JP2020079903A - Developing device, process cartridge, and image forming device - Google Patents

Abstract

To provide a developing device with which, when using a developing device constructed so as to convey a developer to a developing chamber from a storage chamber arranged downward of the developing chamber, it is possible to circulate the developer between the developing chamber and the storage chamber by a simple structure and achieve high image quality.SOLUTION: In a use-time attitude, there are included in the internal space of a developing chamber 18b, when seen along the longitudinal direction of a toner supply roller 20, a first space located between a partition wall part 30 and the tonner supply roller 20, the area of which increases as it goes toward the downstream side in the direction of rotation of the toner supply roller 20, with a narrow part where the interval between the partition wall part 30 and the toner supply roller 20 is narrowest reckoned as a starting point, and a second space located between the partition wall part 30 and the toner supply roller 20, the area of which increases as it goes toward the upstream in the direction of rotation of the toner supply roller 20, with the narrow part reckoned as a starting point, the lower limit position of an opening 30d being upward of the lower limit position of the toner supply roller 20.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus that forms an image on a recording material using an electrophotographic method, and more particularly to a developing device and a process cartridge applied to the image forming apparatus.

As a device configuration of an image forming apparatus such as a printer or a copier, a recording is performed such that a photoreceptor is below an intermediate transfer body as a transfer body to which a toner image is transferred, or a recording material as the transfer body is conveyed. There is one arranged below the material carrier (see Patent Document 3). When the photoconductor is arranged below the intermediate transfer body or the recording material carrying body, for example, a fixing device and a developing device (or, The exposure device) can be disposed at a position away from each other. Therefore, there is an advantage that the developing device (or the exposure device) is less likely to be affected by the heat of the fixing device.
On the other hand, in the configuration in which the photosensitive member is arranged below the intermediate transfer member or the recording material carrying member as described above, the developing device has a developing roller (developer carrying member) and a supply roller against the gravity from the developer accommodating portion. In some cases, the device configuration may require supplying the developer to the (supply member). Then, in patent document 1, the method of making a receiving sheet contact the lower side of the supply member is disclosed as a means for supplying the developer to the supply member. According to this method, the receiving sheet prevents the developer adhering to the supply member from falling due to gravity, so that the developer that can be supplied to the developer carrying member does not decrease, and the decrease in the density of a solid image is suppressed. It
Further, in Patent Document 2, a conveying member is provided below the supply member in the developing chamber located above the developer accommodating portion, the conveying member conveys the developer to the lower surface of the supplying member, and toner aggregation in the developing chamber occurs. A method of suppressing is disclosed.
Further, in Patent Document 3, in the developing chamber located above the developer accommodating portion, the surface of the supply member and the surface of the developer carrier move in the same direction and from the upper side to the lower side. A method is disclosed in which a developer is circulated in a storage chamber to suppress toner aggregation.

JP, 2003-173083, A JP, 2009-222931, A JP, 2013-228584, A

However, in the method of supplying a developer as disclosed in Patent Document 1, when images having a low printing rate are continuously output, the developer stays and aggregates between the supply member and the receiving sheet, and image quality such as uneven density occurs. Degradation may occur.
In the configuration as disclosed in Japanese Patent Laid-Open No. 2004-242242, a transport member is required as an additional member in the developing chamber in addition to the supply member, which may complicate the apparatus configuration. Further, there is a concern that friction with the transport member in the developing chamber may cause deterioration of the developer. Further, when images with a high printing rate are continuously output, there are cases where image quality deterioration such as density decrease or density unevenness occurs.
In the configuration of Patent Document 3, the rotation direction of the surface of the supply member is the same as the rotation direction of the surface of the developer carrying member, so the mechanical peeling force for the developer remaining on the developer carrying member after development is weakened. , A ghost image may occur.

An object of the present invention is to provide a simple structure between the developing chamber and the accommodating chamber when a developing device configured to convey the developer from the accommodating chamber arranged below the developing chamber to the developing chamber is used. It is to provide a developing device capable of improving the image quality while circulating the developer.

In order to achieve the above object, the developing device of the present invention comprises
A developer carrying member that carries a developer and is rotatable,
A supply member for supplying a developer to the developer carrying member, wherein a nip portion is formed between the developer carrying member and the surface of the supply member at the nip portion in the posture during use is gravity. A supply member that moves along the direction from the lower side to the upper side of the direction, and that is rotatable in the same rotation direction as the developer carrying member;
A regulating member for regulating the amount of the developer carried on the developer carrying body by contacting the developer carrying body;
A developing chamber in which the developer carrier, the supply member, and the regulating member are arranged; and a storage chamber which is located below the developing chamber in a posture in use and stores the developer to be supplied to the developing chamber, A frame body having a partition wall portion having an opening communicating the storage chamber and the developing chamber;
A developing device comprising:
In the posture during use, when viewed along the longitudinal direction of the supply member, in the internal space of the developing chamber,
Located between the partition wall portion and the supply member, starting from a narrow portion where the distance between the partition wall portion and the supply member is the narrowest, the area becomes smaller toward the downstream side in the rotation direction of the supply member. The expanding first space,
A second space that is located between the partition wall portion and the supply member and has an area that increases toward the upstream side in the rotation direction of the supply member, starting from the narrow portion. ,
The position of the lower end of the opening is higher than the position of the lower end of the supply member.
In order to achieve the above object, the process cartridge of the present invention,
A process cartridge attachable to and detachable from the main body of the image forming apparatus,
An image carrier on which a latent image is formed,
A developing device of the present invention;
It is characterized by including.
In order to achieve the above object, the image forming apparatus of the present invention,
An image forming apparatus for forming an image on a recording material,
An image carrier on which a latent image is formed,
A developing device of the present invention;
It is characterized by including.

  According to the present invention, when the developing device configured to convey the developer to the developing chamber from the containing chamber disposed below the developing chamber is used, the developing device and the containing chamber have a simple structure. Thus, it is possible to provide a developing device capable of achieving high image quality while circulating the developer.

Schematic configuration cross-sectional view of an image forming apparatus according to an embodiment of the present invention Schematic configuration cross-sectional view of a process cartridge according to an embodiment of the present invention Explanatory drawing of arrangement configuration of a process cartridge according to an embodiment of the present invention 1 is a schematic diagram showing the movement of toner in a developing device according to an embodiment of the present invention. Schematic cross-sectional view of a process cartridge according to another embodiment of the present invention Schematic cross-sectional view of a process cartridge of a comparative example Schematic configuration cross-sectional view of a process cartridge according to a modification of the embodiment of the present invention

  MODES FOR CARRYING OUT THE INVENTION Modes for carrying out the present invention will be exemplarily described in detail below based on embodiments with reference to the drawings. However, the dimensions, materials, shapes, and their relative arrangements of the components described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. That is, the scope of the present invention is not intended to be limited to the following embodiments.

[Example 1]
[Overall configuration of image forming apparatus]
First, the overall configuration of the electrophotographic image forming apparatus (image forming apparatus) according to the present invention will be described. FIG. 1 is a schematic cross-sectional view of the image forming apparatus 100 of this embodiment. Examples of the image forming apparatus to which the present invention can be applied include a copying machine and a printer using an electrophotographic method. Here, a case where the present invention is applied to a laser printer will be described. The image forming apparatus 100 according to the present exemplary embodiment is a full-color laser printer that employs an inline method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) according to the image information. The image information is input to the image forming apparatus main body 100A from an image reading apparatus connected to the image forming apparatus main body 100A or a host device such as a personal computer communicatively connected to the image forming apparatus main body 100A.

The image forming apparatus 100 includes first, second, and third image forming units for forming images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. , And fourth image forming units SY, SM, SC, SK. In this embodiment, the first to fourth image forming units SY, SM, SC and SK are arranged in a line in a direction intersecting the vertical direction.
In this embodiment, the configurations and operations of the first to fourth image forming units SY, SM, SC and SK are substantially the same except that the colors of the images to be formed are different. Therefore, hereinafter, unless particularly distinguished, the subscripts Y, M, C, and K given to the reference numerals to represent the elements provided for any color are omitted, explain.

  In this embodiment, the image forming apparatus 100 has four drum-type electrophotographic photosensitive members, that is, the photosensitive drums 1, that are arranged in parallel in a direction intersecting the vertical direction, as a plurality of image carriers. The photosensitive drum 1 is rotationally driven in the direction of arrow A (clockwise) in the drawing by a driving unit (driving source) not shown. Around the photoconductor drum 1, a charging roller 2 as a charging means for uniformly charging the surface of the photoconductor drum 1, a laser based on image information is irradiated with a laser, and an electrostatic image (electrostatic image) is formed on the photoconductor drum 1. A scanner unit (exposure device) 3 as an exposure unit for forming a latent image is arranged. Further, around the photosensitive drum 1, a developing unit (developing device) 4 as a developing means for developing an electrostatic image as a toner image, and toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner). A cleaning member 6 is disposed as a cleaning unit for removing the. Further, an intermediate transfer belt 5 as an intermediate transfer member for transferring the toner image on the photosensitive drums 1 to the recording material 12 is arranged facing the four photosensitive drums 1.

  In the present embodiment, the developing unit 4 uses a non-magnetic one-component developer toner as the developer. Further, in the present embodiment, the developing unit 4 carries out reversal development by bringing a developing roller (described later) as a developer carrying member into contact with the photosensitive drum 1. That is, in the present embodiment, the developing unit 4 is a portion where the charge charged to the same polarity (negative polarity in this embodiment) as the charging polarity of the photosensitive drum 1 is attenuated by the exposure on the photosensitive drum 1 ( The electrostatic image is developed by being attached to the image area and exposed area.

In the present embodiment, the photosensitive drum 1, the charging roller 2 as a process means acting on the photosensitive drum 1, the developing unit 4, and the cleaning member 6 are integrated, that is, integrally formed into a cartridge, The process cartridge 7 is formed. The process cartridge 7 is attachable/detachable to/from the image forming apparatus 100 via a mounting means such as a mounting guide and a positioning member provided on the image forming apparatus main body 100A. In this embodiment, all the process cartridges 7 for each color have the same shape, and the process cartridges 7 for each color have yellow (Y), magenta (M), cyan (C), and black ( The toner of each color of K) is stored.

  The intermediate transfer belt 5 formed of an endless belt as an intermediate transfer member contacts all the photoconductor drums 1 and cyclically moves (rotates) in the direction of arrow B (counterclockwise direction) in the drawing. The intermediate transfer belt 5 is stretched around a driving roller 51, a secondary transfer counter roller 52, and a driven roller 53 as a plurality of supporting members.

