JP2001305861A - Image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy-duty image forming device capable of stabilizing the property of developer and dispensing with the exchange of developer using amorphous silicon photoreceptor and a cleaning-less system. SOLUTION: A container 5a for the replenishing developer consisting of toner and carriers and a container 5b for the recovered developer discharged from the developer container 2 of the developer device 1 are integrally mounted to the developer device as a developer cartridge 5 capable of mounting and dismounting so as to exchange the degraded developer containing the residual toner to new developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer, and a process cartridge.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus, an organic photoconductor (hereinafter, referred to as "OPC drum") has been generally used as a photoconductor.

[0003] However, OPC drums generally have the disadvantage of low mechanical durability. In other words, paper powder, toner, a cleaning blade for cleaning the surface of the photoreceptor, and the like physically contact and rub against the photoreceptor, thereby causing wear and scratches on the surface of the photoreceptor. At the same time, the cleaning blade also wears due to friction with the photoreceptor, which makes it difficult to use the cleaning blade for a long time. Therefore, with the long-term use of the image forming apparatus, it is necessary to replace the photosensitive member and the cleaning blade.

As a solution to this problem, it has been proposed to use an amorphous silicon drum (hereinafter referred to as "a-Si drum") as a photosensitive member. a-
The Si drum has a very high hardness and a high mechanical durability as compared with the OPC drum, so that the above-described problem does not occur and the photoconductor does not need to be replaced.

Further, by adopting a so-called cleaningless system in which the transfer residual toner on the photoreceptor is collected by the developing device, it is not necessary to replace the cleaning blade.

As a result, an image forming apparatus with high maintainability and low running cost can be provided.

On the other hand, in recent years, as the market for copiers / printers has expanded and various functions have been required, high durability has been particularly emphasized. Therefore, there is a need to extend the service life of the image forming apparatus greatly, to further improve the maintainability, and to reduce the running cost.

[0008]

However, in an image forming apparatus using the a-Si drum as described above and employing a cleaning-less system, if the life of the apparatus is to be greatly extended as compared with the conventional one, the following problem will occur. Problems have arisen.

That is, most of the transfer residual toner collected from the photoreceptor by the developing device is agitated in the developer, recharged, and developed again. Accumulates in the developing device. Since the accumulated transfer residual toner has a small toner particle size and a small amount of the external additive, the characteristics of the developer itself are adversely affected, and so-called deterioration of the developer is promoted.

When a contact type magnetic brush charger is used as a charger for the photoreceptor, the charging carrier adhered to the photoreceptor from the charger enters the developing device and is mixed with the developer to further deteriorate. Promoted.

Therefore, despite the fact that the photosensitive drum and the cleaning blade are not required to be replaced,
A very troublesome replacement operation of the developer is required in a relatively short time.

The same applies to a process cartridge in which at least the photosensitive member and the developing device are integrally formed as a cartridge, and this cartridge is detachably mounted on the main body of the image forming apparatus.

Accordingly, a main object of the present invention is to stabilize the characteristics of a developer in an image forming apparatus using an amorphous silicon photoreceptor and employing a cleaning-less system, and it is not necessary to replace the developer. To provide a highly durable image forming apparatus.

Another object of the present invention is to provide a process cartridge using an amorphous silicon-based photoreceptor and employing a cleaning-less system, which stabilizes the characteristics of the developer and eliminates the need to replace the developer. It is to provide a durable process cartridge.

[0015]

The above object is achieved by an image forming apparatus and a process cartridge according to the present invention. In summary, the present invention provides an amorphous silicon-based photoreceptor, and a developing device containing a two-component developer containing a toner and a carrier for developing an electrostatic latent image formed on the amorphous silicon-based photoreceptor. In an image forming apparatus provided with a cleaning-less system,
A first container containing a toner and a carrier to be supplied to the developing device, and a second container discharged from the developing device.
And a second container for collecting the component developer.

According to one embodiment of the present invention, at least the amorphous silicon photoconductor and the developing device are integrally configured as a process cartridge,
It is detachable from the image forming apparatus main body. Further, a plurality of the process cartridges are provided, and a plurality of color images are formed by transferring the toner images formed on the amorphous silicon-based photoreceptor onto a transfer material carried by a transfer material transporting unit or an intermediate transfer body in a superimposed manner. And an image forming apparatus for forming the image.

According to another aspect of the present invention, there is provided an amorphous silicon-based photoconductor, and a two-component developer including a toner and a carrier for developing an electrostatic latent image formed on the amorphous silicon-based photoconductor. A process container having an integrated cleaning device and a cleaning-less system detachable from the image forming apparatus main body; a first container storing toner and a carrier for replenishing the development device; A second container for collecting the two-component developer discharged from the developing device.

