JPH08202143A - Developing device, image forming device and use method of developing device - Google Patents

Abstract

PURPOSE: To prevent surface staining of an image by applying voltage between a conductive material part and a carrying member for a developer near the conductive material part to generate an electric field in the direction which forces a developer to the wall side of the developing device. CONSTITUTION: The developing device is equipped with a vane-like member 11 as an agitator in a hopper 6. The member 11 consists of conductive 'Myler(R)' and is electrically connected with the axis of the agitator 5. When a toner having negative polarity is used, the bottom of the hopper 6 is made of an aluminum plate and grounded. By applying a bias voltage to give positive polarity on the agitator axis, a positive polarity toner produced as an inverted polarity toner is attracted to the bottom of the hopper 6 by the 'Mylar(R)' vane 11 of the agitator so that the toner is not carried to the contact part between a supplying roller and a developing roller. Thereby, even when the amt. of the inverted polarity toner increases in the hopper 6, the toner is accumulated in the bottom of the hopper 6, which prevents contamination in the base of an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a facsimile and a printer, and more specifically, a reverse charging developer in a developing device using a one-component developer. It also relates to the prevention of defects caused by the cohesive developer.

[0002]

2. Description of the Related Art In an image forming apparatus in which a latent image is formed on an image bearing member and visualized by a developer, a one-component developer is used from the viewpoints of downsizing, cost reduction, high reliability of the developing apparatus. A developing device using is advantageous. Particularly for colorization, it is advantageous to use a non-magnetic one-component developer because of its high transparency. As a developing device using a one-component developer, a developer carrying member carrying a one-component developer on its surface and carrying it along a predetermined circulation path including a developing region,
Storage means for storing the one-component developer, and developer supplying means for contacting the developer carrying member and supplying the one-component developer stored in the developer storing means to the developing and developing agent carrier. Are known (for example, JP-A-60-2).
29057 and JP-A-61-42672).

In this type of developing device, a developer accommodating space is ensured in the developing device accommodating the developer carrying member, and the developing device itself is used as the developer storing means. It is also known that the developing device itself is provided with a developer inlet (for example, the above-mentioned JP-A-61-42).
(See the apparatus of FIG. 1 of Japanese Patent No. 672b). In such a developing device, for example, a developer container (toner cartridge) containing a developer for input is charged before the amount of the developer remaining in the developing device becomes small and the image formation starts to be hindered. Set it in the mouth and do not hinder the functions of the developer supply unit in the developing device, and at the same time put a predetermined amount of toner that is set within the range that does not overflow from the developing device into the developing device. To do. According to this, a developer accommodating portion as the developer storing means is formed in the apparatus separately from the developing device, and the developer accommodating portion and the developing device are connected by a toner conveying member such as a screw. As compared with the case where such a structure is adopted, the developing device can be downsized and the mechanism can be simplified.

In this type of developing apparatus, various proposals have been made for increasing the amount of carried developer per unit area on the developer carrying member. For example, the present applicant has previously used a developer carrier including a dielectric part whose surface is regularly or irregularly distributed in a minute area and a conductive part grounded as the developer carrier. At the contact portion between the body and the developer supply member rotating at a position in contact with the surface, the one-component developer is frictionally charged, and the dielectric portion is frictionally charged by the developer supply member and the one-component developer. Then, a large number of minute electric fields are formed near the surface of the developer carrier,
A developing device has been proposed in which a one-component type developer is transferred from the developer supply member to the developer carrier by this minute electric field and carried in multiple layers on the developer carrier (JP-A-4-12717).
No. 7). FIG. 1A is a plan view showing a part of the surface of a developing roller as a developer carrying member in a specific example of the developing device according to this proposal, and FIG. 1B is an X in FIG. -X
It is sectional drawing. This developing roller has a conductive portion 51 which is grounded.
And a dielectric part 52 made of a dielectric material have a surface regularly distributed in a minute area, and a minute electric field represented by the lines of electric force shown in FIG. The proposal of such a developing device has been made in view of the following background.

