Particle layer forming device, developing device, and image forming apparatus

Abstract

To restrict a particle carried on a surface of a particle carrier to the particle that is sufficiently thin and has the stable layer thickness.SOLUTION: A development device 26 (particle layer formation device) for forming a toner image (particle layer) on a surface of a photoreceptor drum 21 (supply object) includes: a development roller 26a (particle carrier) which is in contact with (or opposed to) the photoreceptor drum 21 and rotates in a prescribed rotation direction; a supply roller 26b (particle supply rotor) which is in contact with the development roller 26a at a first contact part N1 (contact part) and rotates in the reverse direction to the rotation direction to supply toner (particles) to the development roller 26a; and a first regulation part 26d (regulation member) which is in contact with the supply roller 26b on the upstream side in the rotation direction of the supply roller 26b with respect to the first contact part N1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a particle layer forming device that forms a particle layer such as a toner image on the surface of a receiving body such as a photosensitive drum, a developing device that forms a toner image on a latent image formed on the surface of the photosensitive body, and an image forming device equipped with the same. [Background technology]

[0002] Conventionally, developing devices (particle layer forming devices) installed in image forming devices such as copiers and printers are known that are composed of a particle carrier (developing roller) that abuts against or faces a photosensitive drum (receiving body), and a particle supply rotating body (supply roller) that supplies particles (toner) to the surface of the particle carrier (see, for example, Patent Document 1).

[0003] In detail, the developing device (particle layer forming device) in Patent Document 1 is composed of a developing roller (particle carrier) that contacts a photosensitive drum (supply recipient), a doctor blade that regulates the amount of toner (particles) carried on the surface of the developing roller, and a supply roller (particle supply rotor) that contacts the developing roller at a position upstream of the doctor blade in the rotational direction. The toner supplied to and carried on the surface of the developing roller by the supply roller is regulated to an appropriate amount at the position of the doctor blade, and a portion of the toner carried on the surface of the developing roller is supplied to the latent image formed on the surface of the photosensitive drum at a position facing the photosensitive drum, forming a desired toner image on the surface of the photosensitive drum.

[0004] On the other hand, Patent Document 2 discloses a developing method in which one toner particle is supplied per one level of change in the gradation of an electrostatic latent image, with the aim of obtaining a stable and good image. Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional technologies have been unable to regulate the particles (toner) carried on the surface of a particle carrier (developing roller) to a sufficiently thin and stable layer thickness, resulting in problems such as a thick and uneven particle layer being formed on the supplying body (photosensitive drum).

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a particle layer forming device, a developing device, and an image forming device that can regulate the particles carried on the surface of a particle carrier to a sufficiently thin and stable layer thickness. [Means for solving the problem]

[0007] The particle layer forming apparatus of the present invention is a particle layer forming apparatus for forming a particle layer on a surface of a supply target body, and includes: a particle carrier that rotates in a predetermined rotation direction in contact with or facing the supply target body; a particle supply rotor that contacts the particle carrier at a contact portion and rotates in a direction opposite to the rotation direction to supply particles to the particle carrier; and a regulating member that contacts the particle supply rotor upstream of the contact portion in the rotation direction of the particle supply rotor. At least a portion of the regulating member that abuts against the particle supply rotor is formed in a mesh shape, and a space that can pump up particles contained inside the particle layer forming device is formed between a portion of the particle supply rotor that is upstream of the portion that abuts against the regulating member in the rotation direction of the particle supply rotor and downstream of the abutment portion in the rotation direction of the particle supply rotor and an inner wall of a case of the particle layer forming device in which the particles are contained. It is something. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a particle layer forming device, a developing device, and an image forming device that can regulate the particles carried on the surface of a particle carrier to a sufficiently thin and stable layer thickness. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. 2 is an enlarged view showing a main part of the developing device. [Figure 4] FIG. 4 is an enlarged view showing a part of the surface of the regulating member. [Figure 5]FIG. 10 is an enlarged view showing a main part of a developing device according to a first modified example. [Figure 6] FIG. 10 is an enlarged view showing a main part of a developing device according to a second modified example. [Figure 7] FIG. 11 is a diagram showing a part of a medicine supply device as a third modification. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0011] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 in this embodiment is a tandem color image forming apparatus in which a plurality of process cartridges 20Y, 20M, 20C, and 20BK are arranged side by side so as to face an intermediate transfer belt 40. In addition, a developing device 26 (see FIG. 2) serving as a particle layer forming device is installed so as to face the photosensitive drums 21 of the plurality of process cartridges 20Y, 20M, 20C, and 20BK.

