Image forming device

Abstract

To provide an image forming apparatus that can form a single-layer particle layer on a particle carrier to improve image quality and reduce cost.SOLUTION: An image forming apparatus has a rotating particle carrier, and a plate-like particle layer regulation member that forms a particle layer on the particle carrier. The particle layer regulation member is arranged to be in a counter direction with respect to the direction of rotation of the particle carrier, and projects toward the upstream side in the direction of rotation of the particle carrier from the contact position with or the closest position to the particle carrier. A leading end of the particle layer regulation member has a tapered shape, and a surface at the leading end of the particle layer regulation member and on the opposite side of a surface facing the particle carrier is an inclined surface with respect to a surface direction of the plate. In the particle layer regulation member, when the shortest distance from the position of the leading end of the particle layer regulation member to the particle carrier is defined as an entrance height h, and in a particle, when a value half the volume average particle diameter of the particle is defined as a radius r of the particle, r≤h≤3r is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In electrophotographic image forming apparatuses, it is known that when applying developer to a developer carrier, a regulating blade is used to form a layer of developer on the developer carrier. In conventional technology, an image is formed by forming, for example, about two thin layers of charged toner on the developer carrier and developing the electrostatic latent image on the electrostatic latent image carrier.

[0003] Patent Document 1 discloses that the tip of the regulating blade has a radius of curvature R, the volume average particle diameter of the developer is 2r, and R≦r is satisfied. According to Patent Document 1, it is possible to use the device for a long period of time and to prevent image degradation caused by fusion of the developer. Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional techniques using a regulating blade have difficulty forming a monolayer particle layer on a particle carrier such as a developer carrier. For example, Patent Document 1 aims to suppress toner adhesion, but does not consider forming a monolayer particle layer on a particle carrier, and thus was unable to form a monolayer particle layer on a particle carrier. If the particle layer formed on the particle carrier is not monolayer, it may be difficult to obtain high-quality images. For example, the particle size distribution of the toner particles may cause a charge distribution, resulting in toner with opposite polarity, making it difficult to form the desired particle layer on the particle carrier. In this case, the image obtained by transferring the particles to a recording medium may not be of high quality. Furthermore, if the particle layer is not monolayer, it is difficult to use FM screening processing, making it difficult to achieve high image quality. Furthermore, if the particle layer is not monolayer, color images must be formed by overlapping multiple color particles, which increases costs.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that can form a single particle layer on a particle carrier, thereby achieving high image quality and reducing costs. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the image forming apparatus of the present invention is an image forming apparatus having a rotating particle carrier and a flat particle layer regulating member that forms a particle layer on the particle carrier, wherein the particle layer regulating member is arranged so as to be in a counter direction to the rotation direction of the particle carrier, and protrudes from a position of contact with or the closest position to the particle carrier to an upstream side in the rotation direction of the particle carrier, the tip side of the particle layer regulating member has a tapered shape, and the surface of the tip side of the particle layer regulating member opposite to the surface facing the particle carrier is inclined with respect to the surface direction of the flat plate, and when the shortest distance from the tip end position of the regulating member to the particle carrier is defined as an inlet height h, and when half the value of the volume average particle diameter of the particles is defined as a radius r, r≦h≦3r The present invention is characterized in that: However, if the contact position or closest position between the regulating member and the particle carrier is not determined to be a single point, the contact position or closest position is determined to be the most upstream position in the rotation direction of the particle carrier among the contact positions or closest positions between the regulating member and the particle carrier. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an image forming apparatus that can form a single particle layer on a particle carrier, thereby achieving high image quality and reducing costs. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. [Figure 2] 10A and 10B are schematic diagrams for illustrating the formation of a particle layer by a particle layer regulating member. [Figure 3] 5A and 5B are schematic diagrams illustrating examples of arrangement of particle layer regulating members. [Figure 4A] 10A and 10B are schematic diagrams illustrating an example of particle movement caused by a particle layer regulating member. [Figure 4B] 10A and 10B are schematic diagrams for explaining another example of particle movement caused by the particle layer regulating member. [Figure 4C] 4A and 4B are schematic diagrams for explaining another example of particle movement caused by a particle layer regulating member.FIG. 4C is a diagram showing a configuration not included in the present invention. [Figure 5] FIG. 10 is a schematic diagram illustrating an example of a particle layer regulating member, and is a diagram illustrating an inclination angle. [Figure 6] 10 is a schematic diagram for explaining another example of the particle layer regulating member, which is an example in which the protrusion amount L is variable. FIG. [Figure 7] 10A and 10B are schematic diagrams illustrating another example of a particle layer regulating member and illustrating the thickness of the tip end thereof. [Figure 8] 10A and 10B are schematic diagrams illustrating another example of the particle layer regulating member, and are diagrams illustrating the shape of the tip end thereof. [Figure 9] 5A and 5B are schematic diagrams illustrating another example of a particle layer regulating member. DETAILED DESCRIPTION OF THE INVENTION

[0009] The image forming apparatus according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and other modifications, additions, corrections, deletions, and other changes can be made within the scope of what a person skilled in the art can conceive. Any modification that achieves the functions and effects of the present invention is included in the scope of the present invention.

