JP2019164231A - Developing device and process cartridge unit and image forming apparatus - Google Patents

Abstract

To regulate the size and positions of holes required in fixing a regulation member so as to reduce variations in magnetic force of a regulation member resulting from the regulation member.SOLUTION: A developing device 4 according to the present invention comprises: a developer carrier 5 that includes magnetic field generation means 5b and carries and conveys a developer; and a regulation member 121 that is formed of a magnetic material. The regulation member 121 is provided with holes 122 for fixing its position, and the relationship between the diameter R of the holes 122 and the length Lfrom the holes 122 to a regulation-side end 121a of the regulation member is made 0.9963R+3.0671≤L1≤7.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a developing device, a process cartridge unit, and an image forming apparatus.

  In an image forming apparatus that forms an image using toner as a developer on an image carrier, a plate-shaped regulating member is provided in the developing unit to regulate the amount of toner supplied. In general, this member is composed of a member having magnetism and is often referred to as a doctor blade, and is fixed to the base of the developing device with a screw serving as a fixing member or by caulking with a pin serving as a fixing member It is fixed. As such a fixing structure of the regulating member, and a developing device and an image forming apparatus using the same, for example, Patent Document 1 can be cited.

When fixing the restricting member with screws or caulking, a hole for inserting a fixing member such as a screw or pin is formed in the restricting member. A variation in force occurs, and the amount of pumping up only in the peripheral part of the hole due to the falling of the developer ears may cause a vertical band image (abnormal image) to occur.
An object of the present invention is to reduce variations in the magnetic force of the regulating member due to the regulating member by regulating the size and position of the holes required when fixing the regulating member.

In order to achieve the above object, a developing device according to the present invention includes a developer carrying member that includes a magnetic field generation unit and carries and conveys a developer, and a regulating member that is configured by a magnetic material, the member, the position and the hole is provided for fixing, the diameter R of the hole, the width _{L 1} from the hole to the regulating end portion of the regulating member, 0.9963R + 3.0671 ≦ L1 ≦ 7 of It is characterized by a relationship.

  According to the present invention, it is possible to reduce the magnetic force variation of the regulating member caused by the regulating member.

1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a developing device according to an embodiment of the present invention. The figure explaining the structure of the control member with which a developing device is provided. It is a figure explaining the structure of a control member, (a) is sectional drawing of a part without a hole, (b) is sectional drawing of a part with a hole. It shows the measurement results of the relationship between the position L ₁ of the normal magnetic force and holes immediately below the hole. It shows the measurement results of the relationship between the position L ₂ of the normal magnetic force and holes immediately below the hole. It shows the measurement results of the relationship between the position L ₁ of the hole and the regulating gap G _d. Diagram for explaining the characteristics of the normal magnetic force due to a difference in position L ₁ and the diameter of the hole. Diagram for explaining the characteristics of the normal magnetic force due to a difference in position L ₁ and the diameter of the hole when changing the Figure 8 and conditions. The figure which shows the relationship between the diameter of the hole which can obtain the effect of this invention, and the position of a hole. The figure explaining the modification of a control member.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the embodiment, components having the same functions and configurations are denoted by the same reference numerals, and redundant description is omitted as appropriate. The drawings may be partially omitted or schematically shown in order to facilitate understanding of some configurations.
In the developing device according to the present invention, when a plate-like restricting member made of a magnetic member is fixed by fastening with screws or caulking, the position of the hole formed in the restricting member is separated from the end of the restricting member, By optimizing the distance between the restricting end of the restricting member and the hole depending on the size, the magnetic force drop around the hole is suppressed, and the longitudinal deviation of the pumping amount is reduced to stabilize the image quality. It is a thing. With the configuration of the present embodiment, the magnetic force variation in the longitudinal direction (main scanning direction) caused by the restricting member in calculation can be reduced to 20% or less, and the image quality can be stabilized.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a tandem type color laser copying machine (hereinafter simply referred to as “copying machine”) in which a plurality of photoconductors are arranged in parallel will be described.
A basic configuration of the copying machine according to the embodiment will be described. FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment. The copying machine includes a printer unit 100, a paper feeding device 200 on which the printer unit 100 is placed, a scanner 300 fixed on the printer unit 100, and the like. An automatic document feeder (hereinafter referred to as ADF) 400 fixed on the scanner 300 is also provided.
The printer unit 100 includes four image forming units (process cartridge units) 18Y, 18M, 18C, and 18K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 20 is provided. The suffixes Y, M, C, and K attached to the end of each symbol indicate members for yellow, magenta, cyan, and black (the same applies hereinafter).
In addition to the image forming units 18Y, 18M, 18C, and 18K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a resist roller pair 49, a belt fixing type fixing device 25, and the like are disposed. Yes. The optical writing unit 21 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of a photoconductor to be described later with laser light based on image data.

