JP2006084487A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of realizing a space-saved configuration and also suppressing toner from scattering at an opening part in a developing device. <P>SOLUTION: The image forming apparatus comprises: an image carrier 1; a charging device 2; an exposing device 3; a developing device 4; a toner supply means 8; a toner conveyance part 24 connecting the toner supply means 8 and developing device 4; a transfer device 5; and a cleaning device 6. In the image forming apparatus, the developing device 4 is equipped with a developer carrier 11 and a developer storage part 10, which has two developer conveying screws 12 and 13, a partition plate 10b partitioning the developer storage part 10 into two, and opening parts E provided at both end parts of the partition plate 10b, the toner conveyance part being provided with a pressure release filter 25. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrostatic copying process such as a copying machine, a printer, and a fax machine, which includes a developing device using a two-component developer, a one-component developer, and a color developer.

Conventionally, in a developing device provided in an image forming apparatus adopting an electrophotographic method, an electrostatic recording method, etc., for example, a developer container, a developing sleeve as a developer carrier, and a developer conveying means 2. Description of the Related Art There is known a developing device that includes a stirring screw and a developer returning member and is disposed to face a photosensitive drum that is a latent image carrier.
In particular, the agitating screw as the developer conveying means described above is composed of a developing roller side screw disposed in the vicinity of the developing roller and a toner replenishing side screw disposed on the side away from the developing roller. A developing device configured to circulate and convey a developer while being stirred by a screw and supply the developer to a developing roller is excellent in agitation, space-saving, and excellent in lateral conveyance.
In the developing device having the above-described configuration, the developer accommodating portion is largely divided into a developing roller side and a side spaced apart from the developing roller, for example, by a partition plate or the like, and the conveying screw is disposed in each. The developer in the developing device is transported by the transport screw and circulates in the developer accommodating portion through openings of partition plates provided at both ends.
However, in the developing device having such a configuration, there is a problem that toner scatters from the developing device opening facing the photosensitive member.

Regarding the toner scattering, in the developing process on the photosensitive member, a direct current voltage or a developing bias is applied from the bias power source to the developing sleeve under the formation of the developer magnetic brush by the developing pole N1 in the developing region of the photosensitive member. An alternating voltage in which an alternating voltage is superimposed on a direct current voltage is applied to transfer the toner in the magnetic brush onto the photosensitive drum, and the latent image on the photosensitive drum is developed and developed, and the latent image is used as a toner image. At this time, the developer that has not been consumed in the development is taken in and collected in the developer accommodating portion at the taking-in portion near the contact portion between the photosensitive member and the developing sleeve by the rotation of the developing sleeve. Here, in the taking-in portion, the developer to be conveyed, together with air, tries to enter the developer containing portion through the taking-in port that is a gap between the developing sleeve and the developer containing portion. As a result, the internal pressure rises, and the air that is about to be transported together with the developer at the intake port does not enter the developer accommodating portion and blows out. The toner released from the carrier is scattered along with the blown air. If the developer is scattered outside the developer accommodating portion, the inside of the image forming apparatus may be soiled, the optical sensor or the like may be soiled, and malfunction may be caused.
As a method for reducing the toner scattering in the above-described taking-in portion, an electrode member is provided in the taking-in portion of the developer containing portion, and a voltage having the same polarity as the toner is applied to develop the separated non-magnetic toner. Conventionally, a method of attracting to the sleeve 3 side, adhering to the magnetic carrier there, and taking it into the developer accommodating portion has been taken.
However, with the recent increase in the image forming speed, the rotation speed of the developing sleeve has increased, and the internal pressure in the developer accommodating portion has been more likely to rise. Therefore, the method described above sufficiently suppresses toner scattering. I can't do that.
In order to obtain high-definition images, attempts have been made to reduce the particle size of the toner. However, there are many small particle size toners that have a small binding force on the carrier. Furthermore, it is becoming difficult to suppress toner scattering.

  Therefore, in order to further reduce toner scattering, in Patent Document 1, in order to release the internal pressure of the developing container, an opening for communicating the internal space and the external space of the developing container is formed in the developing container, and the stirring screw is conveyed. The region is positioned in the vicinity of the opening of the developing container, and a filter that prevents the developer from leaking while allowing the passage of air from the inside of the developing container to the outside is provided in the opening.