[0010] The image forming apparatus of the present invention has a rotating particle carrier and a flat particle layer regulating member that forms a particle layer on the particle carrier, wherein the particle layer regulating member is disposed in a counter direction to the rotation direction of the particle carrier and protrudes from a position of contact with or closest to the particle carrier to an upstream side in the rotation direction of the particle carrier, the tip side of the particle layer regulating member has a tapered shape, and the surface of the tip side of the particle layer regulating member opposite to the surface facing the particle carrier is inclined with respect to the surface direction of the flat plate, and when the shortest distance from the tip end position of the regulating member to the particle carrier is defined as an inlet height h, and when half the volume average particle diameter of the particles is defined as a radius r, r≦h≦3r The present invention is characterized in that: However, if the contact position or closest position between the regulating member and the particle carrier is not determined to be a single point, the contact position or closest position is determined to be the most upstream position in the rotation direction of the particle carrier among the contact positions or closest positions between the regulating member and the particle carrier.

[0011] Fig. 1 is a schematic diagram illustrating an image forming apparatus according to this embodiment, which may be a cross-sectional view or a side view. The image forming apparatus 10 of this embodiment includes a rotating particle carrier 21 and a flat particle layer regulating member 22 that forms a particle layer on the particle carrier 21. In addition, the image forming apparatus 10 of this embodiment includes an electrostatic latent image carrier 1 (also called a photoreceptor), a charging unit 7, an exposure unit 8, a transfer unit 9, etc.

[0012] The charging means 7 uses a charging member to charge the electrostatic latent image carrier 1. The charging means 7 uses, for example, a charging roller as the charging member, and the arrow in the figure indicates the rotation direction of the charging roller.

[0013] The exposure means 8 irradiates the electrostatic latent image carrier 1 with light L to expose the electrostatic latent image carrier 1 and form an electrostatic latent image. Exposure is performed according to the image to be formed.

[0014] The image forming apparatus of this embodiment may include a particle image forming device 20. The particle image forming device 20 includes a particle carrier 21 and a particle layer regulating member 22, and applies particles 3 to the electrostatic latent image carrier 1 to form a particle image on the electrostatic latent image carrier 1. The particle image forming device 20 of this embodiment contains particles 3 in, for example, a particle container 24, and transports the particles 3 to the particle carrier 21 by a supply member 23. The particle layer regulating member 22 is brought into contact with the particles 3 on the particle carrier 21, charging the particles 3, and forming a particle layer made of the particles 3 on the particle carrier 21.

[0015] When a developer is used as the particles 3, the particle image forming device 20 can be used as, for example, a developing means, a developing device, a developing unit, etc. The particle layer regulating member may also be called a regulating member, a regulating blade, etc.

[0016] The transfer means 9 transfers the particle image formed on the electrostatic latent image carrier 1 onto a recording medium 11 . The particle image formed on the electrostatic latent image carrier 1 is moved to the recording medium 11 by applying a voltage to a transfer member, such as a transfer roller, of the transfer means 9. This causes the particle image to be formed on the recording medium 11. The arrow in the figure indicates the direction of rotation of the transfer roller.

[0017] The particle image forming device 20 in this embodiment is equipped with a particle carrier 21 that rotates in a position facing the electrostatic latent image carrier 1. The particle image forming device 20 has a particle layer regulating member 22 that is flat and disposed in a counter direction to the rotation direction of the particle carrier 21, and forms a single particle layer on the particle carrier 21. The particles 3 on the particle carrier 21 migrate to the electrostatic latent image carrier 1 by an electric field, and a particle image is formed on the electrostatic latent image carrier 1.

[0018] When a developer is used as the particles 3, the particle carrier can be used as, for example, a developer carrier or a developing roller.

[0019] The electrostatic latent image carrier 1 and the particle carrier 21 may be in contact with each other or may not be in contact with each other.

