Image forming apparatus

Abstract

To suppress the occurrence of an adverse effect in an image resulting from a cleaning failure.SOLUTION: An image forming apparatus controls to perform an image forming operation, which forms a toner image on a recording material, and a toner supply operation, which supplies a toner to a cleaning blade nip portion. The image forming apparatus sets a region of an image carrier facing a developer carrier at a developing portion as a first region, sets a region of the image carrier facing the developer carrier at the developing portion after the region of the developer carrier facing the first region makes one revolution as a second region, sets a region between the first region and the second region as a third region. When the toner supply operation is performed, the image forming apparatus forms, in the third region, a toner supply pattern formed from a first pattern for exposing and a second pattern for not exposing or for exposing with an exposure amount smaller than an exposure amount with which the first pattern exposes. In the toner supply pattern, the length of the second pattern is larger than the length of the first pattern in a rotational direction, and the first pattern and the second pattern are repeatedly formed.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] In an image forming apparatus such as a printer using an electrophotographic image forming method, a process cartridge is configured to be detachable. In a process cartridge, a toner image on an image carrier (hereinafter referred to as a photoconductor or drum) may remain after being transferred to a recording material, and a known method for removing the remaining toner is to bring a cleaning member into contact with the surface of the drum. A widely adopted cleaning member is configured to be made of an elastic body made of urethane rubber or the like and a supporting metal plate that supports the elastic body.

[0003] Here, a new process cartridge does not have a cleaning prevention layer made of an external additive between the drum and the cleaning member, and the cleaning performance is unstable, which can cause the problem of poorly cleaned images.

[0004] In response to this problem, Patent Document 1 proposes a toner supply sequence that efficiently discharges toner onto the drum when a new product is used, thereby suppressing image defects. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-187707 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the configuration of Patent Document 1 had the following problems. For example, when a new product is first used, the initial friction coefficient of the drum is high, and if the amount of toner supplied per unit area of ​​the drum in the toner supply sequence is large in an L / L (low temperature / low humidity) environment (15°C / 10%), the toner may slip through the cleaning member. In such cases, image problems occur due to poor cleaning. [Means for solving the problem]

[0007] Therefore, the present invention has been made in consideration of the above problems, and provides an image forming apparatus including: a rotatable image carrier; an exposure unit that exposes the surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a rotatable developer carrier that supplies toner to the surface of the image carrier in a developing section to develop the electrostatic latent image as a toner image; a cleaning member that contacts the image carrier to form a contact section and removes toner adhering to the surface of the image carrier at the contact section; and a control section that controls the image carrier and the developer carrier to rotate and the exposure unit to execute: i) an image forming operation that forms the toner image on a recording material; and ii) a toner supplying operation that is an operation different from the image forming operation and moves the toner from the developer carrier to the image carrier and supplies it to the contact section. The area of ​​the image carrier facing the developer carrier is defined as a first area, the area of ​​the image carrier facing the developer carrier in the developing unit after the area of ​​the developer carrier facing the first area has made one rotation is defined as a second area, and the area of ​​the image carrier between the first area and the second area in the rotation direction of the image carrier is defined as a third area. When performing the toner supply operation, the control unit controls to form a toner supply pattern in the third area, the toner supply pattern being formed from a first pattern, a portion of which is exposed by the exposure unit, and a second pattern, a portion of which is not exposed or is exposed with an exposure amount smaller than the exposure amount for exposing the first pattern, and the toner supply pattern is configured such that the length of the second pattern is longer than the length of the first pattern in the rotation direction, and the first pattern and the second pattern are repeatedly formed. Effect of the Invention

[0008] According to the present invention, it is possible to suppress image defects caused by poor cleaning. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a process cartridge in the first embodiment. [Diagram 3] FIG. 2 is a block diagram showing a control configuration of the image forming apparatus according to the first embodiment. [Figure 4] FIG. 2 is a surface diagram of the photoreceptor in Example 1 after the surface roughening treatment. [Diagram 5] 1 is a schematic diagram of a surface roughening treatment device for a photoconductor in Example 1. FIG. [Figure 6] FIG. 2 is a schematic diagram of a toner according to a first embodiment. [Figure 7] 2 is a flowchart according to the first embodiment. [Figure 8] FIG. 2 is an explanatory diagram of a toner supply pattern in Examples 1 to 3. [Figure 9] FIG. 2 is a definition diagram of regions on the surface of a photoconductor in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following description is merely an example, and the present invention is not limited to the contents thereof. In addition, in each of the following drawings, description of components that are not necessary for the description of the embodiment will be omitted as appropriate. For convenience, the magnitude (high / low) of a voltage or potential refers to the magnitude (high / low) when compared in absolute value, unless otherwise specified.

[0011] Example 1 <Overall configuration of image forming apparatus> First, the overall configuration of the image forming apparatus of this embodiment will be described. FIG. 1 is a schematic cross-sectional view of the image forming apparatus 100 of this embodiment. The image forming apparatus 100 of this embodiment is a full-color laser printer that employs an in-line system and an intermediate transfer system. The image forming apparatus 100 can form a full-color image on a sheet-shaped recording material P (e.g., recording paper, a plastic sheet, cloth, etc.) according to image information. The image information is input to the image forming apparatus 100 from an external device (not shown) such as an image reading device or a personal computer that is communicably connected to the image forming apparatus 100.

[0012] The image forming apparatus 100 has a first, second, third, and fourth image forming units SY, SM, SC, and SK as a plurality of image forming units for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). The same or corresponding elements provided for each color may be generally described by omitting the Y, M, C, and K at the end of the reference numerals indicating that the elements are for any of the colors. In this embodiment, the image forming unit S is composed of a photoconductor 1 as an image carrier, a charging roller 2 as a charging member, an exposure device 3 as an exposure unit, a developing device 4 as a developing unit, and a cleaning device 5 as a cleaning unit, which will be described later. In this embodiment, the image forming unit S is further composed of a pre-exposure device 6 as a pre-exposure unit. In this embodiment, the exposure device 3 is configured as a single unit that exposes the photoconductor 1 of each image forming unit S, but may be provided independently for each image forming unit S. In each image forming station S, the photoconductor 1, the charging roller 2 as a process means acting on the photoconductor 1, the developing device 4, and the cleaning device 5 are integrated together to form a process cartridge 7. Figure 2 is a schematic cross-sectional view showing one representative process cartridge 7.

[0013] A rotatable drum-type (cylindrical) photoconductor (photoconductor drum) 1 serving as an image carrier for carrying an electrostatic latent image and a toner image is driven to rotate in the direction of arrow R1 (clockwise direction) in FIG. 2 by a driving force transmitted from a driving unit 80 (FIG. 3) serving as a driving means. In this embodiment, four photoconductors 1 are arranged side by side in a direction intersecting the vertical direction. In this embodiment, the rotation speed of the photoconductor 1 is set to 321 mm / sec in normal mode. As will be described later, the speed in a low-speed mode in which the rotation speed of the photoconductor 1 is slower than that in the normal mode is set to 91 mm / sec. The rotation speed of the photoconductor 1 is also the speed at which image processing is performed in the image forming operation, and is therefore sometimes collectively referred to as PS (process speed).

[0014] The surface of the rotating photoconductor 1 is charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by the charging roller 2, which is a roller-type charging member serving as a charging means. In this embodiment, the charging roller 2 is a single-layer roller made of a conductive core metal and a conductive rubber layer (elastic layer) provided around the core metal, and has an outer diameter of 7.5 mm and a volume resistivity of 10 3 ~10 6The surface resistance is Ω·cm. The charging roller 2 is disposed in contact with the surface of the photoconductor 1, pressed against the photoconductor 1, and rotates in accordance with the rotation of the photoconductor 1. During image formation (charging), a predetermined charging voltage (charging bias) which is a direct current (DC) voltage of a predetermined polarity (negative in this embodiment) is applied to the charging roller 2 by a charging power source (high voltage power source) 71 (FIG. 3) as a charging voltage application unit. In this embodiment, a charging voltage of −1000V is applied to the charging roller 2, and the surface of the photoconductor 1 is uniformly charged to −500V, which is Vd as a dark area potential (non-image area potential). In other words, a charging voltage Vd+Vth, which is a DC voltage, is applied to the charging roller 2, and the surface of the photoconductor 1 is uniformly charged to Vd by discharge. Here, Vd is the dark area potential (non-image area potential), which is −500V in this embodiment. Also, Vth is the discharge start voltage, which is −500V in this embodiment. When the charging voltage applied to the charging roller 2 is small, the surface potential on the photoconductor 1 does not increase due to discharge, but when the charging voltage applied to the charging roller 2 becomes equal to or greater than the discharge start voltage Vth, the surface potential of the photoconductor 1 starts to increase due to discharge. The position in the rotation direction of the photoconductor 1 where the charging process of the surface of the photoconductor 1 is performed by the charging roller 2 is the charging portion (charging position) P1. In this embodiment, the surface of the photoconductor 1 is charged by discharge generated in minute gaps formed upstream and downstream of the contact portion between the photoconductor 1 and the charging roller 2 in the rotation direction of the photoconductor 1. However, for convenience, the contact portion between the photoconductor 1 and the charging roller 2 may be considered as the charging portion P1.

[0015] The charged surface of the photoreceptor 1 is scanned and exposed by the exposure device 3 as an exposure means or exposure unit, and an electrostatic latent image (electrostatic image) is formed on the photoreceptor 1. The exposure device 3 irradiates the surface of the photoreceptor 1 with laser light based on image information, forming an electrostatic latent image on the photoreceptor 1. The surface potential of the photoreceptor 1 irradiated with the laser light changes to -100 V, which is the light area potential (image area potential) Vl. The position in the rotation direction of the photoreceptor 1 where the exposure device 3 irradiates the surface of the photoreceptor 1 with light is the exposure area (exposure position) P2.

[0016] The electrostatic latent image formed on the photoconductor 1 is developed (visualized) by the developing device 4 as a developing means, which supplies toner as a developer, and a toner image (toner image, developer image) is formed on the photoconductor 1. The developing device 4 has a developing roller 41 as a developing member (developer carrier). The outer diameter of the developing roller 41 is φ12, and the ratio of the peripheral speed of the developing roller 41 to the rotation speed of the photoconductor 1 is 90%. During image formation (development), a predetermined developing voltage (developing bias), which is a DC voltage of a predetermined polarity (negative polarity in this embodiment), is applied to the developing roller 41 by a developing power source (high voltage power source) 72 (FIG. 3) as a developing voltage application unit. In this embodiment, a developing voltage Vdc of −300 V is applied to the developing roller 41, so that toner adheres to the Vl portion on the photoconductor 1. Thus, in this embodiment, toner charged with the same polarity as the charge polarity of the photoconductor 1 (negative polarity in this embodiment) adheres to the image area on the photoconductor 1 that has been uniformly charged and then exposed to reduce potential (reversal development method). In this embodiment, the normal charge polarity of the toner, which is the main charge polarity of the toner during development, is negative polarity. The developing device 4 will be described in further detail later. The position in the rotational direction of the photoconductor 1 where the developing device 4 supplies toner to the surface of the photoconductor 1 (the contact point between the photoconductor 1 and developing roller 41 in this embodiment) is the developing section (developing position) P3.

[0017] Opposing the four photoconductors 1, an intermediate transfer belt 31 constituted by an endless belt as an intermediate transfer body is disposed. The intermediate transfer belt 31 is stretched around a driving roller 33 and a tension roller 34 as a plurality of tension rollers and tensioned with a predetermined tension. The intermediate transfer belt 31 rotates (circulates, moves around) in the direction of arrow R2 in FIG. 1 (counterclockwise direction) as the driving roller 33 is rotated by a driving force transmitted from a driving unit 80 (FIG. 3) as a driving means. On the inner peripheral surface side of the intermediate transfer belt 31, primary transfer rollers 32, which are roller-type primary transfer members as primary transfer means, are disposed so as to face each photoconductor 1 via the intermediate transfer belt 31. The primary transfer rollers 32 are pressed toward the photoconductor 1 and come into contact with the photoconductor 1 via the intermediate transfer belt 31 to form a primary transfer portion (primary transfer nip) N1 where the photoconductor 1 and the intermediate transfer belt 31 come into contact with each other. The toner image formed on the photoconductor 1 is transferred (primary transfer) onto the rotating intermediate transfer belt 31 as a transferee by the action of the primary transfer roller 32 at the primary transfer portion N1. During image formation (primary transfer), a primary transfer voltage (primary transfer bias) which is a DC voltage of the opposite polarity (positive polarity in this embodiment) to the normal charging polarity of the toner is applied to the primary transfer roller 32 by a primary transfer power source (high voltage power source) 73 (FIG. 3) as a primary transfer voltage application portion. For example, when a full-color image is formed, the toner images of yellow (Y), magenta (M), cyan (C), and black (K) formed on each photoconductor 1 are transferred in sequence onto the intermediate transfer belt 31 so as to be superimposed on each other. The position where the toner image is transferred from the surface of the photoconductor 1 to the intermediate transfer belt 31 in the rotation direction of the photoconductor 1 is the primary transfer position P4 (the above-mentioned primary transfer portion N1 which is the contact portion between the photoconductor 1 and the intermediate transfer belt 31 in this embodiment).

