JPH09185248A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a toner-image streak, which occurs due to foreign matters, by making gaps by the uncontacted arrangement of a photoreceptor and a developing sleeve and the uncontacted arrangement of the developing sleeve and a doctor blade, thereby preventing the foreign matters from blocking areas between them. SOLUTION: The developing sleeve 11 is disposed opposite the photoreceptor 7 with the gap G1 left between the surface of the photoreceptor 7 and itself, and holds and carries developer D toward a developing area DA, in the area of the gap G1, where an electrostatic latent image is rendered visible. Also, the doctor blade 14 is disposed opposite the developing sleeve 11 with the gap G left between the surface of the developing sleeve 11 and itself, and regulates an amount of the developer D which is carried to the developing area DA. This prevents foreign matters, such as paper powder and peeled or broken fragments of a photoreceptive layer, in toner returned to the developing device 10 from blocking the gaps. It is preferable that the gap G1 between the photoreceptor 7 and developing sleeve 11 and the gap G between the developing sleeve 11 and doctor blade 14 be set more than zero but 2mm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 the toner image transferred onto a transfer material. A cleaning device that removes and collects the toner remaining on the image carrier after the cleaning, and a toner returning 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 includes a developer conveying member that is opposed to an image carrier and that conveys and conveys a developer toward a developing region where an electrostatic latent image is visualized. The present invention relates to an image forming apparatus having a developer regulating unit that regulates the amount of developer that is conveyed.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as a copying machine, a printer, a facsimile machine or a composite machine thereof, the toner removed from the surface of an image carrier is conveyed to a developing device by a toner returning device, The toner can be reused in the developing device. According to such an image forming apparatus, as compared with an image forming apparatus of a type in which the toner removed from the surface of the image carrier is discarded, there is an advantage that the economical burden on the user can be reduced and the amount of waste can be reduced.

However, the problem here is that the toner removed from the image carrier is contaminated with foreign matter such as paper dust and peeled fragments of the surface layer of the image carrier. Paper dust floats in the main body of the image forming apparatus, and when such paper dust adheres to the image carrier, or when the paper dust of the transfer paper to which the 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 bearing member is peeled off, the peeled fragments are also removed from the image bearing member together with the residual toner by the cleaning device.

[0004] In this way, the paper particles and the delaminated fragments of the surface layer of the image carrier are mixed in the toner collected by the cleaning device. When the toner is returned to the developing device, the developer is removed. Foreign matter such as paper dust or peeling fragments of the image carrier is clogged between the conveying member and the agent regulating means,
Due to the influence of the foreign matter, linear streaks lacking toner are formed on the toner image formed on the image carrier, and the image quality is deteriorated.
Further, even if foreign matter is caught between the image carrier and the developer transport member, linear streaks are similarly formed on the toner image, and the image quality is deteriorated.

However, in the conventional image forming apparatus, 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 relationship with the above, there is a possibility that the above-mentioned foreign matter may be clogged between the developer transport member and the agent regulating means, or between the developer transport member and the image carrier. If such clogging occurs, as described above, due to the influence of the foreign matter, linear streaks lacking toner are formed on the toner image formed on the image bearing member, and the image quality thereof deteriorates.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned novel recognition, and its purpose is to eliminate the above-mentioned conventional drawbacks and return the cleaning device to the developing device. It is possible to prevent foreign matter such as paper dust mixed in the toner from being clogged between the developer transport member and the agent control unit or between the developer transport member and the image carrier, and the foreign matter caused by the foreign matter causes the toner. An object of the present invention is to provide an image forming apparatus capable of preventing a defect that an image has streaks.

[0007]

To achieve the above object, the present invention provides an image carrier on which an electrostatic latent image is formed, and a developing device for visualizing the electrostatic latent image as a toner image. A cleaning device for removing and collecting the toner remaining on the image carrier after transferring the toner image to a transfer material, and the toner for removing the toner removed by the cleaning device in the developing device. And a toner returning device for returning to the developing device, the developing device is opposed to the surface of the image carrier with a gap, and the electrostatic latent image is visualized in the gap region. A developer carrying member carrying and carrying the developer toward the developing area and a surface of the developer carrying member are opposed to each other with a gap, and regulate the amount of the developer carried to the developing area. Have drug control means It proposes an image forming apparatus according to claim bets (claim 1).

In this case, in the image forming apparatus according to the first aspect, 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 larger than zero. It is advantageous to set the gap to 2 mm or less (Claim 2).

