JP7073818B2 - Develop device, process cartridge unit and image forming device - Google Patents

Description

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

An image forming apparatus that forms an image on an image carrier using toner, which is a developer, includes a plate-shaped restricting member in order to regulate the amount of toner supplied in the developing unit. Generally, this member is composed of a magnetic member and is often referred to as a doctor blade. It is fixed to the base of a developing device with a screw that is a fixing member, or is caulked by a pin that is a fixing member. It is fixed. As a fixed structure of such a regulating member, a developing device using the fixed structure, and an image forming device, for example, Patent Document 1 can be mentioned.

When fixing the regulating member with screws or caulking, a hole for inserting the fixing member such as a screw or pin is formed in the regulating member, but the normal magnetic force at the hole is relatively weakened and the magnetism is increased. Vertical band images (abnormal images) may occur due to variations in the force, which causes the ears of the developer to fall asleep and the amount of pumped up to increase only around the holes.
An object of the present invention is to reduce the variation in magnetic force of the regulating member due to the regulating member by defining the size and position of the holes required for fixing the regulating member.

In order to achieve the above object, the developing apparatus according to the present invention includes a developing agent carrier that includes a magnetic field generating means and carries and conveys the developing agent, and a regulating member, and the regulating member is a developing agent. It is composed of an advanced magnetic plate, which is a magnetic material that constitutes the tip facing the carrier, and a main body that holds the advanced magnetic plate. The advanced magnetic plate is provided with a hole for fixing the position with respect to the main body. The feature is that the diameter R of the hole and the width L ₁ from the hole to the regulated end of the tip magnetic plate have a relationship of 0.9963R + 3.0671 ≦ L1 ≦ 7.

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

The figure which shows the schematic structure of the image forming apparatus which concerns on embodiment of this invention. The figure explaining the structure of the developing apparatus which concerns on embodiment of this invention. The figure explaining the structure of the regulation member provided in the developing apparatus. It is a figure explaining the structure of the regulation member, (a) is the sectional view of the part without a hole, (b) is the sectional view of the part with a hole. The figure which shows the measurement result of the relation between the normal magnetic force just under _a hole and the position L1 of a hole. _The figure which shows the measurement result of the relationship between the normal magnetic force just under a hole and the position L2 of a hole. The figure which shows the measurement result of the relationship between the hole position L ₁ and the regulation gap G _d . _The figure explaining the characteristic of the normal magnetic force by the difference between the hole position L1 and the diameter. FIG. 8 is _a diagram illustrating the characteristics of the normal magnetic force due to the difference in diameter between the hole position L1 and the hole when the conditions are changed. The figure which shows the relationship between the diameter of a hole which can obtain the effect of this invention, and the position of a hole. The figure explaining the deformation example of the regulation member.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the embodiment, those having the same function or configuration are designated by the same reference numerals, and duplicate description will be omitted as appropriate. The drawings may be partially omitted or schematically shown to aid in understanding the composition.
In the developing apparatus according to the present invention, when a plate-shaped regulating member made of a magnetic member is fixed by fastening with screws or caulking, the position of the hole formed in the regulating member is separated from the end of the regulating member, and the hole is formed. By optimizing the distance between the regulation side end of the regulation member and the hole according to the size, it is possible to suppress the decrease in magnetic force around the hole, reduce the longitudinal deviation of the pumped amount, and stabilize the image quality. It is the one that was made. With the configuration of the present embodiment, the variation in magnetic force in the longitudinal direction (main scanning direction) caused by the restricting member can be reduced to 20% or less in calculation, 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 copier (hereinafter, simply referred to as “copier”) in which a plurality of photoconductors are arranged in parallel will be described.
The 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. This 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. It also includes an automatic document transfer device (hereinafter referred to as ADF) 400 fixed on the scanner 300.
The printer unit 100 has four image forming units (process cartridge units) 18Y, 18M, 18C, 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 subscripts Y, M, C, and K added to the end of each code indicate that the members are 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 arranged. There is. The optical writing unit 21 has a light source, a polygon mirror, an f−θ lens, a reflection mirror, and the like, and irradiates the surface of a photoconductor, which will be described later, with laser light based on image data.