  On the inner peripheral surface side of the intermediate transfer belt 5, four primary transfer rollers 8 as primary transfer means are arranged in parallel so as to face each photoconductor drum 1. The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photoconductor drum 1 and forms a primary transfer portion N1 where the intermediate transfer belt 5 and the photoconductor drum 1 contact each other. Then, a bias having a polarity opposite to the regular charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) as a primary transfer bias applying unit (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  Further, a secondary transfer roller 9 as a secondary transfer unit is arranged at a position facing the secondary transfer counter roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 9 is pressed against the secondary transfer counter roller 52 via the intermediate transfer belt 5 to form a secondary transfer portion N2 where the intermediate transfer belt 5 and the secondary transfer roller 9 come into contact with each other. Then, a bias having a polarity opposite to the regular charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) as a secondary transfer bias applying unit (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondarily transferred) to the recording material 12.

  More specifically, at the time of image formation, the surface of the photosensitive drum 1 is first uniformly charged by the charging roller 2. Then, the surface of the charged photosensitive drum 1 is scanned and exposed by the laser light emitted from the scanner unit 3 according to the image information, and an electrostatic image according to the image information is formed on the photosensitive drum 1. Next, the electrostatic image formed on the photosensitive drum 1 is developed as a toner image by the developing unit 4. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5 by the action of the primary transfer roller 8.

For example, when forming a full-color image, the above-described process is sequentially performed in the first to fourth image forming units SY, SM, SC, SK, and the toner images of the respective colors are superposed on the intermediate transfer belt 5 next. Is primarily transcribed.
Then, the recording material 12 is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5. The four-color toner images on the intermediate transfer belt 5 are collectively secondarily transferred onto the recording material 12 by the action of the secondary transfer roller 9 that is in contact with the intermediate transfer belt 5 via the recording material 12.

  The recording material 12 to which the toner image is transferred is conveyed to the fixing device 10 as a fixing unit. By applying heat and pressure to the recording material 12 in the fixing device 10, the toner image is fixed on the recording material 12. The recording material 12 on which the toner image has been fixed is conveyed further downstream from the fixing device 10 and discharged outside the machine.

  The primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer process is removed and collected by the cleaning member 6. Further, the secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer step is cleaned by the intermediate transfer belt cleaning device 11.

  It should be noted that the image forming apparatus 100 can form a single-color or multi-color image by using only one desired image forming unit or only some (not all) image forming units. It is like this.

[Process cartridge configuration]
Next, the overall configuration of the process cartridge 7 mounted in the image forming apparatus 100 of this embodiment will be described. In this embodiment, the configuration and operation of the process cartridge 7 for each color are substantially the same, except for the type (color) of the contained toner.
FIG. 2 is a schematic cross-sectional view (main cross-sectional view) of the process cartridge 7 of the present embodiment as viewed along the longitudinal direction (rotational axis direction) of the photosensitive drum 1. The attitude of the process cartridge 7 in FIG. 2 is an attitude in a state where the process cartridge 7 is mounted in the image forming apparatus main body, and when the positional relationship and direction of each member of the process cartridge are described below, the positional relationship and direction in this attitude are described. Etc. are shown. That is, the vertical direction of the paper surface in FIG. 2 corresponds to the vertical direction, and the horizontal direction of the paper surface corresponds to the horizontal direction. It should be noted that the setting of the arrangement configuration is set on the assumption that the image forming apparatus is installed on a horizontal plane in a normal installation state.

  The process cartridge 7 is configured by integrating the photoconductor unit 13 including the photoconductor drum 1 and the like and the developing unit 4 including the developing roller 17 and the like.

  The photoconductor unit 13 has a cleaning frame body 14 as a frame body that supports various elements in the photoconductor unit 13. The photosensitive drum 1 is rotatably attached to the cleaning frame 14 via a bearing (not shown). The photosensitive drum 1 is rotationally driven in a direction indicated by an arrow A (clockwise direction) in accordance with an image forming operation by transmitting a driving force of a drive motor (not shown) serving as a driving unit (driving source) to the photosensitive unit 13. To be done. In this embodiment, the photosensitive drum 1, which is the center of the image forming process, is an organic photosensitive drum in which an outer surface of an aluminum cylinder is coated with a subbing layer, a carrier generation layer, and a carrier transfer layer, which are functional films, in that order. 1 is used.

  Further, in the photoconductor unit 13, the cleaning member 6 and the charging roller 2 are arranged so as to contact the peripheral surface of the photoconductor drum 1. The transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls and is contained in the cleaning frame 14. The charging roller 2 serving as a charging unit is driven to rotate by pressing the roller portion made of a conductive rubber into contact with the photosensitive drum 1.

  Here, a predetermined DC voltage is applied to the core metal of the charging roller 2 with respect to the photosensitive drum 1 as a charging process, whereby a uniform dark portion potential (Vd) is applied to the surface of the photosensitive drum 1. Is formed. The spot pattern of the laser light emitted by the laser light from the scanner unit 3 corresponding to the image data exposes the photosensitive drum 1, and the exposed portion has a surface charge due to carriers from the carrier generation layer. It disappears and the potential drops. As a result, an electrostatic latent image having a predetermined bright portion potential (Vl) on the exposed portion and a predetermined dark portion potential (Vd) on the unexposed portion is formed on the photosensitive drum 1. In this embodiment, Vd=-500V and Vl=-100V.

On the other hand, the developing unit 4 supports the developing roller 17 as a developer carrying member for carrying the toner 80, the toner supplying roller 20 as a supplying member for supplying the toner to the developing roller 17, and rotatably supporting them. And a developing device frame 18. The developing device frame 18 includes a toner storage chamber (developer storage chamber) 18a for storing the toner 80, and a developing chamber 18b in which the developing roller 17 and the toner supply roller 20 are arranged. The toner storage chamber 18a and the developing chamber 18b communicate with each other through the opening 30d. A stirring/transporting member 22 is rotatably provided in the toner storage chamber 18a. In the toner accommodating chamber 18a, the toner accommodating portion (developer accommodating portion), which is a region that mainly stays in the statically accumulated state, not in a state where the toner is agitated by the stirring and conveying member 22, is the toner accommodating chamber 18a. It becomes the lower area in. In this embodiment, the toner storage portion of the toner storage chamber 18a is located below the toner supply roller 20 in the gravity direction (vertical direction).

In this embodiment, as the toner 80, a toner having an aggregation degree of 5 to 40% in the initial state is used. In order to secure the fluidity of the toner throughout the durability, it is desirable to use the toner having such a cohesion degree. Further, the degree of aggregation of the toner was measured as follows.
As a measuring device, a powder tester (manufactured by Hosokawa Micron Co.) having a digital vibrometer (DEGITAL VIBLATION METER MODEL 1332 SHOWA SOKKI CORPORATION) was used.
As a measuring method, sieves of 390 mesh, 200 mesh, and 100 mesh are placed on the vibrating table in the order of the narrowest openings, that is, the 390 mesh, 200 mesh, and 100 mesh sieves are piled in the order so that the 100 mesh sieve is at the top. did. Add 5 g of the sample (toner) accurately weighed on the set 100 mesh sieve, adjust the displacement value of the digital vibrometer to 0.60 mm (peak-to-peak), and add vibration for 15 seconds. It was Then, the mass of the sample remaining on each sieve was measured to obtain the cohesion degree based on the following formula.
The measurement samples at that time were left in advance at 23° C. and 60% RH environment for 24 hours, and the measurement was performed at 23° C. and 60% RH environment.
Aggregation degree (%)=(remaining sample mass on 100 mesh sieve/5 g)×100+(remaining sample mass on 200 mesh sieve/5 g)×60+(remaining sample mass on 390 mesh sieve/5 g)×20

  Further, the toner supply roller 20 comes into contact with the developing roller 17 from the side and a nip portion N of the toner 80 with the developing roller 17 (a portion where the toner 80 is sandwiched between the developing roller 17 and the toner supply roller 20). Forming and rotating.

  An agitating/conveying member 22 is provided in the toner storage chamber 18a. The agitating/conveying member 22 is for agitating the toner 80 accommodated in the toner accommodating chamber 18a and for conveying the toner toward the upper portion of the toner supply roller 20 in the direction of arrow G in the figure. In the present embodiment, the stirring and conveying member 22 is driven and rotated at 30 rpm (revolutions per minute: representing the number of rotations per minute (unit time)).

  The developing blade 21 is arranged below the developing roller 17 as a regulating member and is in contact with the developing roller 17 at a counter. That is, the direction of the developing blade 21 extending from the fixed end 21 a fixed to the developing device frame 18 toward the free end 21 b contacting the developing roller 17 is such that the peripheral surface of the rotating developing roller 17 is the developing blade 21. The direction is substantially opposite to the moving direction in the facing area. By the contact of the developing blade 21, the coating amount of the toner 80 on the developing roller 17 supplied by the toner supplying roller 20 is regulated and the electric charge is applied. In this embodiment, as the developing blade 21, a 0.1 mm-thick leaf spring-shaped thin plate made of SUS is used, and the contact pressure is formed by utilizing the spring elasticity of the thin plate, and the surface thereof is the toner 80 and the developing roller. 17 is abutted. Here, the material of the developing blade 21 is not limited to this, and a metal thin plate such as phosphor bronze or aluminum may be used. Alternatively, the surface of the developing blade 21 may be coated with a thin film of polyamide elastomer, urethane rubber, urethane resin or the like.

On the peripheral surface of the developing roller 17, the toner 80 is frictionally charged by the sliding friction between the developing blade 21 and the developing roller 17 to be given an electric charge, and at the same time the layer thickness is regulated. Further, in this embodiment, a predetermined voltage is applied to the developing blade 21 from a blade bias power source (not shown) to stabilize the toner coat. In this embodiment, V=-500V was applied as the blade bias.

  The developing roller 17 and the photosensitive drum 1 rotate in the same direction. That is, the surfaces of the two facing portions rotate so as to move in opposite directions. In this embodiment, the developing roller 17 rotates so as to move in a direction from the bottom to the top at the portion facing the photosensitive drum 1, and the photosensitive drum 1 moves from the top at the portion facing the developing roller 17. Rotate to move downward.

  In this embodiment, the contact developing system in which the developing roller 17 and the photosensitive drum 1 are arranged in contact with each other is adopted. However, the developing roller 17 and the photosensitive drum 1 are placed close to each other with a predetermined gap. A non-contact developing method of arranging may be used.

  In the present embodiment, the toner negatively charged by frictional charging is detected from the potential difference between the predetermined DC bias applied to the developing roller 17 and the surface potential of the photosensitive drum 1 in the developing portion in contact with the photosensitive drum 1. , Transfer only to the light potential portion of the photosensitive drum 1. As a result, the electrostatic latent image is visualized on the photosensitive drum 1. In this embodiment, by applying V=−300V to the developing roller, a potential difference ΔV=200V from the light potential portion was formed, and a toner image was formed.

