sectional view of the belt cleaning device 34.

  The belt cleaning device 34 includes a cleaning blade 35, a waste toner container 36, a scoop sheet 37, and a support member 38.

  The cleaning blade 35 is a plate-like member that is long in one direction and is molded with urethane rubber, which is an example of a rubber material as an elastic body, to a thickness of 2 mm. The cleaning blade 35 extends along a direction (hereinafter, also referred to as “thrust direction”) in which one side in the longitudinal direction of the two sides that are substantially perpendicular to each other is substantially perpendicular to the belt conveyance direction. The end side contacts the intermediate transfer belt 30. The cleaning blade 35 is bonded and fixed to the support member 38. The support member 38 is fixed to the waste toner container 36 with screws. As a result, the tip of the cleaning blade 35 is in contact with the moving direction of the intermediate transfer belt 30 in the counter direction at a predetermined contact angle θ and intrusion amount δ. In other words, in this embodiment, the cleaning blade is attached to the intermediate transfer belt 30 such that the free end is upstream of the fixed transfer end connected to the support member 38 in the short direction. Abutted.

  In the present embodiment, the contact angle θ of the cleaning blade 35 is set to 24 °, the penetration amount δ is set to 1.5 mm, and the contact pressure is set to 0.6 N / cm. Here, the contact angle θ corresponds to the tangent line of the tension roller 31 at the intersection of the intermediate transfer belt 30 and the cleaning blade 35 (more specifically, the end surface on the free end side) and the cleaning blade 35 (more specifically, the thickness thereof). The angle formed by one surface substantially perpendicular to the vertical direction). Further, the intrusion amount δ is the length in the thickness direction in which the cleaning blade 35 overlaps the tension roller 31. Further, the contact pressure is defined by the pressing force (linear pressure in the longitudinal direction) from the cleaning blade 35 at the blade contact portion B, and a film type pressure measurement system (trade name: PINCH, manufactured by Nitta Corporation) is used. Measured.

  The rake sheet 37 is formed by cutting a sheet material of polyethylene terephthalate resin having a thickness of 20 to 50 μm. The tip portion of the rake sheet 37 is in contact with the intermediate transfer belt 30 so as to be in the forward direction with respect to the moving direction of the intermediate transfer belt 30, and the toner collected by the cleaning blade 35 is scattered to the outside again. Suppress.

  Here, as described above, in the new belt unit 39, toner as a lubricant is not present in the blade contact portion B. For this reason, when the intermediate transfer belt 30 moves in the initial initialization operation, the above-described phenomenon may occur due to friction between the surface of the intermediate transfer belt 30 and the cleaning blade 35. That is, the tip of the cleaning blade 35 may be chipped, the cleaning blade may be turned over, or abnormal noise may be generated. Here, the initial initializing operation is a preparatory operation performed after the new belt unit 39 is mounted on the main body of the image forming apparatus 10 until the first image formation is performed. In this initial initialization operation, an operation involving rotation of the intermediate transfer belt 30 is performed in order to detect the circumference of the intermediate transfer belt 30, registration detection, density detection, and the like.

  Therefore, in this embodiment, as will be described in detail below, a toner supplying operation for supplying toner to the intermediate transfer belt 30 and supplying it to the blade contact portion B when it is detected that the belt unit 30 is new. Execute.

3. Control Mode FIG. 3 shows a schematic control mode of the main part of the image forming apparatus 10 of the present embodiment. The control unit 100 provided in the image forming apparatus 10 includes a CPU that is a central element that performs arithmetic processing, a memory such as a ROM and a RAM that are storage elements, and the like. The RAM stores sensor detection results, calculation results, and the like, and the ROM stores control programs, data tables obtained in advance, and the like. In the present embodiment, the control unit 100 includes the primary transfer power supply 51 (51a, 51b, 51c, 51d), the secondary transfer power supply 52, the separation mechanism 29 of the secondary transfer roller 27, and the like. Overall control. Further, the control unit 100 reads information indicating whether or not the belt unit 39 is new, which is stored in a memory tag 40 as new article detection means provided in the belt unit 39, and supplies toner to be described later according to the information. Run the action.

4). Toner Supply Operation Next, a toner supply operation for supplying toner to the blade contact portion B by attaching toner to the intermediate transfer belt 30 in this embodiment will be described.

  In this embodiment, the control unit 100 causes the following toner supply operation to be executed. First, a predetermined toner image is formed on the first photosensitive drum 22c among the plurality of photosensitive drums 22, and the predetermined toner image formed on the first photosensitive drum 22c is electrostatically transferred to the intermediate transfer belt 30. . In addition, a part of the toner of the predetermined toner image transferred to the intermediate transfer belt 30 is disposed on the downstream side of the first photosensitive drum 22 c in the moving direction of the intermediate transfer belt 30 among the plurality of photosensitive drums 22. The photosensitive drum 22d is electrostatically recovered. Then, the toner of a predetermined toner image remaining on the intermediate transfer belt 30 without being collected on the second photosensitive drum 22d is supplied to the contact portion B between the cleaning blade 35 and the intermediate transfer belt 30 by the movement of the intermediate transfer belt 30. To do. In this embodiment, a belt unit 39 including the intermediate transfer belt 30 and the cleaning blade 35 is detachable from the apparatus main body of the image forming apparatus 10. Then, when the belt unit 39 is replaced with a new one, the control unit 100 executes a toner supply operation before the first image formation is performed. This will be described in more detail below.

