JP2004046244A - Toner carrying device, image forming unit, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade foreign substances such as paper powder mixed into toner returned from a cleaning device to a developing device from clogging between a developing sleeve and a doctor blade or between the developing sleeve and a photoreceptor, and to prevent a toner image formed on the photoreceptor from being striped caused by the foreign substances. <P>SOLUTION: The image forming unit 1 is provided with the developing sleeve 11 opposed to the photoreceptor 7 at a certain gap and the doctor blade 14 opposed to the developing sleeve 11 at a certain gap. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an image carrier on which an electrostatic latent image is formed, a developing device for visualizing the electrostatic latent image as a toner image, and an image carrier after transferring the toner image to a transfer material. A cleaning device that removes and collects toner remaining in the developing device, and a toner returning device that returns the toner to the developing device so that the toner removed by the cleaning device can be reused in the developing device. A developer transport member that is opposed to the image carrier and carries and transports the developer toward a development area where the electrostatic latent image is visualized; and a developer transport member that transports the developer toward the development area. The present invention relates to an image forming apparatus having an agent regulating unit for regulating an amount.

In an image forming apparatus of the above type configured as a copier, a printer, a facsimile or a multifunction peripheral thereof, the toner removed from the surface of the image carrier is transported to a developing device by a toner returning device, and the toner is transferred to the developing device. Can be reused. According to such an image forming apparatus, it is possible to reduce the economic burden on the user and to reduce the amount of waste as compared with an image forming apparatus in which the toner removed from the surface of the image carrier is discarded.

However, the problem here is that foreign matter such as paper dust and debris from the surface layer of the image carrier is mixed in the toner removed from the image carrier. Paper dust is floating in the image forming apparatus main body, and when such paper dust adheres to the image carrier, or when paper dust of transfer paper to which a toner image is transferred at the time of transfer adheres to the image carrier, This is removed together with the residual toner from the image carrier by the cleaning device. Further, when a part of the surface layer of the image carrier is peeled off, the peeled fragments are removed from the image carrier together with the residual toner by the cleaning device.

In the toner collected by the cleaning device in this manner, paper dust, debris separated from the surface layer of the image carrier, and the like are mixed, and when the toner is returned to the developing device, the developer conveying member and Foreign matter, such as paper dust or delamination fragments of the image carrier, is clogged between the toner carrier and the agent regulating means, and due to the influence of the foreign matter, linear streaks lacking toner are formed on the toner image formed on the image carrier. Image quality is degraded. Further, even if foreign matter between the image carrier and the developer conveying member is clogged, linear streaks are similarly formed on the toner image, and the image quality is deteriorated.

However, in the conventional image forming apparatus, the relationship between the gap between the developer conveying member in the developing device and the agent regulating means opposed thereto, and the gap between the developer conveying member and the image carrier. Since no particular consideration has been given to the above, there is a possibility that the foreign matter may be clogged between the developer conveying member and the agent regulating unit or between the developer conveying member and the image carrier. When such clogging occurs, as described above, the toner image formed on the image carrier has a linear streak lacking toner due to the influence of the foreign matter, and the image quality deteriorates.

The present invention has been made based on the above-described novel recognition, and an object of the present invention is to eliminate the above-described conventional disadvantages and remove paper dust and the like mixed in the toner returned from the cleaning device to the developing device. Foreign matter can be prevented from clogging between the developer conveying member and the agent regulating unit or between the developer conveying member and the image carrier, and a problem that a streak in a toner image due to the foreign matter can be prevented. An object of the present invention is to provide an image forming apparatus.