In each of the above inventions, the toner is preferably a polymerized toner.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus and a process cartridge according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS.

FIG. 2 shows the image forming apparatus of the present embodiment.
This will be described below.

The surface of the photosensitive drum 28 uniformly charged by the charger 21 is exposed to laser light from the laser 22 to form an electrostatic latent image on the photosensitive drum 28 in accordance with image information. The electrostatic latent image is developed by the developing device 1 to form a toner image on the photosensitive drum 28.

In this embodiment, a non-contact corona charger is used as the charger, but a contact charging system using a charging roller or magnetic particles may be used. Also, the photosensitive drum 28
Is an a-Si drum (amorphous photoconductor) using hydrogenated amorphous silicon as a photosensitive layer.

The toner image is transferred to the recording paper 27 conveyed by the transfer belt 24 by the transfer bias of the transfer charger 23, and then the recording paper 27 is separated from the transfer belt 24 and pressed by the fixing device 25. Heating to fix the toner image to obtain a permanent image;

The image forming apparatus of this embodiment employs a cleaningless system. There is no cleaning device for the photosensitive drum 28, and the residual toner remaining on the photosensitive drum 28 after the transfer is transferred to the developing device 1 at the same time. It is removed from the photosensitive drum 28 by cleaning.

Here, the simultaneous cleaning with development is a method of recovering by fogging bias during development (a DC voltage applied during development and a potential difference Vback on the surface of the photoconductor).

As is well known, the a-Si drum has a Vickers hardness of 1500 to 2000 kg / cm ² (= 1.5 ×
10 ^{2 to} 2.0 × 10 ² MPa), which is extremely high in mechanical strength. Further, by adopting a cleaning-less system, abrasion and scratches on the drum surface due to long-term use do not occur.

Next, the developing device 1 will be described in detail with reference to FIG.

The developing device 1 contains a two-component developer composed of a non-magnetic toner and a magnetic carrier, and the mixing ratio thereof is about 1: 9 by weight. This ratio should be properly adjusted in accordance with the charge amount of the toner, the particle size of the carrier, the configuration of the image forming apparatus, and the like, and does not necessarily have to follow this numerical value. The non-magnetic toner is a negatively charged polyester resin, produced by a pulverization method, and externally added with colloidal silica fine powder having an average particle size of 7.0 μm.

The developing device 1 has an opening in a developing region facing the photosensitive drum 28, and the developing sleeve 3 is rotatably disposed so as to be partially exposed at the opening. The developing sleeve 3 is made of a non-magnetic material and includes a fixed magnet 4 as a magnetic field generating means. The developing sleeve 3 rotates in the direction of the arrow in FIG.
The two-component developer contained in the developing container 2 is held and transported in a layered form and supplied to a developing area facing the photosensitive drum 28,
At the same time as developing the electrostatic latent image formed on the photosensitive drum 28, the transfer residual toner is removed from the photosensitive drum 28.

After the electrostatic latent image is developed, the toner removed from the photosensitive drum 28 as transfer residual toner is conveyed along with the rotation of the developing sleeve 3 and collected in the developing container 2. In the developing container 2, a first developer circulating screw 2a is arranged on a side closer to the developing sleeve 3, and a second developer circulating screw 2b is arranged on a side farther from the developing sleeve 3. By these operations, the developer is turned into the developing container. 2 and then mixed and stirred. Transfer residual toner in the developer is
It is recharged by the mixing and stirring at this time, and is again conveyed to the developing area. In this embodiment, the direction of the developer circulation is from the near side to the far side of FIG. 1 on the first developer circulating screw 2a side, and from the far side of FIG. 1 to the near side on the second developer circulating screw 2b side. It is the direction to go.

Next, the replenishment and recovery of the developer, which is a feature of the present invention, will be described in detail.

In the present embodiment, the developer supply container 5a, which is the first container storing the supply developer, and the collection developer container 5b, which is the second container for collecting the deteriorated developer,
As shown in FIG. 3, in order to make the configuration simple, the configuration is made as an integral type developer cartridge 5 and is easily detachable from the image forming apparatus main body. When the developer cartridge 5 is inserted into the main body of the image forming apparatus from the near side, the shutter mechanism 6b 'of the collected developer container 5b slides to open the developer collecting port 6b, and further to the front side of the developer supply container 5a. By twisting the provided handle 5c in the right direction in the drawing, that is, in the direction of arrow R, the developer supply container 5a rotates while the collected developer container 5b is fixed to the image forming apparatus main body, and the developer supply port 6a is opened. I do.