  In the present embodiment, detection of whether or not the belt unit 39 is new is performed based on information in the memory tag 40 provided in the belt unit 39. When the belt unit 39 is used, the control unit 100 records the usage history of the belt unit 39 in the memory tag 40. The control unit 100 determines whether or not the belt unit 39 is new based on the presence or absence of the use history of the belt unit 39 recorded in the memory tag 40. The control unit 100 always reads the information of the memory tag 40 when the belt unit 39 is attached to the apparatus main body, determines that the belt unit 39 is new when there is no use history, and executes the toner supply operation. Let

  FIG. 4 is a schematic diagram around the intermediate transfer belt 30 for explaining the toner supply operation in the present embodiment. In the toner supply operation, first, as shown in FIG. 4A, for example, in the third station Sc, a toner image satisfying requirements of a predetermined length and a predetermined width (to be described later in detail) (hereinafter referred to as “supply toner image”). Also, I1 is formed and transferred to the intermediate transfer belt 30. At this time, the primary transfer roller 26c of the third station Sc receives a DC voltage having a polarity opposite to the normal charging polarity of the toner from the primary transfer power source 51c, for example, +1000 V, as in normal image formation. Apply a voltage of.

  Here, as the supply toner image formed on the intermediate transfer belt 30 in the toner supply operation, it is preferable to use a solid image instead of an image using a halftone screen. A solid image is an image in which toner is placed on all the drawable dots within a predetermined range.

  FIG. 5 is a schematic cross-sectional view at an arbitrary position in the thrust direction of the intermediate transfer belt 30 in the vicinity of the blade contact portion B, and shows how toner on the intermediate transfer belt 30 enters the blade contact portion B. Show. FIG. 5A shows a state in which an image using a halftone screen enters, and FIG. 5B shows a state in which a uniform solid image enters. In this embodiment, the shape of the intermediate transfer belt 30 in the vicinity of the blade contact portion B is a curved surface along the tension roller 31. However, for convenience of explanation, the intermediate transfer belt 30 is shown as a flat surface here. ing.

  When an image using a halftone screen enters the blade contact portion B, the toner distribution is as shown in FIG. 10A, and the toner is unevenly distributed. For this reason, as shown in FIG. 5A, the unevenly distributed portion T of toner and the gap portion G between them enter the blade contact portion B alternately. When the unevenly distributed portion T of toner enters the blade contact portion B, the toner functions as a lubricant and is sequentially scooped up by the cleaning blade 35 and then collected in the waste toner container 36. On the other hand, when the gap portion G enters the blade contact portion B, in a normal state, the sliding action between the intermediate transfer belt 30 and the cleaning blade 35 is caused by the lubricating action of the toner that has just entered the blade contact portion B. Performed smoothly. However, in the new belt unit 39, the contact state of the cleaning blade 35 with the intermediate transfer belt 30 is unstable, and a sufficient effect cannot be obtained only by the lubricating action of the toner that has entered the blade contact portion B immediately before. Sometimes. Therefore, even when the toner is supplied at a small interval such as the pitch of the halftone screen, the friction between the intermediate transfer belt 30 and the cleaning blade 35 may increase in the gap portion G between them. As a result, the tip of the cleaning blade 35 may be chipped, the cleaning blade 35 may be turned over, or abnormal noise may be generated.

  On the other hand, when a solid image is formed on the intermediate transfer belt 30 and a large amount of toner in the solid image enters the blade contact portion B as it is, the force for the toner to enter the blade contact portion B is increased. It gets too big. For this reason, a large amount of toner slips through the unstable blade contact portion B of the new belt unit 39, which may impair the cleaning performance during image formation and cause image defects.

  Therefore, in this embodiment, as shown in FIG. 4B, a part of the toner of the supply toner image transferred to the intermediate transfer belt 30 by the primary transfer portion N1c of the third station Sc is transferred to the fourth station Sd. In the primary transfer portion N1d, the photosensitive drum 22d collects the toner. In this embodiment, when the supply toner image I1 on the intermediate transfer belt 30 passes through the primary transfer portion N1d of the fourth station Sd, the following voltage is applied to the primary transfer roller 26d of the fourth station Sd. Apply. That is, a voltage of, for example, -1300 V, which is a DC voltage having the same polarity as the normal charging polarity of the toner (opposite polarity during normal image formation), is applied from the primary transfer power supply 51d. As a result, a part of the toner of the supply toner image I1 is transferred to the photosensitive drum 22d of the fourth station Sd and collected. In the drawing, I1L represents a toner image remaining on and adhered to the intermediate transfer belt 30 (hereinafter also referred to as “residual toner image”), and I1C represents toner collected on the photosensitive drum 22d. The toner collected on the photosensitive drum 22d is removed from the photosensitive drum 22d and collected by the drum cleaning device 28d.