The toner supply roller 20 has its surface rotated in the direction from the lower end to the upper end of the nip portion N, and the developing roller 17 has its surface rotated in the direction from the upper end to the lower end of the nip portion N. That is, the toner supply roller 20 rotates in the direction of arrow E (counterclockwise) in the drawing, and the developing roller 17 rotates in the direction of arrow D (counterclockwise). The toner supply roller 20 is an elastic sponge roller in which a foam layer (urethane foam layer 20b) is formed on the outer circumference of a conductive core metal (core metal electrode 20a). The toner supply roller 20 and the developing roller 17 have a predetermined penetration amount, that is, as shown in FIG. 4, the toner supply roller 20 has a recess amount ΔE in which the developing roller 17 makes the toner supply roller 20 concave. And the developing roller 17 are in contact with each other. The toner supply roller 20 and the developing roller 17 rotate in the nip portion N in opposite directions with a peripheral speed difference, and by this operation, the toner supply roller 20 supplies toner to the developing roller 17. .. At this time, the toner supply amount to the developing roller 17 can be adjusted by adjusting the potential difference between the toner supplying roller 20 and the developing roller 17. In this embodiment, the toner supply roller 20 is driven to rotate at 130 rpm and the developing roller 17 is driven to rotate at 100 rpm, and a DC bias is applied to the toner supply roller 20 so that the toner supply roller 20 has the same potential as the developing roller 17.
The number of revolutions (rpm) of the toner supply roller 20 and the developing roller 17 per unit time shown here is an example, and is appropriately set by the relative balance of the moving speeds of the respective peripheral surfaces. That is, in the nip portion N, the peripheral surface of the toner supply roller 20 moves in a direction opposite to the direction in which the peripheral surface of the developing roller 17 moves, and moves from the lower side to the upper side, and has the same peripheral speed difference as that of the configuration of the present embodiment. The number of rotations shown here is not limited as long as it is configured to rotate.

In this embodiment, the developing roller 17 and the toner supply roller 20 both have an outer diameter of 15 mm, and the amount of the toner supply roller 20 entering the developing roller 17, that is, the toner supply roller 20 is concave by the developing roller 17. The dent amount ΔE, which is considered to be, was set to 1.0 mm. As shown by the broken line in FIG. 4, the dent amount ΔE is a virtual value of the developing roller 17 and the toner supply roller 20 when viewed in the rotation axis direction of the developing roller 17 or the toner supply roller 20 without being deformed due to contact. It is defined as the amount of overlap between the two. Specifically, as shown in FIG. 4, when viewed in the rotation axis direction, one point on the outer circumference of the developing roller 17 that is most intruded into the toner supply roller 20 and the toner most intruded into the developing roller 17. The length of a line segment connecting one point on the outer circumference of the supply roller 20 is the recess amount ΔE. Alternatively, when viewed in the rotation axis direction, the length of the line segment area that intersects with the line connecting the rotation centers of the toner supply roller 20 and the developing roller 17 in the overlapping portion of the virtually overlapping toner supply roller 20 and the developing roller 17 Is the amount of depression ΔE.
Further, the toner supply roller 20 and the developing roller 17 are arranged so that their center heights are the same.

Details of the toner supply roller 20 used in this embodiment will be described below.
The toner supply roller 20 in this embodiment includes a conductive support and a foam layer (foam) supported by the conductive support. Specifically, the toner supply roller 20 is a foam including a cored bar electrode 20a having an outer diameter of φ5 (mm), which is a conductive support, and an open cell body (open cell) in which bubbles are connected to each other. A urethane foam layer 20b as a layer is provided, and the urethane foam layer 20b rotates in the direction of E in the figure.

A large amount of toner can enter the inside of the toner supply roller 20 by forming the surface layer urethane into an open-cell body. Further, the resistance of the toner supply roller 20 in this embodiment is 1×10 ⁶ (Ω). As the resistance value, 1×10 ⁵ to 10 ⁹ (Ω) can be used.

  Here, a method of measuring the resistance of the toner supply roller 20 will be described. The toner supply roller 20 is brought into contact with an aluminum sleeve having a diameter of 30 mm so that the entering amount is 1.5 mm. By rotating this aluminum sleeve, the supply roller 2 is driven to rotate at 30 rpm with respect to the aluminum sleeve. Next, a DC voltage of -50 V is applied to the aluminum sleeve. At this time, a resistance of 10 kΩ is provided on the ground side, the voltage across the resistance is measured to calculate the current, and the resistance of the toner supply roller 20 is calculated.

  Further, in this embodiment, the surface cell diameter of the toner supply roller 20 is set to about 300 μm. As the cell diameter, 50 μm to 1000 μm can be used. Here, the cell diameter refers to the average diameter of the foam cells of an arbitrary cross section, first measures the area of the foam cells that is the maximum from the enlarged image of the arbitrary cross section, and converts the true circle equivalent diameter from this area to the maximum cell diameter. To get Then, the average value of the individual cell diameters obtained by similarly converting the remaining individual cell areas after eliminating the foamed cells that are ½ or less of the maximum cell diameter as noise is meant.

  The flow of toner in the developing chamber will be described with reference to FIGS. FIG. 4 is an enlarged schematic cross-sectional view of the inside of the developing chamber, and FIG. 4A shows a state in which toner is conveyed from the stirring and conveying member 22 to the toner supply roller 20. In FIG. 4, for the sake of explanation, the flow of toner is illustrated in a time series order of (a) to (d).

The developing device frame 18 has a wall portion (partition wall portion) 30 that divides the internal space into a toner storage chamber 18a and a developing chamber 18b. The wall portion 30 is connected to a first wall portion 30a that partitions the internal space of the developing device frame 18 above the opening portion 30d, a second wall portion 30b that partitions below the opening portion 30d, and a second wall portion 30b. 20 and a third wall portion 30c that partitions below the developing roller 17. The first wall portion 30a and the second wall portion 30b extend in a direction inclined with respect to the vertical direction so that the opening direction of the opening portion 30d from the toner storage chamber 18a toward the developing chamber 18b is directed to the upper side than the horizontal direction. ing. The opening 30d is opened in a region of the wall 30 opposite to the developing roller 17 with respect to the toner supplying roller 20 so as to face a space above the toner supplying roller 20 in the developing chamber 18b. As a result, the internal space of the developing chamber 18b expands in the horizontal direction as it goes upward, and the opening portion 30d easily receives the toner 80 that is pumped up from the lower portion of the toner storage chamber 18a to the upper portion of the stirring and conveying member 22. To be done. The third wall portion 30c extends from the lower end of the second wall portion 30b below the toner supply roller 20 and the developing roller 17 in a substantially horizontal direction. The third wall portion 30c, together with the second wall portion 30b, is configured to receive the toner 80 spilled from the toner supply roller 20 and the developing roller 17 among the toner 80 that has passed through the opening 30d (toner 80 storage tank). Is formed. The configuration including the second wall portion 30b and the third wall portion 30c extends from one side surface to the other side surface of the developing device frame 18 in the longitudinal direction (direction along the rotation axis of the developing roller 17 or the toner supply roller 20). Has been formed.

  Here, the internal space of the developing chamber 18b will be considered by being divided into a first space, a second space, and a third space. In FIG. 4, the first space is shown by S1, the second space is shown by S2, and the third space is shown by S3.

  The third space refers to a space above the nip portion N in the developing chamber 18b. More specifically, in the third space, in the inner space of the developing chamber 18b, the peripheral surfaces of the toner supply roller 20 and the developing roller 17 and the inner wall surface of the developing chamber 18b are above each other above the nip portion N. It is a space area facing each other. The third space is a region above the nip portion N on the peripheral surfaces of the toner supply roller 20 and the developing roller 17, an inner wall surface of the developing chamber 18b facing these, and both side surfaces in the longitudinal direction of the developing chamber 18b. Surrounded by,.

The first space refers to a space provided in the developing chamber 18b such that the space expands in the downstream direction of rotation of the toner supply roller 20 with a narrow portion below the toner supply roller 20 as a boundary (starting point).
Here, the narrowed portion refers to a portion where the space between the third wall portion 30c of the wall portion 30 that defines the internal space of the developing chamber 18b and the peripheral surface of the toner supply roller 20 is the narrowest.
More specifically, the first space is closer to the downstream side in the rotation direction of the toner supply roller 20 with the narrow portion as a boundary (start point) in the space where the peripheral surface of the toner supply roller 20 and the third wall portion 30c face each other. The space between the peripheral surface of the toner supply roller 20 and the third wall portion 30c is a space area where the distance gradually increases. The first space is located downstream of the narrow portion in the rotation direction of the toner supply roller 20, and the third wall portion 30c, the area of the peripheral surface of the toner supply roller 20 and the developing roller 17 facing the third wall portion 30c, and the developing blade 21. And both side surfaces in the longitudinal direction of the developing chamber 18b.

The second space refers to a space provided inside the developing chamber 18b such that the space expands in the upstream direction of rotation of the toner supply roller 20 with the narrow portion as a boundary (starting point). More specifically, in the second space, the toner supply roller 20 is moved toward the upstream side in the rotation direction with the narrow portion as a boundary (start point) in the space where the peripheral surface of the toner supply roller 20 and the third wall portion 30c face each other. The space between the peripheral surface and the third wall portion 30c is a spatial region in which the distance gradually increases. The second space is located on the upstream side in the rotation direction of the toner supply roller 20 with respect to the narrow portion, the second wall portion 30b and the third wall portion 30c, the area of the peripheral surface of the toner supply roller 20 that faces them, and the developing chamber 18b. And both side surfaces in the longitudinal direction of.
In this embodiment, the first space is wider than the second space in the cross sections shown in FIGS.

The toner 80 drawn up by the agitating/conveying member 22 gets over the toner supply roller 20 because the upper end of the opening 30d (the boundary with the lower end of the first wall 30a) is arranged higher than the upper end of the toner supply roller 20. Is supplied above the nip portion N (third space). The toner 80 supplied above the nip portion N (third space) is sucked into the inside of the toner supply roller 20 (within the bubble cavity of the foam layer) due to the deformation of the toner supply roller 20, and the rotation of the toner supply roller 20. Moves counterclockwise in the figure to reach the lower end of the nip portion N. Further, a part of the toner 80, which has been pumped up by the agitating/conveying member 22 and supplied to the surface of the toner supply roller 20, returns to the toner storage chamber 18a by the rotation of the toner supply roller 20 in the arrow E direction. The remaining toner 80 is conveyed toward the area below the toner supply roller 20 (second space→first space) (FIG. 4A).

