Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent an increase in torque of a developer carrier and the occurrence of an image defect.SOLUTION: An image forming apparatus comprises an image forming unit. The image forming unit includes an image carrier, an electrifying device, an exposure device, and a developing device. The developing device has a developer container, a developer carrier, and a regulation member. The developer container stores one-component developer including toner. Resin fine particles are externally added to the surface of the toner. A coating forming unit coats the surface of the developer carrier or the regulation member with the resin fine particles. A control unit controls the image forming unit and the coating forming unit. The control unit can execute an image forming mode for forming an image and a coating mode for coating the surface of the developer carrier or the regulation member with the resin fine particles.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A conventional image forming apparatus is disclosed in Patent Document 1. This image forming apparatus includes an image forming unit. The image forming unit includes an image carrier, a charging device, an exposure device, and a developing device. The image carrier has a photosensitive layer formed on its surface. The charging device charges the surface of the image carrier. The exposure device exposes the image carrier charged by the charging device to light to form an electrostatic latent image. The developing device forms a toner image by attaching toner to the electrostatic latent image formed on the image carrier.

[0003] The developing device has a developing container, a developer carrier, and a regulating member. The developing container contains a one-component developer containing toner. The developer carrier is rotatably supported in the developing container and is disposed opposite the image carrier, carrying toner on its outer circumferential surface as it rotates, thereby supplying toner to the image carrier. The regulating member contacts the outer circumferential surface of the developer carrier to adjust the thickness of the toner layer formed on the outer circumferential surface of the developer carrier. Resin fine particles are externally added to the surface of the toner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-180910 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of Patent Document 1, components contained in the toner other than the resin particles may adhere to the surface of the developer carrier or the regulating member, which may increase the torque of the developer carrier. Also, there is a possibility that image defects such as white spots or white streaks may occur in solid images.

[0006] SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image forming apparatus capable of suppressing an increase in the torque of a developer carrier and the occurrence of image defects. [Means for solving the problem]

[0007] In order to achieve the above object, a first aspect of the present invention is an image forming apparatus having an image forming unit. The image forming unit includes an image carrier, a charging device, an exposure device, and a developing device. The image carrier has a photosensitive layer formed on its surface. The charging device charges the surface of the image carrier. The exposure device exposes the image carrier charged by the charging device to light to form an electrostatic latent image. The developing device forms a toner image by attaching toner to the electrostatic latent image formed on the image carrier. The developing device includes a developing container, a developer carrier, and a regulating member. The developing container contains a one-component developer containing toner. The developer carrier is rotatably supported in the developing container and disposed opposite the image carrier. The developer carrier carries toner on its outer circumferential surface and rotates to supply toner to the image carrier. The regulating member contacts the outer circumferential surface of the developer carrier to adjust the thickness of the toner layer formed on the outer circumferential surface of the developer carrier. Resin fine particles are externally added to the surface of the toner. The device further includes a coating forming unit and a control unit, and the coating forming unit coats the surface of the developer carrier or the regulating member with resin particles. The control unit controls the image forming unit and the coating forming unit. The control unit is capable of executing an image forming mode for forming an image and a coating mode for coating the surface of the developer carrier or the regulating member with resin particles. [Effects of the Invention]

[0008] According to the first aspect of the present invention, it is possible to provide an image forming apparatus that can suppress an increase in the torque of the developer carrier and the occurrence of image defects. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side cross-sectional view showing the internal configuration of an image forming apparatus 100 according to an embodiment of the present invention. [Figure 2]FIG. 1 is a partially enlarged view of the periphery of an image forming unit 300 including a control path of an image forming apparatus 100 according to an embodiment of the present invention. [Figure 3] Schematic diagram of toner contained in a developing device 1 according to an embodiment of the present invention. [Figure 4] A flowchart showing an example of the execution of an operation in the image forming apparatus 100 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An image forming apparatus equipped with a developing device according to this embodiment will be described below using a monochrome printer as an example.

[0011] <Overall configuration of image forming apparatus> 1 is a side cross-sectional view showing the internal configuration of an image forming apparatus 100 of this embodiment. The image forming apparatus 100 includes an image forming section 300 and a paper feed cassette 200.