  FIG. 6 shows the residual toner image I1L on the intermediate transfer belt 30 in an enlarged manner. The residual toner image I1L on the intermediate transfer belt 30 has a reduced toner amount and a low density by collecting a part of the toner in the supply toner image I1. However, the toner (I1C) is uniformly collected on the photosensitive drum 22d by the action of the electric field formed on the primary transfer portion N1d from the supply toner image I1 that is a uniform solid image formed on the intermediate transfer belt 30. The Therefore, the residual toner image I1L on the intermediate transfer belt 30 is also thin and uniform without toner being unevenly distributed, unlike the image using the halftone screen shown in FIG.

  Note that the supply toner image has a maximum image width that can be output by the image forming apparatus 10 in the thrust direction from the viewpoint of more reliably suppressing image defects due to wear of the intermediate transfer belt 30 or chipping of the cleaning blade 35. It is desirable to form over the whole area. In addition, it is desirable that the length of the supply toner image in the belt conveyance direction is appropriately set to a length sufficient to ensure the stability of cleaning by the cleaning blade 35. In this embodiment, the length of the supply toner image in the belt conveyance direction is set to the length of one turn of the intermediate transfer belt 30 (720 mm).

  In this manner, the residual toner image I1L on the intermediate transfer belt 30 enters the blade contact portion B while maintaining uniformity. This residual toner image I1L passes through the secondary transfer portion N2 immediately before entering the blade contact portion B. In this embodiment, the secondary transfer belt 27 is separated from the intermediate transfer belt 30 by the separation mechanism 29 during the toner supply operation so that the toner does not adhere to the secondary transfer roller 27 at this time. Instead of separating the secondary transfer roller 27 from the intermediate transfer belt, a voltage having the same polarity as the normal charging polarity of the toner (that is, a polarity opposite to that during secondary transfer) is applied to the secondary transfer roller 27. Also good. Accordingly, it is possible to prevent the residual toner image I1L from adhering to the secondary transfer roller 27 by the electrostatic repulsive force.

  As described above, the toner image supplied to the blade contact portion B in the toner supply operation is made into a thin and uniform image. As a result, when the image enters the blade contact portion B, the toner does not slip through the blade contact portion B and can remain as a lubricant. As a result, it is possible to suppress phenomena such as chipping of the tip of the cleaning blade 35, turning over of the cleaning blade 35, and generation of abnormal noise.

5. Toner Amount of Residual Toner Image Next, a preferable toner amount (mounting amount, adhesion amount) of the residual toner image I1L on the intermediate transfer belt 30 supplied to the blade contact portion B in the toner supply operation will be described.

The amount of the residual toner image I1L that is preferable for obtaining the above-described effect was examined for each temperature and humidity environment in which the image forming apparatus 10 operates. The applied amount of the residual toner image I1L can be adjusted by changing the value of the primary transfer bias of the fourth station Sd. Here, the applied amount of the residual toner image I1L was adjusted to 0.005 mg / cm ² , 0.01 mg / cm ² , 0.1 mg / cm ² , 0.2 mg / cm ² , and 0.3 mg / cm ² . Then, the state of occurrence of chipping of the cleaning blade 35 and toner slipping after the initializing operation performed when the new unit 39 was installed was evaluated. In the initializing operation in the initial stage, an operation involving rotation of the intermediate transfer belt 30 about 10 turns is performed for detecting the circumference of the intermediate transfer belt 30, registration detection, density detection, and the like. The temperature / humidity environment in which the image forming apparatus 10 is installed is normally 23 ° C./50% RH as an environment equivalent to an office, 15 ° C./10% RH as a low temperature / low humidity environment, and 30 ° C. as a high temperature / high humidity environment. It was examined under 3 environments of 80% RH. The results are shown in Table 1. The values of the primary transfer bias shown in Table 1 are representative values in an environment equivalent to a normal office, and the same loading amount is realized in a low temperature and low humidity environment and a high temperature and high humidity environment. Therefore, the value of the primary transfer bias was adjusted as appropriate.

As a result, the tip of the cleaning blade 35 was chipped at 0.005 mg / cm ² in a high temperature and high humidity environment, and slipping occurred at 0.3 mg / cm ² in a low temperature and low humidity environment. Further, when the applied amount of the residual toner image I1L was 0.01 to 0.2 mg / cm ² , these phenomena did not occur in any environment. Further, in the situation where the tip of the cleaning blade 35 was not chipped, the cleaning blade 35 was not turned over and no abnormal noise was observed. As described above, it is preferable that the control unit 100 controls the toner amount of the residual toner image to be 0.01 mg / cm ² or more and 0.2 mg / cm ² or less in the toner supply operation.