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

The intermediate transfer unit 17 has an intermediate transfer belt 110, a belt cleaning device 90, and the like. It also has a tension roller 14, a drive roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, 62M, 62C, 62K and the like. The intermediate transfer belt 110 is tension-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 arranged so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive the application of the primary transfer bias from the power source. Further, the intermediate transfer belt 110 is pressed from the inner peripheral surface side toward the photoconductors 1Y, 1M, 1C, 1K to form a primary transfer nip for Y, M, C, K. At each primary transfer nip, a primary transfer electric field is formed between the photoconductor and the primary transfer bias roller due to the influence of the primary transfer bias.

The Y toner image formed on the photoconductor 1Y for Y is primarily transferred onto the intermediate transfer belt 110 by the influence of the primary transfer electric field and the nip pressure. On the Y toner image, the M, C, K toner images formed on the photoconductors 1M, C, K for M, C, K are sequentially superposed and primary transferred. By this superposition primary transfer, a four-color superposition toner image (hereinafter referred to as a four-color toner image), which is a multi-color 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 body by a secondary transfer nip described later. The transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by the belt cleaning device 90 that sandwiches the belt with the drive roller 15 on the left side in the drawing.
At the lower part of the figure of the intermediate transfer unit 17, a secondary transfer device 22 in which a paper transport belt 24 is stretched by two tension rollers 23 is arranged. The paper transport belt 24 is endlessly moved in the counterclockwise direction in the drawing by rotationally driving at least one of the tension rollers 23. Of the two tension rollers 23, one of the rollers arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the intermediate transfer unit 17 and the secondary transfer backup roller 16. I'm 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 come into contact with each other. Then, a secondary transfer bias having a polarity opposite to that of the toner is applied to the tension roller 23 by the power supply.

By applying the secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is electrostatically moved from the belt side toward the one tension roller 23 side to the secondary transfer nip. A transfer electric field is formed. The recording sheet fed to the secondary transfer nip in synchronization with the four-color toner image on the intermediate transfer belt 110 by the resist roller pair 49 described later was affected by the secondary transfer electric field and nip pressure 4. The color toner image is secondarily transferred.

In the paper feed device 200 provided at the bottom of the copier main body, a plurality of paper feed cassettes 44 capable of stacking and accommodating a plurality of recording sheets in the form of a bundle of paper are arranged so as to be vertically overlapped with each other. Has been done. Each paper cassette 44 presses the paper feed roller 42 against the recording sheet at the top of the paper bundle. Then, by rotating the paper feed roller 42, the top recording sheet is sent out toward the paper feed path 46.
The paper feed path 46 that receives the recording sheet sent out from the paper cassette 44 has a plurality of transport roller pairs 47 and a resist roller pair 49 provided near the end of the transport roller pair 47. Then, the recording sheet is conveyed toward the resist roller pair 49. The recording sheet conveyed toward the resist rollers vs. 49 is sandwiched between the rollers of the resist rollers vs. 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 resist roller pair 49 sends out the recording sheet sandwiched between the rollers at a timing that allows the recording sheet to be brought into close contact with the four-color toner image by the secondary transfer nip.

In 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 to obtain 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 transport belt 24 moves endlessly, and then is sent from the top of the paper transport 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 transport belt 24 is sandwiched therein. Of the two rollers in the belt unit, the roller pressed by the pressurizing roller 27 has a heat source inside, and the heat generated by the roller pressurizes the fixing belt 26. The pressurized fixing belt 26 heats the recording sheet sandwiched between the fixing nips. Due to the influence of this heating and nip pressure, a full-color image is fixed on the recording sheet.
The recording sheet subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided on the outside of the left side plate in the drawing of the printer housing, or the toner image is formed on the other side as well. Is it returned to the above-mentioned secondary transfer nip?

When a copy of the original is taken, for example, a bundle of sheet originals is set on the platen 30 of the ADF400. However, if the original is a single-bound original that is closed like a book, it is set on the contact glass 32. Prior to this set, the ADF 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. After that, the one-sided binding document is pressed by the closed ADF400.
When the copy start switch is pressed after the document is set, the document reading operation by the scanner 300 starts. However, when the sheet document is set in 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 both start traveling, 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 the mirror provided in the second traveling body 34, passes through the imaging lens 35, and then is incident on the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

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

Almost at the same time as 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 fed out from one of the paper feeding cassettes 44 housed in the paper bank 43 in multiple stages. The sent recording sheets are separated one by one by the separation roller 45, enter the paper feed path 46, and then are conveyed toward the secondary transfer nip by the transfer roller pair 47. Instead of such paper feeding from the paper feed cassette 44, paper feeding may be performed from the manual feed tray 51. In this case, after the manual paper feed roller 50 is selectively rotated to feed out the recording sheet on the manual feed tray 51, the separation roller 52 separates the recording sheets one by one and supplies them to the manual paper feed path 53 of the printer unit 100. Paper.