[0020] When the electrostatic latent image carrier 1 and the particle carrier 21 are in contact with each other, it is preferable that the particle carrier 21 is an elastic body. This allows the particle carrier 21 to be in stable contact with the electrostatic latent image carrier 1. The elastic body may be made of, for example, polyurethane rubber or silicone rubber.

[0021] The electrostatic latent image carrier 1 and the particle carrier 21 may be non-contact, and a particle image can be formed by providing a minute gap and applying a development electric field. When the electrostatic latent image carrier 1 and the particle carrier 21 are non-contact, the gap between the electrostatic latent image carrier 1 and the particle carrier 21 is preferably 200 μm or less. By moving the particles in an electric field across a minute gap, it is possible to reduce the cost and torque of the particle carrier.

[0022] The reason why the distance between the electrostatic latent image carrier 1 and the particle carrier 21 is preferably 200 μm or less is that the average particle size of the particles is preferably 200 μm or less. When the distance between the electrostatic latent image carrier 1 and the particle carrier 21 is 200 μm or less, the particles can be easily and stably moved to the electrostatic latent image carrier. Although not particularly limited, the distance between the electrostatic latent image carrier 1 and the particle carrier 21 is preferably, for example, 50 μm or more.

[0023] When the electrostatic latent image carrier 1 and the particle carrier 21 are not in contact with each other, it is preferable that the particle carrier 21 is a rigid body. This is because, in order to stably form a minute gap, it is preferable to use a rigid body with little roundness or environmental diameter fluctuation. The rigid body may be, for example, a metal rod or hollow metal made of iron or aluminum.

[0024] Furthermore, when the particle carrier 21 is a rigid body, it is preferable that the particle carrier 21 has a coating layer on its surface. When a rigid body is used, a metal rigid body is generally used, but if the resistance of the particles is low, the charged charge will escape, so it is preferable that the particle carrier have a semiconductive coating layer. The coating layer may be made of, for example, a urethane resin.

[0025] 2 is a diagram for schematically illustrating the formation of a particle layer by particle layer regulating member 22, and corresponds to the portion circled by a dashed line in FIG. 1. As shown in the figure, particle layer regulating member 22 divides the flow of particles 33. The black arrow in the figure indicates the rotation direction of particle carrier 21, and the white arrow in the figure schematically indicates the direction in which particles 33 move.

[0026] As shown in the figure, particles 33 flowing toward the particle layer regulating member 22 are divided by the particle layer regulating member 22 into particles that move toward the particle carrier 21 and particles that move in a direction different from the particle carrier 21. The direction different from the particle carrier 21 may be referred to as the back side of the particle layer regulating member 22, etc.

[0027] As shown in the figure, the tip side of the particle layer regulating member 22 in this embodiment has a tapered shape, and the surface of the particle layer regulating member 22 on the tip side opposite to the surface facing the particle carrier 21 is inclined with respect to the surface direction of the flat plate. This makes it easier for the particles 33 to move in a direction different from the particle carrier 21 side, and makes it possible to suppress disturbances in the particle layer formed on the particle carrier 21.

[0028] 3 is a diagram illustrating the protrusion amount L and the inlet height h, and is another diagram corresponding to the portion circled by the dashed line in FIG. 1. As described above, the particle layer control member 22 in this embodiment is flat and disposed so as to be in a counter direction to the rotation direction of the particle carrier 21. As shown in the figure, the "counter direction" can be expressed, for example, as the direction from the base side to the tip side of the particle layer control member 22 being the opposite direction to the rotation direction of the particle carrier 21. However, the direction from the base side to the tip side of the particle layer control member 22 does not need to be parallel to the tangent to the particle carrier 21 at the contact position or the closest position of the particle layer control member 22 and the particle carrier 21, and may be angled with respect to the tangent to the particle carrier 21.

[0029] The tip of the particle layer regulating member 22 is tapered, and the surface of the particle layer regulating member 22 opposite to the surface facing the particle carrier 21 at the tip is inclined relative to the surface direction of the flat plate. In the drawing, the inclined surface of the particle layer regulating member 22 is indicated by the symbol 22a.

[0030] The particle layer control member 22 can be appropriately selected, for example, a SUS plate with a thickness of t0.1. It is desirable to select the material, including the coating, in accordance with the charging characteristics of the particles.