  In this embodiment, during the toner supply operation, the blade contact portion B is used as a lubricant for about a half turn of the intermediate transfer belt until the timing when the toner of the residual toner image enters the blade contact portion B for the first time. The toner is in a depleted state. Therefore, in this embodiment, the lubricant is applied to the tip of the cleaning blade 35 in advance when the cleaning blade 35 is assembled. In this example, as the lubricant, a fluorinated graphite having a mean particle size of 3 μm (trade name Cefbon: manufactured by Central Glass Co., Ltd.) dispersed in a hydrofluoroether (HFE) solvent at a weight ratio of 10% is used. It was. Then, after applying a lubricant to the cleaning blade 35, it was allowed to stand at room temperature and dried. However, the lubricant that has been applied in advance as described above can intervene in the blade contact portion B and exhibit its performance only during the time when the intermediate transfer belt 30 makes one or two turns. After that, if the initial transfer operation is continued by repeating the rotation of the intermediate transfer belt 30, the pre-applied lubricant is depleted from the blade contact portion B, and the phenomenon caused by friction as described above occurs. There is. Therefore, the above-described toner supply operation is the first operation when starting the image forming apparatus 10 after the new belt unit 39 is set in the image forming apparatus 10 (at least the operation before the pre-applied lubricant is depleted). It is preferable to carry out as The toner supply operation may be included in the initial initialization operation.

  As described above, according to this embodiment, the toner supply operation is executed when it is detected that the belt unit 39 is new. At this time, the remaining residual toner image obtained by electrostatically collecting a part of the toner of the supply toner image electrostatically transferred is supplied to the blade contact portion B. As a result, phenomena such as toner slipping, chipping of the tip of the cleaning blade 35, turning of the cleaning blade 35, and generation of abnormal noise can be suppressed.

  In the present embodiment, the image forming apparatus 10 detects that a new belt unit 39 has been set and automatically executes the toner supply operation. However, the present invention is not limited to this. In addition to or instead of a mechanism for detecting a new belt unit, the toner supply operation to the image forming apparatus through an operation unit such as an operation panel of an apparatus connected to the image forming apparatus or the image forming apparatus by an operator. May be allowed to be executed. For example, an operator such as a user or a service person who sets a new belt unit 39 may instruct execution of the toner supply operation.

  In this embodiment, the supply toner image is formed at the third station Sc and a part of the toner of the supply toner image is collected at the fourth station Sd. However, the present invention is not limited to this. Any station may be used as long as a supply toner image is formed at an upstream station and a part of the toner of the supply toner image is collected at a station downstream from the station. Further, the station for forming the supply toner image and the station for collecting a part of the toner may be adjacent stations, or may be separated from each other with another station. When there is another station in between, the voltage applied to the primary transfer roller may be adjusted so that the supply toner image passes through the primary transfer portion in the other station. Further, since sufficient toner can be supplied to the blade contact portion, at least one of a station for forming a supply toner image or a station for collecting a part of the toner may be a plurality of stations. The supply toner images formed at a plurality of stations may be formed so as to be superimposed on the intermediate transfer belt, or may be formed at different positions on the intermediate transfer belt. Then, it is possible to collect a part of the toner of the supply toner image formed on the intermediate transfer belt on the photosensitive drum of one station and collect another part of the toner on the photosensitive drum of another station. is there.

Example 2
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions and configurations as those of the first embodiment or corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  This embodiment is different from the first embodiment in the timing of executing the toner supply operation and the method of collecting a part of the toner of the supply toner image in the toner supply operation.

  In the first exemplary embodiment, the toner supply operation is performed when a new belt unit 39 is set in the image forming apparatus 10. This is because the new belt unit 39 tends to increase the friction at the blade contact portion B during the initial operation. Similarly, for example, when an image is formed in a high-temperature and high-humidity environment that is easily affected by moisture, or when low-printing-rate image formation that reduces the lubricating effect of toner is continuously performed, the blade contact portion B It is effective to execute the toner supply operation in an operation situation in which the friction at the surface tends to increase. Therefore, in this embodiment, the toner supply operation is executed when a predetermined execution condition is satisfied based on information on the environment where the image forming apparatus 10 is installed and information on the printing rate of the image formed image.

  In Example 1, a part of the toner of the supply toner image formed on the intermediate transfer belt 30 was electrostatically collected on the photosensitive drum 22. Similarly, any member (collecting member) that can electrostatically collect a part of the toner of the toner image on the intermediate transfer belt 30 can be used. Therefore, in this embodiment, a part of the toner of the supply toner image transferred to the intermediate transfer belt 30 at the primary transfer portion N1 of an arbitrary station S is collected by the secondary transfer roller 27 at the secondary transfer portion N2. . As a result, similarly to the first embodiment, the toner image entering the blade contact portion B is made thin and uniform, and the chipping of the tip of the cleaning blade 35 and the cleaning blade 35 are turned over while suppressing the slipping of the toner. Suppresses phenomena such as abnormal noise.