[0018] A secondary transfer roller 9, which is a roller-type secondary transfer member serving as a secondary transfer means, is disposed at a position facing the driving roller 33, which also serves as a secondary transfer opposing roller, on the outer peripheral surface side of the intermediate transfer belt 31. The secondary transfer roller 9 is pressed toward the driving roller 33 and abuts against the driving roller 33 via the intermediate transfer belt 31, forming a secondary transfer portion (secondary transfer nip) N2 where the intermediate transfer belt 31 and the secondary transfer roller 9 abut. The toner image formed on the intermediate transfer belt 31 is transferred (secondarily transferred) to a recording material P, which is a transfer target material that is sandwiched and conveyed between the intermediate transfer belt 31 and the secondary transfer roller 9, at the secondary transfer portion N2. During image formation (secondary transfer), a secondary transfer voltage (secondary transfer bias), which is a DC voltage of the opposite polarity (positive polarity in this embodiment) to the normal charging polarity of the toner, is applied to the secondary transfer roller 9 by a secondary transfer power source (high voltage power source) 74 (FIG. 3) serving as a secondary transfer voltage application portion. A recording material (transfer material, recording medium, sheet) P is stored in a cassette 10 serving as a recording material storage section, and is sent out of the cassette 10 by a feed roller 11 serving as a feed member, and is sent to a registration roller 12 serving as a transport member. This recording material P is transported by the registration roller 12 to the secondary transfer section N2 in synchronization with the toner image on the intermediate transfer belt 31.

[0019] The recording material P onto which the toner image has been transferred is conveyed to a fixing device 13 serving as a fixing means. The fixing device 13 applies heat and pressure to the recording material P bearing the unfixed toner image, thereby fixing (melting and bonding) the toner image onto the recording material P. The recording material P onto which the toner image has been fixed is discharged (output) onto a tray 14 serving as a discharge unit provided outside the device body 110 of the image forming apparatus 100.

[0020] On the other hand, the surface potential of the photoconductor 1 after the toner image is transferred to the intermediate transfer belt 31 is non-uniform due to the primary transfer voltage. The surface of the photoconductor 1 is pre-exposed (full-surface exposure, full-surface light irradiation) by the pre-exposure device 6 as a charge removing means, and the surface potential of the photoconductor 1 that became non-uniform due to the previous image formation is uniformly leveled. In other words, the residual charge on the surface of the photoconductor 1 is removed by the pre-exposure. The pre-exposure device 6 exposes the surface of the photoconductor 1 downstream of the primary transfer section P4 and upstream of the charging section P1 in the rotation direction of the photoconductor 1. The light source of the pre-exposure device 6 can be an LED, a halogen lamp, or the like. Although the light source to be used is not particularly limited, it is preferable to use an LED from the viewpoint of low driving voltage and easy miniaturization of the device. In this embodiment, an LED is used as the light source of the pre-exposure device 6. The position where the pre-exposure device 6 irradiates light onto the surface of the photoconductor 1 in the rotation direction of the photoconductor 1 is the pre-exposure section (pre-exposure position) P5.

[0021] Further, the toner (primary transfer residual toner) remaining on the surface of the photoreceptor 1 without being transferred to the intermediate transfer belt 31 is removed from the surface of the photoreceptor 1 and collected by the cleaning device 5 as a photoreceptor cleaning means. The cleaning device 5 scrapes off the transfer residual toner from the surface of the rotating photoreceptor 1 by a cleaning blade 51 as a cleaning member that abuts against the surface of the photoreceptor 1. A contact portion P6 is formed by the abutment of the cleaning blade 51 and the surface of the photoreceptor 1, and a nip portion where a blocking layer is formed is formed at the contact portion P6. The waste toner is then stored in a waste toner storage chamber 52 provided below the cleaning blade 51. In this embodiment, in order to provide an explanation even in an initial state where a blocking layer is not formed at the contact portion P6, the contact portion P6 and the nip portion are distinguished for convenience, but after the toner and external additives are supplied to the contact portion P6, the contact portion P6 and the nip portion are used in the same sense. The setting conditions of the cleaning blade 51 in this embodiment are as follows. The set angle with respect to the photoreceptor 1 was 22°, the penetration amount was 1.0 mm, and the hardness of the cleaning blade 51 was 70 degrees (Asker-C, 500 gf load).

[0022] In addition, any adhesions such as toner (secondary transfer residual toner) remaining on the surface of the intermediate transfer belt 31 without being transferred to the recording material P are removed from the surface of the intermediate transfer belt 31 and collected by a belt cleaning device 35 serving as an intermediate transfer body cleaning means.

[0023] The intermediate transfer belt 31 can be brought into contact with and separated from each photoconductor 1 by a belt contact / separation mechanism 90 (FIG. 3). In this embodiment, the belt contact / separation mechanism 90 separates the intermediate transfer belt 31 from the photoconductor 1 by moving the primary transfer roller 32 in a direction away from the photoconductor 1. Also, the belt contact / separation mechanism 90 is configured to bring the intermediate transfer belt 31 into contact with the photoconductor 1 by moving the primary transfer roller 32 in a direction approaching the photoconductor 1.

[0024] <Process cartridge configuration> Next, the process cartridge 7 to be mounted in the image forming apparatus 100 of this embodiment will be further described.

[0025] The process cartridge 7 is detachably attached to the main body 110 of the image forming apparatus 100 via attachment means (not shown) such as an attachment guide or a positioning member provided in the image forming apparatus 100. In this embodiment, the main body 110 is the portion of the image forming apparatus 100 excluding the process cartridge 7. In this embodiment, the process cartridges 7 for each color all have the same shape, and the toner t of each color, yellow (Y), magenta (M), cyan (C), and black (K), is accommodated in the process cartridge 7 for each color. In this embodiment, the configuration and operation of the process cartridges 7 for each color are substantially the same except for the type (color) of the toner t accommodated therein. The process cartridge 7 has a developing device (developing unit) 4 and a photoconductor unit 8.

[0026] The developing device (developing unit) 4 has a developing container (developing frame) 46. The developing container 46 is partitioned into a developing chamber 46a and a toner containing chamber (developer containing portion) 46b.

[0027] The toner accommodating chamber 46b accommodates toner t, which is a non-magnetic one-component developer. A toner transport member (developer transport member) 44 is provided in the toner accommodating chamber 46b. The toner transport member 44 is rotated in the direction of arrow R5 in FIG. 2 (clockwise direction) by a driving force transmitted from a driving unit 80 (FIG. 3) as a driving means, and transports the toner t to the developing chamber 46a.

[0028] In the developing chamber 46a, a developing roller 41 is disposed as a developing member (developer carrier). During image formation (development), the developing roller 41 is brought into contact with the photoconductor 1 and rotated in the direction of the arrow R3 in FIG. 2 (counterclockwise direction) by a driving force transmitted from a driving unit 80 as a driving means. In this embodiment, the developing roller 41 and the photoconductor 1 rotate so that their surfaces move in the forward direction in the developing section P3 where the developing roller 41 and the photoconductor 1 face each other (contact each other). In this embodiment, the developing roller 41 is made of a conductive core metal and a conductive rubber layer (elastic layer) provided around the core metal. The rotation direction of the developing roller 41 is not limited to the rotation direction in this embodiment, and may be a rotation direction in which the surface of the developing roller 41 and the surface of the photoconductor 1 move in opposite directions in the developing section P3.

[0029] In addition, in the developing chamber 46a, a supply roller 42 is disposed as a supply member that supplies the toner t conveyed from the toner storage chamber 46b to the developing roller 41. The supply roller 42 is disposed in contact with the developing roller 41. During image formation (development), the supply roller 42 is rotated in the direction of the arrow R4 in FIG. 2 (counterclockwise direction) by a driving force transmitted from a driving unit 80 as a driving means. In this embodiment, the supply roller 42 and the developing roller 41 rotate such that the surfaces of the supply roller 42 and the developing roller 41 move in opposite directions at the contact portion between the supply roller 42 and the developing roller 41. The rotation direction of the supply roller 42 is not limited to the rotation direction in this embodiment, and may be a rotation direction in which the surfaces of the supply roller 42 and the developing roller 41 move in the forward direction at the contact portion between the supply roller 42 and the developing roller 41.

[0030] Further, in the developing chamber 46a, a developing blade 43 is disposed as a regulating member for regulating the coating amount of the toner t on the developing roller 41 supplied by the supply roller 42 and for applying a charge to the toner t.

[0031] Independent voltages are applied from a high-voltage power supply to the developing roller 41, the supply roller 42, and the developing blade 43. The toner t supplied to the developing roller 41 by the supply roller 42 is frictionally charged by rubbing between the developing roller 41 and the developing blade 43, and is given a charge and its layer thickness is regulated. The toner t on the developing roller 41, whose layer thickness has been regulated, is transported by the rotation of the developing roller 41 to the developing section P3, which is the portion facing (contacting) the photoconductor 1, and adheres to the image portion of the electrostatic latent image on the photoconductor 1 to form a toner image on the photoconductor 1.

[0032] During image formation (development), a predetermined development voltage (development bias) Vdc, which is a DC voltage of a predetermined polarity (negative in this embodiment), is applied to the development roller 41 by a development power source (high voltage power source) 72 (FIG. 3) as a development voltage application unit. In this embodiment, the development voltage Vdc is set to -300V. As a result, in the development unit P3, the development contrast Vcont (=Vl-Vdc), which is the potential difference between the light area potential Vl on the photoconductor 1 and the development bias (potential of the development roller 41), becomes +200V. Also, during image formation (development), a predetermined supply voltage (supply bias) Vrs, which is a DC voltage of a predetermined polarity (negative in this embodiment), is applied to the supply roller 42 by a supply power source (high voltage power source) 75 (FIG. 3) as a supply voltage application unit. In this embodiment, the supply voltage Vrs is set to -350V. By adjusting the potential difference (ΔVr) between the supply roller 42 and the development roller 41, the amount of toner t supplied to the development roller 41 can be adjusted. In this embodiment, ΔVr (=Vdc-Vrs) is set to +50V. This allows the negatively charged toner t to easily move from the supply roller 42 to the development roller 41. During image formation (development), a predetermined regulated voltage (regulated bias) which is a DC voltage of a predetermined polarity (negative in this embodiment) is applied to the development blade 43 by a regulated power source (high voltage power source) 76 (FIG. 3) as a regulated voltage application unit. In this embodiment, the regulated voltage is set to -350V, similar to the supply voltage. The settings of the above-mentioned development bias Vdc and the like are default settings when the apparatus main body 110 and the process cartridge 7 are in a new state.

[0033] As mentioned above, the magnitude (high / low) of voltage or potential refers to the magnitude (high / low) when compared in absolute value, unless otherwise specified. In other words, regarding potential or applied voltage, a high potential refers to an absolute value that is large on the negative polarity side (for example, -1000V compared to -500V), and a low potential refers to an absolute value that is small on the negative polarity side (for example, -300V compared to -500V). This is because in this embodiment, the negatively charged toner t is considered as the reference. Also, the voltage is expressed as a potential difference with respect to the earth potential (0V). Therefore, a development voltage of -300V means that there is a potential difference of -300V due to the development voltage applied to the core metal of the development roller 41 with respect to the earth potential. This is also true for other voltages such as charging voltage.

[0034] The photoreceptor unit 8 has a photoreceptor unit container (photoreceptor unit frame) 53. The photoreceptor 1 is rotatably attached to the photoreceptor unit container 53 via a bearing (not shown). The photoreceptor 1 is driven to rotate in the direction of the arrow R1 in FIG. 2 (clockwise direction) by receiving a driving force transmitted from a driving unit 80 (FIG. 3) as a driving means. The photoreceptor unit 8 also has a charging roller 2 and a cleaning blade 51, which is a plate-shaped elastic body, arranged so as to contact the surface (outer circumferential surface) of the photoreceptor 1. The charging roller 2 is rotatably attached to the photoreceptor unit container 53 via a bearing (not shown). One end (fixed end) of the cleaning blade 51 is fixed to a plate-shaped metal sheet metal attached to the photoreceptor unit container 53, and the other end (free end) abuts against the photoreceptor 1 to form a cleaning nip, which is the abutment portion with the photoreceptor 1. The cleaning blade 51 rubs against the surface of the photoreceptor 1, scraping off the toner t and fine particles remaining on the photoreceptor 1 after the primary transfer process, and stores them in a waste toner storage chamber 52 formed in a photoreceptor unit container 53. This makes it possible to prevent the toner t from adhering to the charging roller 2 or the toner t from being carried around by the photoreceptor 1, which makes it impossible to form an appropriate image. The cleaning blade 51 and the waste toner storage chamber 52 (photoreceptor unit container 53) form a cleaning device 5.