[0012] In Figure 1, 1 indicates the main body of a color copier as an image forming device, 2 indicates a document transport unit that transports a document to a document reading unit 3, 3 indicates a document reading unit that reads image information from the document, and 4 indicates a writing unit (exposure unit) that emits laser light L (see Figure 2) based on input image information. Also, 20Y, 20M, 20C, and 20BK indicate process cartridges corresponding to the respective colors (yellow, magenta, cyan, and black), and 40 indicates an intermediate transfer belt onto which toner images of multiple colors are transferred in an overlapping manner. Also, 61 denotes a paper feed device in which sheets P such as paper are stored, 65 denotes a secondary transfer roller that transfers the toner image formed on the intermediate transfer belt 40 to the sheet P, 66 denotes a fixing device that fixes the unfixed image on the sheet P, and 70 denotes a toner container for replenishing toner of each color to each developing device 26 corresponding to the multiple process cartridges 20Y, 20M, 20C, and 20BK.

[0013] 2, each of the process cartridges 20Y, 20M, 20C, and 20BK integrates a photosensitive drum 21 (image carrier) as a supplying body and a charging device 22. Each of the process cartridges 20Y, 20M, 20C, and 20BK is replaced with a new one for the image forming apparatus main body 1 when it reaches the end of its life. Furthermore, each developing device 26 (particle layer forming device) is installed so as to face the photosensitive drum 21 (supply receiving body) of each process cartridge 20Y, 20M, 20C, 20BK. When the developing device 26 reaches the end of its life, it is replaced with a new one in the image forming apparatus main body 1. Note that the operation of attaching and detaching the developing device 26 to and from the image forming apparatus main body 1 and the operation of attaching and detaching the process cartridges 20Y, 20M, 20C, 20BK to and from the image forming apparatus main body 1 can be performed separately and independently. A toner image of each color (yellow, magenta, cyan, black) is formed on the photosensitive drum 21 (toner receiving member) of each of the process cartridges 20Y, 20M, 20C, and 20BK.

[0014] Hereinafter, the operation of the image forming apparatus during normal color image formation will be described. First, the document is transported from the document table by the transport rollers of the document transport unit 2 and placed on the contact glass of the document reading unit 3. Then, the document reading unit 3 optically reads the image information of the document placed on the contact glass. Then, the image information for each color of yellow, magenta, cyan, and black is sent to the writing unit 4. Then, from the writing unit 4, laser light L (exposure light) based on the image information for each color is irradiated onto the surface of the photosensitive drum 21 (see FIG. 2) of the corresponding process cartridge 20Y, 20M, 20C, 20BK.

[0015] Meanwhile, the photosensitive drums 21, which serve as four photosensitive bodies, each rotate in a clockwise direction in FIGS. 1 and 2. First, the surface of the photosensitive drum 21 is uniformly charged at a position facing the charging device 22 (charging roller) (charging process). In this way, a charging potential is formed on the photosensitive drum 21. Thereafter, the charged surface of the photosensitive drum 21 reaches a position where the laser light L is irradiated by each writing unit 4, and an electrostatic latent image based on image information is formed at that position (exposure process).

[0016] The laser light corresponding to the yellow component is irradiated onto the surface of the photosensitive drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the laser light of the yellow component is scanned in the direction of the rotation axis (main scanning direction) of the photosensitive drum 21 by a polygon mirror rotating at high speed. In this way, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 21 after it has been charged by the charging device 22. Similarly, the cyan laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20C, which is the second from the left on the paper, and an electrostatic latent image of the cyan component is formed. The magenta laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20M, which is the third from the left on the paper, and an electrostatic latent image of the magenta component is formed. The black laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20BK, which is the fourth from the left on the paper, and an electrostatic latent image of the black component is formed.

[0017] Thereafter, the surface of the photosensitive drum 21 on which the electrostatic latent image of each color is formed reaches a position facing the developing device 26. Then, toner of each color is supplied from each developing device 26 onto the photosensitive drum 21, and the latent image on the photosensitive drum 21 is developed (this is the developing process). Thereafter, the surfaces of the photosensitive drums 21 after the development process reach positions facing the intermediate transfer belt 40. Here, primary transfer rollers 24 are installed at each of the facing positions so as to abut against the inner circumferential surface of the intermediate transfer belt 40. Then, at the positions of the primary transfer rollers 24, the toner images of each color formed on the photosensitive drums 21 are transferred onto the intermediate transfer belt 40 in order, superimposed on top of each other (this is the primary transfer process).

[0018] After that, the surface of the photosensitive drum 21 after the primary transfer process is neutralized by a neutralization device (not shown). Thereafter, the surfaces of the photosensitive drums 21 reach positions facing the developing devices 26. Then, the developing devices 26 collect untransferred toner remaining on the photosensitive drums 21 (cleaning process). In this manner, the developing devices 26 in this embodiment are configured to be able to collect untransferred toner remaining on the surfaces of the photosensitive drums 21 (photosensitive bodies). That is, the image forming apparatus 1 in this embodiment employs a cleanerless system. Thus, a series of image forming processes on the photosensitive drum 21 is completed.