  FIG. 7 shows a schematic control mode of the main part of the image forming apparatus 10 of this embodiment. In this embodiment, the control unit 100 includes an environment sensor (temperature / humidity sensor) 81 as an environment detection unit that detects the temperature and humidity of the environment in which the image forming apparatus 10 is installed. In this embodiment, the control unit 100 also has a function as a counting unit 101 that counts the number of image formations, and a printing rate calculation unit (calculation storage unit) 102 that calculates and stores the printing rates of the formed images. .

  In this embodiment, the toner supply operation is executed when image formation with a low printing rate is continuously executed for a predetermined page (100 pages in this embodiment) in a high temperature and high humidity environment. In the present embodiment, the control unit 100 calculates the image dot ratio of the image data for each station S for each page, and calculates the added value for the four stations of the image dot ratio as the printing rate. Here, the image dot ratio is a value obtained by dividing the number of dots of the ON signal in the image data by the total number of dots that can be drawn on one page. When the job is executed, the control unit 100 stores the cumulative value of the number of pages on which images have been formed and the printing rate for each page, and the image for the most recent predetermined page (100 pages in this embodiment). The average printing rate of formation is calculated. Here, a job refers to a series of image forming operations on a single or a plurality of recording materials according to one start instruction.

  FIG. 8 is a flowchart showing a procedure until the toner supply operation in this embodiment is executed.

  Upon receiving a job request, the control unit 100 executes image formation (F101), stores the cumulative number of pages and the printing rate for each page, and calculates the average printing rate for the last 100 pages. Subsequently, the control unit 100 determines whether or not the cumulative number of pages is 100 or more (F102). If the number is not 100 or more (“No”), the control unit 100 determines whether or not there is a next image formation (“No”). F107). If it is 100 or more in the determination of F102 (“Yes”), the control unit 100 determines whether or not the average printing rate of the last 100 pages is 2% or less (F103). If the result of determination in F103 is not 2% or less (“No”), the control unit 100 proceeds to F107. If it is 2% or less in the determination of F103 (“Yes”), the control unit 100 determines that image formation with a low printing rate is continuous, and detects the environmental temperature and humidity with the environmental sensor 81. Then, it is determined whether or not the operating environment is a high temperature and high humidity environment (F104). If it is determined in F104 that the environment is not a high-temperature and high-humidity environment ("No"), the control unit 100 proceeds to F107. If it is determined in F104 that the environment is a high-temperature and high-humidity environment ("Yes"), the control unit 100 causes the toner supply operation to be executed (F105). Subsequently, the control unit 100 resets the stored value of the accumulated page number (F106), and proceeds to F107. If it is determined in F107 that there is a next image formation (“No”), the control unit 100 returns to F101 to continue image formation. On the other hand, if there is no next image formation (“Yes”), the job is terminated.

  According to the above procedure, when image formation with a low printing rate continues and the operation is performed in a high-temperature and high-humidity environment (specifically, the average printing rate in the most recent 100-page image formation is When it becomes 2% or less), the toner supply operation is executed.

  In this embodiment, the toner supply operation is performed by interrupting the job, but substantially the same operation as the image forming operation performed without supplying the recording material P is performed. Is not turned off, and the toner supply operation may be continued.

  FIG. 9 is a schematic view around the intermediate transfer belt 30 for explaining the toner supply operation in the present embodiment. In the toner supply operation, first, as shown in FIG. 9A, for example, in the fourth station Sd, a supply toner image I2 to be a solid image is formed and transferred to the intermediate transfer belt 30. At this time, the primary transfer roller 26d of the fourth station Sd is supplied with a DC voltage having a polarity opposite to the normal charging polarity of the toner from the primary transfer power source 51d, for example, +1000 V, as in normal image formation. Apply a voltage of.

  Next, as shown in FIG. 9B, when the supply toner image I2 on the intermediate transfer belt 30 passes through the secondary transfer portion N2, the secondary transfer power source 52 is connected to the secondary transfer roller 27. A voltage of, for example, +200 V, which is a DC voltage having a polarity opposite to the normal charging polarity of the toner, is applied. At this time, the recording material P is not supplied to the secondary transfer portion N2. Thus, a part of the toner of the supply toner image I2 is transferred to the secondary transfer roller 27 and collected. In the drawing, I2L indicates a residual toner image remaining on and adhered to the intermediate transfer belt 30, and I2C indicates toner temporarily collected by the secondary transfer roller 27. The residual toner image I2L on the intermediate transfer belt 30 enters the blade contact portion B while maintaining uniformity, as in the first embodiment. In this embodiment, the length of the supplied toner image in the belt conveyance direction is 50 mm.

  Further, immediately after the toner image on the intermediate transfer belt 30 passes through the secondary transfer portion N2, the secondary transfer roller 27 applies a DC voltage having the same polarity as the normal charging polarity of the toner from the secondary transfer power source 52. For example, a voltage of −1000 V is applied. As a result, the toner I2c adhering to the secondary transfer roller 27 is discharged to the intermediate transfer belt 30. In this embodiment, the operation of alternately applying +1000 V and −1000 V to the secondary transfer roller 27 from the secondary transfer power supply 52 is repeated a plurality of times. Accordingly, the toner I2c is more reliably discharged from the secondary transfer roller 27 to the intermediate transfer belt 30. The toner discharged to the intermediate transfer belt 30 is supplied to the blade contact portion B. As described above, the controller 100 causes the toner once collected by the secondary transfer roller 27 to be discharged to the intermediate transfer belt 30 in the toner supply operation. The toner discharged to the intermediate transfer belt 30 is supplied to the contact portion B between the cleaning blade 35 and the intermediate transfer belt 30 by the movement of the intermediate transfer belt 30.