[0031] The particle layer control member 22 may or may not be in contact with the particle carrier 21. The example shown in FIG. 3 is an example in which the particle layer control member 22 and the particle carrier 21 are in contact, and Nip in the figure represents a contact Nip. The circumstances in which the particle layer control member 22 and the particle carrier 21 are brought into contact can be appropriately selected. For example, when the particle carrier 21 is an elastic member, or, alternatively, when the surface layer of the particle carrier 21 is an elastic member, the particle layer control member 22 and the particle carrier 21 may be brought into contact. In such a case, even if the particle layer control member 22 and the particle carrier 21 are in contact with each other, in other words, even if the particle layer control member 22 and the particle carrier 21 have a contact Nip, particles can pass through the contact Nip, and a single particle layer can be formed.

[0032] Examples of cases where the particle layer regulating member 22 and the particle carrier 21 are not in contact include when the particle carrier 21 is made of metal, and also when the surface layer of the particle carrier 21 is made of metal. Even when the particle carrier 21 is made of metal or when the surface layer of the particle carrier 21 is made of metal, the particle layer regulating member 22 and the particle carrier 21 may be in contact. It is sufficient that a single particle layer is formed by the particle layer regulating member 22.

[0033] In this embodiment, the particle layer regulating member 22 protrudes upstream in the rotation direction of the particle carrier 21 from the contact position or the closest position with the particle carrier 21. However, if the contact position or the closest position between the particle layer regulating member 22 and the particle carrier 21 is not fixed at a single point, the most upstream position in the rotation direction of the particle carrier 21 among the contact positions or the closest positions between the particle layer regulating member 22 and the particle carrier 21 is taken as the contact position or the closest position.

[0034] 3 is an example in which the particle layer regulating member 22 and the particle carrier 21 are in contact with each other, and the contact nip in this example has a width. In this example, the contact position between the particle layer regulating member 22 and the particle carrier 21 is not fixed to a single point. Therefore, when considering whether the particle layer regulating member 22 protrudes upstream in the rotation direction of the particle carrier 21, the most upstream position in the rotation direction of the particle carrier 21 among the contact positions (contact positions) between the particle layer regulating member 22 and the particle carrier 21 is considered to be the contact position. Then, it is considered whether the particle layer regulating member 22 protrudes from this contact position.

[0035] 3, the particle layer regulating member 22 protrudes from the upstream-most position in the rotation direction of the particle carrier 21 at the contact Nip. As shown in the figure, the length of the part of the particle layer regulating member 22 that protrudes upstream in the rotation direction of the particle carrier 21 from the position of contact with or closest to the particle carrier 21 is defined as a protrusion amount L. In other words, the protrusion amount L is the length of the particle layer regulating member 22 from the position of contact with or closest to the particle carrier 21 to the tip of the particle layer regulating member 22. In this embodiment, L>0.

[0036] As shown in the figure, the inlet height h of the particle layer regulating member 22 is the shortest distance from the tip of the particle layer regulating member 22 to the particle carrier 21. The inlet height h can also be said to be the distance from the tip of the particle layer regulating member 22 to the surface of the particle carrier 21 on a line segment from the center O of the particle carrier 21 to the tip of the particle layer regulating member 22. In other words, the inlet height h can also be said to be the distance from the tip of the particle layer regulating member 22 to the surface of the particle carrier 21, moving toward the center O of the particle carrier 21.

[0037] In this embodiment, the entrance height h must satisfy a predetermined relationship, which will be described with reference to Figures 4A to 4C and other figures.

[0038] 4A to 4C are diagrams for schematically illustrating how particles are diverted by the particle layer regulating member 22, and are other diagrams corresponding to the portion circled by the dashed line in FIG. 1. The protrusion amount L is changed in FIGS. 4A to 4C, and increases in the order of FIGS. 4A to 4C. The protrusion amount L is shown schematically in the figures. As the protrusion amount L increases, the inlet height h increases in the order of FIGS. 4A to 4C. In FIGS. 4A to 4C, the particle layer regulating member 22 and the particle carrier 21 are in contact with each other via particles (similar to FIG. 2).

[0039] Here, the radius r of the particles 33 is defined as half the volume average particle size of the particles 33. In this embodiment, it is necessary to satisfy r≦h≦3r. In the formula, the inlet height h and the particle radius r are in the same unit, such as μm. By satisfying r≦h≦3r, a single particle layer can be formed on the particle support 21.