In order to achieve the above object, the present invention provides an image carrier on which an electrostatic latent image is formed, a developing device for visualizing the electrostatic latent image as a toner image, and transferring the toner image to a transfer material. A cleaning device that removes and collects the toner remaining on the image carrier after the cleaning, and a toner return device that returns the toner to the developing device in order to reuse the toner removed by the cleaning device in the developing device. The developing device is opposed to the surface of the image bearing member with a gap, and carries the developer toward a developing region where the electrostatic latent image is visualized in the gap region. A developer conveying member that conveys the developer and the developer conveying member; and a developer regulating unit that is opposed to the surface of the developer conveying member with a gap therebetween and regulates an amount of the developer that is conveyed to the developing area. Image forming apparatus Suggest (claim 1).

In this case, in the image forming apparatus according to claim 1, the gap between the image carrier and the developer transport member and the gap between the developer transport member and the developer regulating unit are gaps larger than zero. Therefore, it is advantageous to set the gap to 2 mm or less (claim 2).

In the image forming apparatus according to the second aspect, it is advantageous that both gaps are set to 20 μm or more.

Further, in the image forming apparatus according to any one of claims 1 to 3, at least a developer case of the developing device, a cleaning case of the cleaning device, and a casing that defines a toner conveying path of the toner returning device are integrated. Is advantageously formed (claim 4).

According to the image forming apparatus of the present invention, when foreign matters such as paper dust and delamination fragments of the surface layer of the image carrier are mixed in the toner returned from the cleaning device to the developing device, Can be prevented from clogging between the image carrier and the developer transporting member and between the developer transporting member and the developer regulating means, and image quality can be prevented from deteriorating due to the clogging.

According to the image forming apparatus of the second aspect, foreign matter such as paper dust and photosensitive layer peeling fragments is generated by the gap between the image carrier and the developer transport member and the gap between the developer transport member and the developer regulating unit. It is possible to effectively prevent clogging in the gap between them, and prevent image quality from deteriorating due to the clogging. Moreover, the agent regulating function and the developing function are not impaired.

According to the image forming apparatus of the third aspect, clogging at each gap, such as paper dust and delamination fragments of the surface layer of the image carrier, can be more effectively prevented, and the image quality is reduced due to the clogging. Deterioration can be prevented.

According to the image forming apparatus of the fourth aspect, it is possible to prevent the developer from leaking when the developing device, the cleaning device, the toner returning device, and the like are separately assembled, and to reduce the number of parts of the image forming device. And the cost can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the inside of an image forming apparatus according to an embodiment of the present invention from the front side. The image forming apparatus shown here is configured as a copying machine, and this copying machine can have functions such as a printer and a facsimile. As shown in FIG. 1, an image forming unit 1 is detachably mounted on the image forming apparatus main body 100.

FIG. 2 is a vertical sectional view of the image forming unit 1 mounted on the image forming apparatus main body 100 as shown in FIG. 1, and FIG. 3 is an external perspective view of the image forming unit 1. The image forming unit 1 is pushed into the image forming apparatus main body 100 in a direction indicated by an arrow A in FIG. 3 (a direction perpendicular to the paper surface of FIG. 1), so that the image forming unit 1 is moved to FIGS. The image forming unit 1 can be taken out from the image forming apparatus main body 100 by loading and setting it at a predetermined position in the image forming apparatus main body shown in the figure and pulling out the image forming unit 1 in the direction opposite to the arrow A.

As shown in FIGS. 2 and 3, the image forming unit 1 includes a unit case 2 and various image forming elements described later incorporated therein, and the unit case 2 illustrated as an example in FIG. 3, a case cover 4 mounted thereon, a developing case cover 5 forming an upper wall of the developing device described later, and a part of an upper wall of a toner conveying path and a part of the upper wall of the developing device also described later. The case cover 4, the developing case cover 5, and the upper cover 6 are detachably locked to the case body 3 by snap-fitting (so-called patching). The opening 16 (FIG. 3) formed in the developing case cover 5 is covered by a developer cartridge 43 (FIG. 2).

FIG. 4 is an external perspective view showing a state in which the case cover 4, the developing case cover 5, and the upper cover 6 shown in FIGS. 2 and 3 are removed from the case body 3, and FIG. It is sectional plan view.