[0019] Meanwhile, the surface of the intermediate transfer belt 40 onto which the images of each color on the photosensitive drum 21 are transferred and superimposed runs in the direction of the arrow in the figure and reaches the position of the secondary transfer roller 65. Then, at the position of the secondary transfer roller 65, the full-color image on the intermediate transfer belt 40 is secondarily transferred onto the sheet P (secondary transfer process). Thereafter, the surface of the intermediate transfer belt 40 reaches the position of the intermediate transfer belt cleaning device, and the untransferred toner on the intermediate transfer belt 40 is collected by the intermediate transfer belt cleaning device, completing the series of transfer processes on the intermediate transfer belt 40.

[0020] Here, the sheet P conveyed to the position of the secondary transfer roller 65 is conveyed from the paper feeder 61 via the registration roller 64 and the like. More specifically, a sheet P fed by a paper feed roller 62 from a paper feed device 61 that stores sheets P passes through a conveyance path and is then guided to the position of a registration roller 64. The sheet P that has reached the position of the registration roller 64 is conveyed toward the position of a secondary transfer roller 65 in synchronization with the toner image on the intermediate transfer belt 40.

[0021] Thereafter, the sheet P onto which the full-color image has been transferred is guided to the position of the fixing device 20. Then, in the fixing device 20, the color image is fixed onto the sheet P at the nip between a fixing roller and a pressure roller. After the fixing process, the sheet P is discharged as an output image outside the apparatus main body 1 by a discharge roller 69, and then stacked on the discharge tray 5, completing a series of image forming processes.

[0022] Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIG. The four image forming units installed in the image forming apparatus main body 1 have almost the same structure except for the color of the toner used in the image forming process, so they are illustrated without the alphabetical symbols (Y, M, C, BK) for components such as process cartridges and developing devices (particle layer forming devices).

[0023] As shown in FIG. 2, the process cartridge 20 mainly includes a photosensitive drum 21 (photosensitive member) as a toner supplying member, and a charging device 22 housed integrally in a case. As explained above, the image forming unit in this embodiment is a cleanerless type image forming unit, and does not have a dedicated cleaning device (cleaning blade) for cleaning untransferred toner (residual toner) on the photosensitive drum 21, and the function of such a cleaning device is performed by the developing device 26.

[0024] The photosensitive drum 21 as a toner supplying member is a negatively chargeable organic photosensitive member, and is formed by providing a photosensitive layer etc. on a drum-shaped conductive support. The charging device 22 is a charging roller made of a conductive core metal and a medium-resistance elastic layer coated on the outer periphery thereof. A predetermined voltage is applied to the charging device 22 (charging roller) from a power supply unit, thereby uniformly charging the surface of the opposing photosensitive drum 21.

[0025] 2, the developing device 26 as a particle layer forming device is mainly arranged so that the developing roller 26a as a particle carrier (developer carrier) contacts the photosensitive drum 21 with a predetermined pressure, and a development area (development nip) is formed between the developing roller 26a and the photosensitive drum 21. The developing device 26 contains toner T (a non-magnetic or magnetic one-component developer) as particles. The developing device 26 develops the electrostatic latent image formed on the surface of the photosensitive drum 21 (forms a toner image).

[0026] The configuration and operation of the developing device 26 as a particle layer forming device, which is a feature of this embodiment, will be described in detail below. The developing device 26 in this embodiment functions as a particle layer forming device that forms a particle layer on the surface of a supply object. Specifically, as previously described with reference to Fig. 1 etc., the developing device 26 forms a toner image as a particle layer on a latent image formed on the surface of a photosensitive member (photosensitive drum 21) that serves as a supply object.

[0027] Referring now to FIG. 2, the developing device 26 in this embodiment is a contact single-component developing type developing device, and is installed separately from the process cartridge 20 so as to be detachable (replaceable) with respect to the image forming apparatus main body 1. As shown in Figures 2 and 3, the developing device 26 is composed of a developing roller 26a (developer carrier) as a particle carrier, a supply roller 26b as a particle supply rotor, a regulating blade 26c consisting of a first regulating portion 26d (regulating member) and a second regulating portion 26e (second regulating member), and the like.

[0028] The developing roller 26a, which serves as a particle carrier, carries toner T (developer) as particles on its surface and rotates in a predetermined direction (counterclockwise in FIG. 2) to supply the toner T to the electrostatic latent image formed on the photosensitive drum 21. In this embodiment, the developing roller 26a (particle carrier) is disposed so as to contact the photosensitive drum 21 (supply recipient). The developing roller 26a may be one having a roller portion made of a conductive elastic material mounted on a rotating shaft portion (core metal) made of a conductive metal material such as stainless steel.

[0029] The supply roller 26b as a particle supply rotor contacts the developing roller 26a (particle carrier) at a first contact portion N1 (located below the developing roller 26a). That is, the supply roller 26b contacts the developing roller 26a at a lower position. The supply roller 26b rotates in the opposite direction (clockwise in FIGS. 2 and 3) to the rotation direction of the developing roller 26a, and functions as a particle supply rotor that supplies toner T (particles) to the developing roller 26a (particle carrier). That is, the supply roller 26b is a roller member that supplies toner T to the developing roller 26a while rotating in the co-rotating direction with the developing roller 26a.