[0035] The image forming apparatus 100 also has a contact / separation mechanism 60 for bringing each developing roller 41 into contact with and away from each photoconductor 1. In this embodiment, the developing container 46 is swingably coupled to the photoconductor unit container 53, and the developing container 46 is biased in a direction in which the developing roller 41 contacts the photoconductor 1 by a pressure spring, which is a biasing member serving as a biasing means. The contact / separation mechanism 60 is configured to move (rotate) the developing container 46 against the biasing force of the pressure spring, thereby separating the developing roller 41 from the photoconductor 1. The contact / separation mechanism 60 is configured to allow the developing container 46 to move (rotate) by the biasing force of the pressure spring, thereby allowing the developing roller 41 to contact the photoconductor 1. In this embodiment, when the image forming apparatus 100 is stopped, the developing roller 41 is separated from the photoconductor 1 by the contact / separation mechanism 60. During image formation (development), the developing roller 41 is brought into contact with the photoconductor 1 by the contact / separation mechanism 60. The contact / separation mechanism 60 is driven by a driving force transmitted from a driving unit 80 (FIG. 3) serving as a driving means.

[0036] <Control configuration of image forming apparatus> Next, a description will be given of the control configuration of the image forming apparatus 100 of this embodiment. Fig. 3 is a block diagram showing the control configuration of the main parts of the image forming apparatus 100 of this embodiment.

[0037] The image forming apparatus 100 is provided with a control unit 202 that controls the operation of the image forming apparatus 100. Signals indicating various information are input to and output from the control unit 202 via electrical connections. The control unit 202 processes signals input from various process devices and sensors, and processes signals output to instruct the various process devices to operate. The controller 200 provided in the image forming apparatus 100 inputs and outputs various signals to and from an external device (host device), and inputs and outputs various signals to and from the control unit 202 via an interface 201 provided in the image forming apparatus 100. The control unit 202 comprehensively controls the operation of the image forming apparatus 100 according to a predetermined control program and reference table in response to an instruction from the controller 200.

[0038] The control unit 202 has a CPU 221 as a calculation processing means which is a central element for performing various calculation processes, and a main memory 222 such as a RAM, a ROM, and a non-volatile memory which are storage elements for storing information. The RAM temporarily stores the detection results of the sensor, the count results of the counter, the calculation results, and the like. The ROM stores a control program, a data table obtained in advance by experiments, and the like. The non-volatile memory stores the count results of the counter, various setting information, the results of the sensor, and the like. The control unit 202 is connected to each control target, sensor, counter, and the like in the image forming apparatus 100. The control unit 202 controls the input and output of various signals, the timing of driving each unit, and the like, to control a predetermined image forming sequence.

[0039] The control unit 202 controls, for example, the charging power supply 71, the developing power supply 72, the supply power supply 75, the regulating power supply 76, the exposure device 3, the primary transfer power supply 73, the secondary transfer power supply 74, and the drive unit 80. In addition, the control unit 202 controls the contact / separation mechanism 60, the charging current detection unit (charging current detection circuit) 61 that detects the charging current flowing in the charging unit P1 (charging roller 2, charging power supply 71), and the belt contact / separation mechanism 90.

[0040] Although not shown in the figure, in this embodiment, the charging power source 71, the developing power source 72, the supply power source 75, the regulating power source 76, the primary transfer power source 73, the contact / separation mechanism 60, and the charging current detection unit 61 are provided independently for each image forming unit S. Also, the driving unit 80 is configured to have a driving motor as a driving source, a drive transmission member, and the like. The driving sources that drive the photoconductor 1, the intermediate transfer belt 31, the rotating members of the developing device 4, the contact / separation mechanism 60, and the belt contact / separation mechanism 90 may be provided independently, or at least a part of them may be shared. Also, the driving sources that drive the elements for each color may be provided independently, or at least a part of them may be shared.

[0041] Here, the image forming apparatus 100 executes an image forming operation (print job) which is a series of operations for forming and outputting an image on one or more recording materials P, which is started by one start instruction. The image forming operation generally includes an image forming process, a pre-process (pre-rotation process, pre-print operation), a paper-interval process in the case of forming images on multiple recording materials P, and a post-process (post-rotation process, post-print operation). The image forming process is a period during which an electrostatic latent image of an image to be actually formed on a recording material P and output is formed, a toner image is formed, and the toner image is primarily transferred, secondary transferred, and fixed, and the image forming time refers to this period. More specifically, the timing of the image forming time differs depending on the position where each process of charging, exposure, development, primary transfer, secondary transfer, and fixing is performed. The pre-process is a period during which a preparatory operation is performed before the image forming process from when a start instruction is input until the image actually starts to be formed. The paper-interval process is a period corresponding to the period between recording materials P when image formation is performed continuously on multiple recording materials P (continuous image formation). The post-rotation process is a period in which a rearrangement operation (preparatory operation) is performed after the image forming process. The non-image forming time is a period other than the image forming time, and includes the above-mentioned pre-process, the sheet-interval process, the post-process, and further the pre-multiple-rotation process, which is a preparatory operation when the image forming apparatus 100 is turned on or when the image forming apparatus 100 returns from a sleep state. In addition, in this embodiment, a toner supply operation, which will be described later, can be performed. The toner supply operation is performed at a timing different from the image forming operation, and is an operation of supplying toner t from the developing roller 41 to the photoconductor 1 and supplying toner t to the contact portion P6 between the cleaning blade 51 and the photoconductor 1. In addition, regarding the toner supply operation, a first toner supply operation and a second toner supply operation can be performed based on the conditions stored in the memory m1. The first toner supply operation and the second toner supply operation will be described in detail later, but the first toner supply operation is an operation that is mainly performed when the process cartridge 7 is initially installed in the image forming apparatus 100. And the second toner supply operation is a toner supply operation that is performed after the first toner supply operation is performed.

[0042] <Photoconductor Structure> Next, the photoconductor 1 in this embodiment will be further described.

[0043] The photoreceptor 1 may be a cylindrical drum base made of aluminum, nickel, or the like and a photosensitive material such as OPC (organic photoconductor), amorphous selenium, or amorphous silicon. The photoreceptor 1 may further include a wear-resistant protective layer on the outermost layer to improve wear resistance. By providing a protective layer, the durability of the photoreceptor 1 may be improved. In this embodiment, the photoreceptor 1 is an OPC photoreceptor whose photosensitive layer is made of an organic photoconductor. In this embodiment, the photoreceptor 1 is made of a cylindrical, conductive metallic support having an outer diameter of 24 mm, a conductive layer as an undercoat layer of the support, a photosensitive layer (charge generation layer, charge transport layer) formed on the undercoat layer, and a protective layer formed on the photosensitive layer.

[0044] The protective layer preferably contains conductive particles and / or a charge transport material and a resin. Examples of the conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred. Examples of the resin include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenolic resins, melamine resins, and epoxy resins. Among these, polycarbonate resins, polyester resins, and acrylic resins are preferred.

[0045] The protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the reaction include thermal polymerization, photopolymerization, and radiation polymerization. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an acrylic group and a methacrylic group. A material having a charge transport function may be used as the monomer having a polymerizable functional group.

[0046] The protective layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0047] The average thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less In this embodiment, the average thickness of the protective layer was set to 3 μm.

[0048] The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0049] Furthermore, in this embodiment, a roughening treatment is performed on the surface of the photoreceptor 1. When a photoreceptor 1 that has been subjected to an appropriate roughening treatment is used, the metal soap 45c fills the grooves formed on the surface of the photoreceptor 1, and the metal soap 45c is not removed and can remain on the surface of the photoreceptor 1. This further sustains the effect of the metal soap application operation, and the metal soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time.

[0050] In order to achieve the above-described effects, when the surface of the photoreceptor 1 is roughened, the photoreceptor 1 that satisfies the following conditions is used. The ten-point average surface roughness (Rz) of the circumferential surface of the photoreceptor 1 is 0 < Rz ≤ 0.70 (μm) (preferably, 0.10 ≤ Rz ≤ 0.50 (μm)), and the average interval (Sm) of the unevenness on the circumferential surface is 0 < Sm ≤ 70 (μm) (preferably, 5 ≤ Sm ≤ 70 (μm)). By setting the above ranges, it is possible to stably maintain the metal soap 45c on the surface of the photoreceptor 1, and as a result, image flow can be suppressed over a long period. Therefore, in this embodiment, the durability of the photoreceptor 1 is maintained even in a configuration with a longer lifespan by performing a roughening process to form appropriate unevenness on the surface of the photoreceptor 1.

[0051] In the photoreceptor 1 of this embodiment, a roughening process for forming minute unevenness on the surface is performed to maintain the durability of the photoreceptor 1. According to Japanese Patent No. 4027407, a plurality of grooves having a width in the range of 0.5 μm or more and 40 μm or less extending in a substantially circumferential direction of the circumferential surface are formed in the longitudinal direction (generatrix direction, rotation axis direction of the photoreceptor 1) on the circumferential surface of the photoreceptor 1.

[0052] FIG. 4 shows an example of the state of the grooves 1b formed on the circumferential surface 1a of the photoreceptor 1. As shown in FIG. 4, each groove 1b is an annular groove extending in the circumferential direction on the circumferential surface 1a of the photoreceptor 1, and is formed so as to be arranged at intervals in the generatrix direction of the circumferential surface 1a. That is, the circumferential surface 1a has a configuration in which a flat portion 1c where the groove 1b is not formed and the groove 1b are alternately formed in the generatrix direction. Note that the region where the groove 1b is formed on the circumferential surface 1a only needs to include at least the region where the cleaning blade 51 abuts, and does not necessarily need to be formed over the entire longitudinal direction of the circumferential surface 1a.

[0053] As described in the above publication, the grooves 1b are not limited to being formed so as to extend in the same direction as the circumferential direction as shown in FIG. 4. For example, the grooves 1b may be formed at an angle of 10° with respect to the circumferential direction. Alternatively, the grooves 1b may be formed at an angle of ±30° with respect to the circumferential direction, and the grooves 1b with different angles may intersect with each other. In this embodiment, the term "approximately circumferential direction" includes a case where the grooves are completely circumferential and a case where the grooves are almost circumferential, and the term "approximately circumferential direction" specifically refers to a direction that is less than ±60° with respect to the circumferential direction.

[0054] Next, a polishing method for polishing the surface of the photoreceptor 1 will be described. FIG. 5 is a schematic diagram of a polishing device for polishing the surface of the photoreceptor 1. The polishing sheet 40 is taken up in the direction of the arrow by a take-up mechanism (not shown). The photoreceptor 1 rotates in the direction of the arrow. The backup roller 39 rotates in the direction of the arrow. As the polishing conditions, a polishing sheet manufactured by Riken Corundum Co., Ltd. (product name: GC#3000, base layer sheet thickness: 75 μm) was used as the polishing sheet 40. A urethane roller (outer diameter: 50 mm) with a hardness of 20° was used as the backup roller 39, and the feed direction of the polishing sheet 40 and the rotation direction of the photoreceptor 1 were set to the same as the penetration amount: 2.5 mm, the sheet feed amount: 200 to 400 mm / s, and polishing was performed for 5 to 30 seconds. The surface roughness of the photoreceptor 1 after polishing was measured under the following conditions using a surface roughness measuring device (product name: SE700, SMB-9, manufactured by Kosaka Laboratory Co., Ltd.). In the longitudinal direction of the photoreceptor 1, measurements were taken at positions 30, 110, and 185 mm from the top of the coating, and after rotating 120° forward, measurements were taken at positions 30, 110, and 185 mm from the top of the coating in the same manner. After rotating 120° forward, measurements were taken in the same manner, for a total of nine points. The measurement conditions were: measurement length: 2.5 mm, cutoff value: 0.8 mm, feed speed: 0.1 mm / s, filter characteristics: 2CR, leveling: straight line (all areas). In this embodiment, the surface of the photoreceptor 1 was roughened, but it is not necessary to perform the roughening treatment.

[0055] <Toner composition> Next, the composition of the toner t will be further described.