  Here, the length of the supply toner image in the belt conveyance direction in this embodiment is shorter than that in the first embodiment. This is because the state of the blade contact portion B when performing the toner supply operation in this embodiment is more stable than when the belt unit 39 is new, and even a shorter length of toner is sufficiently stable. This is because it is possible to ensure the state of the blade contact portion B.

  In this embodiment, the residual toner image I2L on the intermediate transfer belt 30 that has passed through the secondary transfer portion N2 and the toner I2c that is subsequently discharged from the secondary transfer roller 27 to the intermediate transfer belt 30 are the same as those in the first embodiment. Similarly, it is thin and uniform. Since these toners maintain the state and enter the blade contact portion B, they do not pass through the blade contact portion B. Accordingly, it is possible to suppress phenomena such as chipping of the tip of the cleaning blade 35, turning of the cleaning blade 35, and generation of abnormal noise.

  Instead of discharging the toner I2c collected by the secondary transfer roller 27 to the intermediate transfer belt 30, a secondary transfer member cleaning device for cleaning the surface of the secondary transfer roller 27 is provided. It may be removed and collected.

  As described above, in the present exemplary embodiment, the control unit 100 forms a predetermined toner image on the photosensitive drum 22 and electrostatically applies the predetermined toner image formed on the photosensitive drum 22 to the intermediate transfer belt 30 in the toner supply operation. Transcription. Further, a part of toner of a predetermined toner image transferred to the intermediate transfer belt 30 is electrostatically collected by the secondary transfer roller 27. The toner of a predetermined toner image remaining on the intermediate transfer belt 30 without being collected by the secondary transfer roller 27 is supplied to the contact portion B between the cleaning blade 35 and the intermediate transfer belt 30 by the movement of the intermediate transfer belt 30. .

Next, as in Example 1, a preferred toner amount (mounting amount, adhesion amount) of the residual toner image I2L on the intermediate transfer belt 30 supplied to the blade contact portion B in the toner supply operation was examined. The applied amount of the residual toner image I2L can be adjusted by changing the value of the secondary transfer bias. Here, the applied amount of the residual toner image I2L was controlled to 0.005 mg / cm ² , 0.01 mg / cm ² , 0.1 mg / cm ² , 0.2 mg / cm ² , and 0.3 mg / cm ² . Then, the state of occurrence of chipping of the cleaning blade 35 and toner passing through when image formation was performed after the toner supply operation was evaluated in each environment similar to Example 1. The results are shown in Table 2. Note that the values of the secondary transfer bias shown in Table 2 are representative values in an environment equivalent to a normal office, and the same loading amount is realized in a low temperature and low humidity environment and a high temperature and high humidity environment. Therefore, the value of the secondary transfer bias was adjusted as appropriate.

As a result, as in Example 1, when the applied amount was 0.01 to 0.2 mg / cm ² , the phenomenon such as chipping of the cleaning blade 35 and toner slipping did not occur in any environment. Further, in the situation where the tip of the cleaning blade 35 was not chipped, the cleaning blade 35 was not turned over and no abnormal noise was observed.

  As described above, according to the present exemplary embodiment, the above-described toner supply operation is executed when image formation with a low printing rate continues in a high temperature and high humidity environment. At this time, the remaining residual toner image obtained by electrostatically collecting a part of the toner of the supply toner image electrostatically transferred is supplied to the blade contact portion B. As a result, phenomena such as toner slipping, chipping of the tip of the cleaning blade 35, turning of the cleaning blade 35, and generation of abnormal noise can be suppressed.

  It should be noted that an appropriate value may vary depending on various conditions constituting the image forming apparatus, such as setting of the cumulative number of pages and the threshold of the average printing rate as the execution condition of the toner supply operation, or the length of the residual toner in the belt conveyance direction. Therefore, it is not limited to the value of this embodiment. These values may be appropriately determined in consideration of the balance between the deterioration in usability due to downtime (a period during which an image cannot be output due to an adjustment operation or the like) and the effect obtained by the toner supply operation.

  In this embodiment, the supply toner image is formed in the fourth station Sd. However, the station S for forming the supply toner image is arbitrary. However, the station S for forming the supply toner image is located more downstream in the moving direction of the intermediate transfer belt 30 until the toner is supplied to the blade contact portion B after the toner supply operation is started. The distance traveled by the transfer belt 30 can be shortened. Therefore, in a situation where it is desirable to supply toner to the blade contact portion B, it is possible to supply toner to the blade contact portion B more quickly. When the supply toner image is formed at a place other than the fourth station Sd, the toner at the supply toner image is not collected at the downstream station S and passes through the primary transfer portion N1 without being collected. The primary transfer bias may be adjusted. Further, when the supply toner image is formed at a place other than the fourth station Sd, a method of collecting a part of the toner of the supply toner image in the first embodiment on the photosensitive drum 22 of at least one station S may be combined. Good. That is, a part of the toner of the supply toner image formed on the intermediate transfer belt can be collected on the photosensitive drum of one station, and the other part of the toner can be collected on the secondary transfer roller.