Each of the image forming units 18Y, 18M, 18C, and 18K includes a drum-shaped photoreceptor 1, a charger, a developing device 4, a drum cleaning device, a static eliminator, and the like. Hereinafter, the yellow image forming unit 18Y will be described as an example. The surface of the photoreceptor 1Y is uniformly charged by a charger as charging means. The surface of the photoreceptor 1 </ b> Y that has been subjected to the charging process is irradiated with laser light modulated and deflected by the optical writing unit 21. Then, the potential of the irradiation part (exposure part) is attenuated. By this attenuation, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y as developing means to become a Y toner image.
The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device. Thereafter, the surface of the photoreceptor 1Y is neutralized by a static eliminator. Then, it is uniformly charged by the charger and returns to the initial state. A series of processes as described above are similarly performed in the other image forming units 18M, 18C, and 18K.

The intermediate transfer unit 17 includes an intermediate transfer belt 110, a belt cleaning device 90, and the like. Further, it also includes a tension roller 14, a driving roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, 62M, 62C, and 62K. The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14. Then, it is endlessly moved in the clockwise direction in the figure by the rotational drive of the drive roller 15 driven by the belt drive motor.
The four primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive a primary transfer bias from a power source. Further, the intermediate transfer belt 110 is pressed from the inner peripheral surface toward the photoreceptors 1Y, 1M, 1C, and 1K to form primary transfer nips for Y, M, C, and K. In each primary transfer nip, a primary transfer electric field is formed between the photosensitive member and the primary transfer bias roller due to the influence of the primary transfer bias.

The Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 by the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) that is a multiple toner image is formed on the intermediate transfer belt 110.
The four-color toner image superimposed and transferred on the intermediate transfer belt 110 is secondarily transferred to a recording sheet as a recording medium at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 90 that sandwiches the belt with the driving roller 15 on the left side in the drawing.
Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 is moved endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23 arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the secondary transfer backup roller 16 of the intermediate transfer unit 17. It is out. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one stretching roller 23 by a power source.

  By applying the secondary transfer bias, the secondary transfer nip is a secondary transfer electrostatically moving the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 from the belt side toward the one stretching roller 23 side. A transfer electric field is formed. A recording sheet fed to the secondary transfer nip so as to be synchronized with a four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 described later is affected by the secondary transfer electric field and the nip pressure. A color toner image is secondarily transferred.

In the paper feeding device 200 provided in the lower part of the copying machine main body, a plurality of paper feeding cassettes 44 in which a plurality of recording sheets can be stacked and accommodated in a bundle of sheets are arranged so as to overlap in the vertical direction. Has been. Each paper feed cassette 44 presses the paper feed roller 42 against the top recording sheet of the paper bundle. Then, by rotating the paper feed roller 42, the uppermost recording sheet is sent out toward the paper feed path 46.
The paper feed path 46 that receives the recording sheet fed from the paper feed cassette 44 has a plurality of conveyance roller pairs 47 and a registration roller pair 49 provided near the end in the path. Then, the recording sheet is conveyed toward the registration roller pair 49. The recording sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends the recording sheet sandwiched between the rollers at a timing at which the recording sheet can be brought into close contact with the four-color toner image at the secondary transfer nip.