[0056] In this embodiment, the toner t is an inorganic particle-added toner in which inorganic silicon is added to the base particles (toner particles) to ensure fluidity and improve charging performance. The toner t used in this embodiment is a non-magnetic one-component granular polymerized toner with a negative charging polarity and an average particle size of 7 μm.

[0057] 6, metal soap 45c is added to inorganic silicon 45b in order to reduce the coefficient of friction on the surface of photoreceptor 1. Originally, discharge products are highly sticky and increase the coefficient of friction on the surface of photoreceptor 1, but by supplying metal soap 45c to the surface of photoreceptor 1, adhesion of discharge products to the surface of photoreceptor 1 can be suppressed, and the increase in the coefficient of friction can be suppressed.

[0058] Metal soap 45c is a general term for long-chain fatty acids and metal salts other than sodium and potassium. Specific examples include metal salts of fatty acids such as stearic acid, myristic acid, lauric acid, ricinoleic acid, and octylic acid and metal species such as lithium, magnesium, calcium, barium, and zinc. In Example 1, zinc stearate is externally added as metal soap 45c. Note that the type of metal soap 45c is not limited to this, and lead stearate, cadmium stearate, barium stearate, calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, zinc laurate, zinc myristate, and the like are also possible, and at least one of these may be selected.

[0059] The amount of metal soap 45c added externally is preferably 0.6 wt% or less. The more the amount added externally, the more effective it is in suppressing adhesion of discharge products to the photoconductor 1, but adding too much externally reduces the fluidity of the toner, lowering the image density in the latter half of the image. This is a phenomenon called solid image followability degradation, in which followability decreases as the image approaches the rear end of the recording material when outputting a solid black image. On the other hand, the amount of metal soap 45c added externally is preferably 0.05 wt% or more. If the amount is too small, the effect of the metal soap 45c is less likely to be achieved.

[0060] The average particle size of the metal soap 45c is preferably 0.15 μm or more and 2.0 μm or less. If the average particle size of the metal soap 45c is smaller than 0.15 μm, it becomes difficult to apply the metal soap 45c to the surface of the photoreceptor 1. This is particularly noticeable when the surface of the photoreceptor 1 has grooves, which will be described later. On the other hand, if the particle size is larger than 2.0 μm, it cannot pass through the toner regulating member 43 in the developing unit 4 and is left behind in the developing chamber 46, making it difficult to supply the metal soap 45c to the surface of the photoreceptor 1. Hereinafter, the combination of the toner base particles 45a and the external additives 45b and 45c will be referred to as the toner.

[0061] The method for measuring the average particle size of the metal soap 45c will be described. 10 mL of ethanol was added to 0.5 g of the metal soap 45c, and ultrasonic dispersion was performed for 5 minutes using an ultrasonic disperser manufactured by Nippon Seiki Co., Ltd. Next, ethanol was circulated as a measurement solvent. Then, the obtained dispersion liquid of the metal soap 45c was added to a microtrack laser diffraction / scattering type particle size distribution measuring device (SPA type) manufactured by Nikkiso Co., Ltd. until the DV (diffracted light amount) value, which is a value related to the integrated value of the scattered light amount of the particles, reached 0.6 to 0.8. Then, the particle size distribution in this state was measured, and the median diameter obtained as the cumulative median diameter, which is the 50% diameter, was taken as the average particle size.

[0062] The metal soap 45c having the above average particle size may be produced, for example, by a double decomposition method in which an aqueous solution of a fatty acid salt and an aqueous solution or dispersion of an inorganic metal salt are reacted with each other.

[0063] In Example 1, zinc stearate having an average particle size of 0.60 μm was used. The zinc stearate as the metal soap 45c is attached to the toner particles by being charged with a polarity opposite to that of the toner particles, and is supplied onto the photoconductor 1 during non-image formation.

[0064] Next, a method for producing the toner particles will be described.

[0065] The toner particles can be produced by a known method, such as a kneading and grinding method or a wet production method. From the viewpoint of uniform particle size and shape controllability, the wet production method is preferred. Furthermore, the wet production method can be a suspension polymerization method, a dissolution suspension method, an emulsion polymerization aggregation method, an emulsion aggregation method, or the like.

[0066] In this embodiment, the suspension polymerization method was adopted. In the suspension polymerization method, first, a polymerizable monomer for producing a binder resin and other additives such as a colorant as required are uniformly dissolved or dispersed using a dispersing machine such as a ball mill or an ultrasonic dispersing machine to prepare a polymerizable monomer composition. This process is called a preparation process of a polymerizable monomer composition. At this time, a multifunctional monomer, a chain transfer agent, a wax as a release agent, a charge control agent, a plasticizer, and the like can be appropriately added as required. As the polymerizable monomer in the suspension polymerization method, the vinyl polymerizable monomers shown below can be suitably exemplified.

[0067] Styrene; styrene derivatives such as α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate acrylic polymerizable monomers such as ethyl acrylate and 2-benzoyloxyethyl acrylate; methacrylic polymerizable monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, diethyl phosphate ethyl methacrylate, and dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, and vinyl formate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropyl ketone.

[0068] Next, the polymerizable monomer composition is put into a previously prepared aqueous medium, and droplets of the polymerizable monomer composition are formed into a desired toner particle size by a stirrer or disperser having high shear force. This process is called a granulation process. It is preferable that the aqueous medium in the granulation process contains a dispersion stabilizer in order to control the particle size of the toner particles, to sharpen the particle size distribution, and to suppress the coalescence of toner particles during the manufacturing process. Dispersion stabilizers are generally broadly classified into polymers that exhibit repulsive force due to steric hindrance and poorly water-soluble inorganic compounds that stabilize dispersion by electrostatic repulsive force. Fine particles of poorly water-soluble inorganic compounds are preferably used because they dissolve in acid or alkali and can be easily removed by washing with acid or alkali after polymerization.

[0069] As the dispersion stabilizer of the poorly water-soluble inorganic compound, one containing any one of magnesium, calcium, barium, zinc, aluminum, and phosphorus is preferably used. It is more preferable that one of magnesium, calcium, aluminum, and phosphorus is contained. Specifically, the following can be mentioned.

[0070] Magnesium phosphate, tricalcium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, hydroxyapatide.

[0071] The above dispersion stabilizer may be used in combination with an organic compound such as polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, or starch. These dispersion stabilizers are preferably used in an amount of 0.01 to 2.00 parts by mass per 100 parts by mass of the polymerizable monomer.

[0072] Furthermore, in order to make these dispersion stabilizers finer, a surfactant may be used in an amount of 0.001 to 0.1 parts by mass relative to 100 parts by mass of the polymerizable monomer. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and calcium oleate are preferably used.

[0073] After or during the granulation step, the temperature is preferably set to 50° C. or more and 90° C. or less to polymerize the polymerizable monomer contained in the polymerizable monomer composition, thereby obtaining a toner particle dispersion. This step is called the polymerization step. In the polymerization step, it is preferable to perform a stirring operation so that the temperature distribution in the container is uniform. When a polymerization initiator is added, it can be added at any timing and for any required time. In addition, the temperature may be raised in the latter half of the polymerization reaction in order to obtain a desired molecular weight distribution, and further, in order to remove unreacted polymerizable monomers, by-products, etc. from the system, a part of the aqueous medium may be distilled off by a distillation operation in the latter half of the reaction or after the reaction is completed. The distillation operation can be performed under normal pressure or reduced pressure.

[0074] In the suspension polymerization method, an oil-soluble initiator is generally used as the polymerization initiator. Examples of the initiator include the following:

[0075] azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile; peroxide initiators such as acetylcyclohexylsulfonyl peroxide, diisopropyl peroxycarbonate, decanonyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, acetyl peroxide, tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, tert-butyl peroxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxypivalate, and cumene hydroperoxide.

[0076] The polymerization initiator may be used in combination with a water-soluble initiator as necessary. Examples of the water-soluble initiator include the following.

[0077] Ammonium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethyleneisobutyromidine) hydrochloride, 2,2'-azobis(2-aminodinopropane) hydrochloride, azobis(isobutylamidine) hydrochloride, 2,2'-azobisisobutyronitrile sodium sulfonate, ferrous sulfate, or hydrogen peroxide.

[0078] These polymerization initiators can be used alone or in combination of two or more. In order to control the degree of polymerization of the polymerizable monomer, a chain transfer agent, a polymerization inhibitor, etc. can also be further added.

[0079] The toner t may contain an organosilicon polymer, and the organosilicon polymer may have 1 to 3 carbon atoms directly bonded to the silicon atom. 3 / 2 Here, R may be a hydrocarbon group having 1 to 6 carbon atoms, or R may be a hydrocarbon group having 1 to 3 carbon atoms.

[0080] The amount of inorganic silica transferred by washing with water was controlled by changing the external addition conditions, that is, the amount of external addition, the rotation speed (circumferential speed) of the tip of the blade, and the time (hours) during which the blade rotates, using a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) as a surface modification device. The external addition conditions of toner t in this embodiment are shown in Table 1 below. Details of the surface modification device and the external addition conditions, that is, the peripheral speed and time of the surface modification device, are as described in JP 2016-38591 A. In addition, 0.20 wt % of zinc stearate was externally added to the toner t used in this embodiment.

[0081] [Table 1]

[0082] <Lubricant composition> At the time of cartridge shipment, the lubricant applied to the developing roller 41 is the toner t with inorganic particles added thereto as shown in Fig. 6, and has an average particle size of 7 µm. However, the type of lubricant is not limited to the toner t with inorganic particles added thereto, and may be silicone resin or the like. Also, it is not necessary to apply a lubricant to the surface of the developing roller 41.

[0083] <Toner supply sequence execution requirements and overview> In the first embodiment, a toner supply sequence operation (toner purging operation) is executed when a new process cartridge 7 is installed in the image forming apparatus 100. The toner supply sequence will be outlined with reference to FIG.

[0084] FIG. 7 is a flow chart showing the operation of discharging the toner from the developing roller when the process cartridge 7 is new.

[0085] For example, when the image forming apparatus 100 is turned on or the cartridge replacement panel is opened and closed to enter an operable (standby ON) state (S1), the control unit 202 starts an operation for determining whether to execute a toner supply sequence (S2).

[0086] First, the control unit 202 communicates with the memory m1 mounted in the process cartridge 7 through the memory communication unit 222, and reads information related to the usage amount of the process cartridge 7 (S3). Here, the memory m1 is disposed on the photoconductor unit 8 side, but may be disposed on the developing unit 4 side.

[0087] Thereafter, the control unit 202 determines whether or not a new cartridge is included based on the information relating to the usage amount of the process cartridges 7 (S4).

[0088] If a new cartridge is not included (NO in S4), the control unit 202 controls so as not to execute the toner supply sequence, and the process proceeds to the image forming process (S6).

[0089] If the control unit 202 determines in (S4) that a new cartridge is included (S4 YES), it executes a toner supply sequence (S5) to be described later. After the toner supply sequence is executed, the process proceeds to the image formation process (S6).

[0090] In the initial stage of use of the process cartridge 7, the coefficient of friction of the surface of the photoreceptor 1 is high, and it is desirable to immediately and proactively supply metal soap 45c to the surface of the photoreceptor 1 to reduce the coefficient of friction. At the contact portion P6 where the photoreceptor 1 and the cleaning blade 51 come into contact, a cleaning blocking layer made of an external additive has not yet been sufficiently formed, and the cleaning performance is unstable. Therefore, special care is required when supplying toner to the surface of the photoreceptor 1 and sending the toner to the contact portion P6. In particular, it has been found that when the surface of the photoreceptor 1 is roughened as employed in this embodiment, it is difficult to form a blocking layer at the nip portion.

[0091] Therefore, in the first embodiment, driving is started under high voltage conditions and driving conditions for image formation so that the potential difference formed between the supply roller 42 and the development roller 41, which causes an electrostatic force to act on the metal soap 45c in the direction from the supply roller 42 to the development roller 41, is reduced. Then, a laser is irradiated onto the photoconductor 1 to supply a fixed amount of toner. The voltages applied to each member during the toner supply sequence are set to Vd=-500V, Vdc=-350V, and Vrs=-400V.

[0092] In the first embodiment, the timing for executing the toner supply sequence operation is described as being performed when the toner is new, but the present invention is not limited to this. The toner supply sequence operation may be performed at a timing designated by the user, at a timing when the driving torque is determined to be high, or at a timing when an image defect such as uneven density or cleaning failure occurs.

[0093] <Details of toner supply pattern during toner supply sequence> Here, the discharge pattern of the toner image discharged onto the photoconductor 1 will be described.

[0094] FIG. 8 is a timing chart when the exposure unit 3 is controlled to form a toner supply pattern with laser light during a toner supply operation as a toner supply sequence.