A drum-shaped photoconductor 7 as an example of an image carrier and a charging roller 8 as an example of a charging device are rotatably mounted in the unit case 2, and the charging roller 8 is attached to the photoconductor 7. It extends parallel to it. FIG. 4 illustrates the charging roller 8 in a state where the charging roller 8 is separated from the photoconductor 7.

During the image forming operation, the photoconductor 7 is driven to rotate clockwise in FIG. 2 by a driving device (not shown), and at this time, static elimination light L1 from a static elimination device (not shown) supported by the image forming apparatus main body 100 is emitted. Then, the light enters the unit case 2 through an opening 34 formed in the case cover 4 and irradiates the surface of the photoconductor 7. As a result, the surface potential of the photoconductor 7 is averaged to a reference potential of, for example, 0 to -150V.

On the other hand, the charging roller 8 is pressed against the surface of the photoreceptor 7 and uniformly charges the photoreceptor 7 such that the surface potential thereof is, for example, about -1100 V while being rotated by the rotation of the photoreceptor 7. . During this charging operation, a voltage is applied to the charging roller 8 from a power supply (not shown). Further, the charging roller 8 of this embodiment is mounted on the unit case 2 so as to be able to contact and separate from the photoconductor 7, and is separated from the photoconductor 7 when the charging operation on the photoconductor 7 is not performed.

(4) The exposed portion 9 irradiates the light-modulated laser beam L2 to the surface portion of the photoconductor 7 charged to a predetermined polarity as described above. The laser light L2 is emitted from the exposure optical system unit 32 (FIG. 1) supported by the image forming apparatus main body 100, and enters the unit case 2 through the opening 35 of the case cover 4. With this exposure, a predetermined electrostatic latent image is formed on the photoconductor 7. For example, the photoconductor portion (image portion) irradiated with the laser beam L2 has a surface potential of 0 to -290 V, and the photoconductor portion (background portion) not irradiated with the laser beam L2 has a surface potential of -1100 V described above. Maintain around the front and back. It is also possible to form an electrostatic latent image by illuminating a document (not shown) and forming a reflected light image on the photoreceptor 7.

On the other hand, the developing sleeve 11 (not shown in FIG. 4) of the developing device 10 is rotatably supported on the unit case 2 as shown in FIGS. The developing sleeve 11 is made of a non-magnetic material, and is rotated counterclockwise in FIG. 2 during an image forming operation. Further, a part of the case main body 3 in the unit case 2 and the developing case cover 5 (FIG. 3) covering the upper part thereof constitute a developer case 12 of the developing device 10, and the developer chamber of the developer case 12 A two-component developer D (FIG. 2) having a toner and a carrier is accommodated in 90. Inside the developing sleeve 11, a plurality of magnets indicated by reference numeral 13 are immovably arranged. A doctor blade 14 facing the developing sleeve 11 is fixed to an upper portion of the developer case 12. The toner and the carrier of the developer D are frictionally charged to opposite polarities by the stirring action, and in this example, the toner is negatively charged and the carrier is positively charged.

As the developing sleeve 11 rotates as described above, the developer D in the developer case 12 is conveyed while being carried on the developing sleeve 11 by the magnetic force of the magnet 13, and the amount of the conveyed developer is determined by the doctor. It is regulated by the scraping action of the blade 14. The regulated developer is carried to the developing area DA between the developing sleeve 11 and the photoconductor 7, and at this time, a developing bias voltage of, for example, about -800 V is applied to the developing sleeve 11, so that the developing area DA The negative polarity toner in the developer conveyed to the DA is electrostatically transferred to and adheres to the image portion on the photoconductor 7, and a predetermined toner image is formed on the photoconductor 7. The electrostatic latent image formed on the photoconductor 7 is visualized as a toner image.