JP 2003-0764142 A

However, in order to make the developing device space-saving, in the invention of Patent Document 1, it is difficult to dispose the filter at a position where the distance from the developer surface is sufficiently maintained. There is a problem that defects are likely to occur.
In view of the above circumstances, an object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of toner scattering at the developing device opening while realizing a space-saving configuration.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. The image forming apparatus of the present invention comprises an image carrier that carries a latent image, a charging device that uniformly charges the surface of the image carrier, and the surface of the charged image carrier is exposed based on image data, An exposure device for writing a latent image, a developing device for supplying toner to the latent image formed on the surface of the latent image carrier to make it visible, and a toner supplying means for supplying toner to the developing device; A toner conveying section connecting the toner replenishing means and the developing device, a transfer device for transferring a visible image on the surface of the latent image carrier to a recording paper, a cleaning device for cleaning the surface of the image carrier after the transfer, In the image forming apparatus, the developing device includes a developer carrying member that carries a developer, and a developer containing unit that contains the developer, and the developer containing unit is in the axial direction of the image carrier. Two developer transport disks arranged in parallel with each other And a partition plate that is disposed between the two transport screws and divides the developer containing portion into two, and openings provided at both ends of the partition plate. Is characterized by providing a pressure relief filter.
2. The image forming apparatus according to the present invention includes: In the invention described in item 1, the distance between the pressure relief filter surface and the developer upper surface in the developer accommodating portion is 50 mm or more.
3. The image forming apparatus according to the present invention includes: Or 2. In the invention described in the item 1, the inside of the toner conveying portion is divided into a toner conveying path and a pressure releasing path.
4). In addition, the image forming apparatus of the present invention includes: In the invention described in (1), the pressure release path forms a rib and is bent or bent at least once.
5. The image forming apparatus according to the present invention includes: Or 4. In the invention described in item 1, the developer accommodating portion, the toner conveying portion, and the toner replenishing means are separable.

  By the means for solving the above-described problem, the image forming apparatus of the present invention is space-saving and can prevent an increase in the internal pressure of the developing container and prevent toner scattering even during long-term use.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view of a main part of an image forming apparatus according to the present invention. The image forming apparatus of the present invention is an image forming apparatus using an electrostatic copying process, such as a copying machine, a facsimile machine, a printer, and the like. In the following embodiments, a two-component monochrome copying machine is shown. The present invention can also be applied to a one-component developing copier, monochrome printer, FAX, and two-component developing, or one-component developing color copier and color printer.
In the figure, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, a cleaning device 6, a charge eliminating value 7, and a toner replenishing device 8 are provided around a drum-shaped photoconductor 1 as an image carrier. Yes. The photoreceptor 1 is driven to rotate by a driving device (not shown), and the surface thereof is charged to a predetermined polarity by the charging member of the charging device 2 of the proximity charging method. The charged surface of the photosensitive member 1 is exposed by the exposure device 3 to form an electrostatic latent image corresponding to the image information. This electrostatic latent image is developed with toner as a developer supplied from the developing device 4 to the surface of the photoreceptor 1 to be visualized as a toner image. The toner of the developing device 4 is supplied from the toner replenishing device 8, and the mechanism thereof will be described in detail later.
Further, the visible image on the surface of the photoconductor 1 is transferred to a recording sheet by the transfer device 5, and the surface of the photoconductor 1 after the transfer is cleaned by the cleaning device 6.

FIG. 2 is a perspective view showing the internal configuration of the developing device 4 of the present invention.
In this embodiment, the developing device 4 uses a two-component developer composed of a toner and a magnetic carrier, but the present invention can also use a one-component developer.
The developing device 4 includes a developer accommodating portion frame 10a having an opening D, and a developer carrying member 11 (for carrying the developer) disposed so as to face the photoreceptor 1 in the opening D ( Hereinafter, it is referred to as a developing roller). The developing roller 11 is a sleeve that includes a magnet roller (not shown) in which a magnet is fixedly disposed.
Further, the developer container 10 that stores the developer in the developer container frame 10a is largely divided into two by a partition plate 10b that is a part of the developer container frame 10a. The developing roller side screw 12 as the first screw is in the space near the developing roller 11, and the toner replenishing side screw as the second screw is in the space farther from the developing roller 11. 13 are arranged so as to be parallel to the axial direction of the image carrier 1.
Moreover, the opening part E is provided in the both ends of the partition plate 10b facing. The developer conveyed by the conveying screw is configured to circulate in the direction indicated by the arrow A through the opening E through the developing device 4.

Next, the toner replenishing device 8 as the toner replenishing means of the present invention will be described.
FIG. 3 is a perspective view showing the toner supply device 8 of the present invention. The toner replenishing device 8 includes a toner bottle 20 that is detachable as a toner container, and a toner transport unit 21 that transports toner discharged from the toner bottle 20 to the developing device 4. When the toner bottle 20 is attached / detached, the operation is performed by sliding the toner conveying means 21 in the direction of arrow B.