[0095] At the initial installation of the cartridge, a cleaning prevention layer made of an external additive or the like is not yet sufficiently formed at the contact portion P6 formed between the photoreceptor 1 and the cleaning blade 51, and the cleaning performance is in an unstable state. Therefore, it is not desirable to select a pattern that supplies a large amount of toner to the contact portion P6. That is, it is desirable to control the laser light so that it becomes an ejection pattern that can supply a small amount at a time and an amount sufficient to form a blocking layer on the surface of the photoreceptor 1. Specifically, in order to appropriately form the cleaning prevention layer, it is necessary to level the rotation for a certain period after the toner is supplied to the contact portion P6. Therefore, it is a feature of this embodiment to provide a leveling section in which a small amount of toner is ejected and no toner is ejected for a certain period. Further, in this embodiment, a repetitive operation of providing a leveling section in which no toner is ejected for a certain period after a small amount of toner is ejected is required. Therefore, as shown in FIG. 8(a), the pattern of the toner image formed on the surface of the photoreceptor 1 repeats a uniform line pattern in the longitudinal direction a certain number of times. By forming this pattern on the surface of the photoreceptor 1 and supplying toner, a small amount at a time and the required amount are supplied. In this embodiment, the nip width of the nip formed at the contact portion P6 between the photoreceptor 1 and the cleaning blade 51 is 100 μm.

[0096] In Example 1, there are a development (purge) width A (first pattern, third pattern) and a non-development (purge) width B (second pattern, fourth pattern) in the circumferential direction of the rotation direction (circumferential direction) of the photoreceptor 1, and toner is ejected so as to be repeated a plurality of times with the relationship of A < B. Here, the non-development width B corresponds to the above leveling section. The control unit 202 controls so that the development width A = 1 mm, the non-development width B = 9 mm, the number of repetitions = 5 times, and the laser light amount = 0.40 μJ / cm 2 At this time, the toner t developed on the exposure surface corresponding to the development width A exposed with the laser light amount = 0.40 μJ / cm formed on the surface of the photoreceptor 1 is 0.40 mg / cm on the surface of the development roller 41. 2 で露光された現像幅Aに対応する露光面に現像されるトナーtは、現像ローラ41の表面に0.40mg / cm 2In this state, the toner t is carried on the developing roller 41 in an amount of 100%. The toner t is developed on the exposed surface from the developing roller 41 toward the photoconductor 1 at a rate of almost 100%. Here, in this embodiment, the PS of the toner supply operation is set to 91 mm / sec, which is a low-speed mode. Therefore, the ratio of the peripheral speed of the developing roller 41 to the rotation speed of the photoconductor 1 is 90%, and the peripheral speed of the developing roller 41 is 1 cm 2 0.36 mg is developed per one development roller. In this embodiment, the development opening width in the direction of the rotation axis of the development roller 41 (the maximum width at which toner t can be supplied to the surface of the development roller 41) is 220 mm. The maximum width that can be exposed by the exposure unit 3 is set to a width that allows exposure up to an area outside the above-mentioned 220 mm. In this embodiment, the first pattern corresponding to the development width A is formed uniformly in the longitudinal direction. This makes it possible to supply toner uniformly in the longitudinal direction to the contact portion P6 between the photoconductor 1 and the cleaning blade 51. Of course, a configuration in which the above-mentioned pattern is formed in a portion of the longitudinal direction is also acceptable.

[0097] When the photoconductor 1 and the developing roller 41 are rotating, the area of ​​the photoconductor 1 facing the developing roller 41 at the developing portion P3 is defined as the first area. The area of ​​the photoconductor 1 facing the developing roller 41 at the developing portion P3 after the developing roller 41 has made one rotation is defined as the second area. The area of ​​the photoconductor 1 between the first area and the second area in the rotation direction of the photoconductor 1 is defined as the third area. A diagram showing the definitions of the areas is shown in FIG. 9.

[0098] The toner supply pattern used when performing the toner supply operation will be described in detail later.

[0099] The following first, second, third, and fourth patterns are formed in the third region, that is, the region of the photoconductor 1 corresponding to one rotation of the developing roller 41. That is, the following first, second, third, and fourth patterns are formed in the region of the photoconductor 1 corresponding to the outer diameter of the developing roller 41, φ12×π×(1 / (90 / 100))=41.9 mm (90 is the ratio of the circumferential speed of the developing roller 41 to the rotational speed of the photoconductor 1).

[0100] In this embodiment, the outer diameter of the photoconductor 1 is φ24, so that φ24×π=75.4 mm is the outer circumferential length of the photoconductor 1. 41.9 mm, which corresponds to one revolution of the developing roller 41, corresponds to approximately 55% of one revolution of the photoconductor 1. The development width A, which is a pattern in which a part is exposed by the exposure unit 3, is defined as the first pattern. The non-development width B, which is a pattern in which no exposure is performed after the first pattern in the rotation direction, is defined as the second pattern. The second development width A, which is a pattern in which a part is exposed by the exposure unit after the second pattern in the rotation direction, is defined as the third pattern. The second non-development width B, which is a pattern in which no exposure is performed after the third pattern in the rotation direction, is defined as the fourth pattern. The control unit 202 controls to form a toner supply pattern formed of the first pattern, the second pattern, the third pattern, and the fourth pattern. Here, the toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotation direction. Also, the length of the fourth pattern is longer than the length of the third pattern in the rotation direction. In particular, in this embodiment, the first pattern and the second pattern are formed repeatedly, that is, the first pattern and the third pattern are the same pattern, and the second pattern and the fourth pattern are the same pattern.

[0101] The second and fourth patterns may be exposed with a smaller amount of exposure than the amount of exposure for exposing the first pattern to form non-developed areas. If the toner supply section and the leveling section are configured as described above, the toner supply section may not be formed by exposure, but may be developed with toner on the surface potential Vd of the photoconductor 1 formed by the charging roller 2. Specifically, the control unit 202 sets the developing voltage so that the absolute value is larger than Vd. Then, a potential difference is formed between the developing roller 41 and the photoconductor 1 such that the negatively charged toner t moves from the surface of the developing roller 41 to which the developing voltage is applied to the surface of the photoconductor 1 on which the surface potential Vd is formed.

[0102] In this embodiment, the surface of the developing roller 41 is provided with a toner t containing inorganic particles as a lubricant. The control unit 202 reads information on the amount of use of the process cartridge 7 and controls the toner supply operation to be performed when the cartridge is new. Therefore, when the process cartridge 7 is initially installed in the image forming apparatus 100, it is necessary to prevent the photoconductor 1 and the cleaning blade 51 from continuing to rotate in a state of contact with each other under a high torque. For this reason, it is necessary to quickly and effectively send the lubricant to the contact portion P6 between the photoconductor 1 and the cleaning blade 51. Therefore, it is necessary to perform the toner supply operation for at least one revolution of the developing roller 41, and in this embodiment, the amount is set to a value that includes a part of the toner supply pattern in the area corresponding to the third area.

[0103] In this embodiment, when the process cartridge 7 is not in a start-of-use state, the control unit 202 controls to execute a second toner supplying operation different from the first toner supplying operation, which is the above-mentioned toner supplying operation. The second toner supplying operation is executed using a second toner supplying pattern different from the first toner supplying pattern, which is the above-mentioned toner supplying pattern. In the second toner supplying operation, the development width A formed on the surface of the photoconductor 1 is 12.6 mm. The development width A in the second toner supplying operation is preferably about 10 to 20 mm. The toner supplying pattern in the second toner supplying operation is not a repeated pattern, but is an operation that is completed in one supply.

[0104] The first toner supply operation repeats toner supply and leveling to provide a lubricating effect at the contact portion P6 between the photoconductor 1 and the cleaning blade 51 at the beginning of use of the cartridge. The amount of toner supplied at one time is controlled to be the minimum amount so that cleaning failure does not occur and a blocking layer is formed. On the other hand, the second toner supply operation is an operation performed when the cartridge has been used to a certain extent. As an example, the second toner supply operation is performed during a post-rotation operation after an image forming operation, or during a paper-to-paper operation between image forming operations when image forming operations are performed consecutively. Here, in the aspect where the second toner supply operation is performed, a blocking layer formed of toner and external additives is formed at the contact portion P6 between the photoconductor 1 and the cleaning blade 51. Since the second toner supply operation is for maintaining the blocking layer, more toner is supplied than in the first toner supply operation. That is, the amount of toner supplied to the contact portion P6 by the first toner supply pattern according to the first pattern formed on the surface of the photoconductor 1 is made smaller than the amount of toner supplied to the contact portion P6 by the second toner supply pattern formed on the surface of the photoconductor 1. This means that the second toner supply operation supplies more toner at one time than the first toner supply operation. Furthermore, the amount of toner supplied to the contact portion P6 by the first toner supply pattern is made smaller than the amount of toner supplied to the contact portion P6 by the second toner supply pattern formed on the surface of the photoconductor 1. This means that the total amount of toner supplied as one toner purge operation is made larger in the second toner supply operation than in the first toner supply operation. By setting the above conditions, it is possible to appropriately use the toner supply operation according to the situation.

[0105] Furthermore, the control unit 202 controls the photoconductor 1 to rotate at a first rotation speed when the first toner supply operation is performed, and controls the photoconductor 1 to rotate at a second rotation speed faster than the first rotation speed when the second toner supply operation is performed. The aim is to improve the tracking of the cleaning blade 51 to the photoconductor 1 and to reduce the amount of toner supplied per unit time by relatively slowing down the speed of the first toner supply operation. In other words, by reducing the momentum of the toner, a state is created in which the cleaning blade 51 can easily clean the toner. In this embodiment, the rotation speed of the photoconductor 1 during the second toner supply operation is 321 mm / sec, which is the speed in the normal mode. On the other hand, the rotation speed of the photoconductor 1 during the first toner supply operation is 91 mm / sec in the low speed mode in which the rotation speed of the photoconductor 1 is slower than in the normal mode.

[0106] Furthermore, in this embodiment, the intermediate transfer belt 31 can be brought into contact with and separated from each photoconductor 1 by a belt contact / separation mechanism 90 (FIG. 3). In this embodiment, the belt contact / separation mechanism 90 separates the intermediate transfer belt 31 from the photoconductor 1 by moving the primary transfer roller 32 in a direction away from the photoconductor 1. Also, the intermediate transfer belt 31 is configured to contact the photoconductor 1 by moving the primary transfer roller 32 in a direction approaching the photoconductor 1. When the first toner supply operation is performed, the control unit 202 controls the intermediate transfer belt 31 to be in contact with the photoconductor 1, and when the second toner supply operation is performed, the control unit 202 controls the intermediate transfer belt 31 to be separated from the photoconductor 1. Also, when the first toner supply operation is performed, the transfer voltage is controlled as follows. The transfer voltage applied to the transfer roller 32 in the first toner supply operation is made smaller than the absolute value of the transfer voltage applied in the image forming operation. Then, the transfer contrast, which is the potential difference between the transfer voltage and the surface potential of the photoconductor 1 at the transfer portion P4, is made smaller than the transfer contrast during the image forming operation. The reason for the above control regarding transfer will be explained below.

[0107] The first toner supply operation is mainly performed in the initial stage of use of the process cartridge 7 as described above. In that case, the contact between the photoconductor 1 and the cleaning blade 51 is very unstable. Due to the instability, the rotation of the photoconductor 1 may be unstable, and cleaning failures may occur due to the unstable contact state of the cleaning blade 51. Therefore, in this embodiment, the intermediate transfer belt 31 is brought into contact with the photoconductor 1 during the first toner supply operation by moving the transfer roller 32 in a direction approaching the photoconductor 1. As a result of the contact between the intermediate transfer belt 31 and the photoconductor 1, the rotation of the photoconductor 1 is stabilized, and the above instability is suppressed. In addition, the intermediate transfer belt 31 is brought into contact with the photoconductor 1 during the first toner supply operation to rotate the photoconductor 1, so that the toner t that has moved from the developing roller 41 onto the surface of the developed photoconductor 1 passes through the transfer portion P4. In the transfer portion P4, a transfer voltage is applied so that the lubricant containing the toner t (in this embodiment, the toner t with inorganic particles added thereto) is not transferred to the intermediate transfer belt 31 as much as possible. In this embodiment, a transfer voltage of a polarity opposite to the normal polarity of the toner is applied to the transfer roller 32. The transfer voltage is made larger toward the normal polarity side, i.e., toward the negative polarity side, when the polarity opposite to the normal polarity of the toner is used as a reference than the transfer voltage in the image forming operation. Alternatively, the transfer voltage may be turned off, or a voltage of the same polarity as the normal polarity of the toner may be applied in the first place. As a result, an electric field that makes it more difficult to move the toner t toward the intermediate transfer belt 31 side than in the image forming operation is formed in the transfer portion P4, and the lubricant containing the toner t can be supplied to the contact portion P6 between the photoconductor 1 and the cleaning blade 51.