As shown in FIG. 5, two stirring members 44 and 45 are arranged in the developer chamber 90 of the developer case 12, and these stirring members 44 and 45 are respectively connected to their respective shafts 63 and 64 and to the shafts 63 and 64. It has fixed stirring blades (not shown in FIG. 4) 65 and 66, each shaft 63 and 64 of which is rotatably supported by the unit case 2. The developer D is stirred while being conveyed as indicated by an arrow Y in FIG. Due to such a stirring action, the toner and the carrier are frictionally charged to opposite polarities as described above. When the toner concentration of the developer D is reduced, the toner supply chamber 68 in the unit case 2 from the toner bottle 67 set in the image forming apparatus main body 100 through the toner supply port 30 (FIG. 3) formed in the unit case 2. Is supplied to the developer chamber 90.

The developing sleeve 11 and a plurality of magnets 13 provided therein constitute an agent transporting unit that carries and transports a two-component developer used for development. In this example, the magnet 13 is fixed, The developing sleeve 11 is configured to be rotationally driven. Conversely, the magnet may be rotationally driven to fix the developing sleeve, or the magnet and the developing sleeve may be rotationally driven to rotate the developer. May be transported.

On the other hand, in the image forming apparatus main body 100, as shown in FIGS. 1 and 2, a transfer roller 15, which is an example of a transfer device, is rotatably supported opposite to the photoconductor 7.

As shown in FIG. 1, an appropriate number of paper feeders 33, 33a, 3b, and 33c are provided on the image forming apparatus main body side, and an example of a transfer material from the selected paper feeder 33, 33a, 33b, or 33c. Is transferred to the transfer section 22 (FIG. 2) between the photoconductor 7 and the transfer roller 15.

Each of the paper feeding devices 33, 33a, 33b, and 33c has paper feeding cassettes 36, 36a, 36b, and 36c containing transfer paper P of each size, and paper feeding rollers 37, 37a, 37b, and 37c, respectively. The paper feed roller of the fed paper feed device is driven to rotate, and the transfer paper in the paper feed cassette is fed one by one. For example, when the lowermost sheet feeding device 33c is selected, the sheet feeding roller 37c rotates and the transfer sheet P stored in the sheet feeding cassette 36c is conveyed by the series of conveying roller pairs 38 in the direction of arrow B. The sheet is conveyed along a path 39 and fed to the transfer section 22 (FIG. 2) between the photoconductor 7 and the transfer roller 15 at a predetermined timing by a pair of registration rollers 40.

As shown in FIG. 2, the transfer paper P fed as described above is moved between the photosensitive member 7 and the transfer roller 15 with the leading end thereof aligned with the leading end of the toner image formed on the photosensitive member 7 as shown in FIG. It passes through the transfer unit 22. The transfer roller 15 rotates counterclockwise in FIG. 2 while contacting the photoconductor 7 via the transfer paper P. At this time, since the transfer voltage is applied to the transfer roller 15, the toner on the photoconductor 7 The image is transferred to the transfer paper P.

The transfer paper P leaving the photoreceptor 7 is conveyed to the fixing device 41 as indicated by an arrow B1 in FIGS. 1 and 2, where the toner image is fused onto the transfer paper P by the action of heat and pressure. It is worn and fixed. The transfer paper P that has passed through the fixing device 41 is discharged as copy paper out of the image forming apparatus main body 100, and is stacked on a paper discharge tray 42.

In this example, transfer paper P was used as a transfer material, and the toner image on the photoconductor 7 was transferred to the transfer paper P. It is also possible to adopt a configuration in which the toner image on the intermediate transfer member is secondarily transferred to a transfer sheet, which is the final transfer material, after the primary transfer to the transfer member.

(2) The residual toner adhering to the photoconductor 7 after the transfer of the toner image is scraped off the surface of the photoconductor 7 by the cleaning blade 18 of the cleaning device 17 shown in FIG. In this way, the surface of the photoconductor 7 is cleaned, and the process proceeds to the next image forming operation again. The cleaning device 17 has a cleaning case 19 formed by a part of the case main body 3 in the unit case 2, and the toner T (FIG. 2) scraped off by the cleaning blade 18 is disposed in the cleaning case 19. The toner is discharged out of the cleaning device 17 by the rotation of the toner discharge member 20. The toner T removed from the photoconductor 7 by the cleaning device 17 is returned to the developing device 10 by a toner return device described later, and is reused here.