Further, 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 casing defining a developer case of the developing device, a cleaning case of the cleaning device, and a toner conveying path of the toner returning device. It is advantageous to integrally form and (claim 4).

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below 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 the copying machine can be provided with functions such as a printer and a facsimile. As shown in FIG. 1, the image forming apparatus main body 1
The image forming unit 1 is detachably attached to the device 00.

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 sheet 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 has a unit case 2 and various image forming elements incorporated therein, which will be described later. The unit case 2 shown as an example in the drawings is A case main body 3, a case cover 4 attached to the upper part thereof, a developing case cover 5 constituting an upper wall of a developing device described later, and an upper wall of a toner transport path and an upper wall of the developing device also described later. And a case cover 4, a developing case cover 5, and an upper cover 6 that 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 with the 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.
[Fig. 3] is a partial cross-sectional plan view in the same state.

Inside the unit case 2, a drum-shaped photosensitive member 7 which is an example of an image carrier and a charging roller 8 which is an example of a charging device are rotatably assembled.
The charging roller 8 extends parallel to the photoconductor 7. In FIG. 4, the charging roller 8 is shown separated from the photoconductor 7.

During the image forming operation, the photosensitive member 7 is rotationally driven in the clockwise direction in FIG. 2 by a driving device (not shown). At this time, the photoconductor 7 is removed from a static eliminating device (not shown) supported by the image forming apparatus main body 100. The lightning L1 passes through the opening 34 formed in the case cover 4 and the unit case 2
The light enters the inside and irradiates the surface of the photoconductor 7. This allows
The surface potential of the photoconductor 7 is averaged to a reference potential of 0 to -150V, for example.

On the other hand, the charging roller 8 is pressed against the surface of the photoconductor 7 and is rotated by the rotation of the photoconductor 7 while the photoconductor 7 is uniformly rotated so that the surface potential thereof is, for example, about -1100V. To be charged. During this charging operation,
A voltage is applied to the charging roller 8 from a power source (not shown). Further, the charging roller 8 of this example is attached to the unit case 2 so as to be able to come into contact with and separate from the photoconductor 7, and is separated from the photoconductor 7 when the photoconductor 7 is not charged.

The light-modulated laser beam L2 is applied to the surface portion of the photoconductor 7 charged with a predetermined polarity as described above in the exposure section 9. The laser light L2 is applied to the exposure optical system unit 3 supported by the image forming apparatus main body 100.
2 (FIG. 1) and enters the unit case 2 through the opening 35 of the case cover 4. By 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 -290V, and the surface potential of the photoconductor portion (background portion) not irradiated with the laser beam L2 is maintained at about -1100V. It is also possible to illuminate a document (not shown) and form a reflected light image on the photoconductor 7 to form an electrostatic latent image.

On the other hand, the unit case 2 rotatably supports a developing sleeve 11 (not shown in FIG. 4) of the developing device 10 as shown in FIGS. The developing sleeve 11 is made of a non-magnetic material, and is driven to rotate counterclockwise in FIG. 2 during an image forming operation. Further, a developer case 12 of the developing device 10 is constituted by a part of the case body 3 in the unit case 2 and a developing case cover 5 (FIG. 3) covering the upper part thereof, and a developer chamber of the developer case 12 is formed. 90 contains a two-component developer D (FIG. 2) containing toner and carrier, and the developing sleeve 1
Inside 1, a plurality of magnets indicated by the whole numeral 13 are arranged immovably. Further, on the upper part of the developer case 12, a doctor blade 14 facing the developing sleeve 11 is provided.
Has been fixed. The toner of the developer D and the carrier are triboelectrically charged with opposite polarities due to the stirring action, and in this example, the toner is negatively charged and the carrier is positively charged.

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

As shown in FIG. 5, two agitating members 44, 45 are arranged in the developer chamber 90 of the developer case 12, and these agitating members 44, 45 have their shafts 63, 6 respectively.
4 and stirring blades (not shown in FIG. 4) 65, 66 fixed to the shaft 4, and their respective shafts 63, 64 are rotatably supported by the unit case 2 and are driven to rotate. The developer D in the developer chamber 90 is agitated while being conveyed as shown 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 lowered, the toner replenishing chamber 68 in the unit case 2 is passed from the toner bottle 67 set in the image forming apparatus main body 100 through the toner replenishing port 30 (FIG. 3) formed in the unit case 2. The toner supplied to the developer chamber 90
Resupplied to

The developing sleeve 11 and the plurality of magnets 13 provided therein constitute an agent carrying means for carrying and carrying the two-component developer to be used for development. In this example, the magnet 13 is Although it is fixed and the developing sleeve 11 is rotationally driven, conversely, the magnet may be rotationally driven to fix the developing sleeve, or both the magnet and the developing sleeve may be rotationally driven. You may comprise so that a developer may be conveyed.