Others While the present invention has been described with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

  For example, the appropriate amount of the residual toner image on the intermediate transfer belt may vary depending on the material of the intermediate transfer belt and the cleaning blade, the contact condition of the cleaning blade, or the property of the toner to be cleaned. Therefore, the applied amount of the residual toner image is not limited to that described above.

  Further, as described above, it is preferable to use a solid image as the pattern of the toner image formed on the intermediate transfer belt. However, the effect similar to that shown in the above-described embodiment can be obtained if the gap when the toner image enters the blade contact portion is small. From this point of view, the supply toner image is not limited to a solid image.

  In the first embodiment, the toner supply operation is executed when the belt unit is new. On the other hand, when at least one of the intermediate transfer belt and the cleaning blade is separately replaceable, the toner supply operation is executed when at least one of the intermediate transfer belt and the cleaning blade is new. It may be.

  In the second embodiment, the temperature and humidity information is used as the environment information in which the image forming apparatus is installed. However, the friction between the intermediate transfer belt and the cleaning blade is higher than a certain level. It can be said that it is easy to increase. Therefore, at least one of temperature and humidity can be used as information on the environment in which the image forming apparatus is set. In the second embodiment, it is determined whether or not the toner supply operation is to be executed using both the environmental information and the printing rate information. However, each of them separately and independently executes the toner supply operation. It can be used to determine whether or not. In other words, an environment detection unit that detects at least one of the temperature and humidity of the environment of the image forming apparatus is provided, and when the controller detects at least one of the temperature or humidity detected by the environment detection unit is greater than or equal to a threshold value, the toner supply operation May be executed. In addition, a calculation unit that obtains a printing rate of an image formed in the image forming apparatus may be provided, and the control unit may execute the toner supply operation when the printing rate obtained by the calculation unit is equal to or less than a threshold value. .

  In the second exemplary embodiment, the job is interrupted when a predetermined execution condition is satisfied (that is, the interval between images (interval between sheets) during non-image formation is widened), and the toner supply operation is executed. It is not limited to this. For example, when a predetermined execution condition is satisfied during the execution of a job, during non-image formation, during a preparatory operation after completion of the job (during rotation), or during a preparatory operation before the next job (pre-rotation) And the like, the toner supply operation may be executed.

  The image forming apparatus may be configured to execute both the toner supply operation of the first embodiment and the toner supply operation of the second embodiment. Note that the operation in the second embodiment may be adopted as the toner supply operation executed when a new belt unit is set as in the first embodiment. Conversely, as in the second embodiment, the operation in the first embodiment may be employed as a toner supply operation that is executed when a predetermined execution condition is satisfied during use of the belt unit.

  In the above-described embodiments, the image carrier and the secondary transfer member are used as the collecting member that collects a part of the toner of the supplied toner image. However, the present invention is not limited to this. As the recovery member, any member can be used as long as it is disposed upstream of the cleaning blade in the moving direction of the moving body and can electrostatically recover toner from the moving body. For example, it is possible to separately provide a roller similar to the secondary transfer roller of Example 2, and to control a voltage applied to the roller to collect a part of the toner of the supply toner image. Further, similarly to the case of the secondary transfer roller of the second embodiment, an operation of discharging the collected toner may be performed. The roller can be separated from the intermediate transfer belt during image formation other than during the toner supply operation.

  The present invention can also be applied to a direct transfer type image forming apparatus that directly transfers a toner image from an image carrier onto a transfer material carried on a recording material. The direct transfer type image forming apparatus has a recording material carrier belt formed of an endless belt as a recording material carrier, instead of the intermediate transfer belt in the above-described embodiments. The recording material carrying belt is an example of a movable body that conveys a recording material onto which toner is transferred from an image carrying body. The toner images formed on the photosensitive drums are sequentially transferred onto the recording material carried on the recording material carrier at each transfer unit. Even in such an image forming apparatus, the deposits on the surface of the recording material carrier may be cleaned by a cleaning device of a blade cleaning type. For example, it is for cleaning toner that adheres to a non-image portion (fogging toner), jam (paper jam), and the like, and a toner image for control for image density control. Therefore, the present invention can be applied to such an image forming apparatus, and the same effects as those in the above-described embodiments can be obtained.

  Further, the moving body that is an intermediate transfer member or a recording material carrier is not limited to an endless belt, and is formed in a drum shape by, for example, stretching a sheet on a frame. May be.