When the developer cartridge 5 is detached from the main assembly of the image forming apparatus, the handle 5c is twisted in the left direction in the drawing, that is, in the direction of arrow L to close both openings 6a and 6b, and the powder contained therein is removed. There is no leakage.

A stirring member 7 for stirring the replenished developer is built in the replenishment developer container 5a. FIG. 3 shows a part of the inside of the developer cartridge 5. The stirring member 7 is formed by spirally rotating a resin film or the like as shown in FIG. Yes, the developer is rotated appropriately to stir the developer in the developer supply container 5a, and to assist in the supply of the developer.

The toner consumed by the image formation passes from the developer supply container 5a through the developer supply port 6a by the rotational force and gravity of the stirring member 7, and is supplied to the supply screw 8 attached to the developer container 2. Is supplied to the developing container 2 as the supply screw 8 rotates.

In this way, the replenishment developer is supplied from the developer cartridge 5 to the developing device 1.

The mixing ratio of the toner and the carrier in the replenishment developer is about 9: 1 by weight, but is not particularly limited to this value. That is, the replenishment developer is such that the amount of toner is overwhelmingly larger than the ratio of the two-component developer in the developing container 2 of the developing device 1, and a small amount of carrier is mixed in the toner in consideration of the volume ratio. It can also be considered. That is, when supplementing the toner consumed by image formation, a small amount of carrier is gradually supplied. If the ratio of the carrier of the replenishment developer increases, the replacement amount of the carrier increases with the same amount of toner replenishment,
Although the two-component developer in the developing device 1 approaches a fresh state, the consumption of the carrier increases accordingly. For this reason, it is preferable to determine an appropriate mixing ratio in each device separately.

The amount of toner (and carrier) supplied is roughly determined by the number of rotations of the supply screw 8, and this number of rotations is determined by toner supply amount control means (not shown). There are two methods for controlling the toner supply amount.
Various methods are known, such as a method of optically or magnetically detecting the toner density of the component developer, and a method of developing a reference latent image on the photosensitive drum 28 and detecting the density of the toner image. Either method can be appropriately selected.

When toner consumption by image formation and toner replenishment by the toner replenishment amount control means are repeated, the number of carriers replenished together with toner replenishment in the developing container 2 increases. Since the toner concentration of the two-component developer is kept substantially constant by the toner supply amount control means, the amount of the developer in the developing container 2 increases. The excess two-component developer exceeds the opening of the developer collecting port 6b in the collected developer container 5.
b and is stored.

As shown in FIG. 3, the developer recovery port 6b is located at the back side in the axial direction of the developing container 2, and the developer supply port 6a is located slightly closer to the developer supply port 6a. That is, the developer collection port 6b is located upstream of the developer supply port 6a with respect to the direction of circulation of the developer in the developer container 2,
The fresh carrier supplied from the developer supply port 6a is circulated and mixed with the two-component developer contained in the developing container 2 for approximately one round in the developing container 2, and is transferred to the collected developer container 5b. Most of the collected developer is an old developer containing the untransferred toner, in which image formation is repeated in the developing device 1.

In this manner, the replacement of the two-component developer is performed gradually.

As described above, the image forming apparatus of the present embodiment
By using an a-Si drum and having a cleaningless system, high durability can be achieved without replacing the drum or cleaning blade, and the deteriorated developer including the transfer residual toner can be replaced with a new developer. With a mechanism that gradually replaces the developer, the characteristics of the entire developer are stabilized, eliminating the need for developer replacement work.
High maintainability and low running cost can be achieved.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, as shown in FIG. 4, the developing device 1, the photosensitive drum 28, and the charger 2 in the first embodiment are used.
1 and the developer cartridge 5 are integrally formed as a process cartridge 9 and can be easily attached to and detached from the image forming apparatus main body via a mounting means (not shown).

In this embodiment, the two-component developer is replaced with the developing device 1 of the process cartridge 9 by the developer cartridge 5 described in the first embodiment.

In this embodiment, the same effects as in the first embodiment can be obtained.

Embodiment 3 Next, a third embodiment of the present invention will be described.

In this embodiment, the non-magnetic toner in the developer in the first and second embodiments is a polymerized toner. Other configurations are the same as those of the first and second embodiments.

As a method for producing the toner, spherical monomer particles were obtained by suspending a monomer composition obtained by adding a colorant and a charge control agent to a monomer of a polymerization method in an aqueous medium and polymerizing the same. . The production method is not limited to the above-mentioned method, and may be produced by an emulsion polymerization method or the like, or may contain other additives.