The toner discharging member 20 is formed in an appropriate form such as a toner conveying screw or a toner conveying coil extending parallel to the photoconductor 7 and extending over the entire length of the photoconductor 7. The cleaning blade 18 is an example of a cleaning member that cleans the surface of the photoconductor 7 after the transfer of the toner image, and is fixed and held on the case body 3.

The toner T scraped off from the photoreceptor 7 by the cleaning blade 18 of the cleaning device 17 shown in FIGS. 2 and 4 and collected in the cleaning case 19 is moved forward in the cleaning case 19 by the rotating toner discharging member 20. It is conveyed and discharged to the outside through a pipe 88 (FIG. 4) integrally projecting from the case 19. A gear (not shown) is fixed to a rear end portion of the toner discharge member 20, and the rotation of the photoconductor 7 is transmitted to the toner discharge member 20 via this gear and another gear. Is driven to rotate. In connection with the toner discharge member 20, each element of the toner return device 31 is provided as shown below.

As shown in FIGS. 4, 6, and 7, the toner return device 31 has a casing 50, and a toner transport path 51 is defined therein. In the illustrated example, the casing 50 of the toner return device 31 is formed by the gutter-like portion 94 formed by a part of the case main body 3 and the above-described upper cover 6 (see also FIG. 3) covering the upper opening. Is configured.

The toner returning device 31 further transports the toner T collected by the cleaning device 17 as described above and discharged from the cleaning case 19 of the cleaning device 17 by the toner discharging member 20 to the developing device 10 (FIG. 2). In the present embodiment, the toner conveying means includes a toner conveying belt 92. The toner conveying belt 92 is wound around a plurality of rollers, in the illustrated example, two rollers 91 and 95, and is driven in a running manner by a flexible endless belt 52, and along the running direction C of the endless belt 52. The endless belt 52 has a plurality of elastic fins 96 integrally connected to the endless belt 52 and projecting outward from the outer surface of the endless belt 52. The toner transport belt 92 is formed by, for example, integrally molding rubber, soft synthetic resin, or the like.

In the present embodiment, as shown in FIG. 6, one of the above-mentioned rollers 91 is integrally fixed to the front end of the toner discharge member 20 protruding outside the cleaning case 19 (FIG. 2). Is provided with a pair of pins 89 (not shown in FIG. 7) projecting in opposite directions. On the other hand, the endless belt 52 of the toner conveying belt 92 is formed with a number of long holes 93 (not shown in FIG. 7) arranged along the circumferential direction. , Respectively. The roller 91 constitutes a driving roller.

On the other hand, the other roller 95 described above constitutes a driven roller, and the roller 95 is rotatably supported by a gutter-like portion 94 of the casing 50. An endless belt 52 is wound.

When the toner discharge member 20 is rotationally driven as described above, the roller 91 integrated therewith rotates, and at this time, each pin 89 sequentially engages with the long hole 93 of the toner conveying belt 92, thereby The toner transport belt 92 is driven in a direction indicated by an arrow C in FIG. At this time, the elastic fins 96 of the toner conveying belt 92 are in sliding contact with the gutter-like portion 94 constituting the casing 50 and the inner wall surface of the upper cover 6, that is, the bottom surface 53 of the casing 50 and the upper surface 54 thereof.

The toner discharged by the toner discharge member 20 to the outside of the cleaning case 19 of the cleaning device 17 passes through the long hole 93 of the belt 92 while the toner is steadily moving near the transfer portion with the toner conveying belt 92. , Falls on the bottom surface 53 of the casing 50. Then, the toner is conveyed in the toner conveying path 51 in the arrow X direction in FIG. 7 by the elastic fins 96 of the driven toner conveying belt 92, and is sent into the developer chamber 90 of the developing device 10. At this time, since the elastic fins 96 are in pressure contact with the bottom surface 53 of the casing 50, the toner is efficiently transported to the developing device 10. The toner returned to the developing device 10 in this manner is reused in the developing device 10.