At the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the recording sheet. Then, it is secondarily transferred onto the recording sheet and becomes a full-color image on the white recording sheet. The recording sheet on which the full-color image is formed in this way exits the secondary transfer nip as the paper conveying belt 24 moves endlessly, and then is sent from the paper conveying belt 24 to the fixing device 25.
The fixing device 25 includes a belt unit that moves the fixing belt 26 endlessly while being stretched by two rollers, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the recording sheet received from the paper conveying belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source therein, and pressurizes the fixing belt 26 by the heat generated by the heat source. The pressed fixing belt 26 heats the recording sheet sandwiched in the fixing nip. A full color image is fixed on the recording sheet by the influence of the heating and the nip pressure.
The recording sheet subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided outside the left side plate in the drawing of the printer housing, or forms a toner image on the other surface. To the secondary transfer nip described above.

When a document is copied, for example, a bundle of sheet documents is set on the document table 30 of the ADF 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the ADF 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the one-sided original is pressed by the closed ADF 400.
When the copy start switch is pressed after the original is set, the original reading operation by the scanner 300 starts. However, when a sheet document is set on the ADF 400, the ADF 400 automatically moves the sheet document to the contact glass 32 prior to the document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such document reading operation, each device in the image forming units 18Y, 18M, 18C, and 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 start driving. Then, based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, and K toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K. Is done. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the recording sheet is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed recording sheets are separated one by one by the separation roller 45 and enter the paper feed path 46, and then conveyed toward the secondary transfer nip by the conveyance roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the recording sheets on the manual feed tray 51, the separation roller 52 separates the recording sheets one by one and feeds them to the manual feed path 53 of the printer unit 100. Make paper.

  In the case of forming a multicolor image composed of two or more colors of toner, the intermediate transfer belt 110 is stretched so that the upper stretched surface thereof is substantially horizontal, and all the photoreceptors 1Y, 1Y, 1M, 1C, and 1K are brought into contact. On the other hand, when a monochrome image consisting of only K toner is formed, the posture of the intermediate transfer belt 110 is tilted to the lower left in the drawing by the posture adjusting mechanism, and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, not only the photoreceptors 1Y, 1M, and 1C but also the developing devices are stopped to prevent unnecessary consumption of the photoreceptor and developer.

FIG. 2 is an enlarged view showing the developing device 4 and the photoreceptor 1 in any one of the four image forming units 18Y, 18M, 18C, and 18K. Since the four image forming units 18Y, 18M, 18C, and 18K have substantially the same configuration except that the colors of the toners to be handled are different from each other, in FIG. The subscript K is omitted.
The surface of the photoreceptor 1 is charged by a charging device while rotating in the direction of arrow A in the figure. The charged surface of the photosensitive member 1 carries an electrostatic latent image by the laser light emitted from the optical writing unit 21. By supplying toner from the developing device 4 to the electrostatic latent image, the electrostatic latent image is developed into a toner image.
The developing device 4 has a developing roller 5 as a developer carrying member for developing the electrostatic latent image by supplying toner to the electrostatic latent image on the surface of the photoreceptor 1 while rotating in the direction of arrow B in the figure. Yes. A supply conveyance path 9 having a supply screw 8 as a supply conveyance member for conveying the developer in a direction orthogonal to the paper surface of the drawing while supplying the developer to the developing roller 5 is provided. In the supply conveyance path 9, the developer containing the magnetic carrier and the toner is conveyed in the screw rotation axis direction by the rotation drive of the supply screw 8.