[0108] In this way, by setting the conditions for executing the toner supply operation, it is possible to reduce the amount of toner per unit time that enters the contact point P6 between the photosensitive member 1 and the cleaning blade 51, thereby maintaining cleaning performance while supplying components that form a cleaning prevention layer.

[0109] <Verification of effectiveness> In the above-mentioned Example 1, after executing the toner supply sequence for a new product, a comparative verification was performed between Example 1 and the comparative example by observing the amount of toner adhered to the charging roller 2. The verification was performed with a cartridge filled with 400 g of toner under a low temperature and low humidity environment (temperature 15°C, humidity 10%) where cleaning defects are likely to occur.

[0110] The toner supply pattern was set as follows.

[0111] Comparative Example 1 has a purge width A (first pattern) of 5 mm, a non-purge width (second pattern) of 0 mm, and a repetition count of 1. This corresponds to the control in which the length of the first pattern is shortened with respect to the second toner supply operation.

[0112] In Comparative Example 2, the purge width A (first pattern) was 1 mm, the non-purge width (second pattern) was 1 mm, and the number of repetitions was 5.

[0113] In Example 1-1, the purge width A (first pattern) was 1 mm, the non-purge width (second pattern) was 9 mm, and the number of repetitions was 5.

[0114] In Example 1-2, the purge width A (first pattern) was 2.5 mm, the non-purge width (second pattern) was 9 mm, and the number of repetitions was 2.

[0115] In both cases, the toner supply amount was the same (5 mm) for comparison.

[0116] <Verification results> The verification results are shown in Table 2.

[0117] [Table 2]

[0118] In Comparative Example 1, when the charging roller 2 was checked after the toner supply sequence was completed, a large amount of toner t adhered, resulting in charging defects due to soiling of the charging roller, and numerous vertical streaks occurred. In Comparative Example 2, although it was less severe than Comparative Example 1, toner t adhered to the charging roller 2, resulting in charging defects due to soiling of the charging roller, and numerous vertical streaks occurred.

[0119] On the other hand, in Example 1-1 and Example 1-2, no image defects occurred. Consider the reasons why the effects were demonstrated with the configurations of Example 1-1 and Example 1-2.

[0120] As conditions for performing the toner supply operation, it is necessary to send the above lubricant promptly and effectively to the contact portion P6 between the photoreceptor 1 and the cleaning blade 51. Therefore, in the present embodiment, at least a toner supply pattern is formed within the region corresponding to the third region. The length of the second pattern, which is a non-purge portion, is configured to be longer than the length of the first pattern, which is a purge portion, in the rotational direction, and the first pattern and the second pattern are configured to be repeatedly formed.

[0121] First, in Example 1-1, the first pattern A is set to 1 mm and the second pattern B is set to 9 mm. In the present embodiment, it is preferable that A is set to less than 50% of B, and it is more preferable that the ratio of B to the toner supply pattern is set to 70% or more. That is, it is preferable that A < B and (B / (A + B)) × 100 ≧ 70% is satisfied. Here, 70% is referred to as the "leveling ratio". A larger leveling ratio means that the leveling time is longer. Since the leveling ratio in Example 1-1 is 90%, it can be seen that a sufficient leveling effect is obtained. On the other hand, the leveling ratio of Comparative Example 1 is 0%, and the leveling ratio of Comparative Example 2 is 50%. From the magnitude of the leveling ratio, the level of Comparative Example 2 is better than that of Comparative Example 1, but both are insufficient results.

[0122] In addition, there is also a suitable range for the length of A. In this embodiment, it is preferably within the range of 0.5 mm to 3.0 mm. In this embodiment, the nip width in the rotational direction of the photoreceptor 1 formed at the contact portion P6 between the photoreceptor 1 and the cleaning blade 51 is 100 μm, and the loading amount of the toner t carried on the developing roller 41 is 0.40 mg / cm 2 is. Here, the developing width A is set to 1 mm as the first pattern, and the peripheral speed ratio of the developing roller 41 to the photoreceptor 1 in the first toner supply operation is 90%. Therefore, when the toner purge operation for 1 mm is performed, the amount of toner entering the nip portion is 0.036 mg / (1 mm×1 cm). In the configuration of this embodiment, it has been experimentally found that the amount of toner that can be tolerated by one toner supply at the nip portion per unit nip (per 1 cm in the longitudinal width) is about 0.11 mg, which corresponds to a developing width A of about 3.0 mm. Therefore, in Comparative Example 1, since A is 5 mm, it can be said that the level of toner adhesion was poor. Also, if the amount of toner supplied at one time is too small, the time of the toner supply operation may become long, or the effect may not be obtained at all. Therefore, a suitable range should be defined according to the configuration. Although it will be described after Example 2, once the blocking layer starts to be formed at the nip portion, the above-mentioned tolerable amount of toner tends to increase.

[0123] In Example 1-2, there was slightly more toner adhesion than in Example 1-1, but the image quality was at a level with no problems. This is also because, for the same reason as in Example 1-1, A < B and (B / (A + B))×100 ≧ 70% is satisfied. Since the leveling ratio in Example 1-2 is 78%, it can be seen that the effect is obtained.

[0124] From this verification, as described above, it was found that by supplying the toner in appropriate small amounts rather than supplying a large amount of toner at one time, the toner that becomes the cleaning blocking layer can be supplied at a low load. As in Example 1, after performing the toner supply, by performing the leveling rotation for a certain period, the toner that becomes the cleaning blocking layer can be supplied at a low load to the contact portion P6 between the photoreceptor 1 and the cleaning blade 51.

[0125] This embodiment has the following configuration.

[0126] The image forming apparatus includes a photoconductor 1 as a rotatable image carrier, and an exposure unit 3 that exposes the surface of the photoconductor 1 to light to form an electrostatic latent image on the surface of the photoconductor 1. The image forming apparatus includes a developing roller 41 as a rotatable developer carrier that supplies toner to the surface of the photoconductor 1 in the developing section P3 to develop the electrostatic latent image into a toner image. The image forming apparatus includes a cleaning blade 51 as a cleaning member that contacts the photoconductor 1 to form a contact section P6 and removes toner attached to the surface of the photoconductor 1 at the contact section P6. The image forming apparatus includes a control unit 202 that controls the following operations by rotating the photoconductor 1 and the developing roller 41 and controlling the exposure unit 3. The control unit 202 controls i) an image forming operation that forms a toner image on a recording material, and ii) a toner supplying operation that is an operation different from the image forming operation and moves toner from the developing roller 41 to the photoconductor 1 to supply toner to the contact section P6. When the photoconductor 1 and the developing roller 41 are rotating, the area of ​​the photoconductor 1 that faces the developing roller 41 in the developing section P3 is defined as a first area. Then, the area of ​​the photoconductor 1 facing the developing roller 41 in the developing section P3 after the area of ​​the developing roller 41 facing the first area has made one revolution is defined as the second area. Furthermore, the area of ​​the photoconductor 1 between the first area and the second area in the rotation direction of the photoconductor 1 is defined as the third area. When performing the toner supply operation, the control unit 202 controls to form the following patterns in the third area. The control unit 202 controls to form a toner supply pattern formed of a first pattern, a part of which is exposed by the exposure unit 3, and a second pattern, a part of which is not exposed or is exposed with an exposure amount smaller than the exposure amount for exposing the first pattern. The toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotation direction, and the first pattern and the second pattern are repeatedly formed.

[0127] Furthermore, the length of the third pattern in the rotational direction is shorter than the length of the first pattern in the rotational direction.

[0128] The control unit 202 further includes a memory m1 that stores information about the toner usage status, and executes a toner supply operation according to the toner supply pattern based on the information stored in the memory m1. The information is for determining whether the toner is in a start-of-use state, and executes a toner supply operation according to the toner supply pattern when the information indicates that the toner is in a start-of-use state. When the information indicates that the toner is not in a start-of-use state, the control unit 202 controls to execute a second toner supply operation different from the first toner supply operation, which is a toner supply operation according to the toner supply pattern. The second toner supply operation is executed using a second toner supply pattern different from the first toner supply pattern, which is a toner supply pattern. The amount of toner supplied to the contact portion P6 by the first toner supply pattern according to the first pattern formed on the surface of the photoconductor 1 is less than the amount of toner supplied to the contact portion P6 by the second toner supply pattern formed on the surface of the photoconductor 1. The amount of toner supplied to the contact portion P6 by the first toner supply pattern formed on the surface of the photoconductor 1 is less than the amount of toner supplied to the contact portion P6 by the second toner supply pattern formed on the surface of the photoconductor 1. The length of the first pattern in the direction of the rotation axis of the photoconductor 1 is a length that allows image formation in the image forming operation. The first pattern is formed uniformly in the direction of the rotation axis of the photoconductor 1.

[0129] The intermediate transfer belt 31 contacts the photoconductor 1 to form a transfer portion P4, and transfers the toner image formed on the surface of the photoconductor 1 to the recording material P at the transfer portion P4. The intermediate transfer belt 31 further includes a belt contact / separation mechanism 90 that can perform a contact operation to bring the intermediate transfer belt 31 into contact with the photoconductor 1 and a separation operation to separate the intermediate transfer belt 31 from the photoconductor 1. When the first toner supply operation is performed, the control unit 202 controls the intermediate transfer belt 31 to be in contact with the photoconductor 1. When the second toner supply operation is performed, the control unit 202 controls the intermediate transfer belt 31 to be in a separated state from the photoconductor 1. The intermediate transfer belt 31 further includes a primary transfer power source 73 that is a transfer voltage application unit that applies a transfer voltage to the intermediate transfer belt 31, i.e., the transfer roller 32. The potential difference formed between the transfer voltage and the surface potential formed on the surface of the photoconductor 1 at the transfer portion P4 is defined as the transfer contrast. The control unit 202 makes the transfer contrast of the first toner supply operation smaller than the transfer contrast of the image forming operation. The control unit 202 controls the absolute value of the transfer voltage of the first toner supply operation to be smaller than the absolute value of the transfer voltage of the image forming operation, or controls the transfer voltage to be OFF. The control unit 202 may control the transfer voltage of the opposite polarity to the polarity of the transfer voltage of the image forming operation to be applied in the first toner supply operation. The control unit 202 controls the photoconductor 1 to rotate at a first rotation speed when performing the first toner supply operation, and controls the photoconductor 1 to rotate at a second rotation speed faster than the first rotation speed when performing the second toner supply operation.

[0130] By adopting the above-mentioned configuration, it is possible to suppress the occurrence of image defects due to poor cleaning.

[0131] 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 image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, the same or corresponding elements as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of embodiment 1, and detailed explanations are omitted.

[0132] <Outline of this Example> In the second embodiment, the toner supply pattern is changed in a configuration similar to that of the first embodiment.

[0133] Specifically, as shown in FIG. 8(b), the non-purged width B is fixed, and the purge width A is made smaller as the number of times increases. In other words, there is a purge width A in the circumferential direction that is developed in the first time and a non-purged width B in the circumferential direction that is not developed, there is a purge width C and a non-purged width B in the circumferential direction that is developed in the second time, and there are a purge width E and a non-purged width B in the circumferential direction that is developed in the third time. In general, the toner t is discharged so that the relationship between the purge width in the circumferential direction that is developed in the nth time and the purge width in the circumferential direction that is developed in the n+1th time is n>n+1. A comparison is made with Comparative Example 2 that was compared in Example 1.

[0134] The toner supply pattern in Example 2 is as follows:

[0135] In Example 2, the purge width was 2.5 mm / 1.5 mm / 1 mm, the non-purge width B was 9 mm, and the number of repetitions was 3.

[0136] The toner supply amount was the same in both cases (5 mm).

[0137] <Verification result 2> The verification results are shown in Table 3.

[0138] [Table 3]

[0139] In Comparative Example 2, as described in Example 1, it is believed that the smoothing rotation distance after the first purge was insufficient, so that the second purge entered the contact point P6 of the cleaning blade 51 before the cleaning prevention layer was formed, causing the toner to slip through.

[0140] In Example 2, toner adhesion to the charging roller due to poor cleaning did not occur. This is because the cleaning member was able to withstand the first purging amount, while the subsequent smoothing rotation of the non-purged portion was long enough to form a sufficient blocking layer, and furthermore, the purging amount was reduced from the second time onwards, making cleaning easier.