  When the toner reaches the lower end of the nip portion N, the toner 80 is discharged from the inside of the toner supply roller 20 (in the bubble cavity of the foamed layer) due to the deformation of the toner supply roller 20, and the toner 80 is rubbed at the nip portion N and reaches the developing roller 17. Supplied. The toner 80 attached to the developing roller 17 is regulated and charged by the developing blade 21, and the toner 80 that has passed through the regulating portion forms a uniform toner coat on the developing roller 17. Further, the toner 80 left undeveloped in the developing portion is also strongly scraped by the surfaces of the toner supply roller 20 and the developing roller 17 rotating in opposite directions at the nip portion N. The toner 80 regulated by the developing blade 21 and separated from the developing roller 17 drops below the developing blade 21 (first space). The toner 80 discharged from the inside of the toner supply roller 20 and not adhered to the developing roller 17 is discharged below the nip portion N (first space) (FIG. 4B).

  When the above operation is repeated, the toner 80 is accumulated in the first space to form a compacted state of the toner 80. When the compacted state is formed, the toner 80 is supplied from the compacted portion to the surface of the toner supply roller 20 or inside. Further, due to the formation of the consolidated state, the toner 80 moves from the first space (consolidated space) to the second space through the narrow portion as shown in FIG. 4C. Due to the pressure of the flow of the toner 80, a part of the toner 80 goes over the upper end of the second wall portion 30b below the opening 30d and is returned to the toner storage chamber 18a (FIG. 4(d)).

With reference to FIG. 3, the details of the arrangement configuration of each member in the developing chamber 18b of this embodiment will be described. FIG. 3 is a schematic cross-sectional view illustrating the positional relationship of each member in the developing device according to this embodiment.
In the present embodiment, (i) the upper end of the opening 30d that separates the developing chamber 18b and the toner storage chamber 18a (the boundary between the opening 30d in the first wall 30a) and the upper end of the toner supply roller 20 is And placed 2 mm above. That is, as shown in FIG. 3, the horizontal line h1 passing through the upper end of the opening end 30d is located above the horizontal line h2 passing through the upper end of the toner supply roller 20.
Further, (ii) the center of the nip portion N (the center portion in the height direction, or the position intersecting the line connecting the rotation centers of the toner supply roller 20 and the developing roller 17) is 4 mm above the lower end of the opening 30d, The lower end of the nip portion N was placed 1 mm above the lower end of the opening 30d. That is, as shown in FIG. 3, the horizontal line h4 passing through the center of the nip portion N passes through the lower end of the opening portion 30d (the upper end of the second wall portion 30b (the boundary between the opening portion 30d in the second wall portion 30b)). It is located above the horizontal line h6. Further, the horizontal line h5 passing through the lower end of the nip portion N is located above the horizontal line h6 passing through the lower end of the opening 30d.
Further, (iii) the lower end of the opening 30d (upper end of the second wall 30b) is located 1 mm above the end 21b of the contact position 21c between the developing blade 21 and the developing roller 17 on the upstream side in the developing roller 17 rotation direction. Placed in. That is, as shown in FIG. 3, the horizontal line h6 passing through the lower end of the opening 30d (the upper end of the second wall portion 30b) is located above the horizontal line h7 passing through the contact position 21c of the developing blade 21 with the developing roller 17. positioned.
Further, (iv) the toner supply roller 20 and the inner wall of the developing chamber 18b (the upper surface of the third wall portion 30c and both side walls in the longitudinal direction of the developing chamber 18b) are arranged so that the vertical distance between them is 1.0 mm. did.
In addition, (v) the upper surface of the third wall portion 30c among the inner surfaces of the developing chamber 18b forming the first space and the second space is arranged as follows. First, a vertical line is drawn with reference to an end portion 21b (free end tip) located upstream of the abutting position 21c of the developing blade 21 with the developing roller 17 in the rotation direction of the developing roller 17 (see FIG. 4A). ). Then, with the position of the intersection of the vertical line and the inner surface of the developing chamber 18b facing the first space (the upper surface of the third wall portion 30c) as a reference, a position 1 mm away from the reference point in the horizontal direction with respect to the narrow portion. To the second space side that sandwiches the narrow portion, the surface extends substantially horizontally.
(Vi) The lower end of the opening 30d is arranged 3.0 mm above the lower end of the toner supply roller 20. That is, as shown in FIG. 3, the horizontal line h6 passing through the lower end of the opening 30d (upper end of the second wall portion 30b) is located above the horizontal line h8 passing through the lower end of the toner supply roller 20.

The effects of the arrangements (i) to (vi) will be described below.
(I) Positional relationship between the upper end of the opening 30d and the upper end of the toner supply roller 20 As described above, the main toner supply to the toner supply roller 20 is that the toner 80 is pumped up by the agitating/conveying member 22 and the upper part of the nip portion N (first 3 space). In the embodiment, since the upper end of the opening 30d is arranged above the upper end of the toner supply roller 20, the toner supply roller 20 over the toner supply roller 20 and above the nip portion N (third space) is sucked. Toner 80 can be supplied to the mouth. (Because the toner supply roller 20 rotates in the counter direction with respect to the developing roller 17, the toner 80 is sucked in above the nip portion N). When the upper end of the opening 30d is located below the upper end of the toner supply roller 20, the upper end of the opening 30d closes the toner supply path, so that the toner is directly supplied to the third space by the stirring and conveying member 22. It was difficult to do. Further, in such a case, the toner 80 supplied to the side surface of the toner supply roller 20 is returned to the toner storage chamber 18 a direction by the rotation of the toner supply roller 20, and is sufficient for the toner supply roller 20. It was not possible to supply various toners. The distance between the upper end of the toner supply roller 20 and the upper end of the opening 30d is preferably 1.0 mm or more.

(Ii) Positional relationship between the center of the nip portion N (the center portion in the height direction) and the lower end of the opening portion 30d The lower end of the opening portion 30d is higher than the center position of the nip portion N (the height of the central portion in the height direction). Then, the height of the toner surface contained in the first space and the second space in the developing chamber 18b exceeds the center of the nip portion N. With such an arrangement, the toner 80 easily enters the nip portion N, and the mechanical peeling force of the toner supply roller 20 with respect to the toner 80 remaining on the developing roller 17 after the developing operation is weakened, resulting in insufficient peeling. The developing streaks that occur are likely to occur. Therefore, the position of the lower end of the opening 30d needs to be provided at least below the upper end of the nip portion N. That is, as shown in FIG. 3, the horizontal line h6 passing through the lower end of the opening 30d is located below the horizontal line h3 passing through the upper end of the nip portion N. Furthermore, it is desirable to arrange the lower end of the opening 30d below the center position of the nip portion N because the peeling performance of the toner supply roller 20 can be improved. Furthermore, by arranging the lower end of the opening 30d below the lower end of the nip portion N, the peeling performance of the toner supply roller 20 can be further improved, which is more desirable. That is, as shown in FIG. 3, it is desirable that the horizontal line h6 passing through the lower end of the opening 30d be located below the horizontal line h5 passing through the lower end of the nip portion N. In this embodiment, the lower end of the opening 30d (the upper end of the second wall portion 30b) is arranged 1 mm below the lower end of the nip portion N.

(Iii) Positional relationship between the lower end of the opening 30d and the leading end of the developing blade 21. The lower end of the opening 30d has an end 21b on the upstream side in the rotation direction of the developing roller 17 at the contact position 21c between the developing blade 21 and the developing roller 17. On the other hand, they may be arranged at the same position or above. By doing so, the excess toner 80 regulated by the developing blade 21 is continuously supplied to the first space. By doing so, the pressure density of the toner 80 in the first space is further increased, and the toner is supplied from the first space to the toner supply roller 20, and the second space is passed over the wall at the lower end of the opening 30d. The flow of the toner 80 returning to the toner storage chamber 18a can be formed. While satisfying the other structural requirements of the present embodiment, the lower end of the opening 30d is lower than the end 21b on the upstream side in the rotation direction of the developing roller 17 with respect to the contact position 21c of the developing blade 21 with the developing roller 17. In the case of 1), it was difficult to increase the pressure density of the first space.

(Iv) Arrangement relationship between the narrowed portion and the inner surface of the developing wall (upper surface of the third wall portion 30c) The toner is supplied from the pressure-tight portion formed in the first space to the toner supply roller 20. Further, a part of the toner 80 that has passed through the narrow portion and moved from the first space (consolidation space) to the second space passes over the wall at the lower end of the opening 30d by the pressure of the flow of the toner 80 and enters the toner storage chamber 18a. To be returned. In order to simultaneously achieve these two processes in a well-balanced manner, a narrow portion is provided below the toner supply roller 20, and the developing chamber is expanded so that the space extends from the narrow portion to the first space and the second space. It was necessary to configure the inside of 18b.

  As in the comparative example of FIG. 6A described later, in the configuration in which the narrow portion is formed wide along most of the lower region on the peripheral surface of the toner supply roller 20, the first space is changed to the second space. The toner 80 becomes difficult to move into the space, which causes an adverse effect on the image. The vertical distance between the toner supply roller 20 and the inner surface of the developing chamber 18b is preferably 5.0 mm or less in order to form an appropriate compacted state. In addition, the width of the narrow portion in the circumferential direction of the toner supply roller 20 between the toner supply roller 20 and the inner surface of the developing chamber 18b is preferably 7.0 mm or less in order to form an appropriate compacted state. When the narrow portion has a certain width, the narrow portion may be configured as shown in FIG. That is, the toner supply roller 20 is provided on the inner surface of the developing chamber 18b so that the distance (gap width) between the lower region of the circumferential surface of the toner supply roller 20 and the inner surface of the developing chamber 18b (the upper surface of the third wall portion 30c) is substantially constant. A bent (curved) region (concave region) along the shape may be provided.

(V) Arrangement relationship of the angle between the front end of the developing blade 21 and the inner wall of the developing container Further, in order to move the toner 80 from the first space to the second space, the first position is set so as not to hinder the movement of the toner 80. It is necessary to appropriately set the angle between the inner surface of the wall of the developing device frame 18 (the upper surface of the third wall 30c) facing the space and the second space. Therefore, in the present embodiment, from a position horizontally separated from the narrow portion from the intersection of the above-described vertical line (see FIG. 4) and the inner surface of the wall portion of the developing device frame 18 (upper surface of the third wall portion 30c). The inner surface of the wall of the developing device frame 18 is configured to be substantially horizontal. By doing so, the toner 80, which is supplied from the toner supply roller 20 to the developing roller 17 and regulated by the developing blade 21, moves to the direction of the second space where the narrow portion is sandwiched by the toner 80 which has dropped into the first space. Easier to do. In the configuration as shown in FIG. 6A, which will be described later, the toner 80 regulated by the developing blade 21 may stay near the developing blade 21 and cause a bad image due to defective circulation.
As shown in FIG. 7A, the toner descends from the first space toward the second space so that the toner can move more easily from the first space toward the second space (first space). The upper surface of the three wall portion 30c may be inclined (inclined surface 30c1). By doing so, the toner circulation from the first space to the second space can be further promoted.