[0040] FIG. 4A is an example when the inlet height h satisfies r ≦ h ≦ 3r. As shown in the figure, by the particle layer regulating member 22, the particles 33 are diverted to the particle carrier 21 side and the back side of the particle layer regulating member 22, and a single-layer particle layer can be formed on the particle carrier 21. By satisfying r ≦ h, it is possible to prevent the particles 33 close to the particle carrier 21 from being stripped off by the particle layer regulating member 22, and a particle layer can be formed on the particle carrier 21. When h < r, the particles 33 close to the particle carrier 21 are stripped off by the particle layer regulating member 22, and no particle layer is formed on the particle carrier 21.

[0041] In addition, when the diameter of the particles 33 is represented by d, when r ≦ h ≦ d, the inlet height h is less than or equal to the diameter of the particles 33, but even in this case, the particles 33 can pass through the contact position or the closest position between the particle layer regulating member 22 and the particle carrier 21. The tip of the particle layer regulating member 22 is located on the opposite side of the particle carrier 21 from the center of the first layer of particles 33, and the first layer of particles can pass through. Also, when the particle carrier 21 is an elastic member, even when the inlet height h is close to the radius r of the particles, it can surely pass through.

[0042] FIG. 4B is an example when the inlet height h satisfies r ≦ h ≦ 3r, and the protrusion amount L and the inlet height h are larger than the example shown in FIG. 4A. As shown in the figure, by the particle layer regulating member 22, the particles 33 are diverted to the particle carrier 21 side and the back side of the particle layer regulating member 22, and a single-layer particle layer can be formed on the particle carrier 21. By satisfying h ≦ 3r for the inlet height h, the second layer of particles 33 moves to the back side of the particle layer regulating member 22, that is, the second layer of particles 33 moves in the direction of the white arrow in the figure. Therefore, a single-layer particle layer can be formed on the particle carrier 21.

[0043] Also, in the example shown in FIG. 4B, since the tip of the particle layer regulating member 22 is located on the particle carrier 21 side from the center of the second layer of particles 33, the second layer of particles 33 moves to the back side of the particle layer regulating member 22. On the other hand, when h > 3r, as shown in FIG. 4C, the second layer of particles 33 moves to the particle carrier 21 side.

[0044] Figure 4C is an example where h > 3r and is an example not included in the present invention. In the example shown in Figure 4C, the protrusion amount L and the inlet height h are larger than those in the example shown in Figure 4B. In this example, h > 3r, and the tip of the particle layer regulating member 22 is located on the side opposite to the particle carrier 21 side from the center of the second layer of particles 33. Therefore, the second layer of particles 33 will invade (move) to the particle carrier 21 side. As a result, the particle layer formed on the particle carrier 21 will not be a single layer.

[0045] Table 1 shows the results when the protrusion amount L and the inlet height h are changed to confirm whether the particle layer formed on the particle carrier 21 is a single layer. Here, particles with a volume average particle diameter of 15 μm were used as the particles. Therefore, r is 7.5 μm and 3r is 22.5 μm. The particle size distribution value (CV value) of the particles used here was 9%. The particle size distribution value will be described later.

[0046]

Table 1

[0047] When h < r, the particles close to the particle carrier 21 were peeled off, and no particle layer was formed on the particle carrier 21. When h > 3r, the particle layer formed on the particle carrier 21 did not become a single layer, and a particle layer with overlapping particles was formed. As can be seen from these results, in order to form a single-layer particle layer, it is necessary to satisfy r ≤ h ≤ 3r.

[0048] According to this embodiment, a single particle layer can be formed on the particle carrier 21, enabling higher image quality and cost reduction. For example, since a single particle layer can be formed on the particle carrier 21, it is easier to apply FM screening processing, and higher image quality and stable image quality can be expected. Furthermore, when forming a color image, particles of multiple colors can be arranged without overlapping, enabling image formation, thereby reducing costs. Furthermore, since the particle layer formed on the particle carrier 21 is a single layer, the particle carrier 21 can be made cleaner-free and cleaning can be reduced, which can be expected to save resources and reduce the size of the device. Furthermore, in this embodiment, the particles are not limited to toner, and application to other fields is also expected.

[0049] The particles used in this embodiment can be appropriately selected. Examples of the particles include toner particles, spacer particles for securing gaps, solder ball particles, and the like.

[0050] In addition to the above, microcapsule particles can also be used as particles in this embodiment. Microcapsule particles have a hard surface and can be used in the image forming apparatus shown in FIG. 1, for example. The contents of the microcapsule particles are liquid or gel-like, for example, and can reduce the heat capacity required for fixing to a recording medium, thereby achieving energy savings. Furthermore, the use of microcapsule particles also makes it possible to fix the image to a recording medium by applying pressure, achieving low power consumption equivalent to that of an inkjet system.