When forming a multicolor image consisting of two or more colors of toner, the intermediate transfer belt 110 is stretched in a posture in which the upper rack surface is almost horizontal, and all the photoconductors 1Y, Contact 1M, 1C, 1K. On the other hand, when forming a monochrome image consisting of only K toner, the posture adjusting mechanism is used to tilt the intermediate transfer belt 110 to the lower left in the figure, and the upper tension surface is Y, M, C. Separated from the photoconductors 1Y, M, and C for use. Then, of the four photoconductors 1Y, 1M, 1C, and 1K, only the photoconductor 1K for K is rotated counterclockwise in the figure to form only the K toner image. At this time, with respect to Y, M, and C, not only the photoconductors 1Y, 1M, and 1C but also the developing device is stopped to be driven to prevent unnecessary consumption of the photoconductor and the developing agent.

FIG. 2 is an enlarged view showing the developing apparatus 4 and the photoconductor 1 in any one of the four image forming units 18Y, M, C, and K. The four image forming units 18Y, 18M, 18C, and 18K have almost the same configuration except that the colors of the toners they handle are different. Therefore, in the figure, Y, M, C, which are added after "4", The subscript K is omitted.
The surface of the photoconductor 1 is charged by the charging device while rotating in the direction of arrow A in the figure. The surface of the charged photoconductor 1 carries an electrostatic latent image by the laser beam emitted from the optical writing unit 21. When toner is supplied from the developing device 4 to the electrostatic latent image, the electrostatic latent image is developed into a toner image.
The developing apparatus 4 has a developing roller 5 as a developer carrier that supplies toner to the electrostatic latent image on the surface of the photoconductor 1 while rotating in the direction of arrow B in the drawing to develop the electrostatic latent image. There is. It has a supply transport path 9 provided with a supply screw 8 as a supply transport member that transports the developer in a direction orthogonal to the paper surface in the figure while supplying the developer to the developing roller 5. In the supply transport path 9, the developer containing the magnetic carrier and toner is conveyed in the direction of the screw rotation axis by the rotational drive of the supply screw 8.

The developing roller 5 includes a rotating developing sleeve 5a having a hollow structure made of a non-magnetic pipe, and a magnet roller 5b which is a magnetic field generating means including a plurality of magnetic poles which are contained so as not to rotate with the developing sleeve 5a and which are arranged in the direction of rotation of the sleeve. have. The developing sleeve 5a having a plurality of V-grooves or a plurality of recesses formed by sandblasting on the surface is made of an aluminum or stainless steel raw tube. When the developing sleeve 5a passes through the portion facing the supply transport path 9 due to its rotation, the developing agent in the supply transport path 9 is pumped and supported by the magnetic force generated by the pumping magnetic pole of the non-rotatable magnet roller 5b. do. As a result, the layer of the developer formed on the surface of the developing sleeve 5a has a predetermined layer 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. It is regulated by the thickness of.

The developer layer that has passed through the regulation gap G and is regulated to a predetermined thickness is conveyed to the developing region facing the photoconductor 1 as the developing sleeve 5a rotates, and contributes to development. After that, as the developing roller 5 rotates, it is conveyed to a position facing the recovery screw 6. A repulsive magnetic field is formed at the opposite positions by the two repulsive magnetic poles of the non-rotatable magnet roller 5b contained in the developing roller 5. The developer layer is separated from the surface of the developing sleeve 5a by the action of the repulsive magnetic field and is recovered by the recovery screw 6 in the recovery transport path 7.
In the vicinity of the regulating blade 12 and on the upstream side of the developing sleeve 5a in the rotation direction of the regulating blade 12, the amount of the developer regulated by the regulating blade 12 and staying on the upstream side of the regulating blade 12 is regulated. The retention control member 13 is arranged. The retention regulating member 13 is an opposing member facing the surface of the developing sleeve 5a via a retention gap larger than the regulation gap G described above.