(Vi) Arrangement Relationship between Lower End of Opening 30d and Toner Supply Roller 20 In the configuration of the present embodiment, the lower end of the opening 30d is arranged 3.0 mm above the lower end of the toner supply roller 20. By doing so, the amount of toner returning from the second space to the toner storage chamber 18a can be controlled to an appropriate amount, and thus an appropriate compaction space can be formed in the first space.

Next, another feature of the arrangement of the present embodiment will be described.
In this embodiment, the surface peripheral speed of the toner supply roller 20 is set higher than that of the developing roller 17. By doing so, the conveying force on the surface of the toner supply roller 20 accompanying the rotational drive of the toner supply roller 20 is relatively increased with respect to the toner supply regulated by the developing blade 21 in the first space, It is possible to more effectively enhance the compaction state of the toner in the first space. When the peripheral speed ratio is 200% or more, the compaction becomes excessively high, which causes an image defect due to defective circulation.

  Further, in the configuration of this embodiment, the rotation speed of the agitating/conveying member 22 is slower than the rotation speed of the toner supply roller 20. By doing so, at a timing when the toner 80 is not being pumped up to the developing chamber 18b by the agitating/conveying member 22, the toner passes over the lower end of the opening 30d from the second space to the second space, and the second space. The toner 80 moves to the storage chamber 18a. Thereby, the toner circulation in the developing chamber 18b can be further promoted.

  Further, in the configuration of this embodiment, an example is shown in which the positions of the upper end of the peripheral surface of the toner supply roller 20 and the upper end of the peripheral surface of the developing roller 17 are the same. Here, as a modification, as shown in FIG. 7B, the upper end of the peripheral surface of the toner supply roller 20 may be arranged above the upper end of the peripheral surface of the developing roller 17. That is, as shown in FIG. 7B, the horizontal line h2-1 passing through the upper end of the peripheral surface of the toner supply roller 20 is positioned above the horizontal line h2-2 passing through the upper end of the peripheral surface of the developing roller 17. .. By doing so, the area where the toner 80 drawn up by the agitating/conveying member 22 is stored expands above the nip portion N (a larger amount of toner 80 can be stored by the height of the horizontal line h2-1 with respect to the horizontal line h2-2). ), the solid density stability is further enhanced.

  Further, in the configuration of this embodiment, the surfaces of the toner supply roller 20 and the developing roller 17 rotate in opposite directions at the nip portion N. By doing so, the undeveloped toner 80 on the developing roller 17 is strongly scraped off, so that it is easy to form a toner coat having a uniform coat amount and a uniform charge amount on the developing roller 17, regardless of the residual toner amount. Therefore, it is possible to provide a high-quality developing device in which solid density unevenness and ghost are minimal.

  As described above, in this embodiment, the toner 80 conveyed from the stirring and conveying member 22 can be efficiently conveyed to the nip portion N between the toner supply roller 20 and the developing roller 17. Further, in the developing chamber 18b, the toner 80 is supplied from the first space to the toner supply roller 20 by forming a compressed state of the toner 80 in the first space with the narrow portion below the toner supply roller 20 as a boundary. be able to. In addition, by forming an appropriate consolidated state in the first space, the toner 80 is returned from the first space to the second space, and from the second space to the toner storage chamber 18a by crossing the lower end of the opening 18b. Be done. Further, the arrangement of the inner surface of the developing chamber 18b in the first and second spaces makes it difficult for the toner 80 regulated by the developing blade 17 to stay in the first space. As a result, it is possible to suppress image defects due to defective circulation. As described above, a developing device, a process cartridge, and an image forming apparatus capable of supplying a high-quality image with a simple structure, which suppresses image defects caused by defective toner circulation and has a stable solid image density. Can be provided.

<Experiment>
In order to show the effect of the present invention, a plurality of experiments were conducted using the examples and comparative examples.

<Comparative Example 1>
FIG. 6A is a schematic cross-sectional view showing the configuration of the process cartridge according to Comparative Example 1. In the configuration of Comparative Example 1 shown in FIG. 6A, most of the toner supply roller 20 below the circumferential portion is a narrow portion. That is, in Comparative Example 1, in the configuration of Example 1, the second wall portion 30b and the third wall portion 30c have a concave shape that follows the peripheral surface of the toner supply roller 20, and the first and second spaces are also narrow. It has a narrow width similar to that of the section. Further, a vertical line is drawn based on the end (free end tip) located upstream of the contact position between the developing blade 21 and the developing roller 17 in the rotation direction of the developing roller 17. In the configuration of Comparative Example 1, the angle of the inner wall surface at the intersection of the vertical line and the inner wall surface of the developing chamber 18b is an angle at which the toner 80 easily moves to the developing blade 17 side. The other configurations of the process cartridge and the overall configuration of the image forming apparatus in Comparative Example 1 are similar to those in Example 1.

<Comparative example 2>
FIG. 6B is a schematic cross-sectional view showing the configuration of the process cartridge according to Comparative Example 2. In Comparative Example 2, as described in the background art (Patent Document 1), the toner receiving member 30 to which the receiving sheet 32 is attached is provided below the toner supply roller 20. One end of the receiving sheet 32 is attached to the toner receiving member 30, and the other end of the receiving sheet 32 is brought into contact with the lower portion of the peripheral surface of the toner supply roller 20 with an appropriate linear pressure.

<Comparative example 3>
FIG. 6C is a schematic cross-sectional view showing the configuration of the process cartridge according to Comparative Example 3. As described in the background art (Patent Document 2) described above, Comparative Example 3 has a configuration of FIG. 6 in which a plurality of toner conveying members 16 are arranged below the toner supply roller 20 in the configuration of Comparative Example 1. .. Each of the toner transport members 16 is a rectangular plate-shaped member that extends along the rotation axis direction of the toner supply roller 20 in the developing chamber 18b, and one end of the toner supply roller 20 downstream in the rotation direction E is rotatably supported. It is rotatably supported by the developing frame by a shaft. The toner conveying member 16 is oscillated such that the one end is a fulcrum (center of rotation) and the other end on the upstream side in the rotation direction E, which is a free end, periodically changes the interval between the toner supply roller 20 and the peripheral surface of the toner supply roller 20. It is configured to perform a dynamic rotational movement. The toner conveying member 16 supplies toner to the toner supply roller 20 by rotating (swinging) at a rotation speed of 200 rpm. The other configurations of the process cartridge and the overall configuration of the image forming apparatus in Comparative Example 3 are the same as those in Comparative Example 1.

<Comparative example 4>
FIG. 6D is a schematic cross-sectional view showing the configuration of the process cartridge according to Comparative Example 4. In Comparative Example 4, as described in the background art (Patent Document 3) described above, in the configuration of Comparative Example 1, the toner supply roller 20 rotates in the direction opposite to the toner supply roller 20 of Example 1 (clockwise). It is configured to do. Further, the toner supply roller 20 is rotationally driven at 100 rpm. The other configurations of the process cartridge and the overall configuration of the image forming apparatus in Comparative Example 4 are similar to those in Comparative Example 1.

Next, the experimental conditions will be described.
(1) Evaluation of density stability of solid image As an evaluation of density stability of a solid image, the amount of decrease in image density was measured when high-printing prints were continuously performed. The evaluation was performed after leaving the image forming apparatus in the evaluation environment at 25.0° C. and 50% Rh for 1 day to adapt to the environment, and after printing 100 sheets. The printing test of 100 sheets was performed by continuously passing a recorded image of horizontal lines with an image ratio of 5%. Then, 10 solid images were continuously output, and the following evaluation was performed from the difference in density between the output front end and the rear end of the 10th solid image using a X-Rite spectrodensitometer 500. The print test and the evaluation image were output in a single color (black).
A: In the solid image, the density difference between the front and rear edges of the paper is less than 0.2 B: In the solid image, the density difference between the front and rear edges of the paper is 0.2 to less than 0.3 C: Solid image , The density difference between the leading edge and the trailing edge of the paper is 0.3 or more.

(2) Ghost Image Evaluation As an evaluation of the ghost image, a halftone image of intermediate density was printed after solid printing, and the density difference from the halftone image in the case of solid non-printing portion was judged. The evaluation was performed after leaving the image forming apparatus in the evaluation environment at 25.0° C. and 50% Rh for 1 day to adapt to the environment, and after printing 100 sheets. The printing test of 100 sheets was performed by continuously passing a recorded image of horizontal lines with an image ratio of 5%. Then, an image for ghost evaluation was output and the level of the halftone density difference was visually determined.
A: Almost no visible difference in density.
B: The density difference is slightly visible.
C: The density difference is clearly visible.

(3) Presence or Absence of Toner Aggregation Toner was evaluated by disassembling the image forming apparatus after the endurance test and investigating whether or not toner aggregation is present in the developing chamber.
A: No toner agglomeration B: Toner agglomeration occurred As a condition of the durability test, a horizontal line having an image ratio of 1% was intermittently passed through 10,000 sheets (printing) in an environment of 32.5° C. and 80% Rh. Intermittent sheet passing means that the next printing is performed after the printing is performed and the standby state is reached.
It should be noted that the term "toner aggregation occurs" here means a state in which the toner is pressed and aggregated below the developing roller and the toner supply roller. If image formation is performed in the state where toner aggregation has occurred, image quality deterioration such as density unevenness occurs.

(4) Presence/absence of toner fusion on the developing blade The toner fusion on the developing roller was evaluated by observing the developing blade of the image forming apparatus whose toner aggregation durability was finished in (3) and observing the toner fusion. I investigated and evaluated the squid.
A: No toner fusion B: Some toner fusion (toner adhered everywhere on the developing blade)
C: Toner is fused (toner is attached to the entire surface of the developing blade)
As a condition of the durability test, a horizontal line having an image ratio of 1% was intermittently passed through 10,000 sheets (printed) in an environment of 32.5° C. and 80% Rh. Intermittent sheet passing means that the next printing is performed after the printing is performed and the standby state is reached.

<Experimental results>
Table 1 below shows the settings of each example and the evaluation results thereof.
Table 1: Experimental results in Example 2

First, the results of Comparative Example 1 will be described. In the configuration of Comparative Example 1, most of the toner 80 supplied on the toner supply roller 20 returns to the toner storage chamber 18a from the opening 30d due to the rotation of the toner supply roller 20. Further, the distance between the lower surface of the toner supply roller 20 and the inner wall surface of the developing chamber 18b facing the peripheral surface is short, and the toner 80 does not enter the position corresponding to the second space in the first embodiment. Further, even if the toner 80 is sucked in above the nip portion N between the toner supply roller 20 and the developing roller 17, the area corresponding to the first space in the first embodiment is narrow, and sufficient toner 80 is supplied to the toner supply roller 20. We cannot supply. Therefore, it is difficult to secure the density stability of the solid image. Further, as a result of continuing to output the image with the image ratio of 1%, the toner 80 in the area corresponding to the first space of the first embodiment exceeds the narrow area over most of the lower surface of the toner supply roller 20 and the toner storage chamber. It does not move back to 18a. Further, the toner 80 regulated by the developing blade 21 in particular gets stuck in the vicinity of the developing blade 21. Therefore, the toner in the vicinity of the developing blade 21 is locally deteriorated, toner aggregation occurs, and toner fusion with the developing blade 21 occurs.