The above-described toner returning device 31 is an example of a device that returns and conveys toner from the cleaning device to the developing device, and it goes without saying that another appropriate toner returning device may be employed.

The toner return device 31 as described above is also referred to as a toner recycling device. However, if such a device is provided, the toner can be used effectively, the economic burden on the user can be reduced, and the amount of waste can be reduced. Excellent benefits are obtained. However, since the paper dust is floating inside the image forming apparatus main body 100, when the paper dust is particularly charged with static electricity, it adheres to the surface of the photoconductor 7. Further, in the transfer unit 22, paper powder may adhere to the surface of the photoconductor. Further, a part of the photosensitive layer, which is the surface layer of the photoconductor 7, may be peeled off and broken, and this may adhere to the surface of the photoconductor. Foreign matter such as the paper dust and the peeled fragments of the photosensitive layer on the surface of the photoconductor 7 are removed from the photoconductor 7 by the cleaning blade 18 of the cleaning device 17. That is, such foreign matter is removed from the photoconductor 7 together with the residual toner adhered to the photoconductor 7 after the transfer of the toner image, and is collected in the cleaning case 19 of the cleaning device 17.

As described above, when the toner containing foreign matter such as paper dust and the separated pieces of the photosensitive layer is returned to the developing device 10 by the toner returning device 31 as described above, the gap between the developing sleeve 11 and the doctor blade 14 is reduced. In addition, the foreign matter is clogged between the photosensitive member 7 and the developing sleeve 11, and the toner image on the photosensitive member 7 may be streaked due to the influence of the foreign matter, and the image quality may be deteriorated. That is, as shown in FIG. 2, when the developer D containing the foreign matter is carried on the developing sleeve 11 as shown in FIG. 2 and conveyed, and passes between the sleeve 11 and the doctor blade 14, as shown in FIG. If foreign matter 21 such as powder or delamination fragments of the photosensitive layer is clogged in the meantime, the amount of the developer supplied to the surface of the photoconductor 7 corresponding to the clogged portion of the foreign matter is insufficient, and a streak is formed in this portion. It will be lost. Also, as shown in FIG. 9, even if such foreign matter is clogged between the photoconductor 7 and the developing sleeve 11, the same streaks appear on the toner image on the photoconductor 1.

Here, in FIG. 2, the drum-shaped photoreceptor 7 is an example of an image carrier on which an electrostatic latent image is formed. The developing device 10 visualizes the electrostatic latent image as a toner image. Further, the cleaning device 17 removes and collects the toner remaining on the image carrier after transferring the toner image to the transfer material. The toner returning device 31 illustrated in FIG. 4 returns the toner removed by the cleaning device 17 to the developing device 10 so that the toner can be reused in the developing device 10. The image forming apparatus of the present embodiment includes such components 7, 10, 17, and 31, and the developing device 10 includes a developing sleeve 11 and a doctor blade 14. The developing sleeve 11 is opposed to the surface of the image carrier, and forms an example of a developer carrying member that carries and carries the developer D toward a developing area DA where the electrostatic latent image is visualized. is there. The doctor blade 14 is an example of an agent regulating unit that is opposed to the surface of the developing sleeve 11 as a developer conveying member and regulates the amount of the developer conveyed to the developing area DA.

Here, in the image forming apparatus of the present embodiment, as shown in FIGS. 2, 8 and 9, the developing sleeve 11 forming the developer conveying member is positioned on the surface of the photosensitive member 7 forming the image carrier. The developer D is carried and conveyed toward a development area DA where the electrostatic latent image is visualized in the area of the gap G1. The doctor blade 14 constituting the developer regulating unit is also opposed to the surface of the developing sleeve 11 constituting the developer carrying member with a gap G therebetween, and regulates the amount of the developer carried to the developing area DA.