  The developing roller 5 includes a rotatable developing sleeve 5a made of a non-magnetic pipe and having a hollow structure, and a magnet roller 5b serving as a magnetic field generating means including a plurality of magnetic poles included so as not to be rotated and arranged in the sleeve rotating direction. have. The developing sleeve 5a having a plurality of V-grooves or a plurality of concave portions formed by sandblasting on the surface is made of a base tube made of aluminum or stainless steel. When the developing sleeve 5a passes through the portion facing the supply conveyance path 9 as it rotates, the developer sleeve 5a draws up the developer in the supply conveyance path 9 and carries it by the magnetic force generated by the magnetic pole pumped up by the non-rotatable magnet roller 5b. To do. As a result, the developer layer formed on the surface of the developing sleeve 5a has a predetermined thickness when passing through the regulating gap G formed between the tip of the regulating blade 12 and the surface of the developing sleeve 5a. The thickness is regulated.

The developer layer that has passed through the regulation gap G and is regulated to a predetermined thickness is transported to a development area facing the photoreceptor 1 as the development sleeve 5a rotates, and contributes to development. Thereafter, the developer roller 5 is conveyed to a position facing the recovery screw 6 as the developing roller 5 rotates. At the opposite position, a repulsive magnetic field is formed by two repulsive magnetic poles of a non-rotatable magnet roller 5 b included in the developing roller 5. The developer layer is separated from the surface of the developing sleeve 5 a by the action of the repulsive magnetic field and is collected by the collecting screw 6 in the collecting conveyance path 7.
The amount of the developer that is regulated by the regulating blade 12 and stays upstream from the regulating blade 12 is regulated in the vicinity of the regulating blade 12 and upstream of the regulating blade 12 in the rotation direction of the developing sleeve 5a. A staying restriction member 13 is provided. The stay restricting member 13 is a facing member that faces the surface of the developing sleeve 5a through a stay gap larger than the restricting gap G described above.

A stirring conveyance path 10 is disposed below the supply conveyance path 9 and on the side of the collection conveyance path 7. In the agitation transport path 10, the developer is transported from the back side to the front side in the direction orthogonal to the paper surface of the drawing, contrary to the supply transport path 9, by the rotational drive of the stirring screw 11. The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. The part which partitions the supply conveyance path 9 and the agitation conveyance path 10 of the first partition wall 133 is an opening at both the front side and the rear side in the direction orthogonal to the paper surface of the drawing, and the supply conveyance path 9 and the agitation The conveyance path 10 communicates.
Both the supply conveyance path 9 and the recovery conveyance path 7 are partitioned by the first partition wall 133, but no opening is provided at a location that partitions the supply conveyance path 9 and the recovery conveyance path 7 of the first partition wall 133. . Further, the two conveyance paths of the stirring conveyance path 10 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the direction orthogonal to the drawing sheet, and the stirring conveyance path 10 and the collection conveyance path 7 communicate with each other.

The supply screw 8, the recovery screw 6, and the stirring screw 11 are made of resin or metal screw members. The supply screw is a screw member having a double-winding structure, and the recovery screw 6 and the stirring screw 11 are screw members having a single-winding structure.
The developer collected in the collection conveyance path 7 is conveyed from the back side perpendicular to the paper surface in the drawing to the near side, and passes through the opening existing near the end on the near side and enters the agitation conveyance path 10. Immediately thereafter, the toner is mixed with new toner replenished from a toner replenishing port provided on the upper side of the agitation transport path 10. The developer that has been transported to the front end of the collection transport path 7 in the drawing enters the supply transport path 9 through an opening provided in the front end of the first partition wall 133 in the drawing.

  The developer that has entered the supply conveyance path 9 from the agitation conveyance path 10 is conveyed from the near side to the back side in the direction orthogonal to the paper surface of the drawing as the supply screw 8 is driven to rotate. In the process, a part of the developer is pumped up to the developing roller 5. The remaining developer is transported to the end of the supply transport path 9 on the back side in the figure, and returns to the stirring transport path 10 through an opening provided at the end of the first partition wall 133 on the back side in the figure. It is. A toner density sensor is provided on the bottom plate of the agitation transport path 10, and the controller drives the toner replenishing device as needed based on the output from the toner density sensor to recover the toner density of the developer.