  Next, the results of Comparative Example 2 will be described. In the configuration of Comparative Example 2, the toner receiving member 30 is provided below the toner supply roller 20. Therefore, the toner 80 conveyed by the toner supply roller 20 is stably supplied without dropping into the toner containing chamber 18a, and only the toner 80 regulated by the developing blade 21 falls into the toner containing chamber 18a. Therefore, the density stability of the solid image can be secured, and the toner fusion on the developing roller 17 does not aggregate near the developing blade 21. However, since the toner receiving sheet 32 is in contact with the toner supplying roller 20, the toner 80 aggregates between the toner supplying member 20 and the toner receiving sheet 32, and uneven image density occurs due to the toner aggregation.

  Next, the results of Comparative Example 3 will be described. In Comparative Example 3, the toner conveying member 16 is arranged below the toner supply roller 20 in the developing chamber 18b. By disposing the toner conveying member 16, the aggregation of the toner in the area below the toner supply roller 20 and the developing roller 17 in the developing chamber 18b is suppressed, and at the same time, the toner 80 below the toner conveying member 16 becomes the toner. It is returned to the storage chamber 18a. Therefore, problems such as density unevenness due to toner aggregation do not occur. However, since the toner deteriorates due to the friction between the toner 80 and the toner conveying member 16, the toner fusion to the developing roller 17 was observed when the image with a low printing rate continued. Further, in the developing chamber 18b, it is necessary to provide the toner conveying member 16 as an additional member in addition to the toner supply roller 20, so that the apparatus configuration is complicated. Further, the toner 80 is pressed against the toner supply roller 20 by the transfer pressure of the toner transfer member 16 to supply the toner 80 to the toner supply roller 20. Therefore, since the pressure of the toner 80 against the toner supply roller 20 is not sufficient, the solid density stability becomes lower than that of the example in the state where 10 sheets are continuously fed.

  Next, the results of Comparative Example 4 will be described. In Comparative Example 4, the toner supply roller 20 is rotated in the opposite direction (clockwise) to the toner supply roller 20 of Comparative Example 1 in the same configuration as that of Comparative Example 1. Therefore, the defective circulation of the toner 80 does not occur at the position corresponding to the first space in the first embodiment. However, since the toner supply roller 20 is rotating in the opposite direction to the first embodiment (clockwise), the force for peeling off the undeveloped toner on the developing roller 17 is weak. Therefore, density unevenness (so-called ghost image) occurs in the halftone image corresponding to one round of the developing roller 17 after the solid image is printed and after the non-printing.

  Next, the results of Example 1 will be described. In the first embodiment, the toner 80 transported from the toner transport member 22 can be efficiently transported to the nip portion N between the toner supply roller 20 and the developing roller 17. Further, the toner 80 is supplied from the first space to the toner supply roller 20 by forming a compacted state of the toner 80 in the first space with the narrow portion below the toner supply roller 20 as a boundary in the developing chamber 18b. You can Further, by forming an appropriate compaction state in the first space, the toner 80 is returned from the first space to the second space, and from the second space to the toner storage chamber 18a by overcoming the lower end of the opening 30d. Be done. Further, the arrangement of the inner surface of the developing chamber 18b in the first and second spaces makes it difficult for the toner 80 regulated by the developing blade 17 to stay in the first space. As a result, it is possible to prevent image defects due to defective circulation. As described above, a developing device, a process cartridge, and an image forming apparatus capable of supplying a high-quality image with a simple configuration, which suppresses image defects caused by defective toner circulation and has a stable solid image density. Can be provided.

Although the present embodiment exemplifies an image forming apparatus capable of forming a color image, the apparatus configuration to which the present invention is applicable is not limited to this, and an image forming apparatus capable of forming a monochrome image can be used. The same effect can be obtained even when the present invention is applied.

  Further, although the printer is illustrated as the image forming apparatus in the first embodiment, the example of the image forming apparatus to which the present invention is applicable is not limited to this. For example, the present invention can be applied to other image forming apparatuses such as a copying machine and a facsimile machine, or other image forming apparatuses such as a multifunction machine that combines these functions. Also, the present invention is applied to an image forming apparatus that uses a recording material carrier such as a recording material transport belt and sequentially transfers toner images of respective colors by superimposing them on the recording material carried on the recording material carrier. The same effect can be obtained.

[Example 2]
The developing unit (developing device) according to the second exemplary embodiment of the present invention is characterized by the toner contained in the developing device frame. Specifically, the developing unit according to Example 2 has a surface layer containing an organosilicon polymer, and has a Martens hardness of 200 MPa or more and 1100 MPa or more when measured under the condition of the maximum load of 2.0×10 ⁻⁴ N. The following toner is used. By using such a toner, it is possible to provide a long-life developing device capable of maintaining good circulation of the toner for a long period of durability of the developing unit and stably forming a high-quality image. The configuration of the second embodiment other than the above is the same as that of the developing unit of the first embodiment, and the description thereof is omitted.
The toner used in Example 2 will be described below.

<Regarding Surface Layer Containing Organosilicon Polymer>
When the toner particles have a surface layer containing an organic silicon polymer, it preferably has a partial structure represented by the formula (1).
R-SiO _3/2 formula (1)
(R represents a hydrocarbon group having 1 to 6 carbon atoms.)

In the organosilicon polymer having the structure of formula (1), one of the four valences of Si atoms is bonded to R and the remaining three are bonded to O atoms. Each of the O atoms has a valence of 2 and is bonded to Si, that is, a siloxane bond (Si-O-Si). Considering Si atoms and O atoms as the organosilicon polymer, two Si atoms have three O atoms, and thus they are expressed as —SiO _3/2 . It is considered that the -SiO _3/2 structure of this organosilicon polymer has properties similar to silica (SiO ₂ ) composed of many siloxane bonds. Therefore, it is considered that it is possible to increase the Martens hardness because it has a structure closer to that of an inorganic substance as compared with the toner formed on the surface layer by the conventional organic resin.

  As a production example of the organosilicon polymer, the sol-gel method is preferable. The sol-gel method is a method in which a liquid raw material is used as a starting raw material for hydrolysis and condensation polymerization, and a gel is formed through a sol state, and is used for synthesizing glass, ceramics, organic-inorganic hybrids, and nanocomposites. By using this manufacturing method, it is possible to manufacture functional materials having various shapes such as surface layers, fibers, bulk bodies, and fine particles from a liquid phase at a low temperature.

Specifically, the organosilicon polymer existing in the surface layer of the toner particles is preferably produced by hydrolysis and polycondensation of a silicon compound represented by alkoxysilane.
By providing the toner particles with the surface layer containing the organosilicon polymer, the environmental stability is improved, and the performance of the toner is less likely to deteriorate during long-term use, and a toner having excellent storage stability can be obtained. ..

Furthermore, since the sol-gel method starts from a liquid and forms the material by gelling the liquid, various fine structures and shapes can be formed. In particular, when the toner particles are manufactured in an aqueous medium, the hydrophilicity of a hydrophilic group such as a silanol group of the organosilicon compound facilitates precipitation on the surface of the toner particles. The fine structure and shape can be adjusted by the reaction temperature, reaction time, reaction solvent, pH and the kind and amount of the organometallic compound.

（式（Ｚ）中、Ｒ_１は、炭素数１以上６以下の炭化水素基を表し、Ｒ_２、Ｒ_３及びＲ_４は、それぞれ独立して、ハロゲン原子、ヒドロキシ基、アセトキシ基、又は、アルコキシ基を表す。） The organosilicon polymer on the surface layer of the toner particles is preferably a polycondensation product of an organosilicon compound having a structure represented by the following formula (Z).

(In the formula (Z), R ₁ represents a hydrocarbon group having 1 to 6 carbon atoms, and R ₂ , R ₃ and R ₄ are each independently a halogen atom, a hydroxy group, an acetoxy group, or Represents an alkoxy group.)

The hydrocarbon group (preferably an alkyl group) of R ₁ can improve hydrophobicity, and toner particles excellent in environmental stability can be obtained. As the hydrocarbon group, an aryl group which is an aromatic hydrocarbon group, for example, a phenyl group can also be used. When R ₁ has a large hydrophobicity, the charge amount tends to increase in various environments. Therefore, in view of environmental stability, R ₁ is preferably a hydrocarbon group having 1 to 3 carbon atoms, It is more preferably a methyl group.

R ₂ , R ₃ and R ₄ are each independently a halogen atom, a hydroxy group, an acetoxy group or an alkoxy group (hereinafter, also referred to as a reactive group). These reactive groups are hydrolyzed, addition-polymerized and polycondensed to form a crosslinked structure, and a toner excellent in member contamination resistance and development durability can be obtained. Hydrolyzability is mild at room temperature, and an alkoxy group having 1 to 3 carbon atoms is preferable, and a methoxy group and an ethoxy group are more preferable, from the viewpoints of the depositability on the surface of the toner particles and the coatability. .. The hydrolysis, addition polymerization and condensation polymerization of R ₂ , R ₃ and R ₄ can be controlled by the reaction temperature, reaction time, reaction solvent and pH.

To obtain the organosilicon polymer used in the present invention, an organosilicon compound having _three reactive groups (R ₂ , R ₃ and R ₄ ) in one molecule excluding R ₁ in the above formula (Z) is used. (Hereinafter, also referred to as trifunctional silane) may be used alone or in combination of two or more.

Further, the content of the organosilicon polymer in the toner particles is preferably 0.5% by mass or more and 10.5% by mass or less.
When the content of the organosilicon polymer is 0.5% by mass or more, the surface free energy of the surface layer can be further reduced, the fluidity can be improved, and member contamination and fogging can be suppressed. .. When the content is 10.5% by mass or less, it is possible to make charge-up less likely to occur. The content of the organosilicon polymer should be controlled by the type and amount of the organosilicon compound used for forming the organosilicon polymer, the method for producing toner particles during the formation of the organosilicon polymer, the reaction temperature, the reaction time, the reaction solvent and the pH. You can

  It is preferable that the surface layer containing the organosilicon polymer and the toner core particles are in contact with each other without any space. As a result, the occurrence of bleeding due to the resin component or the release agent inside the surface of the toner particles is suppressed, and a toner having excellent storage stability, environmental stability, and development durability can be obtained. In addition to the above organosilicon polymer, the surface layer may contain a resin such as a styrene-acrylic copolymer resin, a polyester resin or a urethane resin, and various additives.