On the other hand, FIG.
Further, as shown in FIG. 2, a transfer roller 15 which is an example of a transfer device is rotatably supported so as to face the photoconductor 7.

Further, as shown in FIG. 1, a proper number of sheet feeding devices 33, 33a, 3b, 33c are provided on the image forming apparatus main body side, and transfer is performed from the selected sheet feeding device 33, 33a, 33b or 33c. The transfer paper P, which is an example of the material, is conveyed toward the transfer unit 22 (FIG. 2) between the photoconductor 7 and the transfer roller 15.

Each paper feeding device 33, 33a, 33b, 33c
Are paper feed cassettes 36 containing transfer paper P of each size,
36a, 36b, 36c and paper feed rollers 37, 37a,
The paper feed rollers of the selected paper feeder are driven to rotate, and the transfer paper in the paper feed cassette is fed one by one. For example, the lowest paper feeder 33
When c is selected, the paper feed roller 37c rotates to transfer the transfer paper P stored in the paper feed cassette 36c in a direction indicated by an arrow B in a transfer paper transport path 39 by a series of transport roller pairs 38.
Of the transfer portion 2 between the photoconductor 7 and the transfer roller 15 at a predetermined timing by the registration roller pair 40.
2 (FIG. 2).

As shown in FIG. 2, the transfer sheet P fed as described above has the tip of the toner image formed on the photoconductor 7 and the tip of the toner image formed on the photoconductor 7 aligned with each other. And passes through the transfer unit 22 between. 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 is transferred. The image is transferred to the transfer paper P.

The transfer paper P that has left the photosensitive member 7 is conveyed to the fixing device 41 as shown by an arrow B1 in FIGS. 1 and 2, and the toner image is transferred to the fixing device 41 by the action of heat and pressure.
It is fused and fixed on top. The transfer paper P that has passed through the fixing device 41 is discharged as a copy paper to the outside of the image forming apparatus main body 100 and is stacked on the paper discharge tray 42.

In this example, the transfer paper P is used as the transfer material, and the toner image on the photoconductor 7 is transferred to the transfer paper P. However, the transfer material composed of the intermediate transfer body is used, and the toner image on the photoconductor is used. Can be primarily transferred to the intermediate transfer member, and then the toner image on the intermediate transfer member can be secondarily transferred to the transfer paper which is the final transfer material.

The residual toner adhering to the photoconductor 7 after the toner image is transferred is scraped off from 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 next image forming operation starts again. Cleaning device 1
7 has a cleaning case 19 formed by a part of the case body 3 in the unit case 2, and the toner T scraped off by the cleaning blade 18
(FIG. 2) shows that the cleaning device 17 is rotated by rotating the toner discharging member 20 arranged in the cleaning case 19.
It is discharged outside. The toner T removed from the photoconductor 7 by the cleaning device 17 is returned to the developing device 10 by the toner returning 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 in parallel with 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 by the case body 3.

The cleaning device 1 shown in FIGS. 2 and 4.
The toner T scraped off from the photoconductor 7 by the cleaning blade 18 of No. 7 and collected in the cleaning case 19 is conveyed to the front side in the cleaning case 19 by the rotating toner discharging member 20, and is integrally projected to the case 19. It is discharged to the outside through the pipe 88 (FIG. 4) provided. A gear (not shown) is fixed to the rear end portion of the toner discharging member 20, and the rotation of the photoconductor 7 is transmitted to the toner discharging member 20 via this gear and the other gear, whereby the toner discharging member 20 is rotated. Is driven to rotate. In connection with the toner discharging member 20, each element of the toner returning device 31 is provided as shown below.

As shown in FIGS. 4, 6 and 7, the toner returning device 31 has a casing 50, and a toner conveying path 51 is defined therein. In the illustrated example, the trough-shaped portion 94 formed by a part of the case body 3 described above and the upper cover 6 (FIG.
(See also), the casing 50 of the toner returning device 31 is configured.