[0012] Paper feed cassette 200 is detachably attached to the main body of image forming apparatus 100. Paper feed cassette 200 stores sheets (not shown). When printing in image forming apparatus 100, the sheets in paper feed cassette 200 are used. Sheets that can be used for printing include copy paper, coated paper, overhead projector sheets, cardboard, postcards, tracing paper, and the like.

[0013] The paper feed cassette 200 has a lift plate 201 inside. The sheets in the paper feed cassette 200 are placed on the lift plate 201. The lift plate 201 pivots around one end (the upstream side in the paper feed direction, the rear end side of the sheets) as a fulcrum, swinging the other end (the downstream side in the paper feed direction, the front end side of the sheets) up and down.

[0014] A paper feed roller 202 is provided on the downstream side of the paper feed cassette 200 in the paper feed direction (the sheet feed port). When the lift plate 201 rises, the sheet on the lift plate 201 comes into contact with the outer circumferential surface of the paper feed roller 202. The paper feed roller 202 rotates with the sheet in contact with it. This causes the sheet to be fed out of the paper feed cassette 200.

[0015] Image forming unit 300 receives a sheet fed from paper feed cassette 200. Image forming unit 300 forms a toner image and transfers it onto the sheet. Image forming unit 300 includes a photosensitive drum (image carrier) 301, a charging device 303, an exposure device 304, a developing device 1, and a fixing unit 400.

[0016] The photosensitive drum 301 is rotatably supported and has a photosensitive layer formed on its surface. The transfer roller 302 is pressed against the outer circumferential surface of the photosensitive drum 301, forming a transfer nip between the photosensitive drum 301 and the transfer roller 302.

[0017] Charging device 303 charges the outer peripheral surface of photosensitive drum 301. Exposure device 304 exposes photosensitive drum 301 charged by charging device 303 to light to form an electrostatic latent image. Developing device 1 forms a toner image by attaching toner to the electrostatic latent image formed on the image carrier. The configuration of developing device 1 will be described in detail later.

[0018] Fixing section 400 includes a fixing roller 401 and a pressure roller 402. Fixing roller 401 has a built-in heater. Pressure roller 402 is in pressure contact with fixing roller 401, forming a fixing nip between itself and fixing roller 401.

[0019] A sheet fed from the paper feed cassette 200 enters the transfer nip. As the sheet passes through the transfer nip, an image is printed on the sheet. Specifically, the toner image on the outer peripheral surface of the photosensitive drum 301 is transferred to the sheet. The sheet then enters the fixing nip, where it is heated and pressurized. This fixes the toner image to the sheet. After passing through the fixing nip, the printed sheet is discharged onto the discharge tray ET.

[0020] <Configuration of the developing device> 2 is a partially enlarged view of the periphery of the image forming unit 300, including the control path of the image forming apparatus 100. The image forming apparatus 100 further includes a development voltage power supply 43, a coating power supply (coating forming unit) 44, a torque measuring unit 40, and a main control unit (control unit) 80.

[0021] The developing device 1 is a developing device for non-magnetic one-component development. The developing device 1 has a developing container 10, a supply roller 11, a developing roller (developer carrier) 12, a regulating blade (regulating member) 13, and a sealing member 14. The developing container 10 contains one-component developer including toner. Specifically, the developing container 10 includes a support member 110 and a cover member 120. The developing container 10 has an internal storage space formed by combining the support member 110 and the cover member 120. The toner is stored in the storage space of the developing container 10.

[0022] An agitating paddle SP is provided in the storage space of the developing container 10. The agitating paddle SP agitates the toner in the storage space. Note that a toner supply device (not shown) supplies toner from a toner container to the developing container 10.

[0023] The developing container 10 has an opening on the side where the photosensitive drum 301 is disposed. The opening of the developing container 10 serves as a supply port for toner to the photosensitive drum 301.

[0024] The supply roller 11 and the developing roller 12 are arranged in this order from the inside (i.e., the storage space) of the developing container 10 to the outside. The developing roller 12 is arranged so that its outer circumferential surface 20 faces the outer circumferential surface of the supply roller 11. The developing roller 12 is rotatably supported in the developing container 10, and is arranged facing the photosensitive drum 301, and supplies the toner to the photosensitive drum 301 by rotating while carrying toner on its outer circumferential surface.