[0030] The supply roller 26b is made of a metal core and has a conductive foamed polyurethane layer (electrical resistance value: 10 3 ~10 14 Ω or so.) can be used as a laminate. Although not shown, gears are provided on the shafts of the developing roller 26a and the supply roller 26b, and the gears are configured to mesh with each other. A driving force is input to these gear trains from a drive motor 91 (driving means), and the developing roller 26a and the supply roller 26b are rotated in the directions of the arrows in FIGS. 2 and 3, respectively.

[0031] The restriction blade 26c is a plate-like member (blade-like member) integrally formed with a first restriction portion 26d serving as a restriction member (first restriction member) and a second restriction portion 26e serving as a second restriction member. In other words, the first restriction portion 26d serving as a restriction member is a plate-like member integrally formed with the second restriction portion 26e serving as a second restriction member. Specifically, in this embodiment, as shown in Fig. 2, the regulating blade 26c is formed in a substantially L-shape when viewed in a cross section perpendicular to the rotation axes of the developing roller 26a and the supply roller 26b, and is disposed to the left of the first contact portion N1 in Fig. 2. The regulating blade 26c can be a thin, L-shaped plate member made of a metal material such as stainless steel and subjected to a bending process.

[0032] More specifically, the first regulating portion 26d of the regulating blade 26c functions as a regulating member (first regulating member) that abuts against the supply roller 26b (particle supply rotor) upstream of the first abutment portion N1 (abutment portion) in the rotation direction of the supply roller 26b (particle supply rotor) (the position of the second abutment portion N2 in Figure 3). The first regulating portion 26d as a regulating member serves to reduce the amount of toner (toner layer) supplied from the supply roller 26b to the development roller 26a.

[0033] That is, the developing device 26 in this embodiment forms a thin toner layer on the developing roller 26a without providing a doctor blade (which abuts against the developing roller 26a downstream of the first abutment portion in the rotation direction of the developing roller 26a) as disclosed in Patent Document 1 etc. In other words, in this embodiment, rather than supplying a large amount of toner (a non-thinned toner layer) to the developing roller 26a by the supply roller 26b and then thinning the toner layer on the developing roller 26a, the toner layer is thinned on the supply roller 26b by the first restriction portion 26d and then the thinned toner layer is supplied to the developing roller 26a. In this embodiment, the first restricting portion 26d (restricting member) abuts against the supply roller 26b at an obliquely upward position with a pressure of about 10 to 100 N / m.

[0034] In contrast, the second regulating portion 26e of the regulating blade 26c functions as a second regulating member that abuts against the developing roller 26a upstream of the first abutment portion N1 (abutment portion) in the rotation direction of the developing roller 26a (particle carrier) (the position of the third abutment portion N3 in Figure 3). The second regulating portion 26e as a second regulating member is used to separate from the developing roller 26a untransferred toner (toner that remains on the photosensitive drum 21 without being transferred onto the intermediate transfer belt 40) that has been collected from the surface of the photosensitive drum 21 onto the developing roller 26a, and toner that has not moved onto the photosensitive drum 21 during the development process (undeveloped toner). That is, the untransferred toner that has been collected onto the developing roller 26a and the undeveloped toner on the developing roller 26a are scraped off from the developing roller 26a by the second regulating portion 26e, and toner Q (untransferred toner, undeveloped toner) that falls in the direction of the black arrow in FIG. 3 is collected into the developing device 26 and is used again as toner for development. In this embodiment, the second regulating portion 26e (second regulating member) is integrated with the first regulating portion 26d (regulating member) as the regulating blade 26c, and therefore the number of parts can be reduced compared to when the second regulating portion 26e is provided separately from the first regulating portion 26d.

[0035] In this embodiment, the second regulating portion 26e (second regulating member) abuts downward against the developing roller 26a (particle carrier). Specifically, the second regulating portion 26e (second regulating member) abuts against the developing roller 26a at a position diagonally below the developing roller 26a in the trailing direction (the direction along the rotation direction of the developing roller 26a) with a pressure of about 10 to 100 N / m. In this way, by positioning the second regulating portion 26e (second regulating member) below the developing roller 26a rather than above it, the toner Q (untransferred toner, undeveloped toner) carried on the developing roller 26a is promoted to fall under its own weight. Furthermore, in this embodiment, the second restricting portion 26e is brought into contact with the developing roller 26a in the trailing direction, which makes it easy to integrate the second restricting portion 26e with the first restricting portion 26d.

[0036] 3 and 4, the first restricting portion 26d serving as a restricting member has at least a portion (second contact portion N2) that contacts the supply roller 26b (particle supply rotor) formed in a mesh shape. Specifically, the first restricting portion 26d (restricting member) is a mesh-like member in which a plurality of circular holes 26d1 are formed over the entire surface. In this way, since at least the second contact portion N2 of the first regulating portion 26d is formed in a mesh shape, it becomes easier to secure an escape route for the toner (toner R in Figure 3) scraped off from the supply roller 26b by the first regulating portion 26d. In particular, by forming the entire surface of the first regulating portion 26d in a mesh-like shape, an escape route for the toner T is also secured on the upstream and downstream sides of the second abutment portion N2, thereby preventing the toner from accumulating around the supply roller 26b.