For example, in a developing system using a non-magnetic one-component developer (hereinafter referred to as toner), the amount of toner adhered on the developer carrier is 0.6 to 1.0 mg / c on the image carrier.
Toner adhesion amount of about m ² , 0.5 to 0.7 mg / c on transfer paper
It is desirable that toner adhesion amounts of about m ² can be obtained. The toner adhesion amount on the image carrier and the transfer paper is not limited to the toner adhesion amount on the developer carrier,
It also depends on the relative speed between the image carrier and the developer carrier in the developing area. However, according to this type of developing device that has been put into practical use, the toner adhesion amount on the developer carrying member is 0.2 because the toner amount on the developer carrying member is as small as one layer. ˜0.5 mg / cm ² , and in order to obtain the desired toner adhesion amount on the image bearing member, the speed of the developer bearing member is set to 2 to 4 times the speed of the image bearing member. There was a need. As described above, when the rotation of the developer carrier is set high in order to cover the insufficient toner adhesion amount on the developer carrier, not only it is difficult to increase the image forming speed, but also the solid portion is removed. There is also a phenomenon of "from the toner trailing edge" in which the density of the trailing edge of the image becomes high when developed. This phenomenon is not a big problem for black-and-white images, but in color images, the color is transmitted through the toner and the color is visualized, so the density becomes high at the trailing edge, and in particular in the case of superimposed images, there is a problem that color difference occurs. It was dead.

In order to obtain a desired toner adhesion amount on the image bearing member without causing such a phenomenon "from the rear end of the toner", the speed of the developer bearing member is set to the speed of the image bearing member. It is necessary to approach the speed, that is, to approach the constant-velocity development, and increase the toner adhesion amount on the developer carrying member as compared with the conventional one. Specifically, in order to secure a sufficient toner adhesion amount on the image bearing member or the transfer paper by almost constant speed development, the toner adhesion amount on the developer bearing member is
At least 0.8 mg / cm ² by contact development method with good development efficiency,
At least 1.0 mg / cm ^{2 by} non-contact development method with poor development efficiency
Need to be In order to obtain such a toner adhesion amount on the developer carrying member, the toner layer thickness must be two or more layers. Moreover, if the toner layer on the developer carrying member conveyed to the developing area contains uncharged toner or reversely charged toner, it may cause deterioration of development transfer, background stain, resolution deterioration, etc. It is desirable to form a toner layer in which all the toner in the toner layer is charged, including the toner in the upper layer of the toner layer on the developer carrying member, which tends to be insufficient, and the toner charge amount distribution is stable. The average charge amount of the toner is preferably in the range of 5 to 10 μc / g.

Therefore, the above-mentioned developing device is proposed as a developing device capable of forming a multi-layered toner layer having a stable charge amount on a developer carrying member. According to the developing device according to this proposal, the one-component developer is transferred from the developer supply member to the developer carrying member by the minute electric field on the developer carrying member and is carried in multiple layers on the developer carrying member. A multi-layered toner layer having a stable charge amount can be formed on the developer carrying member, which makes it possible to stabilize the system and improve the image quality.

[0008]

Here, in order to downsize the developing device and simplify the mechanism, the developing device itself is also used as the developer image forming means as described above, and the developer input port is formed in itself. Then, in a one-component developing device that adopts a configuration in which a predetermined amount of developer is added at one time, the development that is input into the developing device at the time of starting with the installation of the image forming device (state where there is no toner in the developing device) Agent is consumed in the subsequent developing operation,
In the development after the second charging of the developer into the developing device, the background stain of the image which has not occurred until then, especially,
It was found that granular ground stains began to occur. In addition, the background stain that occurs after such a second and subsequent introduction of the developer into the developing device causes the developer to be carried in multiple layers on the developer carrying member as described above. I also found that it is particularly likely to occur.