<Method of manufacturing toner particles>
As a method for producing the toner particles, known means can be used, and a kneading and pulverizing method or a wet production method can be used. From the viewpoint of making the particle diameter uniform and controlling the shape, the wet manufacturing method can be preferably used. Further, as the wet production method, a suspension polymerization method, a dissolution suspension method, an emulsion polymerization aggregation method, an emulsion aggregation method and the like can be mentioned.

Here, the suspension polymerization method will be described.
In the suspension polymerization method, first, a polymerizable monomer for forming a binder resin, a colorant and, if necessary, other additives are uniformly dispersed using a ball mill or a disperser such as an ultrasonic disperser. A polymerizable monomer composition dissolved or dispersed in is prepared (step of preparing the polymerizable monomer composition). At this time, if necessary, a polyfunctional monomer, a chain transfer agent, a wax as a release agent, a charge control agent, a plasticizer, etc. can be appropriately added.

Next, the above polymerizable monomer composition is put into an aqueous medium prepared in advance, and a stirrer or a disperser having a high shearing force is used to form droplets of the polymerizable monomer composition. A desired toner particle size is formed (granulation step).
It is preferable that the aqueous medium in the granulation step contains a dispersion stabilizer in order to control the particle size of the toner particles, sharpen the particle size distribution, and suppress coalescence of the toner particles in the manufacturing process. The dispersion stabilizer is generally classified into a polymer that exhibits a repulsive force due to steric hindrance and a poorly water-soluble inorganic compound that stabilizes the dispersion by electrostatic repulsive force. Since the fine particles of the poorly water-soluble inorganic compound are dissolved by an acid or an alkali, they can be easily dissolved and removed by washing with an acid or an alkali after the polymerization, and thus are preferably used.

After the granulation step or while performing the granulation step, the temperature is preferably set to 50° C. or higher and 90° C. or lower to polymerize the polymerizable monomer contained in the polymerizable monomer composition to obtain a toner. A particle dispersion is obtained (polymerization step).
In the polymerization step, it is preferable to carry out a stirring operation so that the temperature distribution in the container becomes uniform. When the polymerization initiator is added, it can be carried out at an arbitrary timing and required time. In addition, the temperature may be raised in the latter half of the polymerization reaction for the purpose of obtaining a desired molecular weight distribution. After that, part of the aqueous medium may be distilled off by a distillation operation. The distillation operation can be performed under normal pressure or reduced pressure.

  The particle diameter of the toner particles is preferably 3.0 μm or more and 10.0 μm or less in terms of obtaining a high-definition and high-resolution image. The weight average particle diameter of the toner can be measured by the pore electrical resistance method. For example, it can be measured by using "Coulter Counter Multisizer 3" (manufactured by Beckman Coulter, Inc.). The toner particle dispersion liquid thus obtained is sent to a filtration step for solid-liquid separating the toner particles and the aqueous medium.

  Solid-liquid separation for obtaining toner particles from the obtained toner particle dispersion liquid can be carried out by a general filtration method, and thereafter, in order to remove foreign substances that could not be completely removed from the toner particle surface, reslurry or washing water is used. Further washing is preferably carried out by washing with water. After sufficient washing is performed, solid-liquid separation is performed again to obtain a toner cake. After that, it is dried by a known drying means, and if necessary, a group of particles having a particle diameter outside the predetermined range is separated by classification to obtain toner particles. The particles having a particle size outside the predetermined range may be reused in order to improve the final yield.

When forming a surface layer having an organosilicon polymer, when forming the toner particles in an aqueous medium, the hydrolysis solution of the organosilicon compound is added as described above while performing the polymerization step in the aqueous medium. The surface layer can be formed. Using the dispersion of toner particles after polymerization as the dispersion of core particles, a hydrolyzed liquid of an organosilicon compound may be added to form the surface layer. Further, in the case of other than an aqueous medium such as a kneading and pulverizing method, the obtained toner particles are dispersed in an aqueous medium and used as a core particle dispersion liquid, and as described above, the hydrolysis liquid of the organosilicon compound is added to the surface layer. Can be formed.

<Method of measuring hardness>
Hardness is one of the mechanical properties on or near the surface of an object, and is the degree of difficulty in deforming or scratching an object when it is about to be deformed or scratched by foreign matter. There are various measurement methods and definitions. For example, the measuring method can be selectively used depending on the size of the measuring area. The Vickers method is used when the measuring area is 10 μm or more, the nanoindentation method is used when the measuring area is 10 μm or less, and the AFM is used when the measuring area is 10 μm or less. Many. As a definition, for example, Brinell hardness or Vickers hardness is used as indentation hardness, Martens hardness is used as scratch hardness, and Shore hardness is used as repulsion hardness.

  In the toner measurement, the nano-indentation method is preferably used since the general particle size is 3 μm to 10 μm. According to the studies by the inventors, the Martens hardness, which represents the scratch hardness, is suitable as the regulation of the hardness for expressing the effect of the present invention. This is because the scratch hardness can represent the strength of the toner against scratching by a hard substance such as a metal or an external additive in the developing machine.

  The method for measuring the Martens hardness of the toner by the nanoindentation method is calculated from the load-displacement curve obtained by a commercially available device conforming to ISO14577-1 according to the procedure of the indentation test specified in ISO14577-1. can do. In the present invention, an ultra-fine indentation hardness tester “ENT-1100b” (manufactured by Elionix Co., Ltd.) was used as a device conforming to the ISO standard. The measuring method is described in the "ENT1100 operation manual" attached to the apparatus, and the specific measuring method is as follows.

  Regarding the measurement environment, the inside of the shield case was kept at 30.0° C. by the attached temperature control device. Keeping the ambient temperature constant is effective in reducing variations in measured data due to thermal expansion and drift. The set temperature was set to 30.0° C. assuming the temperature in the vicinity of the developing device where the toner is rubbed. The standard sample table attached to the device was used as the sample table. After the toner was applied, weak air was blown so that the toner was dispersed, and the sample table was set in the device and held for 1 hour or more before measurement. .

For the indenter, a flat indenter (titanium indenter, the tip of which is made of diamond) having a 20 μm square plane attached to the device was used as the indenter. For a small-diameter and spherical object such as toner, an object to which an external additive is attached, or an object having unevenness on the surface, a flat indenter is used because a sharp indenter greatly affects the measurement accuracy. The maximum load of the test is set to 2.0×10 ⁻⁴ N. By setting this test load, the hardness can be measured without destroying the surface layer of the toner under the condition corresponding to the stress applied to one toner particle in the developing section. In the present invention, since abrasion resistance is important, it is important to measure hardness while maintaining the surface layer without breaking it.

As the particles to be measured, those in which the toner alone is present on the measurement screen (field size: width 160 μm, height 120 μm) by the microscope attached to the apparatus are selected. However, in order to eliminate the error of the displacement amount as much as possible, the particle diameter (D) is selected within a range of ±0.5 μm of the number average particle diameter (D1) (D1-0.5 μm≦D≦D1+0.5 μm). .. The particle diameter of the particles to be measured was measured by measuring the major axis and the minor axis of the toner using software attached to the apparatus, and [(major axis+minor axis)/2] was defined as the particle diameter D (μm). Further, the number average particle diameter is measured by a method described later using "Coulter Counter Multisizer 3 (manufactured by Beckman Coulter, Inc.)".

At the time of measurement, 100 particles of any toner having a particle diameter D (μm) satisfying the above conditions are selected and measured. The conditions to be input at the time of measurement are as follows.
Test mode: Load-unload test Test load: 20.000 mgf (=2.0×10 ⁻⁴ N)
Number of divisions: 1000step
Step interval: 10 msec

  When the analysis menu “Data analysis (ISO)” is selected and measurement is performed, the Martens hardness is analyzed and output by the software attached to the apparatus after the measurement. The above measurement was performed on 100 toner particles, and the arithmetic mean value thereof was defined as the Martens hardness in the present invention.

The means for adjusting the Martens hardness at the time of measurement under the maximum load of 2.0×10 ⁻⁴ N to 200 MPa or more and 1100 MPa or less is not particularly limited. However, since the hardness is significantly higher than the hardness of the organic resin used for a general toner, it is difficult to achieve it by a means that is usually used to increase the hardness. For example, it is difficult to achieve it by means of designing a resin having a high glass transition temperature, increasing the molecular weight of resin, thermosetting, adding a filler to the surface layer, or the like.

The Martens hardness of the organic resin used for a general toner is about 50 MPa to 80 MPa when measured under the condition of the maximum load of 2.0×10 ⁻⁴ N. Further, even when the hardness is increased by designing the resin or increasing the molecular weight, it is about 120 MPa or less. Furthermore, even when a filler such as a magnetic material or silica is filled in the vicinity of the surface layer and cured by heat, it is about 180 MPa or less, and the toner of the present invention is significantly harder than general toner.

<Hardness control method>
As one means for adjusting the specific hardness range, for example, the surface layer of the toner is formed of a substance such as an inorganic material having an appropriate hardness, and the chemical structure or macro structure is controlled to have an appropriate hardness. There is a method of doing.

  As a specific example, a substance that can have the above-described specific hardness includes an organic silicon polymer, and the selection of the material includes the number of carbon atoms directly bonded to the silicon atom of the organic silicon polymer and the carbon chain length. The hardness can be adjusted by. The toner particles have a surface layer containing an organosilicon polymer, and the number of carbon atoms directly bonded to silicon atoms of the organosilicon polymer is 1 or more and 3 or less (preferably 1 or more and 2 or less). , And more preferably 1), since it is easy to adjust to the above specific hardness, which is preferable.

  As a means for adjusting the Martens hardness by the chemical structure, it is possible to adjust the chemical structure such as crosslinking of the surface layer substance or the degree of polymerization. As means for adjusting the Martens hardness by the macro structure, it is possible to adjust the uneven shape of the surface layer or the network structure for connecting the projections. When the organosilicon polymer is used as the surface layer, these adjustments can be made by adjusting the pH, concentration, temperature, time, etc. when pretreating the organosilicon polymer. Further, it can be adjusted by the timing, form, concentration, reaction temperature and the like of applying the surface layer of the organosilicon polymer to the core particles of the toner.

The following method is particularly preferable in the present invention. First, core particles of a toner containing a binder resin and a colorant are manufactured and dispersed in an aqueous medium to obtain a core particle dispersion liquid. The concentration at this time is preferably such that the solid content of the core particles is 10% by mass or more and 40% by mass or less based on the total amount of the core particle dispersion liquid. The temperature of the core particle dispersion liquid is preferably adjusted to 35°C or higher. Further, the pH of the core particle dispersion liquid is preferably adjusted to a pH at which condensation of the organosilicon compound does not easily proceed. Since the pH at which condensation of the organosilicon polymer is difficult to proceed differs depending on the substance, it is preferably within ±0.5 around the pH at which the reaction is most difficult to proceed.