[0025] The supply roller 11 is rotatably supported by the developing container 10. The supply roller 11 rotates in one direction (counterclockwise in FIG. 2). The supply roller 11 carries the toner in the storage space on its outer circumferential surface. The supply roller 11 supplies the toner to the developing roller 12 by rotating with the toner carried on its outer circumferential surface.

[0026] The developing roller 12 is pressed against the photosensitive drum 301 with a predetermined pressure. The developing roller 12 is rotatably supported by a support member 110. That is, the developing roller 12 is rotatably supported in the developer container 10. The developing roller 12 rotates in the same direction as the supply roller 11 (counterclockwise in FIG. 2). At the position where the supply roller 11 and the developing roller 12 face each other, the moving direction of the outer circumferential surface 20 of the developing roller 12 is opposite to the moving direction of the outer circumferential surface of the supply roller 11.

[0027] Developing roller 12 receives toner supplied from supply roller 11 and carries the toner on its outer circumferential surface 20. Developing roller 12 carries the toner on its outer circumferential surface 20 and rotates to supply the toner to photosensitive drum 301.

[0028] The developing voltage power supply 43 is connected to the developing roller 12 (see FIG. 2). During image formation, the developing voltage power supply 43 applies a developing voltage, which is a DC voltage superimposed on an AC voltage, to the developing roller 12. This allows the toner to be efficiently transferred from the developing roller 12 to the photosensitive drum 301.

[0029] The developing roller 12 has a rotating shaft (reference number omitted) and a roller member (reference number omitted) attached to the rotating shaft. The roller member rotates together with the rotating shaft. The roller member is cylindrical. For example, the roller member is a member in which a urethane coating is applied to the surface of a base layer such as silicone rubber. The outer peripheral surface of the roller member is formed with irregularities. A toner layer is formed on the outer peripheral surface 20 of the developing roller 12.

[0030] The torque measuring unit 40 is connected to the developing roller 12 and measures the rotation torque of the developing roller 12 .

[0031] The regulating blade 13 is a leaf spring. Specifically, the regulating blade 13 is a plate-shaped member made of metal. The regulating blade 13 is thin and made of a stainless steel plate. The constituent material of the regulating blade 13 is not particularly limited.

[0032] When viewed from the direction of the rotation axis of the developing roller 12, the regulating blade 13 has one end 131 fixed to the developing container 10. When viewed from the direction of the rotation axis of the developing roller 12, the regulating blade 13 extends from the fixed position relative to the developing container 10 toward the developing roller 12, and the other end 132 opposite to the one end 131 is disposed on the outer circumferential surface 20 of the developing roller 12. In other words, the one end 131 is a fixed end, and the other end 132 is a free end. The other end 132 of the regulating blade 13 comes into contact with the outer circumferential surface 20 of the developing roller 12.

[0033] The regulating blade 13 comes into contact with the outer peripheral surface 20 of the developing roller 12 at a position upstream in the rotation direction of the developing roller 12 from the position where the developing roller 12 faces the photosensitive drum 301. The regulating blade 13 comes into contact with the outer peripheral surface 20 of the developing roller 12 at a predetermined linear pressure (regulating pressure) and bends.

[0034] By bringing the regulating blade 13 into contact with the outer peripheral surface 20 of the developing roller 12, excess toner on the outer peripheral surface 20 of the developing roller 12 is scraped off. As a result, the toner layer formed on the outer peripheral surface 20 of the developing roller 12 can be adjusted to a uniform thickness. That is, the regulating blade 13 contacts the outer peripheral surface 20 of the developing roller 12 to adjust the thickness of the toner layer formed on the outer peripheral surface 20 of the developing roller 12 (i.e., the amount of toner carried on the outer peripheral surface 20 of the developing roller 12). As the toner layer on the outer peripheral surface 20 of the developing roller 12 passes through the regulating blade 13, frictional charging occurs between the regulating blade 13 and the toner, and between the outer peripheral surface 20 of the developing roller 12 and the toner.

[0035] The coating power supply 44 is connected to the regulating blade 13 (see FIG. 2). When a coating mode, which will be described later, is executed, the coating power supply 44 applies a coating voltage, which is a DC voltage superimposed with an AC voltage, to the regulating blade 13.