A developer discharge port 94 is provided in the vicinity of the downstream end of the supply conveyance path 9 in the developer conveyance direction. When the height level of the developer in the supply conveyance path 9 exceeds a threshold value, the developer is discharged. The developer overflows from the discharge port 94. Then, it is discharged to the outside of the developing device 4 by the discharge conveying screw 2a.
In the supply conveyance path 9, the developer develops even though the height level of the developer does not exceed the threshold by jumping due to the momentum when the developer moves and the rotating force of the supply screw 8. It may be discharged from the agent discharge port 94. In order to prevent such discharge, the block member 3 is provided above the supply conveyance path 9, and the developer that jumps as the supply screw 8 rotates is applied to the block member 3 and returned to the supply screw 8. I have to. The block member 3 is an R-shaped resin member whose bottom surface follows the shape of the supply screw 8. Due to the R shape along the shape of the supply screw 8, the bottom surface of the block member 3 can be brought close to the supply screw 8 as a whole so as to cover the entire supply screw 8. Thereby, jumping of the developer can be reliably prevented.

FIG. 3 is a diagram showing a positional relationship between the regulating blade 12 of the developing device 4 and the developing roller 5. 4A and 4B are cross-sectional views of a portion without a fixing hole and a portion with a hole for fixing the regulating blade 12. The regulating blade 12 according to the present embodiment includes a plate-like blade main body 120 and a plate-like tip magnetic plate 121. In the present embodiment, the tip magnetic body is a regulating member. The blade main body 120 made of a stainless steel plate or the like is made of a plate-like member that is formed into a relatively thick plate shape so that the regulation blade 12 as a whole can exhibit a certain degree of rigidity. The thin plate-like tip magnetic plate 121 constitutes a tip portion of the regulation blade 12 that faces the developing sleeve 5a (developing roller 5), and is made of a relatively thin magnetic plate. The tip magnetic plate 121 is fixed to the tip of the blade body 120 on the upstream side in the sleeve rotation direction with a screw 60 serving as a fixing member. Therefore, a plurality of holes 122 for inserting the screws 60 are formed in the front magnetic plate 121 in the longitudinal direction C (see FIG. 3) as shown in FIGS. 3 and 4B. Each of the holes 122 is disposed within a range D of the image forming area width W of the developing roller 5. The image forming area width W is the width in the longitudinal direction of the area where the toner image carried on the developing roller 5 develops the electrostatic latent image on the photoreceptor 1 and also corresponds to the maximum sheet passing width. The lengths from the respective holes 122 to the tip 121a serving as the restriction side end of the tip magnetic plate 121 are the same.
Here, the tip magnetic plate 121 is fixed to the blade body 120 by screws, but a pin may be inserted into the hole 122 and fixed by caulking. In the present invention, when a hole is formed in a magnetic plate-like member, the magnetic material is reduced by the amount of the hole, so that the magnetic force is weaker than the part where the hole is not formed, and the pumping amount varies. The fixing method is not particularly limited as long as it has a technical problem that a vertical band image is generated.

The inventors of the present invention calculated the normal direction magnetic force for each of the part without the hole 122 and the part with the hole 122 to obtain the magnetic force decrease amount at the part with the hole 122. When calculated under conditions that do not care about the diameter of the hole, the position to be formed, etc., as in the case of a conventional regulating member, the normal magnetic force drop of the hole is about 32%. A conventional regulating member may generate a vertical band image, and the image density deviation of the vertical band portion is about ΔID = 0.03. In general, in order to improve to ΔID = 0.02 or less (less than 2/3 of the conventional level), which is a level where the vertical band becomes inconspicuous, it is necessary to reduce the magnetic force to 20% or less (less than 2/3 of the conventional value). is there.
In the present embodiment, as shown in FIG. 4B, the diameter (diameter) of the hole 122 is R, and the length (distance) from the hole 122 to the tip 121a of the tip magnetic plate 121 serving as the restriction side end is L. _1. The length (distance) from the hole 122 to the upper end 121b of the front magnetic plate 121 is L ₂ , and the distance G _d between the front end 121a of the front magnetic plate 121 and the surface of the developing roller 5 (that is, the dimension of the regulation control gap G) The magnetic force was calculated by shaking each of these four parameters. The thickness t of the tip magnetic plate 121 (regulating member) was fixed at 0.3 mm. For pick-up amount becomes proper development conditions, typically, the distance _{G d} is set within a range of about 0.3 to 0.6 mm.