[0141] From this verification, it was found that if the non-purging distance (the distance of the smoothing rotation) is a certain distance longer than the purging distance, a cleaning blocking layer can be formed, and that cleaning becomes easier by reducing the amount of purging from the second time onwards. Furthermore, the time required to form the blocking layer can be shortened compared to the configuration of Example 1-1, and the verification results were better than those of Example 1-2.

[0142] The configuration of this embodiment has the following features.

[0143] The image forming apparatus includes a photoconductor 1 as a rotatable image carrier, and an exposure unit 3 that exposes the surface of the photoconductor 1 to light to form an electrostatic latent image on the surface of the photoconductor 1. The image forming apparatus includes a developing roller 41 as a rotatable developer carrier that supplies toner to the surface of the photoconductor 1 in the developing section P3 to develop the electrostatic latent image into a toner image. The image forming apparatus includes a cleaning blade 51 as a cleaning member that contacts the photoconductor 1 to form a contact section P6 and removes toner attached to the surface of the photoconductor 1 at the contact section P6. The image forming apparatus includes a control unit 202 that controls the following operations by rotating the photoconductor 1 and the developing roller 41 and controlling the exposure unit 3. The control unit 202 controls i) an image forming operation that forms a toner image on a recording material, and ii) a toner supplying operation that is an operation different from the image forming operation and moves toner from the developing roller 41 to the photoconductor 1 to supply toner to the contact section P6. When the photoconductor 1 and the developing roller 41 are rotating, the area of ​​the photoconductor 1 that faces the developing roller 41 in the developing section P3 is defined as a first area. Then, the area of ​​the photoconductor 1 facing the developing roller 41 in the developing section P3 after the area of ​​the developing roller 41 facing the first area has made one revolution is defined as the second area. Furthermore, the area of ​​the photoconductor 1 between the first area and the second area in the rotation direction of the photoconductor 1 is defined as the third area. When performing the toner supply operation, the control unit 202 forms a toner supply pattern consisting of the following first pattern, second pattern, third pattern, and fourth pattern in the third area. The first pattern is a pattern in which a part is exposed by the exposure unit 3. The second pattern is a pattern in which a part is not exposed after the first pattern in the rotation direction of the photoconductor 1. The third pattern is a pattern in which a part is exposed by the exposure unit after the second pattern in the rotation direction of the photoconductor 1. The fourth pattern is a pattern in which a part is not exposed after the third pattern in the rotation direction of the photoconductor 1. These toner supply patterns are configured so that the second pattern is longer than the first pattern in the rotation direction of the photoconductor 1, and the fourth pattern is longer than the third pattern in the rotation direction of the photoconductor 1. The length of the third pattern in the rotation direction of the photoconductor 1 is shorter than the length of the first pattern in the rotation direction.

[0144] By having the configuration as described above, the occurrence of image defects due to cleaning failures can be more effectively suppressed.

[0145] (Example 3) In Example 3, the toner supply pattern is further changed in the same configuration as in Example 1. In Example 2, it was characterized in that the non-purge width B was fixed and the purge width A was made smaller as the rotation number advanced. Specifically, in Example 3, as shown in FIG. 8(c), the control of the first pattern of the toner supply pattern and subsequent patterns is changed. There are regions of the circumferential purge width C developed as the third pattern and the non-purge width D in the circumferential direction not developed as the fourth pattern, and the relationship of the lengths is C < D. Thereafter, there are regions of the circumferential purge width E developed as the fifth pattern and the non-purge width F in the circumferential direction not developed as the sixth pattern, and the relationship is E < F. In this way, the control unit 202 is controlled so that the relationship between the circumferential purge width developed at the n-th development and the circumferential purge width developed at the (n + 1)-th development is n > n + 1. Further, the toner t is discharged so that the relationship between the non-purge width in the circumferential direction not developed at the n-th time and the non-purge width in the circumferential direction not developed at the (n + 1)-th time is n > n + 1. That is, the lengths of the purge part and the non-purge part are always purge part < non-purge part, and even if both widths are shortened each time it is repeated, whether the charging roller is less soiled due to cleaning failures as in Example 1 and Example 2 was compared with Comparative Example 3. Two types of the configuration of Example 3 and one type of the modified example of Example 3 were compared simultaneously.

[0146] In Comparative Example 3, the purge widths A / C / E = 2.5 mm / 1.5 mm / 1 mm, the non-purge widths B / D / F = 9 mm / 1 mm / 1 mm, and the number of repetitions = 3 times.

[0147] In Example 3-1, the purge widths A / C / E = 2.5 mm / 1.5 mm / 1 mm, the non-purge widths B / D / F = 9 mm / 3 mm / 1 mm, and the number of repetitions = 3 times.

[0148] Example 3-2 has a purge width A / C / E = 2.5 mm / 1.5 mm / 1 mm, a non-purge width B / D / F = 9 mm / 7 mm / 5 mm, and a number of repetitions = 3 times.

[0149] Modification 1 has a purge width A / C / E = 2.5 mm / 1 mm / 1.5 mm, a non-purge width B / D / F = 9 mm / 5 mm / 7 mm, and a number of repetitions = 3 times. In both cases, the toner supply amount was the same (5 mm).

[0150] <Verification Result 3> The verification results are shown in Table 4.

[0151]

Table 4

[0152] In Comparative Example 3, since the leveling rotation distance after the second purge was insufficient, the third purge entered the contact portion P6 of the cleaning blade 51 before the cleaning prevention layer was formed, and it is considered that the toner slipped through.

[0153] On the other hand, in Example 3-1, no cleaning failure occurred. This is because a certain amount of the blocking layer was formed at the nip portion in the first pass, and the leveling rotation distance after the second pass could be ensured due to the relationship C < D, indicating that the cleaning prevention layer could be formed more effectively than in Comparative Example 3. And further, due to the relationship E < F, the third purge could also clean to some extent. Here, in Example 3-1, the leveling ratio was 70% in the first pass, but was less than 70% in the second and third passes. Since the foundation of the blocking layer could be constructed in the first pass, the conditions for the second and third passes were slightly relaxed. Therefore, in the toner supply operation after the first pass, as long as C < D and E < F, the occurrence of problems can be suppressed even if the leveling ratio is smaller than that in the first pass.

[0154] Furthermore, also in Example 3-2, toner adhesion to the charging roller 2 due to poor cleaning did not occur. Example 3-2 is a more suitable condition than Example 3-1, and it ensures a uniform ratio of 70% for all the first, second, and third times. As a result, as toner supply conditions to the nip portion, the distances of the non-purged portions after the first, second, and third purges are sufficient, and in all cases, a sufficient cleaning prevention layer is formed. However, compared to Example 3-1, the rotation time of the photoreceptor 1 is slightly longer.

[0155] Subsequently, Modification 1 will be considered. The difference between Example 3-2 and Modification 1 is that the conditions for the second time and the third time are swapped. Therefore, in Modification 1, C < E, and it is characteristic that the toner purge executed later in the toner supply operation has a larger supply toner amount. Also in Modification 1, no image defect occurred, and a suitable blocking layer could be formed. This indicates that the relationship A < C is maintained from the first time to the second time, suggesting that the formation of the blocking layer has progressed to some extent at this point. And even if the supply amount increases from the second time to the third time, it is presumed that the leakage of the toner can be suppressed. If the conditions are advantageous for the formation of the blocking layer, they can also be applied under the conditions like Modification 1. However, the relationships of A < B, C < D, and E < F need to be satisfied.

[0156] Therefore, by performing the above control, in addition to the effects of Example 1, it is possible to further reduce the extra rotation of the process cartridge 7 and suppress the wear of the photoreceptor 1 and the deterioration of the toner t.

[0157] The configuration of this embodiment has the following characteristics.

[0158] The image forming apparatus includes a photoconductor 1 as a rotatable image carrier, and an exposure unit 3 that exposes the surface of the photoconductor 1 to light to form an electrostatic latent image on the surface of the photoconductor 1. The image forming apparatus includes a developing roller 41 as a rotatable developer carrier that supplies toner to the surface of the photoconductor 1 in the developing section P3 to develop the electrostatic latent image into a toner image. The image forming apparatus includes a cleaning blade 51 as a cleaning member that contacts the photoconductor 1 to form a contact section P6 and removes toner attached to the surface of the photoconductor 1 at the contact section P6. The image forming apparatus includes a control unit 202 that controls the following operations by rotating the photoconductor 1 and the developing roller 41 and controlling the exposure unit 3. The control unit 202 controls i) an image forming operation that forms a toner image on a recording material, and ii) a toner supplying operation that is an operation different from the image forming operation and moves toner from the developing roller 41 to the photoconductor 1 to supply toner to the contact section P6. When the photoconductor 1 and the developing roller 41 are rotating, the area of ​​the photoconductor 1 that faces the developing roller 41 in the developing section P3 is defined as a first area. Then, the area of ​​the photoconductor 1 facing the developing roller 41 in the developing section P3 after the area of ​​the developing roller 41 facing the first area has made one revolution is defined as the second area. Furthermore, the area of ​​the photoconductor 1 between the first area and the second area in the rotation direction of the photoconductor 1 is defined as the third area. When performing the toner supply operation, the control unit 202 forms a toner supply pattern consisting of the following first pattern, second pattern, third pattern, and fourth pattern in the third area. The first pattern is a pattern in which a part is exposed by the exposure unit 3. The second pattern is a pattern in which a part is not exposed after the first pattern in the rotation direction of the photoconductor 1. The third pattern is a pattern in which a part is exposed by the exposure unit after the second pattern in the rotation direction of the photoconductor 1. The fourth pattern is a pattern in which a part is not exposed after the third pattern in the rotation direction of the photoconductor 1. These toner supply patterns are configured so that the second pattern is longer than the first pattern in the rotation direction of the photoconductor 1, and the fourth pattern is longer than the third pattern in the rotation direction of the photoconductor 1. The length of the fourth pattern in the rotation direction of the photoconductor 1 is shorter than the length of the second pattern in the rotation direction.

[0159] By adopting the above-mentioned configuration, it is possible to more effectively suppress the occurrence of image defects due to poor cleaning.

[0160] In this embodiment, the toner supply amount is set to 5 mm, but the present invention is not limited to this, and it may be necessary to increase or decrease the toner supply amount depending on the configuration of the image forming apparatus. However, the same effect can be obtained with the combination described in this embodiment.

[0161] Also, although the embodiment has been described for an in-line color image forming apparatus in which the image forming units S are arranged in a straight line, it can also be diverted to a rotary color image forming apparatus. Also, the contents of this embodiment may be diverted to a monochrome image forming apparatus having a single image forming unit S. In that case, instead of a configuration using the intermediate transfer belt 31, a configuration using a recording material transport member may be used, or a configuration in which a toner image is transferred directly to the recording material P without using a recording material transport member may be adopted.

[0162] Although the cartridge of the process cartridge 7 type is adopted, a two-piece cartridge type in which the photoconductor unit 8 and the developing unit 4 are each configured to be mountable to the image forming apparatus 100 may be adopted. In that case, the toner supply operation of this embodiment may be performed when the photoconductor unit 8 is new, or the toner supply operation of this embodiment may be performed when the developing unit 4 is new. The former is because, as described in this embodiment, no blocking layer is formed at the contact portion P6 between the cleaning blade 51 and the photoconductor 1. The latter is because, even if a blocking layer is formed, when the developing unit 4 is new, if new toner t is supplied to the contact portion P6, the blocking layer may be destroyed by the new toner t having a high charge amount. Therefore, the toner supply operation of this embodiment may be performed even when the developing unit 4 is new. Also, the photoconductor unit 8 alone may be fastened to the image forming apparatus, and the photoconductor unit 8 may not be detachable.

[0163] The disclosure of this embodiment includes the following configuration.

[0164] (Configuration 1) A rotatable image carrier; an exposure unit for exposing a surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a rotatable developer carrier in a developing section for supplying toner to a surface of the image carrier to develop the electrostatic latent image into a toner image; a cleaning member that comes into contact with the image carrier to form a contact portion and removes toner adhering to the surface of the image carrier at the contact portion; By rotating the image carrier and the developer carrier and controlling the exposure unit, i) an image forming operation for forming the toner image on a recording material; ii) a toner supplying operation which is an operation different from the image forming operation and which moves the toner from the developer carrier to the image carrier and supplies the toner to the contact portion; A control unit that controls the above steps so that the above steps can be executed; In an image forming apparatus comprising: When the image carrier and the developer carrier are rotating, a region of the image carrier that faces the developer carrier in the developing unit is defined as a first region, a region of the image carrier that faces the developer carrier in the developing unit after the region of the developer carrier that faces the first region has made one rotation is defined as a second region, and a region of the image carrier between the first region and the second region in the rotation direction of the image carrier is defined as a third region, When the control unit executes the toner supplying operation, controlling to form a toner supply pattern in the third region, the toner supply pattern being composed of a first pattern, a portion of which is exposed by the exposure unit, and a second pattern, a portion of which is not exposed or a portion of which is exposed with an exposure amount smaller than that of the first pattern; An image forming device characterized in that the toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotational direction, and the first pattern and the second pattern are repeatedly formed.