[0036] The sealing member 14 is fixed to the support member 110 so as to contact the outer peripheral surface 20 of the developing roller 12. The sealing member 14 closes the gap between the outer peripheral surface 20 of the developing roller 12 and the support member 110. This makes it possible to suppress leakage of toner from the gap between the outer peripheral surface 20 of the developing roller 12 and the support member 110. In other words, it is possible to suppress leakage of toner from the inside of the developing container 10 to the outside.

[0037] The image forming apparatus 100 is provided with a main control unit 80 that is configured with a CPU and the like. The main control unit 80 is connected to a storage unit 70 that is configured with a ROM, RAM and the like. The main control unit 80 controls each unit of the image forming apparatus 100 (such as the charging device 303, the developing device 1, the exposure device 304, the transfer roller 302, the fixing unit 400, the developing voltage power supply 43, the coating power supply (coating forming unit) 44, and the voltage control unit 60) based on the control program and control data stored in the storage unit 70.

[0038] The voltage control unit 60 controls a development voltage power supply 43 that applies a development voltage to the development roller 12 and a coating power supply 44 that applies a coating voltage to the regulating blade 13. The voltage control unit 60 may be configured by a control program stored in the storage unit 70.

[0039] The main control unit 80 is connected to a liquid crystal display unit 90 and a transmission / reception unit 91. The liquid crystal display unit 90 functions as a touch panel for the user to make various settings for the image forming apparatus 100, and also displays the status of the image forming apparatus 100, the image formation status, the number of printed sheets, etc. The transmission / reception unit 91 communicates with the outside world using a telephone line or an internet line.

[0040] As mentioned above, there is a possibility that components (wax components) other than the fluorine-based resin particles contained in the toner may adhere to the surface of the regulating blade 13, increasing the torque of the developing roller 12. In addition, there is a possibility that image defects such as white spots or white streaks may occur in a solid image.

[0041] In this embodiment, the main control section (control section) 80 is capable of executing an image forming mode in which an image is formed, and a coating mode in which the surface of the developing roller 12 is coated with fluorine-based resin particles.

[0042] By executing the coating mode and coating the surface of the regulating blade 13 with fluorine-based resin particles, it is possible to reduce the adhesion of components contained in the toner other than the fluorine-based resin particles to the surface of the regulating blade 13. This makes it possible to suppress an increase in the torque of the developing roller 12 and the occurrence of image defects.

[0043] Here, toner with a core-shell structure is used in development by the developing device 1. A schematic diagram of the core-shell structure is shown in Fig. 3. In Fig. 3, the toner is designated by the reference numeral 50.

[0044] The toner 50 having a core-shell structure has a toner core 51 and a shell layer 52. The shell layer 52 covers the toner core 51.

[0045] The toner core 51 contains a binder resin. The toner core 51 may contain internal additives (for example, a colorant, a release agent, a charge control agent, and a magnetic powder). The shell layer 52 may be made of at least one of a thermosetting resin and a thermoplastic resin.

[0046] An external additive (not shown) is added to the surface of the toner 50. That is, the external additive is added to the shell layer 52. There are no particular limitations on the constituent material of the external additive.

[0047] In this embodiment, silica particles and negatively charged fluorine-based resin particles (resin fine particles) are externally added to the surface of the toner 50. The silica particles impart fluidity to the toner particles. The silica particles are preferably subjected to a surface treatment that imparts positive charging properties. The number-average primary particle diameter of the silica particles is preferably 10 nm or more and 40 nm or less. By making the number-average primary particle diameter of the silica particles 10 nm or more, it is possible to prevent the silica particles from being embedded in the toner cores (toner mother particles) 51.

[0048] Furthermore, by setting the number average primary particle diameter of the silica particles to 40 nm or less, it is possible to prevent the silica particles from being liberated from the toner 50 .

[0049] Examples of fluorine-based resin particles include particles of polytetrafluoroethylene (PTFE, "tetrafluoroethylene resin"), perfluoroalkoxy fluororesin, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, etc. Among these, polytetrafluoroethylene (PTFE) is preferred.

[0050] The number average particle size of the fluororesin particles is preferably 100 nm or more and 300 nm or less, where the number average particle size is calculated by averaging the particle sizes of primary particles measured from a scanning electron microscope photograph.