The toner returning device 31 is further collected by the cleaning device 17 as described above, and the toner discharging member 2
0 has a toner carrying means for carrying the toner T discharged from the cleaning case 19 of the cleaning device 17 to the developing device 10 (FIG. 2). In this example, the toner carrying means has a toner carrying belt 92. . The toner conveying belt 92 includes a plurality of rollers, two in the illustrated example.
A flexible endless belt 52, which is driven to run while being wound around book rollers 91 and 95, is arranged at intervals along the running direction C of the endless belt 52, and the bases thereof are endless belts 52. A plurality of elastic fins 96 that are integrally connected to the endless belt 52 and project outward from the outer surface of the endless belt 52. The toner transport belt 92 is
For example, it is configured by integrally molding rubber or soft synthetic resin.

In this embodiment, the front end of the toner discharging member 20 protruding outside the cleaning case 19 (FIG. 2) is
As shown in FIG. 6, the above-mentioned one roller 91 is integrally fixed, and a pair of pins 89 (not shown in FIG. 7) projecting in the opposite direction are integrally provided on the peripheral surface of the roller 91. Has been done. On the other hand, on the endless belt 52 of the toner conveying belt 92, a large number of long holes 93 (not shown in FIG. 7) arranged along the circumferential direction are formed, and the roller 9 described above is formed.
Each pin 89 of No. 1 has entered into one of the long holes 93, respectively. The roller 91 constitutes a drive roller.

On the other hand, the other roller 95 described above constitutes a driven roller, and the roller 95 is rotatably supported by the trough-shaped portion 94 of the casing 50, and the toner is conveyed to the roller 95 and the roller 9 described above. Endless belt 5 of belt 92
2 is wound.

When the toner discharging member 20 is rotationally driven as described above, the roller 91 integrated with the toner discharging member 20 is rotated, and at this time, the pins 89 are successively engaged with the long holes 93 of the toner conveying belt 92. As a result, the toner conveying belt 92 is driven in the direction indicated by the arrow C in FIG. At this time, the elastic fins 96 of the toner conveying belt 92 are
The gutter-shaped portion 94 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 are in sliding contact with each other.

The toner discharged by the toner discharge member 20 to the outside of the cleaning case 19 of the cleaning device 17 moves in an unstable manner in the vicinity of the transfer portion with the toner conveying belt 92, and the long hole 93 of the belt 92. And falls on the bottom surface 53 of the casing 50. Then, the elastic fins 96 of the driven toner conveying belt 92 are driven.
Thus, the toner is conveyed in the toner conveying path 51 in the direction of the arrow X in FIG. 7, and is fed into the developer chamber 90 of the developing device 10. At this time, the elastic fins 96 are in pressure contact with the bottom surface 53 of the casing 50, so that the toner can be efficiently used for the developing device 1.
It is transported toward zero. The toner thus returned to the developing device 10 is reused in the developing device 10.

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

The toner returning device 31 as described above is also called a toner recycling device. However, if such a device is provided, the toner can be effectively used, the economical burden on the user can be reduced, and the amount of waste can be reduced. The advantage is that However, since paper dust floats 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, at the transfer portion 22, paper dust 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. In this way, the cleaning device 1 can remove foreign matter such as paper dust attached to the photoconductor 7 and peeled fragments of the photoconductive layer on the photoconductor surface.
It is removed from the photoconductor 7 by the cleaning blade 18 of No. 7. That is, such foreign matter is removed from the photoconductor 7 and collected in the cleaning case 19 of the cleaning device 17 together with the residual toner adhering to the photoconductor 7 after the toner image is transferred.

As described above, when the toner mixed with the paper dust or the foreign matter such as the peeled fragments of the photosensitive layer is returned to the developing device 10 by the toner returning device 31, as described above, the developing sleeve 11 and the doctor blade 14 are separated. There is a possibility that the foreign matter is clogged between the photoconductor 7 and the developing sleeve 11 and a streak is formed on the toner image on the photoconductor 7 due to the influence of the foreign matter, and the image quality thereof is deteriorated. That is, as shown in FIG. 2, the developer D mixed with foreign matter is carried on the developing sleeve 11 and conveyed, and when passing between the sleeve 11 and the doctor blade 14, as shown in FIG. If a foreign substance 21 such as powder or a broken piece of the peeled photosensitive layer is clogged in the meantime, the amount of developer supplied to the surface of the photoconductor 7 corresponding to the clogged portion of the foreign substance is insufficient, and streaks are generated in this part. It ends up. Further, as shown in FIG. 9, even if such a foreign substance is clogged between the photoconductor 7 and the developing sleeve 11,
Similar streaks appear on the toner image on the photoconductor 1.