[0165] (Configuration 2) A rotatable image carrier; an exposure unit for exposing a surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a rotatable developer carrier in a developing section for supplying toner to a surface of the image carrier to develop the electrostatic latent image into a toner image; a cleaning member that comes into contact with the image carrier to form a contact portion and removes toner adhering to the surface of the image carrier at the contact portion; By rotating the image carrier and the developer carrier and controlling the exposure unit, i) an image forming operation for forming the toner image on a recording material; ii) a toner supplying operation which is an operation different from the image forming operation and which moves the toner from the developer carrier to the image carrier and supplies the toner to the contact portion; A control unit that controls the above steps so that the above steps can be executed; In an image forming apparatus comprising: When the image carrier and the developer carrier are rotating, a region of the image carrier that faces the developer carrier in the developing unit is defined as a first region, a region of the image carrier that faces the developer carrier in the developing unit after the region of the developer carrier that faces the first region has made one rotation is defined as a second region, and a region of the image carrier between the first region and the second region in the rotation direction of the image carrier is defined as a third region, When the control unit executes the toner supplying operation, a toner supply pattern is formed in the third region, the toner supply pattern being composed of a first pattern, a part of which is exposed by the exposure unit, a second pattern, a part of which is not exposed after the first pattern in the rotation direction or is exposed with an exposure amount smaller than the exposure amount for exposing the first pattern, a third pattern, a part of which is exposed by the exposure unit after the second pattern in the rotation direction, and a fourth pattern, a part of which is not exposed after the third pattern in the rotation direction or is exposed with an exposure amount smaller than the exposure amount for exposing the third pattern, an image forming apparatus characterized in that the toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotation direction, and so that the length of the fourth pattern is longer than the length of the third pattern in the rotation direction.

[0166] (Configuration 3) 3. The image forming apparatus according to claim 2, wherein the length of the third pattern in the rotation direction is shorter than the length of the first pattern in the rotation direction.

[0167] (Configuration 4) The image forming apparatus according to configuration 2 or 3, wherein a length of the fourth pattern in the rotation direction is shorter than a length of the second pattern in the rotation direction.

[0168] (Configuration 5) The toner cartridge further includes a memory for storing information regarding a usage status of the toner. 3. The image forming apparatus according to claim 1, wherein the control unit executes the toner supplying operation according to the toner supplying pattern based on the information stored in the memory.

[0169] (Configuration 6) The information is information for determining whether the toner is in a start-of-use state, 6. The image forming apparatus according to configuration 5, wherein when the information indicates that the toner is in a start-of-use state, the toner supplying operation is performed according to the toner supplying pattern.

[0170] (Configuration 7) when the information indicates that the toner is not in a start-of-use state, the control unit performs control to execute a second toner supply operation different from a first toner supply operation according to the toner supply pattern; 7. The image forming apparatus according to configuration 6, wherein the second toner supply operation is performed using a second toner supply pattern that is different from the first toner supply pattern that is the toner supply pattern.

[0171] (Configuration 8) The image forming apparatus of configuration 7, characterized in that the amount of toner supplied to the contact portion by the first toner supply pattern according to the first pattern formed on the surface of the image carrier is less than the amount of toner supplied to the contact portion by the second toner supply pattern formed on the surface of the image carrier.

[0172] (Configuration 9) The image forming apparatus of configuration 7, characterized in that the amount of toner supplied to the contact portion by the first toner supply pattern formed on the surface of the image carrier is less than the amount of toner supplied to the contact portion by the second toner supply pattern formed on the surface of the image carrier.

[0173] (Configuration 10) 3. The image forming apparatus according to claim 1, wherein the length of the first pattern in the direction of the rotation axis of the image carrier is a length that enables image formation in the image forming operation.

[0174] (Configuration 11) 11. The image forming apparatus according to configuration 10, wherein the first pattern is formed uniformly in the direction of the rotation axis of the image carrier.

[0175] (Configuration 12) a transfer member that contacts the image carrier to form a transfer section and transfers the toner image formed on the surface of the image carrier to a transfer material in the transfer section; a contact / separation mechanism capable of performing a contact operation for bringing the transfer member into contact with the image carrier and a separation operation for separating the transfer member from the image carrier, The image forming apparatus according to configuration 7, wherein the control unit controls the transfer member to be in contact with the image carrier when performing the first toner supply operation, and controls the transfer member to be spaced apart from the image carrier when performing the second toner supply operation.

[0176] (Configuration 13) A transfer voltage application unit that applies a transfer voltage to the transfer member, If the potential difference formed between the transfer voltage and the surface potential formed on the surface of the image carrier in the transfer portion is defined as a transfer contrast, 13. The image forming apparatus according to claim 12, wherein the control unit sets the transfer contrast of the first toner supplying operation to be smaller than the transfer contrast of the image forming operation.

[0177] (Configuration 14) The image forming apparatus according to configuration 13, characterized in that the control unit controls the absolute value of the transfer voltage of the first toner supply operation to be smaller than the absolute value of the transfer voltage of the image forming operation, or controls the transfer voltage to be OFF.

[0178] (Configuration 15) 14. The image forming apparatus according to claim 13, wherein the control unit controls the transfer voltage to be applied in the first toner supplying operation, the transfer voltage having a polarity opposite to that of the transfer voltage in the image forming operation.

[0179] (Configuration 16) The image forming apparatus according to configuration 7, wherein the control unit controls the image carrier to rotate at a first rotational speed when performing the first toner supply operation, and controls the image carrier to rotate at a second rotational speed faster than the first rotational speed when performing the second toner supply operation. [Explanation of symbols]

[0180] 1 photoreceptor 2. Charge roller 3 Exposure unit 7 Process cartridge 41 Developing roller 42 Supply roller 100 Image forming device 202 Control section

Claims

1. A rotatable image carrier; an exposure unit for exposing a surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a rotatable developer carrier in a developing section for supplying toner to a surface of the image carrier to develop the electrostatic latent image into a toner image; a cleaning member that comes into contact with the image carrier to form a contact portion and removes toner adhering to the surface of the image carrier at the contact portion; By rotating the image carrier and the developer carrier and controlling the exposure unit, i) an image forming operation for forming the toner image on a recording material; ii) a toner supplying operation which is an operation different from the image forming operation and which moves the toner from the developer carrier to the image carrier and supplies the toner to the contact portion; A control unit that controls the above steps so that the above steps can be executed; In an image forming apparatus comprising: When the image carrier and the developer carrier are rotating, a region of the image carrier that faces the developer carrier in the developing unit is defined as a first region, a region of the image carrier that faces the developer carrier in the developing unit after the region of the developer carrier that faces the first region has made one rotation is defined as a second region, and a region of the image carrier between the first region and the second region in the rotation direction of the image carrier is defined as a third region, When the control unit executes the toner supplying operation, a control is performed so as to form a toner supply pattern in the third region, the toner supply pattern being formed of a first pattern, a portion of which is exposed by the exposure unit, and a second pattern, a portion of which is not exposed or a second pattern, a portion of which is exposed with an exposure amount smaller than that of the first pattern; An image forming device characterized in that the toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotational direction, and the first pattern and the second pattern are repeatedly formed.

2. A rotatable image carrier; an exposure unit for exposing a surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a rotatable developer carrier in a developing section for supplying toner to a surface of the image carrier to develop the electrostatic latent image into a toner image; a cleaning member that comes into contact with the image carrier to form a contact portion and removes toner adhering to the surface of the image carrier at the contact portion; By rotating the image carrier and the developer carrier and controlling the exposure unit, i) an image forming operation for forming the toner image on a recording material; ii) a toner supplying operation which is an operation different from the image forming operation and which moves the toner from the developer carrier to the image carrier and supplies the toner to the contact portion; A control unit that controls the above steps so that the above steps can be executed; In an image forming apparatus comprising: When the image carrier and the developer carrier are rotating, a region of the image carrier that faces the developer carrier in the developing unit is defined as a first region, a region of the image carrier that faces the developer carrier in the developing unit after the region of the developer carrier that faces the first region has made one rotation is defined as a second region, and a region of the image carrier between the first region and the second region in the rotation direction of the image carrier is defined as a third region, When the control unit executes the toner supplying operation, a toner supply pattern is formed in the third region, the toner supply pattern being composed of a first pattern, a portion of which is exposed by the exposure unit, a second pattern, a portion of which is not exposed after the first pattern in the rotation direction or is exposed with an exposure amount smaller than the exposure amount for exposing the first pattern, a third pattern, a portion of which is exposed by the exposure unit after the second pattern in the rotation direction, and a fourth pattern, a portion of which is not exposed after the third pattern in the rotation direction or is exposed with an exposure amount smaller than the exposure amount for exposing the third pattern, an image forming apparatus characterized in that the toner supply pattern is configured so that the length of the second pattern is longer than the length of the first pattern in the rotational direction, and so that the length of the fourth pattern is longer than the length of the third pattern in the rotational direction.

3. 3 . The image forming apparatus according to claim 2 , wherein a length of the third pattern in the rotation direction is shorter than a length of the first pattern in the rotation direction.

4. 4. The image forming apparatus according to claim 2, wherein a length of the fourth pattern in the rotation direction is shorter than a length of the second pattern in the rotation direction.

5. The toner cartridge further includes a memory for storing information regarding a usage status of the toner.

3. The image forming apparatus according to claim 1, wherein the control unit executes the toner supplying operation according to the toner supplying pattern based on the information stored in the memory.

6. The information is information for determining whether the toner is in a start-of-use state, 6. The image forming apparatus according to claim 5, wherein when the information indicates that the toner is in a start-of-use state, the toner supplying operation is executed according to the toner supplying pattern.

7. the control unit, when the information indicates that the toner is not in a start-of-use state, performs control to execute a second toner supply operation different from a first toner supply operation that is the toner supply operation according to the toner supply pattern; 7. The image forming apparatus according to claim 6, wherein the second toner supply operation is performed using a second toner supply pattern that is different from the first toner supply pattern that is the toner supply pattern.

8. 8. The image forming apparatus according to claim 7, wherein the amount of toner supplied to the contact portion by the first toner supply pattern corresponding to the first pattern formed on the surface of the image carrier is less than the amount of toner supplied to the contact portion by the second toner supply pattern formed on the surface of the image carrier.

9. 8. The image forming apparatus according to claim 7, wherein the amount of toner supplied to the contact portion by the first toner supply pattern formed on the surface of the image carrier is less than the amount of toner supplied to the contact portion by the second toner supply pattern formed on the surface of the image carrier.

10. 3. The image forming apparatus according to claim 1, wherein a length of the first pattern in a direction of a rotation axis of the image carrier is a length that enables image formation in the image forming operation.

11. 11. The image forming apparatus according to claim 10, wherein the first pattern is formed uniformly in the direction of the rotation axis of the image carrier.

12. a transfer member that contacts the image carrier to form a transfer section and transfers the toner image formed on the surface of the image carrier to a transfer material in the transfer section; a contact / separation mechanism capable of performing a contact operation for bringing the transfer member into contact with the image carrier and a separation operation for separating the transfer member from the image carrier, The image forming apparatus according to claim 7, characterized in that, when performing the first toner supply operation, the control unit controls the transfer member to be in contact with the image carrier, and, when performing the second toner supply operation, controls the transfer member to be spaced apart from the image carrier.

13. A transfer voltage application unit that applies a transfer voltage to the transfer member, If the potential difference formed between the transfer voltage and the surface potential formed on the surface of the image carrier in the transfer portion is defined as a transfer contrast, 13. The image forming apparatus according to claim 12, wherein the control unit makes the transfer contrast of the first toner supplying operation smaller than the transfer contrast of the image forming operation.

14. 14. The image forming apparatus according to claim 13, wherein the control unit controls the transfer voltage so that the absolute value of the transfer voltage in the first toner supplying operation is smaller than the absolute value of the transfer voltage in the image forming operation, or controls the transfer voltage to be OFF.

15. 14. The image forming apparatus according to claim 13, wherein the control unit performs control so as to apply, in the first toner supplying operation, the transfer voltage having a polarity opposite to that of the transfer voltage in the image forming operation.

16. The image forming apparatus according to claim 7, characterized in that, when performing the first toner supply operation, the control unit controls the image carrier to rotate at a first rotational speed, and, when performing the second toner supply operation, controls the image carrier to rotate at a second rotational speed faster than the first rotational speed.

Images