[0051] Polytetrafluoroethylene (PTFE) that is suitably used is preferably in the form of particles having a nearly spherical shape produced by emulsion polymerization. Examples of such commercially available products include "KTL-500F" (Kitamura Co., Ltd., number average particle size 300 nm), "Lubron L2" (Daikin Industries, Ltd., number average particle size 300 nm), "Lubron L5" (Daikin Industries, Ltd., number average particle size 200 nm), "Fluon Lubricant L1170J" (Asahi ICI Fluoropolymers Co., Ltd., number average particle size 100 nm), "Fluon Lubricant L172J" (Asahi ICI Fluoropolymers Co., Ltd., number average particle size 0.1 μm), "MP-1100" (DuPont-Mitsui Fluorochemicals Co., Ltd., number average particle size 200 nm), "MP-1200" (DuPont-Mitsui Fluorochemicals Co., Ltd., number average particle size 300 nm), and "TLP-10F-1" (DuPont-Mitsui Fluorochemicals Co., Ltd., number average particle size 200 nm).

[0052] In this embodiment, in the coating mode, while the image formation operation is stopped, the developing roller 12 is rotated, and the coating power supply (coating forming unit) 44 applies a voltage to the regulating blade 13 to form a potential difference between the developing roller 12 and the regulating blade 13.

[0053] At this time, the fluororesin particles have a strong negative charge and a weaker adhesion strength than silica particles. Therefore, when a potential difference is formed between the developing roller 12 and the regulating blade 13, the fluororesin particles added to the toner 50 are released from the toner and move to the surface of the regulating blade 13. At this time, the fluororesin particles are fixed to the surface of the regulating blade 13 by the rotation of the developing roller 12 and a predetermined linear pressure (regulating pressure) applied to the regulating blade 13. As a result, the surface of the regulating blade 13 is efficiently coated with the fluororesin particles, thereby shortening the execution time of the coating mode.

[0054] Furthermore, in the coating mode, the potential difference between the developing roller 12 and the regulating blade 13 is preferably such that the developing roller 12 has a lower potential than the regulating blade 13. This allows the negatively charged fluorine-based resin particles to be efficiently moved to the regulating blade 13.

[0055] Furthermore, it is preferable that the rotation speed of the developing roller 12 during the coating mode is slower than the rotation speed of the developing roller 12 during the image formation mode. This lengthens the time that the regulating blade 13 is in contact with a predetermined rotation position of the developing roller 12, ensuring a longer time for coating with the fluororesin particles. Therefore, the surface of the regulating blade 13 is more efficiently coated with the fluororesin particles.

[0056] Furthermore, when executing the coating mode, the main control unit (control unit) 80 preferably rotates the developing roller 12 for a predetermined time before forming a potential difference between the developing roller 12 and the regulating blade 13. By rotating the developing roller 12, friction occurs between the developing roller 12 and the regulating blade 13, making it easier for the fluorine-based resin particles to be liberated from the toner between the developing roller 12 and the regulating blade 13. Therefore, the liberated fluorine-based resin particles can be efficiently coated onto the regulating blade 13.

[0057] Furthermore, the coating power supply 44 applies a coating voltage in which an AC voltage is superimposed on a DC voltage, and the frequency of the AC voltage of the coating voltage in the coating mode is preferably lower than the frequency of the AC voltage of the developing voltage in the image formation mode. By applying a coating voltage in which an AC voltage is superimposed on a DC voltage to the regulating blade 13 in the coating mode, the fluororesin particles are more likely to be released from the toner by the instantaneous energy of the AC voltage. Furthermore, by making the frequency of the AC voltage of the coating voltage lower than the frequency of the AC voltage of the developing voltage, the application time of the electric field in one direction is extended, and the released fluororesin particles can be efficiently coated on the regulating blade 13.

[0058] Furthermore, as the number of printed pages increases due to the execution of the image formation mode, the silica particles become embedded in the toner core 51, increasing their adhesive strength. At this time, components (wax components) other than the fluorine-based resin fine particles contained in the toner bleed out and become more likely to adhere to the regulating blade 13. For this reason, it is preferable to coat the surface of the regulating blade 13 with more fluorine-based resin particles as the number of printed pages increases.