A stirring transport path 10 is arranged below the supply transport path 9 and on the side of the recovery transport path 7. In the stirring transfer path 10, the developer is conveyed from the back side to the front side in the direction orthogonal to the paper surface in the figure in the direction opposite to the supply transfer path 9 by the rotational drive of the stirring screw 11. The supply transport path 9 and the stirring transport path 10 are partitioned by a first partition wall 133 as a partition member. The portion partitioning the supply transport path 9 and the stirring transport path 10 of the first partition wall 133 has openings at both ends of the front side and the back side in the direction orthogonal to the paper surface in the figure, and the supply transport path 9 and the stirring are stirred. It communicates with the transport path 10.
Both the supply transport path 9 and the recovery transport path 7 are partitioned by the first partition wall 133, but no opening is provided at the portion of the first partition wall 133 that separates the supply transport path 9 and the recovery transport path 7. .. Further, the two transport paths of the stirring transport path 10 and the recovery transport 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 paper surface in the figure, and the stirring transfer path 10 and the recovery transfer path 7 communicate with each other.

The supply screw 8, the recovery screw 6, and the stirring screw 11 are made of a resin or metal screw member. The supply screw is a screw member having a two-thread winding structure, and the recovery screw 6 and the stirring screw 11 are screw members having a one-thread winding structure.
The developer recovered in the recovery transport path 7 is transported from the orthogonal back side of the paper in the figure to the front side, passes through an opening existing near the end portion on the front side, and enters the stirring transport path 10. Immediately after that, it is mixed with new toner replenished from the toner replenishment port provided on the upper side of the stirring transfer path 10. The developer transported to the front end in the drawing of the recovery transport path 7 enters the supply transport path 9 through the opening provided in the front end in the figure of the first partition wall 133.

The developer that has entered the supply transport path 9 from the stirring transfer path 10 is conveyed from the front side to the back side in the direction orthogonal to the paper surface in the figure as the supply screw 8 is rotationally driven. In the process, a part of the developer is pumped up to the developing roller 5. The remaining developer is transported to the inner end of the supply transport path 9 in the drawing, and is returned to the stirring transport path 10 through the opening provided in the inner end of the first partition wall 133 in the figure. Is done. A toner concentration sensor is provided on the bottom plate of the stirring transfer path 10, and the control unit drives a toner replenishing device as necessary based on the output from the toner concentration sensor to recover the toner concentration of the developer.

A developer discharge port 94 is provided near the downstream end of the supply transport path 9 in the developer transport direction, and when the height level of the developer in the supply transport path 9 exceeds the threshold value, the developer is provided. The developer overflows from the discharge port 94. Then, it is discharged to the outside of the developing device 4 by the discharge transport screw 2a.
In the supply transport path 9, the developer develops even though the height level of the developer does not exceed the threshold value due to the momentum when the developer moves and the rotational force of the supply screw 8 causing the developer to jump. It may be discharged from the agent discharge port 94. In order to prevent such discharge, a block member 3 is provided above the supply transport path 9, and a developer that tends to bounce with the rotation of the supply screw 8 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. The R shape that follows the shape of the supply screw 8 makes it possible to bring the bottom surface of the block member 3 as a whole close to the supply screw 8 so as to cover the entire supply screw 8. This makes it possible to reliably prevent the developer from splashing.

FIG. 3 is a diagram showing the positional relationship between the restricting blade 12 of the developing device 4 and the developing roller 5. 4 (a) and 4 (b) are cross-sectional views of a portion without a hole and a portion with a hole for fixing the regulation blade 12. The regulation blade 12 according to the present embodiment has a plate-shaped blade main body portion 120 and a plate-shaped tip magnetic plate 121. In the present embodiment, the advanced magnetic material is a regulating member. The blade main body 120 made of a stainless steel plate or the like is made of a plate-shaped member 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-shaped tip magnetic plate 121 constitutes the tip portion of the regulation blade 12 facing the developing sleeve 5a (development roller 5), and is made of a relatively thin magnetic plate. The tip magnetic plate 121 is fixed to the tip of the surface of the blade main body 120 on the upstream side in the sleeve rotation direction with a screw 60 serving as a fixing member. Therefore, as shown in FIGS. 3 and 4B, a plurality of holes 122 for inserting the screws 60 are formed in the tip magnetic plate 121 in the longitudinal direction C (see FIG. 3). The holes 122 are arranged within the range D of the image forming region width W of the developing roller 5, respectively. The image forming region width W is the width in the longitudinal direction of the region where the toner image carried on the developing roller 5 develops the electrostatic latent image on the photoconductor 1, and is also the width corresponding to the maximum paper passing width. The length from each hole 122 to the tip 121a, which is the regulated end of the tip magnetic plate 121, is the same.
Here, the tip magnetic plate 121 is screwed to be fixed to the blade main body 120, but a pin may be inserted into the hole 122 and caulked to fix it. In the present invention, when a hole is formed in a plate-shaped member having magnetism, the amount of magnetic material is reduced by the amount of the hole, so that the magnetic force is weaker than that of a portion without a hole, and the pumping amount fluctuates. As long as there is a technical problem that a vertical band image is generated in the above, the fixing method is not particularly limited.