[0051] The particle size of the particles applied to the electrostatic latent image carrier can be appropriately selected. The above example is an example of a toner for a printer or copier using electrophotography, and the average particle size of the toner particles in this embodiment is preferably up to about 20 μm.

[0052] In this embodiment, the particles are not limited to toner particles, and therefore the present invention can be applied to fields other than electrophotography, such as liquid crystal panels and 3D printers. For example, in the field of liquid crystal panels, this embodiment can be used for spacer particles between panels. In the field of liquid crystal panels, this embodiment can be applied to applying spacer particles at equal intervals or unevenly in a spacer application device between glass plates that sandwich liquid crystal. Furthermore, in the field of liquid crystal panels, this embodiment can be applied to improving the efficiency of particle utilization in particle control in a spray diffusion manufacturing method. For example, in the field of 3D printers, particles can be fixed with adhesive or the like and layered to produce a three-dimensional object. This embodiment can be applied to the field of 3D printers to improve shape accuracy by improving the layering position accuracy of the layering mold. Furthermore, this embodiment can be applied to the field of 3D printers to improve the accuracy of controlling droplets to solids.

[0053] Next, a preferred example of the particle layer regulating member 22 will be described. 5 is a diagram showing the particle layer regulating member 22 of this example. As described above, the tip side of the particle layer regulating member 22 in this embodiment has a tapered shape, and the surface of the tip side of the particle layer regulating member 22 opposite to the surface facing the particle carrier 21 forms an inclined surface 22a with respect to the surface direction of the flat plate. Note that the surface direction of the flat plate refers to the surface direction of the particle layer regulating member 22.

[0054] To divert particles, it is preferable that the tip of the particle layer regulating member 22 is sharp. For example, it is preferable that the inclined surface 22a of the particle layer regulating member 22 is at an angle of 60° or less with respect to the surface direction of the flat plate. As shown in FIG. 5, it is preferable that the angle θ (also referred to as the inclination angle θ) of the inclined surface 22a with respect to the surface direction of the flat plate is 60° or less. In this case, it is possible to prevent the particle layer on the particle support 21 from being disturbed. If the inclination angle θ becomes obtuse and exceeds 60°, particles are likely to remain at the tip of the particle layer regulating member 22, which may disturb the particle layer.

[0055] Table 2 shows the results when the particle layer formed on the particle carrier 21 was observed while changing the tilt angle θ.

[0056] [Table 2]

[0057] As shown in Table 2, when the inclination angle θ exceeded 60°, the particle layer formed on the particle carrier 21 was a single layer, but the particle layer was disrupted. It is believed that when the inclination angle θ exceeded 60°, particles remained at the tip of the particle layer regulating member 22, causing displacement of the particles in the particle layer. For this reason, it is preferable that the inclination angle of the inclined surface 22a of the particle layer regulating member 22 be 60° or less with respect to the surface direction of the flat plate.

[0058] Next, another preferred example of the particle layer regulating member 22 will be described. 6 is a diagram showing the particle layer regulating member 22 of this example. In the particle layer regulating member 22, it is preferable that the protrusion amount L is adjustable, and in particular, it is more preferable that the protrusion amount L is adjustable according to the volume average particle size of the particles.

[0059] The method for adjusting the protrusion amount L is not particularly limited and can be selected as appropriate. Fig. 6 shows an example of a protrusion amount adjustment means. In the protrusion amount adjustment means 41 shown here, the protrusion amount L can be adjusted using a screw 42. For example, by rotating the screw 42, a support member 43 that supports the particle layer regulating member 22 moves in the direction of arrow a. This moves the particle layer regulating member 22 in the direction of arrow b, and the protrusion amount L is adjusted.

[0060] As described above, in this embodiment, the relationship r≦h≦3r must be satisfied, and as the particle diameter decreases, it becomes difficult to set the particle layer regulating member 22 so that the inlet height h satisfies this formula. Therefore, by making the protrusion amount L adjustable, the inlet height h can be set as desired, making it easier to set the particle layer regulating member 22 so that the above formula is satisfied. Furthermore, even when particles of different diameters are fed, the inlet height h can be set as desired, making it possible to form images without changing the particle layer regulating member 22.

[0061] In the above description, the word "adjust" may be referred to as "adjustment" or the like, and "adjustable" may be referred to as "variable" or the like.