[0037] Specifically, the toner T pumped up onto the supply roller 26b is supported on the supply roller 26b at the position of the second contact portion N2 by the first restricting portion 26d as a thin toner layer of about one particle. At this time, the first restricting portion 26d scrapes off excess toner T from the supply roller 26b at the position of the second contact portion N2, and the scraped toner passes through the hole 26d1 and falls under its own weight in the direction of the white arrow in Figure 3 (towards the back side of the first restricting portion 26d), or it falls under its own weight without passing through the hole 26d1. In contrast, if the first restricting portion 26d is not formed in a mesh shape, some of the excess toner T scraped off from the supply roller 26b by the first restricting portion 26d at the position of the second abutting portion N2 may remain at that position and be re-carried by the supply roller 26b without falling under its own weight. Therefore, compared to when the first restricting portion 26d is formed in a mesh shape, the thinning of the toner layer formed on the supply roller 26b and supplied to the developing roller 26a becomes slower (the toner layer is likely to become about 1.5 layers thicker than one toner layer equivalent to one particle).

[0038] In particular, in the first restricting portion 26d (restricting member) in this embodiment, when the hole diameter (mesh diameter) of the hole portion 26d1 is M and the particle diameter (particle diameter) of the toner T (particles) is D, D <M<5×D The relationship is set to be established. Specifically, in this embodiment, toner T having a particle diameter D of approximately 10 to 100 μm is used, and the hole diameter M of the hole portion 26d1 of the first restricting portion 26d is set to satisfy the above-mentioned formula. If the hole diameter M of the hole portion 26d1 is equal to or smaller than the particle diameter D of the toner T, it becomes difficult for the toner T to pass through the hole portion 26d1. Furthermore, if the hole diameter M of the hole portion 26d1 is equal to or larger than five times the particle diameter D of the toner T, the function of the first restricting portion 26d to form a thin toner layer on the supply roller 26b decreases. For these reasons, the relationship between the hole diameter of the hole portion 26d1 and the particle diameter D of the toner T is determined as shown in the above formula.

[0039] Here, in this embodiment, it is preferable to form an electric field between the supply roller 26b (particle supply rotor) and the first regulating portion 26d (regulating member) so as to separate the toner T (particles) carried on the supply roller 26b toward the first regulating portion 26d. Specifically, in this embodiment, since negative polarity toner T is used, for example, the development power supply 90 applies a voltage of approximately -600 V to the supply roller 26b and a voltage of approximately -400 V to the first regulating portion 26d (regulating blade 26c), thereby forming a potential difference between both members 26b and 26d. By configuring it in this manner, the toner T carried on the supply roller 26b is more likely to move electrostatically toward the first regulating portion 26d, making it easier for the first regulating portion 26d to perform its function of forming a thin toner layer on the supply roller 26b.

[0040] The developing device 26 configured as above operates as follows during a normal developing process. First, a portion of the toner T contained in the developing device 26 is drawn up (carried) onto the supply roller 26b. Then, the toner T carried on the supply roller 26b is thinned, uniformed, and frictionally charged by the first restricting portion 26d at the position of the second contact portion N2. At this time, the toner layer T formed on the supply roller 26b is about the size of one toner particle (one layer). Furthermore, the excess toner T scraped off by the first restricting portion 26d falls under its own weight or falls under its own weight after passing through the hole portion 26d1, and is returned to the developing device 26. Thereafter, the thinned toner layer T on the supply roller 26b is supplied onto the developing roller 26a at the position of the first contact point N1. At this time, the toner carried on the developing roller 26a at the first contact point N1 is further thinned (single layer), uniformed, and frictionally charged, and then reaches a position (developing area) facing the photosensitive drum 21. At this position, the toner is attracted to the electrostatic latent image formed on the photosensitive drum 21 by an electric field (developing electric field) formed in the developing area. In this way, a desired toner image (a toner layer equivalent to about one toner particle (one layer)) is formed on the photosensitive drum 21. At this time, the untransferred toner carried on the photosensitive drum 21 is collected onto the developing roller 26a. That is, after passing through the development area, the surface of the developing roller 26a carries the untransferred toner carried on the photosensitive drum 21 and the toner that did not move onto the photosensitive drum 21 during the development process (undeveloped toner). Then, the toner carried on the developing roller 26a is scraped off by the second restricting portion 26e at the position of the third contact portion N3 and returned to the developing device 26. In the developing device 26 of this embodiment, an agitating member for agitating the toner so that it does not aggregate within the developing device 26 may be provided.