22 Photosensitive drum 26 Primary transfer roller 27 Secondary transfer roller 30 Intermediate transfer belt 34 Belt cleaning device 35 Belt cleaning blade

Claims (15)

A first image carrier for carrying a toner image;
A second image carrier for carrying a toner image;
A movable movable body that conveys a recording material to which toner is transferred from the first and second image carriers or toner is transferred from the first and second image carriers;
A cleaning blade that contacts the moving body and removes toner from the moving body;
A control unit;
Have
In the image forming apparatus, the second image carrier is located downstream of the first image carrier in the moving direction of the movable body.
The control unit causes the first image carrier to form a predetermined toner image, electrostatically transfers the predetermined toner image formed on the first image carrier to the moving body, and Part of the toner of the predetermined toner image transferred to the moving body is electrostatically collected by the second image carrier, and remains on the movable body without being collected by the second image carrier. An image forming apparatus, wherein a toner supply operation is performed to supply toner of the predetermined toner image to a contact portion between the cleaning blade and the moving body by moving the moving body. Corresponding to each of the first and second image carriers, a transfer member that transfers toner from the image carrier to the moving body by applying a voltage,
In the toner supply operation, the controller is configured to transfer toner to the transfer member corresponding to the first image carrier when transferring the predetermined toner image from the first image carrier to the moving body. When a voltage having a polarity opposite to the charging polarity is applied and a part of the toner of the predetermined toner image is collected on the second image carrier, the transfer member corresponding to the second image carrier is applied to the transfer member. The image forming apparatus according to claim 1, wherein a voltage having the same polarity as the charging polarity of the toner is applied. An image carrier for carrying a toner image;
A movable movable body constituting an intermediate transfer body for transferring the toner transferred from the image carrier to a recording material;
A transfer member for transferring toner from the moving body to a recording material;
A cleaning blade that contacts the moving body and removes toner from the moving body;
A control unit;
In an image forming apparatus having
The control unit forms a predetermined toner image on the image carrier, electrostatically transfers the predetermined toner image formed on the image carrier to the moving body, and transfers the toner image to the moving body. Part of the toner of the predetermined toner image is electrostatically collected by the transfer member, and the toner of the predetermined toner image remaining on the moving body without being collected by the transfer member is moved by the movement of the moving body. An image forming apparatus, wherein a toner supply operation for supplying the toner to a contact portion between the cleaning blade and the moving body is executed.   In the toner supply operation, the control unit causes the transfer member to apply a voltage having a polarity opposite to the charging polarity of the toner when the predetermined toner image is transferred from the moving body to the transfer member. The image forming apparatus according to claim 3.   In the toner supply operation, the control unit causes the toner once collected by the transfer member to be discharged to the moving body, and the toner discharged to the moving body is moved by the moving body to move the cleaning blade and the moving body. The image forming apparatus according to claim 3, wherein the image forming apparatus is supplied to a contact portion.   The control unit causes the transfer member to apply a voltage having the same polarity as the charging polarity of the toner when the toner is discharged from the transfer member to the moving body in the toner supply operation. The image forming apparatus described in 1. An image carrier for carrying a toner image;
A movable movable body that conveys a recording material on which toner is transferred from the image carrier or toner is transferred from the image carrier;
A cleaning blade that contacts the moving body and removes toner from the moving body;
A control unit;
In an image forming apparatus having
A recovery member that is disposed upstream of the cleaning blade in the moving direction of the moving body and electrostatically recovers toner from the moving body;
The control unit forms a predetermined toner image on the image carrier, electrostatically transfers the predetermined toner image formed on the image carrier to the moving body, and transfers the toner image to the moving body. A part of the toner of the predetermined toner image is electrostatically collected by the collecting member, and the toner of the predetermined toner image remaining on the moving body without being collected by the collecting member is moved by the movement of the moving body. An image forming apparatus, wherein a toner supply operation for supplying the toner to a contact portion between the cleaning blade and the moving body is executed. The control unit controls the amount of toner remaining on the moving body to be 0.01 mg / cm ² or more and 0.2 mg / cm ² or less in the toner supply operation. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the predetermined toner image is a solid image.   A unit including the moving body and the cleaning blade is detachable from the apparatus main body of the image forming apparatus, and the control unit performs the first image when the unit is replaced with a new one. The image forming apparatus according to claim 1, wherein the toner supply operation is executed before the formation is performed.   An environment detecting unit that detects at least one of an environmental temperature and humidity of the image forming apparatus, and the control unit is configured to detect the temperature or humidity detected by the environment detecting unit when the temperature or humidity is equal to or higher than a threshold value. The image forming apparatus according to claim 1, wherein a toner supply operation is executed.   A calculation unit that obtains a printing rate of an image formed in the image forming apparatus, and the control unit causes the toner supply operation to be executed when the printing rate obtained by the calculation unit is equal to or less than a threshold value; The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The cleaning blade is in contact with the moving body such that a free end is on an upstream side in a moving direction of the moving body rather than a fixed end connected to a support member. The image forming apparatus according to claim 12.   The image forming apparatus according to claim 1, wherein the cleaning blade is formed of a rubber material.   The image forming apparatus according to claim 1, wherein the moving body is an endless belt.