Here, in FIG. 2, the drum-shaped photoconductor 7 is an example of an image carrier on which an electrostatic latent image is formed. Further, 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 the toner image is transferred onto the transfer material. The toner returning device 31 shown 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 example includes the respective elements 7, 10, 17, 31 as described above, and the developing device 10 thereof is
It has a developing sleeve 11 and a doctor blade 14. This developing sleeve 11 is placed opposite to the surface of the image carrier,
It is 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. The doctor blade 14 is an example of an agent regulating unit that is opposed to the surface of the developing sleeve 11, which is a developer conveying member, and regulates the amount of the developer conveyed to the developing area DA.

Here, in the image forming apparatus of this example,
As shown in FIG. 2, FIG. 8 and FIG. 9, the developing sleeve 11 constituting the developer carrying member is opposed to the surface of the photoconductor 7 constituting the image carrier with a gap G1 therebetween, and the gap G1. In this area, the developer D is carried and conveyed toward the developing area DA where the electrostatic latent image is visualized. Further, the doctor blade 14 that constitutes the agent regulating means
Also, it is opposed to the surface of the developing sleeve 11 constituting the developer transporting member with a gap G therebetween, and regulates the amount of the developer transported to the developing area DA.

Considering the presence of foreign matter such as paper dust and photosensitive layer peeling fragments in the toner returned to the developing device, a gap G1 is formed on the surface of the photoconductor 7 as shown in FIG. The developing sleeve 11 and the developing sleeve 1 which are opened and opposed to each other.
As shown in FIG. 8, a doctor blade 14 or the like, which is placed opposite to the surface of No. 1 with a gap G, is used as a component of the image forming apparatus, so that the foreign matter can be prevented from being clogged in the gap. . Photoreceptor 7 and developing sleeve 11, developing sleeve 11 and doctor blade 14
By making both and the non-contact state, 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) in the toner image that are caused by the foreign matter.

The photosensitive member 7 and the developing sleeve 11 shown in FIG.
When the gap G1 between the developing sleeve 11 and the doctor blade 14 and the gap G between the developing sleeve 11 and the doctor blade 14 are set to a gap larger than zero and not larger than 2 mm, foreign matter such as paper dust and photosensitive layer peeling fragments is detected. The clogging in each gap can be effectively prevented, and the function of regulating the amount of developer by the doctor blade 14 is not impaired, and the developing function by the developing sleeve 11 is not impaired. At this time, the gap G1 between the photoconductor 7 and the developing sleeve 11
Is preferably set to be equal to or smaller than the gap G between the developing sleeve 11 and the doctor blade 14.

Further, when both gaps G and G1 are set to 2 mm or less and 20 μm or more, not only clogging of paper powder but also clogging of peeling fragments of the photosensitive layer of the photoconductor 7 is more effectively performed. It can be prevented. Incidentally, the thickness of the photosensitive layer (not shown) of the photoconductor 7 is about 20 μm, and if the gaps G and G1 are 20 μm to 30 μm or more, there is no problem of clogging of peeling fragments of the photosensitive layer. It can be prevented.

The developing device 10 shown in FIG. 2 is a developing device using a two-component type developer having toner and carrier, but the developing device using a one-component type developer having no carrier as shown in FIG. In the image forming apparatus having the device 10A,
The present invention is applicable. The image forming apparatus shown here has the same basic configuration as that of the image forming apparatus shown in FIG. 2, and a photoconductor 7A which is an example of an image bearing member on which an electrostatic latent image is formed, and the electrostatic latent image is a toner image. Device 10 for visualizing as a visual image
A, a cleaning device (not shown) that removes and collects toner remaining on the photoconductor 7A after the toner image is transferred to a transfer material (not shown), and the toner removed by the cleaning device is developed. The apparatus 10A includes a toner returning device (not shown) that returns the toner to the developing device 10A for reuse.

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

The developing roller 11A is opposed to the surface of the photoconductor 7A with a gap, and the developer D1 is directed toward the developing area DA in which the electrostatic latent image is visualized in the gap area. It is an example of a developer transport member that carries and transports. The developing roller 11A is also provided with a gap so that a doctor blade 14 which is an example of an agent regulating means.
A is opposite. The doctor blade 14A is opposed to the surface of the developing roller 11A with a gap, and is conveyed toward the developing area DA.
The amount of toner D1 on A is regulated.