The present inventors calculated the normal magnetic force for each of the portion without the hole 122 and the portion with the hole 122, and obtained the amount of decrease in the magnetic force at the portion with the hole 122. When calculated under the condition that the diameter of the hole and the position where the hole is formed are not taken into consideration as in the conventional regulating member, the decrease in the normal magnetic force of the hole is about 32%. A vertical band image may be generated with a conventional restricting member, and the image density deviation of the vertical band portion is about ΔID = 0.03. In general, in order to improve to the level where the vertical band becomes inconspicuous, ΔID = 0.02 or less (two-thirds or less of the conventional method), it is necessary to reduce the magnetic force reduction to 20% or less (two-thirds or less of the conventional method). be.
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 which is the regulation side end is L. _1. The length (distance) from the hole 122 to the upper end 121b of the tip magnetic plate 121 is L ₂ , and the distance G _d (that is, the dimension of the regulation gap G) between the tip 121a of the tip magnetic plate 121 and the surface of the developing roller 5. ), And the magnetic force was calculated by shaking each of these four parameters. The thickness t of the tip magnetic plate 121 (regulatory member) was fixed at 0.3 mm. Normally, the distance G _d is set in the range of about 0.3 to 0.6 mm in order to obtain a pumping amount that is an appropriate development condition.

FIGS. 5, 6 and 7 are plots of the results of magnetic force calculation of the level swing of the hole positions (L ₁ , L ₂ ). FIG. 5 is a diagram showing a change in the normal magnetic force immediately below the hole when the distance L ₁ is changed. In FIG. 5, the vertical axis indicates the magnetic force ratio (%) with respect to the portion without a hole, and the horizontal axis indicates the hole distance L2 (mm). Here, it is set as (R = 2, L ₁ + L ₂ = 4.46, G _d = 0.48 mm fixed). According to FIG. 5, it can be seen that the smaller the distance (length) L ₂ and the larger the distance (length) L ₁ , the more the decrease in the magnetic force at the hole position can be suppressed. However, if the distance (length) L ₂ is reduced, there is a concern about deformation due to a decrease in rigidity, and there is a limit to the reduction. Therefore, 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 changes in the normal magnetic force immediately below the hole when the distance (length) L ₁ is changed among the hole positions (L ₁ , L ₂ ). In FIG. 6, the vertical axis indicates the magnetic force ratio (%) with respect to the portion without a hole, and the horizontal axis indicates the position of the hole (length from the end to the hole) L1 (mm). According to FIG. 5, when the distance (length) L ₁ is increased, the deformation of the magnetic plate 121 becomes large when the magnetic plate 121 is fixed by caulking or the like, and the flatness of the tip 121a 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 must be 7 mm or less. Actually, it is about 3 to 5 mm. Therefore, when the distance (length) L ₁ is 5 mm or less as described above, the straightness relationship is improved, which is more preferable.

FIG. 7 is a diagram plotting the magnetic force calculation results of the level swing of the distance G _d (that is, the dimension of the regulated 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 larger the distance _Gd , the larger the rate of decrease in the magnetic force of the hole portion, and the smaller the margin of the vertical band image or the like. In order to reduce the decrease in magnetic force to 20% or less, it is necessary to increase the distance (length) L1 as the distance _Gd increases.

₈ and 9 are diagrams plotting the magnetic force calculation results of the level swing of the diameter R and the distance (length) L1. 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 the level swing of ₁ is shown. In FIG. 9, the distance (length) L 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 the level swing of ₁ is shown. In FIGS. 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 decrease in magnetic force at the hole position. Further, the larger the distance (length) L ₁ , the smaller the decrease in magnetic force at the hole position.