As is well known, the polymerized toner has a nearly spherical shape compared to the pulverized toner, so that high transfer efficiency can be achieved, so that the transfer residual toner can be extremely reduced. for that reason,
The transfer residual toner amount accumulated in the developer is also reduced, and the deterioration of the developer is reduced.

Therefore, it is possible to reduce the ratio of the developer to be replenished and to reduce the consumption of the carrier.
Lower running costs can be realized.

Embodiment 4 Next, a fourth embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 5, the image forming apparatus according to the present embodiment forms toner images of a plurality of colors. 9M, 9C, and 9K are arranged in a horizontal direction along a horizontal portion of the intermediate transfer belt 124 as an intermediate transfer body.

The image forming apparatus is provided with developer cartridges 5Y, 5M, 5C, and 5K for supplying and collecting the developer, respectively. The yellow, magenta, cyan, and black toners formed by the process cartridges 9Y, 9M, 9C, and 9K are provided. The images are transferred to the transfer chargers 23Y, 23Y of each process cartridge.
M, 23C, and 23K sequentially transfer the image onto the intermediate transfer belt 124 in a superimposed manner, and thereafter, the image is collectively transferred onto the transfer paper 27 by the secondary transfer charger 123.

In general, the tandem type full-color image forming apparatus as in this embodiment has a problem that the toner transferred from the upstream process cartridge to the intermediate transfer member is re-transferred to the photosensitive drum of the downstream process cartridge. is there. For this reason, the re-transferred toner of another color is mixed into the developing device together with the untransferred toner, causing color mixing or the like, thereby promoting deterioration of the developer.

However, in this embodiment, since the developer containing the untransferred toner and the mixed toner is collected, the above problem, that is, the deterioration of the developer due to the color mixture can be prevented.

In this embodiment, the tandem type full-color image forming apparatus provided with the intermediate transfer member has been described, but each of the process cartridges 9Y, 9M, 9C,
The present invention can also be applied to a tandem-type full-color image forming apparatus in which toner images of each color formed by 9K are sequentially superimposed and transferred onto a transfer paper 27 carried on a transport belt, whereby the deterioration of the developer due to color mixing is achieved. Can be prevented beforehand.

[0059]

As is apparent from the above description, according to the image forming apparatus and the process cartridge of the present invention,
By having a first container containing a toner and a carrier for replenishing the developing device and a second container for frequently collecting the two-component developer discharged from the developing device, the characteristics of the developer can be improved. In addition to stabilization, it is not necessary to replace the developer, and high maintenance and low running cost can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a developing device and a developer cartridge according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention.

FIG. 3 is a perspective view illustrating the developer cartridge of FIG. 1;

FIG. 4 is a schematic configuration diagram showing one embodiment of a process cartridge according to the present invention.

FIG. 5 is a schematic configuration diagram showing another embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 developing device 5 developer cartridge 5a developer supply container (first container) 5b recovered developer container (second container) 9 process cartridge 27 transfer material 28 amorphous silicon photoconductor 124 intermediate transfer belt (intermediate transfer member)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/01 111 G03G 9/08 384 15/08 507B F term (Reference) 2H005 AB06 FA02 2H030 AA07 AB02 AD01 BB71 2H077 AA37 AC16 BA09 CA19 EA03 GA01

Claims (7)

[Claims] An amorphous silicon-based photoconductor, and a developing device for housing a two-component developer containing a toner and a carrier for developing an electrostatic latent image formed on the amorphous silicon-based photoconductor. An image forming apparatus provided with a cleaningless system, comprising: a first container containing toner and a carrier for replenishing the developing device;
A second container for collecting the component developer. 2. The image according to claim 1, wherein at least the amorphous silicon-based photoconductor and the developing device are integrally formed as a process cartridge, and are detachably mountable to an image forming apparatus main body. Forming equipment. 3. A process cartridge comprising a plurality of process cartridges,
4. A multi-color image is formed by transferring a toner image formed on each of the amorphous silicon-based photoconductors onto a transfer material carried by a transfer material conveying unit or onto an intermediate transfer body. 2 image forming apparatus. 4. The image forming apparatus according to claim 1, wherein the toner is a polymerized toner. 5. The image forming apparatus according to claim 1, wherein the first container and the second container are integrally formed, and are detachable from an image forming apparatus main body. 6. An amorphous silicon-based photoconductor and a developing device that contains a two-component developer containing a toner and a carrier for developing an electrostatic latent image formed on the amorphous silicon-based photoconductor are integrally formed. And a container containing a toner and a carrier for replenishing the developing device, and a two-component developer discharged from the developing device. And a container for accommodating therein. 7. The process cartridge according to claim 6, wherein said toner is a polymerized toner.