[0059] In this embodiment, the main control unit (control unit) 80 sets the execution time of the coating mode to be longer as the upper limit of the number of printed pages (the set number of pages within the durability life of the cartridge-type replaceable developer container 10) predetermined based on the volume of developer contained in the developer container 10 is approached. This allows more fluororesin particles to be coated on the surface of the regulating blade 13 as the number of printed pages increases. This makes it possible to prevent components other than the fluororesin fine particles (wax components) from bleeding out and adhering to the regulating blade 13.

[0060] Furthermore, the main control unit (control unit) 80 may execute the next coating mode if the total number of prints after the previous coating mode execution exceeds a preset number, thereby preventing unnecessary execution of the coating mode.

[0061] On the other hand, coated fluororesin particles have low surface free energy, and the frictional resistance decreases as the coating thickness increases. In this embodiment, the main control unit (control unit) 80 ends the execution of the coating mode when the measurement result of the torque measurement unit 40 becomes equal to or less than a predetermined value.

[0062] By terminating the execution of the coating mode when the measurement result of the torque measurement unit 40 falls below a predetermined value, the execution time of the coating mode can be shortened, thereby shortening the waiting time of the user and suppressing deterioration of the toner 50.

[0063] Furthermore, it is preferable that the main control unit (control unit) 80 determines that the thickness of the fluorine-based resin particle coating on the regulating blade 13 has decreased when the measurement result of the torque measurement unit 40 becomes greater than a predetermined value, and starts the execution of the coating mode, thereby preventing unnecessary execution of the coating mode.

[0064] Furthermore, when continuous printing is performed during execution of the image forming mode, the main control section (control section) 80 may execute the coating mode within the paper interval time, thereby shortening the user's waiting time.

[0065] 4 is a flowchart showing an example of the execution of an image forming operation in image forming apparatus 100. In step S1, a normal image forming mode is executed, and the process proceeds to step S2. In step S2, main control unit (control unit) 80 determines whether the thickness of the fluorine-based resin particle coating on regulating blade 13 has decreased based on the detection result of torque measurement unit 40. If it is determined that the thickness of the fluorine-based resin particle coating on regulating blade 13 has decreased, the process proceeds to step S3. On the other hand, if it is determined that the thickness of the fluorine-based resin particle coating on regulating blade 13 has not decreased, the print job is terminated.

[0066] In step S3, the main control unit (control unit) 80 executes the coating mode, rotates the developing roller 12, and applies a coating voltage from the coating power supply 44 to the regulating blade 13. This creates a potential difference between the developing roller 12 and the regulating blade 13, causing the fluororesin particles to be liberated from the toner and move to the surface of the regulating blade 13. At this time, the fluororesin particles are fixed to the surface of the regulating blade 13 by the rotation of the developing roller 12 and a predetermined linear pressure (regulating pressure) applied to the regulating blade 13. As a result, the surface of the regulating blade 13 is coated with the fluororesin particles.

[0067] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the present invention is not limited to the monochrome printer shown in Fig. 1, but can also be applied to various image forming apparatuses that use an intermediate transfer method in which a toner image formed on a photosensitive drum is primarily transferred onto an intermediate transfer belt, such as a color printer, a copier, or a color multifunction printer.

[0068] Furthermore, in this embodiment, by executing the coating mode, the coating power supply (coating forming unit) 44 applies a voltage to the regulating blade 13 to form a potential difference between the developing roller 12 and the regulating blade 13, thereby coating the surface of the regulating blade 13 with fluorine-based resin particles, but the surface of the developing roller 12 may also be coated with fluorine-based resin particles. This makes it possible to reduce the adhesion of components other than the fluorine-based resin particles contained in the toner to the regulating blade 13 onto the surface of the developing roller 12. This makes it possible to suppress an increase in the torque of the developing roller 12 and the occurrence of image defects.

[0069] In this case, the potential difference between the developing roller 12 and the regulating blade 13 in the coating mode is preferably such that the developing roller 12 has a higher potential than the regulating blade 13. This allows the negatively charged fluorine-based resin particles to be efficiently moved to the developing roller 12.