FIG. 10 is _a diagram showing the conditions of the diameter R and the distance (length) L1 at which the decrease in the magnetic force of the hole is 20%. Here, the distance (length) L ₂ = 1. In the figure, the vertical axis shows the distance (length) L ₁ (mm) from the end to the hole, the horizontal axis shows 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 condition of the diameter R and the distance (length) L1 at which the decrease in the magnetic force of the hole 122 is 20% is that the hole is maintained in flatness while maintaining the flatness when the following conditions are satisfied. It was confirmed that the decrease in the magnetic force of 122 was suppressed to 20% or less, and the vertical band image could be suppressed.
0.9963R + 3.0671 ≤ L ₁ ≤ 7

That is, according to the developing apparatus 4 according to the present embodiment, there is a regulation composed of a developing roller 5 which includes a magnet roller 5b which is a magnetic field generating means and serves as a developer carrier which carries and conveys toner, and a magnetic material. In the configuration provided with the tip magnetic body 121 as a member, the diameter R of the hole 122 provided in the tip magnetic body 121 and the width L ₁ from the hole 122 to the regulated end portion 121a of the tip magnetic body 121 are 0.9963R + 3. By setting so as to satisfy .0671 ≤ L1 ≤ 7, it is possible to suppress a decrease in the magnetic force in the peripheral portion of the hole 122. The deviation of the magnetic force can be reduced and the image quality can be stabilized.

Further, if the distance (length) L ₁ from the hole 122 to the regulation side end portion 122a of the regulation member is set so as to satisfy the relationship of 0.9963R + 3.0671 ≦ L1 ≦ 5, that is, the distance (length) L. By setting ₁ to 5 mm or less as described above, the straightness is more preferable than the case where L1 ≦ 7.
Since the holes 122 are provided in the range of the image forming region width of the developing roller 5, the image quality can be further stabilized by forming the holes 122 so as to satisfy the above relationship.

In the above embodiment, the regulating blade 12 serving as a regulating member is composed of two members, a blade main body portion 120 and a tip magnetic plate 121, and a fixing member is provided when the tip magnetic plate 121 is fixed to the blade main body portion 120. Although the positional relationship between the hole 122 to be inserted and the tip 121a, which is the regulated end of the tip magnetic plate 121, is specified, the form of the regulating member is not limited to such a form.
For example, as shown in FIG. 11, a regulation blade 12A in which a hole 122 is formed in the longitudinal direction C of one magnetic plate-shaped member 220 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 at the hole 122 for attaching and fixing the plate-shaped member 220 to the casing 40 and the tip 220a which is the regulated side end of the plate-shaped member 220 is L ₁ , what has been described in the embodiment. It is possible to obtain the same action and effect as above.

The effects described in the embodiments of the present invention merely list the most suitable effects resulting from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. is not.

1 Image forming device 4 (Y, M, C, K) developing device 5 Developing agent carrier (development roller)
5a Develop sleeve 5b Magnetic field generating means (magnet roller)
12, 220 Regulatory member 18 (Y, M, C, K) Process cartridge 60 Fixing member (screw)
120 Blade body 121 Tip magnetic material (regulatory member)
121a Restricted side end (tip)
122 Hole D Area L Length from ₁ hole to the regulation side end R Hole diameter (diameter)
W Image formation area width

Japanese Unexamined Patent Publication No. 2014-085655

Claims (6)

A developer carrier that includes a magnetic field generating means and carries and conveys a developer,
Equipped with regulatory members,
The restricting member includes a tip magnetic plate, which is a magnetic body constituting the tip facing the developer carrier, and the tip magnetic plate.
It is composed of a main body that holds the tip magnetic plate and
The tip magnetic plate is provided with a hole for fixing the position with respect to the _main body portion, and the diameter R of the hole and the length L1 from the hole to the regulated end portion of the tip magnetic plate are defined. ,
A developing apparatus having a relationship of 0.9963R + 3.0671 ≤ L ₁ ≤ 7. The length L ₁ from the hole to the regulated end of the tip magnetic plate is
The developing apparatus according to claim 1, wherein the relationship is 0.9963R + 3.0671 ≤ L ₁ ≤ 5. The developing apparatus according to claim 1 or 2, wherein the hole is provided in the range of the image forming region width of the developing agent carrier. The developing apparatus according to any one of claims 1 to 3, wherein a fixing member is inserted into the hole, and the regulating member is fixed by the fixing member. A process cartridge unit comprising the developing apparatus according to any one of claims 1 to 4. An image forming apparatus comprising the developing apparatus according to any one of claims 1 to 4.

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