5, FIG. 6 and FIG. 7 are plots of the results of magnetic force calculation for level swing of the hole positions (L ₁ , L ₂ ). Figure 5 is a graph showing changes in the normal magnetic force just below the hole when changing the distance L _1. In FIG. 5, the vertical axis represents the magnetic force ratio (%) with respect to the portion without the hole, and the horizontal axis represents the hole distance L2 (mm). Here, (R = 2, L ₁ + L ₂ = 4.46, G _d = 0.48 mm fixed). According to FIG. 5, the distance (length) to reduce the L _2, the distance the larger the (length) L _1, lowering the magnetic force at the hole position is found it can be suppressed. However, if the distance (length) gradually reducing the L _2, such as deformation due to the decrease in rigidity is concerned, the smaller is limited. For this reason, it is desirable that the distance (length) L ₂ = 1 mm. In the subsequent calculations, the distance (length) L ₂ = 1 mm is fixed.

On the other hand, FIG. 6 is a diagram showing a change in the normal magnetic force directly under the hole when the distance (length) L ₁ is changed among the hole positions (L ₁ , L ₂ ). In FIG. 6, the vertical axis represents the magnetic force ratio (%) with respect to a portion having no hole, and the horizontal axis represents the position of the hole (length from the end to the hole) L1 (mm). According to FIG. 5, when the distance is increased (the length) L _1, the flatness of the deformation increases and the tip 121a of the magnetic plate 121 when fixing the magnetic plate 121 in the caulking or the like deteriorates. If the distance (length) L ₁ exceeds 7 mm, the risk of contact with the developing roller 5 exceeding the straightness of 0.3 mm increases, so the distance (length) L ₁ needs to be 7 mm or less. Actually, it is about 3 to 5 mm. Therefore, the distance (length) L ₁ is more preferably the relationship of straightness is not more than 5mm as mentioned above is improved.

FIG. 7 is a graph plotting the magnetic force calculation results of the level swing of the distance G _d (that is, the size of the regulation gap G). In FIG. 7, the vertical axis indicates the distance (length) L ₁ (mm) from the end to the hole, and the horizontal axis indicates the distance G _d (mm). According to FIG. 7, the greater the distance _Gd , the greater the magnetic force decrease rate of the hole portion, and the margin of the vertical band image or the like becomes smaller. To the magnetic force drops below 20%, as the distance (length) Distance G _d is large it is necessary to increase the L1.

FIG. 8 and FIG. 9 are diagrams plotting the magnetic force calculation results of the level swing of the diameter R and the distance (length) L ₁ . FIG. 8 shows the distance (length) L when the distance (length) L ₂ = 1, the distance Gd = 0.3, and the hole size is 4 levels (R = 1, 2, 3, 4). The result of leveling ₁ is shown. FIG. 9 shows the distance (length) L ₂ when the distance (length) L ₂ = 1, the distance Gd = 0.6, and the hole size is 4 levels (R = 1, 2, 3, 4). The result of leveling ₁ is shown. 8 and 9, the diameter R, which is the size of the hole, has a relationship of R1 <R2 <R3 <R4. According to FIGS. 8 and 9, the smaller the diameter (size) R of the hole 122, the smaller the magnetic force drop at the hole position. The distance (length) magnetic force decreases at higher hole position L ₁ is large is small.