  The toner replenishing operation in the present invention will be described with reference to FIGS. The toner discharged from the toner bottle 20 of the toner replenishing device 8 to the toner conveying means 21 is transmitted along the inner wall of the toner conveying means 21 by the rotational movement of the toner conveying member 22 in the direction of arrow C (see FIG. 1). It is discharged from the discharge port 23. Further, the toner passes through the toner transport unit 24 that connects the toner transport unit 21 of the toner replenishing device 8 and the developing device 4, and passes through the toner replenishment port 14 at the top of the toner replenishment side screw 13 of the developer storage unit 10. The toner is introduced into the developing device 4.

The developing device 4 of the present invention includes a developing roller side screw 12 disposed in the vicinity of the developing roller 11 and a toner replenishment side screw 13 disposed on the side away from the developing roller 11. While being stirred by two screws, it is circulated and conveyed through the partition plate 10 b and supplied to the developing roller 11. The developing device of such a system is excellent in stirring property while being space-saving, and is excellent in lateral transportability.
However, in the developing device having such a configuration, toner scattering occurs from the opening D of the developing device 4 facing the photoreceptor 1. In particular, in the opening D, this phenomenon easily occurs at a position downstream of the developing roller side screw 12 in the developer conveying direction.
This is considered to occur due to the pressing force of the developer when the developer roller is hit against the wall surface of the developer container frame 10a on the downstream side of the screw by the developing roller side screw 12.
In order to solve such a problem, it is known to provide a pressure release opening and a filter in the developer accommodating portion 10 in the vicinity of the downstream side of the screw. That is, it is easy to occur and the effect is reduced. In order to avoid such a phenomenon, it is necessary to maintain a sufficient distance between the filter and the developer surface. However, in order to obtain a developing device having a space-saving configuration, such an arrangement is adopted. Things are difficult.
In particular, the developing device 4 of the present invention is for toner replenishment of the developing device 4 so that the toner just after replenishment reaches the developing position in a state of being sufficiently agitated with the developer in the developer accommodating portion 10. An opening 14 is provided on the upstream side of the toner supply side screw 13. This is because the toner is replenished from a position away from the developing roller 11 and reaches the developing position in a more agitated state. However, with such a configuration, the filter mounting position in the developing device 4 for solving the toner scattering is further limited.
Accordingly, in the present invention, the toner replenishing port 14 provided near the downstream side in the transport direction of the developing roller side screw 12 and upstream of the toner replenishment side screw 13 in the transport direction is used as a pressure relief opening. For this purpose, the pressure relief filter 25 is provided in the toner conveying portion 24, thereby minimizing the pressure relief opening and the filter mounting location, thereby preventing the toner scattering.

Hereinafter, based on an Example, the specific structure of this invention is demonstrated.
(First embodiment)
FIG. 4 is a schematic cross-sectional view of the vicinity of the toner conveying portion 24 in the first embodiment. In the drawing, a filter 25 is installed at a position 24 a of the toner transport unit 24. Then, using the deteriorated developer, which is likely to cause toner scattering due to a decrease in charge amount, the developing device 4 was driven for 10 minutes under acceleration conditions, and the presence or absence of toner scattering was observed. Furthermore, the presence or absence of toner scattering was observed when the developing device 4 was driven under the same conditions without installing the pressure relief opening and the filter 25, and the two were compared.
As a result, when the pressure relief opening and the filter 25 are not installed, in the opening D of the developing device 4 facing the photoreceptor 1, the end of the developing roller side screw 12 in the conveyance direction downstream side, Toner scattering occurred.
On the other hand, in the present embodiment shown in FIG. 4, the occurrence of toner scattering from the opening D was not observed. As a result, it is clear that the pressure relief opening and the filter 25 provided in this embodiment are effective in suppressing an increase in internal pressure in the developer accommodating portion 10.
However, when the developing device 4 was further driven for 10 minutes, floating toner adhered to the filter 25, which caused clogging of the filter 25, and toner scattering occurred.
In this embodiment, the filter 25 is provided at a position 24a in FIG. 4, and therefore, the distance between the developer surface in the developer accommodating portion 10a and the filter 25 is short, so that the floating toner It is thought that it was in the state where it was easy to adhere.

(Second embodiment)
FIG. 5 is a schematic cross-sectional view of the vicinity of the toner conveying portion 24 in the second embodiment.
In this embodiment, a filter 25 is provided at a position 24b of the toner conveying portion 24 in FIG. 5, and the distance between the developer surface in the developer containing portion 10a and the filter 25 is set to 50 mm. Then, the developing device 4 was driven for 20 minutes under the same conditions as before, and the presence or absence of toner scattering was observed.
As a result, no toner scattering was observed in this embodiment, and the clogging of the filter 25 could be reduced.
Further, after that, the developing device 4 was driven for 1 hour, but no toner scattering was observed. This is because the problem of clogging in the configuration of the first embodiment has been improved and the pressure relief effect has been improved.