In this way, the developing roller 11A is placed opposite to the photosensitive member 7A with a gap taken into consideration in consideration of foreign matter such as paper dust and fragments of the peeling of the photosensitive layer. Similarly, the doctor blade 14A is also connected to the developing roller 11A. By placing a gap with respect to each other, it is possible to prevent clogging of such foreign matter in each gap. Even in the image forming apparatus using such a one-component developing device, it is possible to return the toner from the cleaning device to the developing device.
It is possible to prevent clogging of the above-mentioned foreign matter in each gap. Each gap in this case is also greater than zero and 2
It is set to be not more than mm, particularly not less than 20 μm and not more than 2 mm.

The advantage of the one-component type developing device is that the image forming device can be made compact because the toner replenishing means for the two-component type developer is unnecessary. Further, since the developer does not require a carrier, a large toner capacity can be secured in the developing device, and a large amount of toner can be recycled, so that the number of copyable sheets can be greatly increased. In the image forming apparatus equipped with the developing device having such advantages, it is possible to prevent clogging of foreign matter in each gap.

By the way, in the image forming unit 1 of the image forming apparatus shown in FIGS. 1 to 9, the developing device 10, the cleaning device 17, and the toner returning device 31 shown in FIG. 4 are integrally assembled. Although it is configured, as in this example, at least the developer case 12 of the developing device 10,
When the cleaning case 19 of the cleaning device 17 and the casing 50 that defines the toner conveying path 51 of the toner returning device 31 are integrally formed, a gap does not occur at an assembly joint portion of these process elements, and toner is not collected from this portion. It can be prevented from leaking. If you configure each process element separately and connect them with screws etc.,
Although many attachment parts such as screws are required, by integrating each process element, such attachment parts are unnecessary, and the number of parts of the image forming apparatus can be reduced and the cost thereof can be reduced. Such a configuration,
It is also applicable to the image forming apparatus shown in FIG.

The image forming unit 1 shown in FIG. 2 has a photosensitive member 7, a charging roller 8 as a charging device, and the like integrated with the above-mentioned process elements. .

[0054]

According to the image forming apparatus of the first aspect, the toner returned from the cleaning device to the developing device is contaminated with foreign matter such as paper dust or peeling fragments of the image carrier surface layer. It is possible to prevent such foreign matter from being clogged between the image carrier and the developer transport member and between the developer transport member and the agent regulating means, and prevent the image quality from being deteriorated due to the clogging. .

According to the image forming apparatus of the second aspect,
It is possible to effectively prevent foreign substances such as paper dust and photosensitive layer peeling fragments from clogging the gap between the image carrier and the developer transport member and the gap between the developer transport member and the agent control means. It is possible to prevent the 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,
It is possible to more effectively prevent clogging of each gap, such as paper dust and peeled fragments of the surface layer of the image carrier, and prevent deterioration of image quality due to the clogging.

According to the image forming apparatus of the fourth aspect,
It is possible to prevent leakage of the developer that occurs when the developing device, the cleaning device, the toner returning device, and the like are separately assembled, and it is possible to reduce the number of parts of the image forming apparatus and reduce the cost thereof.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing the inside of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 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 showing 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.

5 is a partial cross-sectional plan view of the same state as FIG.

FIG. 6 is an enlarged perspective view of a toner conveyance belt.

FIG. 7 is a vertical sectional view of the toner returning device.

FIG. 8 is a perspective view showing a developing sleeve and a doctor blade.

FIG. 9 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. 10 is a vertical sectional view of another example of a developing device included in the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 10 Developing Device 10A Developing Device 12 Developer Case 12A Developer Case 17 Cleaning Device 19 Cleaning Case 31 Toner Return Device 50 Casing 51 Toner Conveying Path D Developer D1 Developer DA Developing Area G Gap G1 Gap

Claims (4)

[Claims] 1. 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 onto a transfer material. The developing device includes a cleaning device that removes and collects the toner remaining on the upper part, and a toner returning device that returns the toner removed by the cleaning device to the developing device in order to reuse the toner in the developing device. , Which is placed opposite to the surface of the image carrier with a gap, and carries and conveys the developer toward a development region in which the electrostatic latent image is visualized in the gap region. A carrying member and a developer carrying member, which are placed opposite to each other with a gap therebetween,
An image forming apparatus comprising: an agent regulating unit that regulates the amount of the developer conveyed to the developing area. 2. 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 not larger than 2 mm. Item 1. The image forming apparatus according to Item 1. 3. The image forming apparatus according to claim 2, wherein both gaps are set to 20 μm or more. 4. The developer case of the developing device, the cleaning case of the cleaning device, and the casing that defines the toner transport path of the toner returning device are integrally formed at least in one unit. Image forming apparatus.