[0070] Furthermore, in this embodiment, the thickness of the toner layer is adjusted using the regulating blade 13, but the thickness of the toner layer may be adjusted using a roller-shaped regulating member instead of the regulating blade. [Industrial Applicability]

[0071] The present invention can be used in developing devices and image forming apparatuses. [Explanation of symbols]

[0072] 1. Developing device 10 Developer container 11 Supply roller 12 Developing roller (developer carrier) 13 Regulating blade (regulating member) 14 Sealing material 20 Outer surface 40 Torque measurement unit 43 Development voltage power supply 44 Coating power supply (coating forming section) 50 toner 51 Toner Core 52 Shell Layer 60 Voltage control section 70 Memory section 80 Main control unit 90 LCD display section 91 Transmitter / Receiver 100 Image forming device 110 Support member 120 Cover member 131 One end 132 Other end 200 Paper Cassette 201 Lift Board 202 Paper feed roller 300 Image forming unit 301 Photosensitive drum (image carrier) 302 Transfer roller 303 Charging device 304 Exposure equipment 400 Fixing unit 401 Fuser roller 402 Pressure roller ET Output Tray SP Stirring Paddle

Claims

1. an image carrier having a photosensitive layer formed on its surface; a charging device that charges the surface of the image carrier; an exposure device that exposes the surface of the image carrier charged by the charging device to light to form an electrostatic latent image; a developing device that forms a toner image by attaching toner to the electrostatic latent image formed on the image carrier; In an image forming apparatus having an image forming unit including: The developing device is a developer container containing a one-component developer containing the toner; a developer carrier that is rotatably supported by the developing container, is disposed opposite the image carrier, and carries the toner on its outer circumferential surface while rotating, thereby supplying the toner to the image carrier; a regulating member that contacts the outer peripheral surface of the developer carrier and adjusts the thickness of the toner layer formed on the outer peripheral surface of the developer carrier, The toner surface has resin fine particles externally added thereto, a coating forming section that coats the resin fine particles on the surface of the developer carrier or the regulating member; a control unit that controls the image forming unit and the coating forming unit, The control unit an image forming mode for forming an image; a coating mode in which the surface of the developer carrier or the regulating member is coated with the resin fine particles.

2. the resin fine particles have negative charging properties, the coating forming section forms a potential difference between the developer carrier and the regulating member, 2. The image forming apparatus of claim 1, wherein in the coating mode, when the resin microparticles are coated on the surface of the developer carrier, the developer carrier has a higher potential than the regulating member, and when the resin microparticles are coated on the surface of the regulating member, the developer carrier has a lower potential than the regulating member.

3. 3. The image forming apparatus according to claim 2, wherein the coating forming section applies a voltage to the regulating member to form a potential difference between the developer carrier and the regulating member.

4. the control unit rotates the developer carrier when the coating mode is executed, 3. The image forming apparatus according to claim 1, wherein the rotation speed of said developer carrier during execution of said coating mode is slower than the rotation speed of said developer carrier during execution of said image forming mode.

5. 4. The image forming apparatus according to claim 2, wherein the control unit, when executing the coating mode, rotates the developer carrier for a predetermined time before forming a potential difference between the developer carrier and the regulating member.

6. a developing voltage power supply that applies a developing voltage, which is a DC voltage superimposed on an AC voltage, to the developer carrier; the reduced development voltage power supply applies the development voltage to the developer carrier when the image forming mode is executed; the coating forming unit applies a coating voltage in which an AC voltage is superimposed on a DC voltage to form a potential difference between the developer carrier and the regulating member; 4. The image forming apparatus according to claim 2, wherein a frequency of the AC voltage of the coating voltage when the coating mode is performed is lower than a frequency of the AC voltage of the development voltage when the image forming mode is performed.

7. 3. The image forming apparatus according to claim 1, wherein the control unit sets the execution time of the coating mode to be longer as the number of printed sheets approaches an upper limit value that is predetermined based on the volume of the developer contained in the developing container.

8. a torque measuring unit for measuring a rotation torque of the developer carrier; 3. The image forming apparatus according to claim 1, wherein the control unit terminates the execution of the coating mode when the measurement result of the torque measurement unit becomes equal to or less than a predetermined value.

9. 3. The image forming apparatus according to claim 1, wherein the control unit executes the next coating mode when a total number of prints after the previous coating mode execution exceeds a preset number.

10. 3. The image forming apparatus according to claim 1, wherein the control unit executes the coating mode within an interval between sheets when a continuous printing operation is being performed during execution of the image forming mode.

Images