  On the other hand, it is preferable to use a hydrolyzed organosilicon compound. For example, the organosilicon compound is hydrolyzed in a separate container as a pretreatment. When the amount of the organosilicon compound is 100 parts by mass, the charged concentration of hydrolysis is preferably 40 parts by mass or more and 500 parts by mass or less of water obtained by removing ion components such as ion-exchanged water and RO water, and more preferably 100 parts by mass of water. It is above 400 parts by mass. As conditions for hydrolysis, the pH is preferably 2 to 7, the temperature is 15 to 80° C., and the time is 30 to 600 minutes.

  By mixing the obtained hydrolyzed liquid and the core particle dispersion liquid and adjusting the pH (preferably 6 to 12, or 1 to 3, and more preferably 8 to 12) suitable for condensation, the organosilicon compound is removed. A surface layer can be applied to the surface of the core particles of the toner while being condensed. Condensation and surface coating are preferably performed at 35° C. or higher for 60 minutes or longer. Further, the surface macrostructure can be adjusted by adjusting the time of holding at 35° C. or higher before adjusting the pH suitable for condensation, but if the time is too long, the toner of Martens hardness of the present invention can be obtained. Since it is difficult, 3 minutes or more and 120 minutes or less are preferable.

  By the means as described above, it is possible to reduce the reaction residues, form irregularities on the surface layer, and further form a network structure between the protrusions, so that it is easy to obtain a toner having the above specific Martens hardness. .. When the surface layer containing the organosilicon polymer is used, the fixing rate of the organosilicon polymer is preferably 90% or more and 100% or less. The method for measuring the sticking rate of the organosilicon polymer will be described later.

<Measurement of toner particle size>
A precise particle size distribution measuring device (trade name: Coulter Counter Multisizer 3) by a pore electric resistance method and dedicated software (trade name: Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.) are used. The aperture diameter is 100 μm, the number of effective measurement channels is 25,000, and the measurement data is analyzed and calculated. The electrolytic aqueous solution used for the measurement may be prepared by dissolving special grade sodium chloride in ion-exchanged water so that the concentration becomes about 1% by mass, for example, ISOTON II (trade name) manufactured by Beckman Coulter, Inc. can be used. Before the measurement and analysis, the dedicated software is set as follows.

In the "Change standard measurement method (SOM) screen" of the dedicated software, the total count number in the control mode is set to 50,000 particles, the number of measurements is once, and the Kd value is (standard particle 10.0 μm, Beckman Coulter, Inc. The value obtained by using the product is set. The threshold and noise level are automatically set by pressing the threshold/noise level measurement button. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II (trade name), and the flash of the aperture tube after measurement is checked.
On the "pulse-to-particle size conversion setting screen" of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm or more and 60 μm or less.

The specific measuring method is as follows.
(1) Approximately 200 mL of the electrolytic aqueous solution was placed in a glass 250 mL round-bottom beaker for exclusive use with Multisizer 3, set on a sample stand, and the stirrer rod was stirred counterclockwise at 24 revolutions/second. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flush" function of the analysis software.
(2) About 30 mL of the electrolytic aqueous solution is placed in a glass 100 mL flat-bottom beaker. Here, a diluted solution of Contaminone N (trade name) (10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments, manufactured by Wako Pure Chemical Industries, Ltd.) diluted with ion-exchanged water 3 times by mass was used. Add 3 mL.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with the phases shifted by 180 degrees, and an ultrasonic disperser with an electrical output of 120 W (trade name: Ultrasonic Dispersion System Tetra 150, manufactured by Nikkaki Bios Co., Ltd.) To prepare. About 2 mL of a predetermined amount of ion-exchanged water and Contaminone N (trade name) are added to the water tank of this ultrasonic disperser.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker becomes maximum.
(5) About 10 mg of toner (particles) is added little by little to the electrolytic aqueous solution in a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so as to be 10°C or higher and 40°C or lower.
(6) To the round-bottom beaker of (1) installed in the sample stand, drop the electrolytic aqueous solution of (5) in which the toner (particles) is dispersed by using a pipette so that the measured concentration becomes about 5%. Adjust to. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the apparatus to calculate the weight average particle diameter (D4). The “average diameter” on the analysis/volume statistical value (arithmetic mean) screen when the graph/volume% is set with the dedicated software is the weight average particle diameter (D4). The number average particle size (D1) is the "average diameter" of the "Analysis/number statistical value (arithmetic mean)" screen when graph/number% is set with dedicated software.

<Experiment>
In order to verify the long life performance of the developing device of Example 2, among the experiments conducted in Example 1, the verification experiments of (3) presence/absence of toner aggregation and (4) presence/absence of toner fusion to the developing blade were conducted. It was In the durability test, the number of printed sheets was 5 times that of the experiment conducted in Example 1, and 50000 sheets of horizontal lines with an image ratio of 1% were intermittently printed (printed) in an environment of 32.5° C. and 80% Rh.

Table 2: Experimental results in Example 2

In Example 2, excellent results were obtained that toner aggregation and toner fusion did not occur even under severe conditions such that the number of sheets printed by the developing device was 5 times as large as the experiment conducted in Example 1. .. This is because a toner having a surface layer containing an organic silicon polymer and having a Martens hardness of 200 MPa or more and 1100 MPa or less when measured under the conditions of a maximum load of 2.0×10 ⁻⁴ N of the toner has high abrasion resistance. This is because.

  In particular, in order to utilize the toner compaction state of the first space in this embodiment to keep the toner circulation in a good state even for long-term durability, a toner having high abrasion resistance is required. Due to the high abrasion resistance toner, the fluidity of the toner is maintained even during the long-term durability, so that the toner circulation from the first space (first consolidation space) to the second space (second consolidation space) is continuously performed. Good results were obtained with continued formation.

  If the Martens hardness is lower than 200 MPa, the effects of the present invention may not be satisfactorily obtained under the severe conditions described above. On the other hand, if the Martens hardness is higher than 1100 MPa, members such as the regulating blade and the developing roller may be damaged in some cases.

As described above, according to Example 2, the toner whose Martens hardness when measured under the condition of the maximum toner load of 2.0×10 ⁻⁴ N is adjusted to 200 MPa or more and 1100 MPa or less is used. By doing so, even when the developing device is durable for a long period of time, good circulation of the developer can be maintained with a simple configuration, and a developing device with a long life capable of stably forming a high-quality image can be provided. it can.

  Reference numeral 100... Image forming device, 4... Developing unit (developing device), 17... Developing roller (developer carrying member), 18... Developing frame member, 18a... Toner accommodating chamber (accommodating chamber), 18b... Developing chamber, 20... Toner Supply roller (supply member), 21... Developing blade (regulating member), 22... Agitation and transport member (transport member), 30... Wall portion, 30a... First wall portion, 30b... Second wall portion, 30c... Third wall Part, 30d... Opening part, 80... Toner (developer), N... Nip part

Claims (19)

A developer carrying member that carries a developer and is rotatable,
A supply member for supplying a developer to the developer carrying member, wherein a nip portion is formed between the developer carrying member and the surface of the supply member at the nip portion in the posture during use is gravity. A supply member that moves along the direction from the lower side to the upper side of the direction, and that is rotatable in the same rotation direction as the developer carrying member;
A regulating member for regulating the amount of the developer carried on the developer carrying body by contacting the developer carrying body;
A developing chamber in which the developer carrier, the supply member, and the regulating member are arranged; and a storage chamber which is located below the developing chamber in a posture in use and stores the developer to be supplied to the developing chamber, A frame body having a partition wall portion having an opening communicating the storage chamber and the developing chamber;
A developing device comprising:
In the posture during use, when viewed along the longitudinal direction of the supply member, in the internal space of the developing chamber,
Located between the partition wall portion and the supply member, starting from a narrow portion where the distance between the partition wall portion and the supply member is the narrowest, the area becomes smaller toward the downstream side in the rotation direction of the supply member. The expanding first space,
A second space that is located between the partition wall portion and the supply member and has an area that increases toward the upstream side in the rotation direction of the supply member, starting from the narrow portion. ,
The developing device is characterized in that the lower end of the opening is located above the lower end of the supply member.   The developing device according to claim 1, further comprising a transporting member that is disposed in the storage chamber and transports the developer from the storage chamber to the developing chamber through the opening.   The developing device according to claim 1, wherein the internal space of the developing chamber includes a third space located above the nip portion.   The position of the lower end of the opening is at the same height as the contact position where the regulation member and the developer carrying member contact, or above the contact position. The developing device according to any one of items.   The developing device according to claim 1, wherein a position of a boundary between the partition wall portion and an upper end of the opening is located above an upper end of the supply member.   The upper end of the nip portion is located above a boundary between the partition wall portion and a lower end of the opening portion in a region facing the second space. The developing device according to 1.   The developing device according to claim 1, wherein the supply member includes a foamed body for holding a developer.   The developing device according to claim 7, wherein the foam has open cells.   The region of the partition wall portion facing the first space extends in the horizontal direction or in a direction inclined so as to become lower toward the narrowed portion. 8. The developing device according to any one of item 8. The regulating member has one end fixed to the frame body and abuts on the developer carrying body on the other end side which is a free end,
In the partition wall portion, the region facing the first space, from a position farther from the narrow portion than the intersection with the vertical line with the other end of the regulating member as a reference, toward the narrow portion, The developing device according to any one of claims 1 to 9, wherein the developing device extends in a horizontal direction or in a direction that is inclined so as to be downward as it approaches the narrow portion.   The center of the nip portion in the height direction is located above a boundary between the partition wall portion and a lower end of the opening in a region facing the second space. The developing device according to any one of items.   The developing device according to claim 1, wherein the first space is wider than the second space.   The area|region which forms the said narrow part with the said supply member in the said partition wall part is bending along the shape of the said supply member, The any one of Claims 1-12 characterized by the above-mentioned. Developing device. The transport member transports the developer from the storage chamber to the developing chamber via the opening by rotating.
The number of rotations of the developer carrier per unit time is higher than the number of rotations of the transport member per unit time,
The developing device according to claim 2, wherein the number of rotations of the supply member per unit time is higher than the number of rotations of the developer carrier per unit time.   The developing device according to claim 1, wherein an upper end of the supply member is located above an upper end of the developer carrier. The developer stored in the storage chamber has a Martens hardness of 200 MPa or more and 1100 MPa or less when measured under a condition of a maximum load of 2.0×10 ⁻⁴ N. 2. The developing device according to item 1.   The developer housed in the housing chamber has a surface layer containing an organic silicon polymer, and the developing device according to claim 1. A process cartridge attachable to and detachable from the main body of the image forming apparatus,
An image carrier on which a latent image is formed,
A developing device according to any one of claims 1 to 17,
A process cartridge comprising: An image forming apparatus for forming an image on a recording material,
An image carrier on which a latent image is formed,
A developing device according to any one of claims 1 to 17,
An image forming apparatus comprising:

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