(Third embodiment)
FIG. 6 is a schematic cross-sectional view of the vicinity of the toner conveying portion 24 in the third embodiment.
In the drawing, the inside of the toner transport unit 24 is divided by a member x into two spaces, a pressure release path and a toner transport path. Thus, the floating toner can be prevented from adhering to the filter 25 when the toner is supplied from the discharge port 23.
As a result, it is possible to avoid the floating toner from adhering to the filter 25 more than in the configurations shown in the first and second embodiments, so that the filter clogging is reduced and the pressure relief effect is further maintained. I can do things.
Thereby, the lifetime for the effect of preventing toner scattering can be further extended.

(Fourth embodiment)
FIG. 7 is a schematic cross-sectional view of the vicinity of the toner conveying portion 24 in the fourth embodiment.
As shown in FIG. 7, the pressure release path in the third embodiment is further divided into two by a rib 26 provided in the middle, and the pressure release path can be bent. Thereby, it is possible to further prevent the floating toner blowing from the developer surface from directly adhering to the filter surface.
Further, it is preferable that the surface of the rib 26 has a wide surface area, for example, the surface of the rib 26 is wavy or a floating material is attached to adsorb floating toner.
Thereby, the filter by the floating toner can be further reduced, and the life of the toner scattering prevention effect can be further extended.

Further, as shown in FIG. 3, the toner conveying means 21 constituting the toner replenishing device 8 is configured to slide back and forth during toner replacement, so that the filter 25 arranged in the toner conveying portion 24 can be easily replaced. Can be done. In other words, the toner conveying means 21 slides back and forth integrally with the toner conveying means, so that it is easy to replace the film separated from the developer accommodating portion frame 10a and disposed in the toner conveying portion 24. It becomes.
If the filter 25 is included in the toner bottle 20, the filter 25 can be replaced frequently when the toner bottle 20 is replaced. Therefore, the filter 25 can be replaced frequently. Thereby, since the depressurization effect can be maintained in a high state, it is more preferable in order to obtain an effect of preventing toner scattering.

1 is a schematic diagram of a main part of an image forming apparatus of the present invention. It is a perspective view which shows the internal structure of the developing device 4 of this invention. It is a perspective view showing a toner replenishing device 8 of the present invention. FIG. 3 is a schematic cross-sectional view of the vicinity of a toner conveying unit 24 in the first embodiment. FIG. 6 is a schematic cross-sectional view in the vicinity of a toner conveyance unit 24 in a second embodiment. FIG. 10 is a schematic cross-sectional view in the vicinity of a toner conveying unit 24 in a third embodiment. FIG. 10 is a schematic cross-sectional view of the vicinity of a toner conveyance unit 24 in a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging apparatus 3 Exposure apparatus 4 Developing apparatus 10 Developer accommodating part 10a Developer accommodating part frame 10b Partition plate 11 Developing roller (developer carrying body)
DESCRIPTION OF SYMBOLS 12 Developing roller side screw 13 Toner replenishment side screw 14 Toner replenishment port 5 Transfer device 6 Cleaning device 7 Static elimination value 8 Toner replenishment device 20 Toner bottle 21 Toner conveyance means 22 Toner conveyance member 23 Discharge port 24 Toner conveyance part 25 Filter 26 Rib D opening E opening x member

Claims (5)

An image carrier for carrying a latent image;
A charging device for uniformly charging the surface of the image carrier;
An exposure device that exposes the surface of the charged image carrier based on image data and writes a latent image;
A developing device that supplies toner to the latent image formed on the surface of the latent image carrier to visualize the latent image;
Toner replenishing means for replenishing toner to the developing device;
A toner conveying portion connecting the toner replenishing means and the developing device, a transfer device for transferring a visible image on the surface of the latent image carrier to a recording sheet,
In an image forming apparatus comprising: a cleaning device that cleans the surface of the image carrier after transfer;
The developing device includes a developer carrying member that carries a developer, and a developer containing unit that contains the developer,
The developer accommodating portion includes two developer conveying screws disposed so as to be parallel to the image carrier axis direction, and two developer accommodating portions disposed between the two conveying screws. A partition plate to be divided, and openings provided at both ends of the partition plate,
An image forming apparatus, wherein the toner conveying section is provided with a pressure relief filter. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein a distance between the pressure relief filter surface and the developer upper surface in the developer accommodating portion is 50 mm or more. The image forming apparatus according to claim 1, wherein
The inside of the toner conveying section is divided into a toner conveying path and a pressure releasing path. The image forming apparatus according to claim 3.
The image forming apparatus, wherein the pressure release path forms a rib and is bent or bent at least once. The image forming apparatus according to claim 1, wherein:
In the image forming apparatus, the developer accommodating portion, the toner conveying portion, and the toner replenishing means are separable.

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