[0062] Next, another preferred example of the particle layer regulating member 22 will be described. 7 is a diagram showing the particle layer regulating member 22 of this example. In the figure, A indicates the thickness of the tip of the particle layer regulating member 22. The thickness A of the tip of the particle layer regulating member 22 can be selected appropriately, and from the viewpoint of particle diversion, it is preferable that the tip of the particle layer regulating member 22 is as sharp as possible. However, from the viewpoint of safety, the tip of the particle layer regulating member 22 may have some thickness.

[0063] From the viewpoint of dividing the particle flow, it is preferable that the thickness of the leading end of the particle layer regulating member 22 is equal to or less than the volume average particle diameter of the particles. In this case, it is possible to prevent the particle layer on the particle support 21 from being disturbed. If the thickness A of the leading end of the particle layer regulating member 22 is larger than the volume average particle diameter of the particles, the particles are likely to remain at the tip of the particle layer regulating member 22, which may disturb the particle layer.

[0064] Table 3 shows the results of observing the particle layer formed on the particle support 21 while changing the thickness of the tip of the particle layer regulating member 22. Here, as in Table 1, particles with a volume average particle size of 15 μm were used.

[0065] [Table 3]

[0066] As shown in Table 3, when the thickness of the particle layer regulating member 22 at its leading edge exceeded the volume average particle diameter (15 μm), the particle layer formed on the particle carrier 21 was a single layer, but the particle layer was disrupted. It is believed that when the thickness of the particle layer regulating member 22 at its leading edge exceeds the volume average particle diameter, particles accumulate at the tip of the particle layer regulating member 22, causing displacement of the particles in the particle layer. For this reason, it is preferable that the thickness of the particle layer regulating member 22 at its leading edge be equal to or less than the volume average particle diameter of the particles.

[0067] Next, another preferred example of the particle layer regulating member 22 will be described. Fig. 8 is a diagram showing the particle layer regulating member 22 of this example. The shape of the tip of the particle layer regulating member 22 can be selected appropriately, and may be pointed or flat, for example, as shown in Fig. 7. Alternatively, the tip of the particle layer regulating member 22 may have a curvature 22r, as shown in Fig. 8.

[0068] In particular, it is preferable that the tip of the particle layer control member 22 has a curvature, in which case the particles are more easily diverted and the particle layer on the particle support 21 is more effectively prevented from being disturbed.

[0069] Next, another preferred example of the particle layer regulating member 22 will be described. 9A and 9B are diagrams showing the particle layer regulating member 22 of this example. Fig. 9A is a diagram showing an example in which the particle layer regulating member 22 is disposed relative to the particle carrier 21, and Fig. 9B is a diagram showing only the particle layer regulating member 22 of this example.

[0070] In this example, the particle layer regulating member 22 has an arc-shaped surface that faces the particle carrier 21 and is concave relative to the particle carrier 21. In the example shown in Fig. 9(a), the particle layer regulating member 22 and the particle carrier 21 are in contact with each other, but the particle layer regulating member 22 and the particle carrier 21 may be in non-contact with each other.

[0071] 9(b) illustrates the arc shape 22b of the particle layer regulating member 22. By providing the particle layer regulating member 22 with such an arc shape 22b, particles passing between the particle layer regulating member 22 and the particle carrier 21 have more opportunities to come into contact with the particle layer regulating member 22 and the particle carrier 21, and are more uniformly charged. By more uniformly charging the particles, it is possible to prevent the particle layer formed on the particle carrier 21 from becoming distorted.

[0072] The curvature of the arc shape 22b of the particle layer regulating member 22 can be appropriately selected. When the curvature of the arc shape 22b of the particle layer regulating member 22 is R1, the curvature of the surface of the particle carrier 21 facing the particle layer regulating member 22 is R2, and the volume average particle diameter of the particles is D, R2 < R1 ≤ R2 + D It is preferable to satisfy. By satisfying R2 < R1, when the particles pass between the particle layer regulating member 22 and the particle carrier 21, the passage of the particles is less likely to be inhibited. By satisfying R1 ≤ R2 + D, when the particles pass between the particle layer regulating member 22 and the particle carrier 21, the particles are likely to contact the particle layer regulating member 22 and the particle carrier 21, and the particles are more likely to be charged uniformly.

[0073] Next, other preferable examples of the particles will be described. In the present embodiment, the particle layer formed on the particle carrier 21 is a single layer, and it is preferable that the particles are densely packed. To achieve this, it is important to consider the particle size distribution and particle circularity of the particles.