[0041] Here, a predetermined voltage is applied to each of the developing roller 26a, the supply roller 26b, and the regulating blade 26c from a developing power supply 90 (power supply unit), thereby promoting electrostatic movement of the toner on the developing roller 26a. In this embodiment, an alternating current voltage (a square wave with an AC frequency of about 500 to 1000 Hz, a peak-to-peak voltage of about 500 to 3000 V, and an application time duty of about 30 to 70%) is applied to the developing roller 26a so that the toner moves back and forth between the developing roller 26a and the photosensitive drum 21 in the development area. Although this embodiment is configured to apply an AC voltage to the developing roller 26a, it is also possible to apply a DC voltage (for example, a DC voltage of about −500 V) to the developing roller 26a. In this case, it is also possible to apply a DC voltage (for example, a DC voltage of about −600 V) to the supply roller 26b, thereby forming an electric field at the first contact portion N1 that promotes the supply of toner from the supply roller 26b to the developing roller 26a. Furthermore, it is also possible to apply a DC voltage (for example, a DC voltage of about −400 V) to the second regulating portion 26e (regulating blade 26c), thereby forming an electric field at the third contact portion N3 that promotes the movement (detachment) of toner from the developing roller 26a to the second regulating portion 26e.

[0042] In this manner, in the present embodiment, the first regulating portion 26d (regulating member) is provided to make the toner layer carried on the supply roller 26b sufficiently thin, so that the toner T carried on the surface of the developing roller 26a can be regulated to a sufficiently thin and stable layer thickness. As a result, a toner image (toner layer) with a sufficiently thin and uniform layer thickness is formed on the photosensitive drum 21, which makes it less likely that problems such as changes in image quality or staining of non-image areas with developer will occur. In particular, in this embodiment, a thin toner layer of about the thickness of one layer of toner particles is formed on the photosensitive drum 21, so image quality is stabilized even when FM screening is applied, and it is also possible to configure an inexpensive device that forms a color image by arranging toner of multiple colors without overlapping them on the intermediate transfer belt 40. Furthermore, because the image forming device 1 in this embodiment is of a cleanerless type, the device can be made low cost, compact, and resource-efficient.

[0043] The following provides a supplementary explanation regarding the above-mentioned effects of the present invention. Generally, the toner (toner particles) used in electrophotographic single-component development devices has a wide particle size distribution, which has traditionally made it difficult to form a toner image with uniform dots, posing a challenge to the creation of high-quality images. Furthermore, due to the wide toner particle size distribution, the toner charge distribution also becomes wide, resulting in the existence of reverse polarity toner. As a result, a problem has conventionally occurred in which toner adheres to non-image areas on the photosensitive drum 21 (areas where toner is not originally intended to adhere) (image contamination in non-image areas). In addition, deterioration of the toner over time (due to cracking of the toner or the release or embedding of external additives) and changes in particle size due to particle size selection also cause changes in the thin layer of toner on the developing roller, resulting in changes in image quality and image contamination in non-image areas. To solve these problems, it is important to regulate the toner carried on the developing roller to a sufficiently thin and stable layer thickness. In particular, when forming a color image, compared to forming a monochrome image, the image is formed by overlapping toner of multiple colors, so it is necessary to thin and stabilize the toner layer on the developing roller for each color, not only from the perspective of image quality but also from the perspective of cost. Furthermore, when a cleanerless imaging unit that does not have a cleaning device is used, the key to improving image quality is to suppress the generation of reverse polarity toner, so it is necessary to thin and stabilize the toner layer on the developing roller.

[0044] In contrast, in the developing device 26 of this embodiment, when the toner is supplied to the developing roller 26a by the supply roller 26b, the toner is already sufficiently thin-layered and stabilized. In detail, when the developing roller 26a passes through the first contact point N1 with the supply roller 26b, a thin layer (a single layer or a toner layer with a thickness close to that) of about one layer of toner particles is formed on the surface of the developing roller 26a. This allows the toner particle size to be uniform and the development process to be carried out with uniformly charged toner without reverse charging, thereby reducing the above-mentioned conventional problems.

[0045] Here, in this embodiment, the toner T (developer) contained in the developing device 26 is set so that the ratio of toner with a particle size of 10% or less and toner with a particle size of 90% or more in the particle size distribution is within 10% of the total. By using such toner T, the above-mentioned effect of the present invention (the effect of thinning and stabilizing the toner layer on the developing roller 26a) can be efficiently exhibited.

[0046] In this embodiment, the writing unit 4 (see FIGS. 1 and 2) is set to form an electrostatic latent image of one dot of a single tone on the surface of the photosensitive drum 21. This configuration makes it possible to effectively use the thin and stabilized toner layer on the developing roller 26a to form a high-quality toner image, i.e., to form a high-quality toner image corresponding to a single-tone, one-dot electrostatic latent image on the surface of the photosensitive drum 21.