In consideration of the presence of foreign matter such as paper dust and photosensitive layer peeling fragments in the toner returned to the developing device, the toner is opposed to the surface of the photoconductor 7 with a gap G1 as shown in FIG. As shown in FIG. 8, the developing sleeve 11 and the doctor blade 14 that is opposed to the surface of the developing sleeve 11 with a gap G therebetween are used as components of the image forming apparatus. However, clogging at the gap can be prevented. By keeping the photoconductor 7 and the developing sleeve 11 and the developing sleeve 11 and the doctor blade 14 out of contact with each other, it is possible to prevent foreign matter from clogging the gap between them. As a result, it is possible to prevent the generation of linear streaks (white streaks) of the toner image generated by the influence of the foreign matter.

If the gap G1 between the photoconductor 7 and the developing sleeve 11 and the gap G between the developing sleeve 11 and the doctor blade 14 shown in FIG. 9 are set to gaps larger than zero and 2 mm or less, It is possible to effectively prevent clogging of foreign matter such as paper dust and photosensitive layer peeling fragments in each gap, and the function of regulating the amount of developer by the doctor blade 14 is not impaired, and the function of developing by the developing sleeve 11 is impaired. Not even. At this time, it is preferable that the gap G1 between the photoconductor 7 and the developing sleeve 11 is set to be equal to or smaller than the gap G between the developing sleeve 11 and the doctor blade 14.

If the gaps G and G1 are set to 2 mm or less and 20 μm or more, not only clogging of paper dust but also clogging of delaminated fragments of the photosensitive layer of the photoconductor 7 can be more effectively prevented. Incidentally, the thickness of the photosensitive layer (not shown) of the photosensitive member 7 is about 20 μm, and if the gaps G and G1 are 20 μm to 30 μm or more, clogging of the photosensitive layer by peeling-off fragments can be performed without any problem. It can be prevented.

The developing device 10 shown in FIG. 2 is a developing device using a two-component developer having a toner and a carrier. However, the developing device 10A using a one-component developer having no carrier as shown in FIG. The present invention can be applied to an image forming apparatus having the same. The image forming apparatus shown here has the same basic configuration as that of the image forming apparatus shown in FIG. 2, and a photosensitive member 7A which is an example of an image carrier on which an electrostatic latent image is formed, and the electrostatic latent image is used as a toner image. A cleaning device (not shown) for removing and collecting toner remaining on the photoconductor 7A after transferring the toner image to a transfer material (not shown); and a cleaning device (not shown). In order to reuse the toner removed by the device in the developing device 10A, a toner return device (not shown) for returning the toner to the developing device 10A is provided.

(4) In the developing device 10A, a one-component developer D1 having no carrier (hereinafter, also referred to as toner) is accommodated in a developer case 12A. The toner D1 is supplied to the developing roller 11A by a toner replenishing roller 45A that rotates while contacting the developing roller 11A.

The developing roller 11A is opposed to the surface of the photoconductor 7A with a gap, and carries the developer D1 toward a developing area DA in the gap area where an electrostatic latent image is visualized. This is an example of a developer conveying member that conveys the developer. A doctor blade 14A, which is an example of a medicine restricting unit, is also opposed to the developing roller 11A with a gap. The doctor blade 14A is opposed to the surface of the developing roller 11A with a gap, and regulates the amount of the toner D1 on the developing roller 11A that is conveyed toward the developing area DA.

As described above, the developing roller 11A is opposed to the photoconductor 7A with a gap in consideration of foreign matters such as paper dust and photosensitive layer peeling fragments, and the doctor blade 14A is similarly moved to the developing roller 11A. By opposing the gaps, it is possible to prevent such foreign matter from clogging in each gap. Even in an image forming apparatus using such a one-component developing device, the toner can be returned from the cleaning device to the developing device, and the foreign matter can be prevented from being clogged in each gap. Each gap in this case is also set to be larger than zero and equal to or smaller than 2 mm, and particularly set to be equal to or larger than 20 μm and equal to or smaller than 2 mm.