[0074] As the particles used in the present embodiment, it is preferable that the particle size distribution value (also referred to as the CV value) obtained below in the particle size distribution is 13% or less, and the average circularity is 0.95 or more. When the circularity is 0.95 or more, the fluidity of the particles is good, and it is easy to form a particle layer on the particle carrier 21. When the particle size distribution value (CV value) is 13% or less, the particles are likely to be densely packed. [Particle size distribution value] Particle size distribution value [%] = (standard deviation / volume average particle diameter) × 100

[0075] Table 4 shows the results when the particle layer formed on the particle carrier 21 is observed by changing the particle size distribution and particle circularity of the particles. Table 4 shows the results regarding the disturbance of the particle layer.

[0076]

Table 4

[0077] As shown in Table 4, when the particle size distribution value exceeded 13% and the average circularity was less than 0.95, the particle layer formed on the particle support 21 was a single layer, but the particle layer was disordered. On the other hand, when the particle size distribution value (CV value) was 13% or less and the average circularity was 0.95 or more, the particle layer was not disordered and the particles were more closely packed than when the particle size distribution value and average circularity were outside these ranges. For this reason, it is preferable that the particle size distribution value be 13% or less and the average circularity be 0.95 or more.

[0078] Particles with a particle size distribution value (CV value) of 13% or less have a uniform particle size and are close to uniform, and therefore may be referred to as mono-sized particles. In this embodiment, it is preferable to use spherical, mono-sized particles, and by using such particles, the particles can roll easily and be aligned when forming a particle layer. Furthermore, because the particles roll easily and have a uniform particle size, if the tip of the particle layer control member 22 is sharpened, it becomes even easier to form a mono-layer. Furthermore, because the particles have a uniform particle size, it becomes easier to uniformly charge the particles, and particles of opposite polarity can be reduced. [Explanation of symbols]

[0079] 1 Electrostatic latent image carrier 3, 33 particles 7 Charging means 8 Exposure means 9. Transfer Method 11 Recording media 20 Image forming device 21 Particle carrier 22 Particle layer control member 22a Slope 22b Arc shape 22r curvature 23 Supply materials 24 Particle container [Prior art documents] [Patent documents]

[0080] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-164826

Claims

1. An image forming apparatus having a rotating particle carrier and a flat particle layer regulating member that forms a particle layer on the particle carrier, the particle layer regulating member is disposed in a counter direction to a rotation direction of the particle carrier, and protrudes from a position of contact with or closest to the particle carrier to an upstream side in the rotation direction of the particle carrier, a tip end of the particle layer regulating member has a tapered shape, and a surface of the tip end of the particle layer regulating member opposite to a surface facing the particle carrier is inclined with respect to a surface direction of the flat plate, In the particle layer regulating member, when the shortest distance from the tip of the particle layer regulating member to the particle carrier is defined as an inlet height h, and when the particle radius r is defined as half the volume average particle diameter of the particle, r≦h≦3r An image forming apparatus characterized by satisfying the above. However, if the contact position or closest position between the particle layer regulating member and the particle carrier is not determined to be a single point, the contact position or closest position is determined to be the most upstream position in the rotation direction of the particle carrier among the contact positions or closest positions between the particle layer regulating member and the particle carrier.

2. 2. The image forming apparatus according to claim 1, wherein the inclined surface is at an angle of 60 degrees or less with respect to the surface direction of the flat plate.

3. When the length of the part of the particle layer regulating member that protrudes from the contact position or the closest position with the particle carrier to the upstream side in the rotation direction of the particle carrier is defined as a protrusion amount L, 3. The image forming apparatus according to claim 1, wherein the protrusion amount L is adjustable.

4. 4. The image forming apparatus according to claim 3, wherein the protrusion amount L is adjustable in accordance with the volume average particle diameter of the particles.

5. 5. The image forming apparatus according to claim 1, wherein the thickness of the particle layer regulating member at the most distal end is equal to or less than the volume average particle diameter of the particles.

6. 6. The image forming apparatus according to claim 1, wherein the tip of the particle layer regulating member has a curvature.

7. the particle layer regulating member has a surface facing the particle carrier that is arc-shaped and concave with respect to the particle carrier; When the curvature of the arc shape is R1, the curvature of the surface of the particle carrier facing the particle layer regulating member is R2, and the volume average particle diameter of the particles is D, R2<R1≦R2+D 7. The image forming apparatus according to claim 1, wherein the following is satisfied:

8. 8. The image forming apparatus according to claim 1, wherein the particles have a particle size distribution value of 13% or less, as determined by the following formula, and an average circularity of 0.95 or more. [Particle size distribution value] Particle size distribution value [%] = (standard deviation / volume average particle size) × 100

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