[0047] <Variation 1> As shown in FIG. 5, in the developing device 26 (particle layer forming device) of the first modified example, the first regulating portion 26d as a regulating member is formed so as to extend in an arc shape along the outer peripheral surface of the supply roller 26b (particle supply rotor). That is, the first regulating portion 26d of the regulating blade 26c in variant 1 is not formed flat like that in Figure 3 when viewed in a cross section perpendicular to the rotation axis of the developing roller 26a or the supply roller 26b, but is formed curved (in variant 1, in an arc range of approximately 90 to 120 degrees). In this way, by using the arc-shaped first restricting portion 26d, it is easier to make the thickness of the toner layer lifted up and carried on the supply roller 26b thinner than when a flat first restricting portion 26d is used. Therefore, even if the first restricting portion 26d is not formed in a mesh shape, the toner layer carried on the supply roller 26b and supplied to the developing roller 26a can be made thin, about the thickness of a single particle. Therefore, in the first modification, the toner (particles) carried on the surface of the developing roller 26a (particle carrier) can also be regulated to a sufficiently thin and stable layer thickness. Although the first restricting portion 26d is not formed in a mesh shape in the first modification, the first restricting portion 26d may be formed in a mesh shape, which also reduces the problem of toner accumulating between the first restricting portion 26d and the supply roller 26b.

[0048] <Variation 2> As shown in FIG. 6, in the developing device 26 (particle layer forming device) of the modified example 2, the first regulating portion 26d as a regulating member and the second regulating portion 26e as a second regulating member are not integrated, but are installed as separate members. Even in this configuration, the toner (particles) carried on the surface of the developing roller 26a (particle carrier) can be regulated to a sufficiently thin and stable layer thickness. In this configuration, the second regulating portion 26e serving as the second regulating member can be brought into contact with the developing roller 26a in the counter direction, thereby improving the scraping force of the second regulating portion 26e.

[0049] <Variation 3> As shown in Figure 7, the drug supply device 126 in variant example 3 is a particle layer forming device that forms a layer of drug as a particle layer on the surface of wafer paper W as a supply object, unlike the developing device 26 installed in the image forming device 1. The drug supply device 126 (particle layer forming device) contains drug particles inside. The drug supply device 126 is also composed of an application roller 126a as a particle carrier, a supply roller 126b as a particle supply rotor, and a regulating blade 126c consisting of a first regulating portion 126d (regulating member) and a second regulating portion 126e (second regulating member). The application roller 126a, which serves as a particle carrier, contacts (or faces) the wafer paper W (receiving object) transported between it and the transport roller 121 by a transport mechanism not shown, and supplies the drug to the surface of the wafer paper W while rotating in a predetermined rotational direction. The supply roller 126b as a particle supply rotor abuts against the application roller 126a at a contact portion and rotates in the opposite direction to the rotation direction of the application roller 126a to supply the agent (particles) to the application roller 126a. The first restricting portion 126d as a restricting member abuts against the supply roller 126b on the upstream side in the rotation direction of the supply roller 126b with respect to the abutting portion with the applying roller 126a. The second regulating member 126e abuts against the application roller 126a upstream of the contact point between the application roller 126a and the supply roller 126b in the rotation direction of the application roller 126a, and scrapes off any residual drug that has not been supplied to the wafer paper W on the application roller 126a. The medicine supply device 126 configured in this way can also regulate the medicine (particles) carried on the surface of the application roller 126a (particle carrier) to a sufficiently thin and stable layer thickness.

[0050] As described above, the developing device 26 in this embodiment is a particle layer forming device that forms a toner image (particle layer) on the surface of the photosensitive drum 21 (supply receiving member), and is provided with a developing roller 26a (particle carrier) that abuts against (or faces) the photosensitive drum 21 and rotates in a predetermined rotational direction. Also provided is a supply roller 26b (particle supply rotor) that abuts against the developing roller 26a at a first abutment portion N1 (abutment portion) and rotates in a direction opposite to the aforementioned rotational direction to supply toner (particles) to the developing roller 26a. Also provided is a first regulating portion 26d (regulating member) that abuts against the supply roller 26b upstream of the first abutment portion N1 in the rotational direction of the supply roller 26b. This allows the toner (particles) carried on the surface of the developing roller 26a (particle carrier) to be regulated to a sufficiently thin and stable layer thickness. This configuration is particularly useful for chemicals, as the amount of chemicals must be accurately set.

[0051] In the present embodiment, the developing device 26 is not a component of the process cartridge 20, but is a unit that can be attached to and detached from the image forming apparatus main body 1 independently. However, the developing device 26 can also be one of the components of the process cartridge 20, and configured to be attached and detached from the image forming apparatus main body 1 as a process cartridge. In such a case, the same effect as that of this embodiment can be obtained. In this application, a "process cartridge" is defined as a unit that integrates at least one of a charging device that charges an image carrier, a developing device that develops a latent image formed on the image carrier, and a cleaning device that cleans the image carrier, with an image carrier, and is configured to be detachable from the image forming apparatus main body.