Figure 10 is a diagram showing the radial magnetic force reduction is 20% R of the hole, the distance (length) L ₁ condition. Here, the distance (length) L ₂ = 1. In the figure, the vertical axis indicates the distance (length) L ₁ (mm) from the end to the hole, the horizontal axis indicates the diameter R (mm) of the hole 121, and the change in the distance Gd is plotted.
Based on the result of FIG. 10, the conditions of the diameter R and the distance (length) L ₁ at which the magnetic force drop of the hole 122 is 20% are the conditions satisfying the following conditions, while maintaining the flatness, the hole It was confirmed that the magnetic force decrease of 122 was suppressed to 20% or less, and the vertical band image could be suppressed.
0.9963R + 3.0671 ≦ L ₁ ≦ 7

In other words, according to the developing device 4 according to the present embodiment, the developing roller 5 that includes the magnet roller 5b that is a magnetic field generating unit and that carries and conveys the toner, and the restriction constituted by the magnetic material. in the configuration having a tip magnetic body 121 of the member, and the diameter R of the hole 122 provided at the tip magnetic body 121, the width _{L 1} from the hole 122 to regulating end portion 121a of the tip magnetic 121, 0.9963R + 3 ... 0671 ≦ L1 ≦ 7 is set so that a decrease in magnetic force in the peripheral portion of the hole 122 can be suppressed. Therefore, in a region where the hole 122 is vacant and a region where the hole 122 is not vacant in the longitudinal direction C of the pumping amount The magnetic force deviation can be reduced, and the image quality can be stabilized.

Further, by setting the distance (length) _{L 1} from the hole 122 to regulating end portion 122a of the regulating member so as to satisfy the relation of 0.9963R + 3.0671 ≦ L1 ≦ 5, ie, the distance (length) L _By setting ₁ to 5 mm or less as described above, it becomes more preferable than the case where the straightness is L1 ≦ 7.
Since the hole 122 is provided in the range of the image forming area width of the developing roller 5, the image quality can be further stabilized by forming it so as to satisfy the above relationship.

In the above embodiment, the restriction blade 12 serving as a restriction member is configured by two members, the blade main body 120 and the tip magnetic plate 121, and a fixing member is used when the tip magnetic plate 121 is fixed to the blade main body 120. Although the positional relationship between the hole 122 to be inserted and the tip 121a serving as the restriction side end of the tip magnetic plate 121 is defined, the form of the restriction member is not limited to such a form.
For example, as shown in FIG. 11, the regulation blade 12 </ b> A is configured such that a hole 122 is formed in the longitudinal direction C of a single plate-like member 220 having magnetism, and is directly fixed to the casing 40 of the developing device 4 with a screw 60. It may be. In this case, if the length of the tip 220a of the regulating end portion of the bore 122 and the plate member 220 for fixing by attaching a plate member 220 to the casing 40 and L _1, those described in Embodiment The same effect can be obtained.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 (Y, M, C, K) developing device 5 Developer carrier (developing roller)
5a Developing sleeve 5b Magnetic field generating means (magnet roller)
12, 220 Restriction member 18 (Y, M, C, K) Process cartridge 60 Fixing member (screw)
120 Blade body 121 Tip magnetic body (regulating member)
121a Restriction side end (tip)
122 Hole D region L Length from ₁ hole to the restriction side end R Hole diameter (diameter)
W Image formation area width

JP 2014-085655 A

Claims (6)

A developer carrier that contains magnetic field generating means and carries and conveys the developer;
A regulating member composed of a magnetic body,
The restriction member is provided with a hole for fixing a position, and a diameter R of the hole and a length L ₁ from the hole to a restriction side end of the restriction member are:
A developing device having a relationship of 0.9963R + 3.0671 ≦ L ₁ ≦ 7. The length L ₁ from the hole to the restriction side end of the restriction member is
The developing device according to claim 1, wherein 0.9963R + 3.0671 ≦ L ₁ ≦ 5.   The developing device according to claim 1, wherein the hole is provided in a range of an image forming area width of the developer carrying member.   The developing device according to claim 1, wherein a fixing member is inserted into the hole, and the regulating member is fixed by the fixing member.   5. A process cartridge unit comprising the developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.

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