(1) An advantage of the one-component developing apparatus is that the image forming apparatus can be made compact because a means for supplying toner to the two-component developer is unnecessary. Further, since a carrier is not required for the developer, a large amount of toner occupied in the developing device can be secured, and the large amount of toner can be recycled, so that the number of copies that can be made can be greatly increased. In an image forming apparatus provided with a developing device having such advantages, clogging of foreign matter in each gap can be prevented.

The image forming unit 1 of the image forming apparatus shown in FIGS. 1 to 9 is configured by integrally assembling the developing device 10, the cleaning device 17, and the toner returning device 31 shown in FIG. However, as in this example, at least the developer case 12 of the developing device 10, the cleaning case 19 of the cleaning device 17, and the casing 50 that partitions the toner conveying path 51 of the toner returning device 31 are integrally formed. As a result, no gap is generated in the assembled joint portion of each of the process elements, and it is possible to prevent toner from leaking from this portion. If each process element is configured separately and they are connected with screws or the like, many mounting parts such as screws are required.Integrating each process element makes such mounting parts unnecessary. In addition, the number of parts of the image forming apparatus can be reduced, and the cost can be reduced. Such a configuration can be applied to the image forming apparatus shown in FIG.

In addition, the image forming unit 1 shown in FIG. 2 integrates a photoreceptor 7 and a charging roller 8 as a charging device in addition to the above-described process elements.

FIG. 1 is a front sectional view showing the inside of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a vertical sectional view of the image forming unit mounted on the image forming apparatus main body. FIG. 3 is an external perspective view illustrating an image forming unit without a developer cartridge and a toner bottle. FIG. 4 is a perspective view showing the image forming unit with a case cover, a developing case cover, and an upper cover removed. FIG. 5 is a partial sectional plan view of the same state as in FIG. 4. FIG. 3 is an enlarged perspective view of the toner transport belt. FIG. 4 is a vertical sectional view of the toner returning device. FIG. 4 is a perspective view showing a developing sleeve and a doctor blade. FIG. 4 is a diagram illustrating a gap between a photoconductor and a developing sleeve and a gap between a developing sleeve and a doctor blade. FIG. 5 is a vertical sectional view of another example of a developing device provided in the image forming apparatus according to the embodiment of the present invention.

Explanation of reference numerals

REFERENCE SIGNS LIST 10 developing device 10A developing device 12 developer case 12A developer case 17 cleaning device 19 cleaning case 31 toner returning device 50 casing 51 toner transport path D developer D1 developer DA developing area G gap G1 gap

Claims (4)

An image carrier on which an electrostatic latent image is formed, a developing device for visualizing the electrostatic latent image as a toner image, and toner remaining on the image carrier after transferring the toner image to a transfer material A cleaning device that removes and collects the toner, and a toner return device that returns the toner to the developing device so that the toner removed by the cleaning device can be reused in the developing device. A developer carrying member for carrying and carrying the developer toward a developing region where the electrostatic latent image is visualized in the gap region, which is opposed to the surface of the developing device with a gap; An image forming apparatus comprising: a developer regulating unit that is opposed to a surface of a developer conveying member with a gap therebetween and regulates an amount of the developer conveyed to the developing area. The gap according to claim 1, wherein the gap between the image carrier and the developer conveying member and the gap between the developer conveying member and the agent regulating means are set to a gap larger than zero and a gap of 2 mm or less. Image forming apparatus. 3. The image forming apparatus according to claim 2, wherein both gaps are set to 20 μm or more. 4. The image forming apparatus according to claim 1, wherein at least a developer case of the developing device, a cleaning case of the cleaning device, and a casing that defines a toner conveying path of the toner returning device are integrally formed.

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