[0052] In this embodiment, the present invention is applied to a developing device 26 (particle layer forming device) of a contact one-component development type configured so that the developing roller 26a (particle carrier) abuts against the photosensitive drum 21 (supply receiving body). In contrast, the present invention can also be applied to a developing device (particle layer forming device) of a non-contact one-component development type configured so that the developing roller 26a (particle carrier) faces the photosensitive drum 21 (supply receiving body) with a small gap therebetween. In this embodiment, the present invention is applied to a developing device 26 (particle layer forming device) that uses toner as particles. In Modification 3, the present invention is applied to a drug supplying device 126 (particle layer forming device) that uses a drug as particles. In contrast, the present invention can also be applied to a particle layer forming device that uses particles other than toner or a drug (for example, a device that forms a three-dimensional object by stacking material (particles) one layer (one particle) at a time, such as a 3D printer). In such cases, the same effect as that of this embodiment can be obtained.

[0053] It is clear that the present invention is not limited to the present embodiment, and that within the scope of the technical concept of the present invention, each embodiment may be appropriately modified in addition to what is suggested in each embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components may be any number, position, shape, etc. that is suitable for implementing the present invention.

[0054] In the present specification, the term "below the particle carrier" is defined to mean below a horizontal line passing through the center of rotation of the particle carrier. In addition, in the present specification and the like, the term "facing" in "contact or facing" is defined to mean facing without contact. [Explanation of symbols]

[0055] 1. Image forming apparatus (image forming apparatus main body), 20, 20Y, 20M, 20C, 20BK process cartridges, 21 Photoconductor drum (supplied body, photoconductor), 26 Developing device (particle layer forming device), 26a developing roller (particle carrier, developer carrier), 26b supply roller (particle supply rotor), 26c Regulating blade (plate-shaped member), 26d first restricting portion (restricting member), 26d1 Hole, 26e second restricting portion (second restricting member), 126 Drug supply device (particle layer forming device), N1 1st contact part (contact part), N2 2nd contact part, N3 3rd contact part, T Toner (particles, developer). [Prior art documents] [Patent documents]

[0056] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-305343 [Patent Document 2] Japanese Patent Application Publication No. 10-55080

Claims

1. A particle layer forming apparatus for forming a particle layer on a surface of a supply object, a particle carrier that rotates in a predetermined rotation direction while contacting or facing the object to be supplied; a particle supply rotor that contacts the particle carrier at a contact portion and rotates in a direction opposite to the rotation direction to supply particles to the particle carrier; a regulating member that abuts against the particle supply rotor on the upstream side of the abutting portion in the rotation direction of the particle supply rotor; Equipped with At least a portion of the regulating member that contacts the particle supply rotor is formed in a mesh shape, A particle layer forming device characterized in that a space capable of pumping up particles contained inside the particle layer forming device is formed between a portion of the particle supply rotor upstream of the portion that abuts the regulating member in the rotational direction of the particle supply rotor and downstream of the abutment portion in the rotational direction of the particle supply rotor, and the inner wall of a case of the particle layer forming device in which the particles are contained.

2. 2. The particle layer forming apparatus according to claim 1, further comprising a second restricting member that contacts the particle carrier upstream of the contact portion in the rotation direction.

3. 3. The particle layer forming apparatus according to claim 2, wherein the regulating member is a plate-like member integrally formed with the second regulating member.

4. The contact portion is located below the particle carrier, 4. The particle layer forming apparatus according to claim 2, wherein the second restricting member abuts against the particle carrier from below.

5. A configuration is provided in which only the particle carrier and the regulating member abut on the particle supply rotor, A particle layer forming apparatus as described in any one of claims 1 to 4, characterized in that there is no component that abuts against the particle carrier downstream in the rotational direction of the particle carrier from the abutment portion, and upstream in the rotational direction of the particle carrier from the portion where the particle carrier abuts or faces the supply object.

6. 6. The particle layer forming device according to claim 1, wherein the regulating member is a mesh-like member having a plurality of circular holes formed over the entire surface thereof.

7. When the hole diameter of the hole portion is defined as M and the particle diameter of the particles is defined as D, the restricting member has the following properties: D<M<5×D 7. The particle layer forming apparatus according to claim 6, wherein the following relationship holds:

8. 8. The particle layer forming apparatus according to claim 1, wherein the regulating member is formed so as to extend in an arc shape along the outer circumferential surface of the particle supply rotor.

9. A particle layer forming apparatus as described in any one of claims 1 to 8, characterized in that an electric field is formed between the particle supply rotor and the regulating member so as to move the particles carried on the particle supply rotor away from the regulating member.

10. A developing device as the particle layer forming device according to any one of claims 1 to 9, forming a toner image as a particle layer on the latent image formed on the surface of the photosensitive member as the toner supply member; The developing device is characterized in that the particle carrier is a developing roller that carries toner.

11. An image forming apparatus comprising: the developing device according to claim 10; and the photosensitive member.

12. 12. The image forming apparatus according to claim 11, wherein the developing device is configured to be able to collect untransferred toner remaining on the surface of the photosensitive member.

Images