Then, the present inventor diligently studied the cause, and found the following fact. The developer remaining in the developing device after the second and subsequent additions of the developer loses its initial fluidity while continuing to be agitated by an agitator and stressed by the conveying member, and the agglomeration of the developers progresses. I'm out. Further, the developer is charged to a predetermined polarity by friction with the developer carrying member, the supply roller (friction charging roller) as the developer supplying means, the developer regulating member, etc., and the developer on the developer carrying member. Although it becomes a layer and is conveyed to the developing area and consumed by the development, the developer having the opposite polarity in the developer layer is returned to the developing device again without being consumed. Therefore, the developer in the developing device at the end of the developer has a high ratio of the reversely charged developer. When a new developer is mixed in the developing device in such a state, the newly supplied developer is preferentially conveyed to the triboelectrification area because of its high fluidity, and the charged state is good so that it is adsorbed to the developer carrier. It has a strong force and forms a uniform developer layer. On the other hand, the developer that has remained in the developing unit for a long time has a weak force of adsorbing to the developer carrier even if it is transported to the vicinity of the developer carrier by an agitator, etc. It becomes granular and adheres to the surface layer of the agent layer. The granular developer is agglomerated and unstable in charging, and is transferred to the image carrier regardless of the image area or the non-image area. For this reason, after the second time the developer is added, there is a problem in that the image has granular background stains. In addition, the developer charged to the opposite polarity and accumulated in the developing device is also transferred to the image carrier and transferred to the non-image area together with the developer layer made of the newly introduced developer on the developer carrier. There was a problem that it caused dirt on the ground.

In the developing device in which the developer is carried in multiple layers on the developer carrying member as described above, since the developer is carried in multiple layers on the developer carrying member, the above-described granular development is carried out. The agent and the like are likely to be transported to the image carrier together with the developer layer made of the newly introduced developer on the developer carrier, and the above-mentioned problems are likely to occur.

The present invention has been made in view of the above problems, and an object of the present invention is likely to occur with the second and subsequent introduction of a developer into a developing device using a one-component developer. It is an object of the present invention to provide a developing device, an image forming device, and a method of using the developing device, which can prevent background stains on an image.

[0012]

In order to achieve the above-mentioned object, the developing device according to claim 1 is a developer in which a one-component developer to which an auxiliary agent is externally added is charged to a desired polarity if necessary. It is carried on a carrier, and the developer on the developer carrier is used to
In a developing device for developing a latent image on a latent image carrier, a carrying member for carrying the developer toward the developer carrying body in the developer carrying body or a developing device containing the developer, and At least a part of each wall portion of the developing device, which is in contact with or close to the carrying member, is formed of a conductive material, and a position opposite to or in contact with both is charged with a polarity opposite to the desired polarity. It is characterized in that a voltage is applied between the portions made of the respective conductive materials so as to form an electric field in the direction of pushing the developer toward the wall portion of the developing device. Here, the transport member rotates in a developer accommodating portion in the developing device and rotates at a position where it contacts the developer agitator or the agitator which sends the developer to the developer carrier side while agitating the developer. Examples thereof include a developer supplying rotating body which supplies the developer to the developer carrying member by rubbing the developer in the container on the surface and rubbing it against the surface of the developer carrying member.

According to a second aspect of the present invention, a one-component type developer, to which an auxiliary agent is externally added, is charged to a desired polarity and carried on a developer carrying member, and development on the developer carrying member is carried out. In a developing device for developing a latent image on a latent image carrier using a developer, at least a part of each of the developer carrier and a developing device wall with which the carrier approaches or contacts is formed of a conductive material. However, at the point where both contact or close,
The developer charged to the opposite polarity to the desired polarity,
It is characterized in that a voltage is applied between portions made of the respective conductive materials so as to form an electric field in the direction of pushing toward the developing device wall portion side.

According to a third aspect of the present invention, in the developing device, a one-component developer externally added with an auxiliary agent is charged to a desired polarity and carried on a developer carrier, and development on the developer carrier is carried out. In a developing device for developing a latent image on a latent image carrier by using a developer, a developer carried by the developer carrier and conveyed before the developer approaches the latent image carrier. An air flow generating means for generating an air flow in a direction opposite to the developer transport direction is provided between the wall portion and the developer carrying member.

In the image forming apparatus according to the present invention, a one-component type developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier. In an image forming apparatus that forms a developer image on the latent image carrier and transfers the developer image to a transfer material to form an image,
The developer image on the latent image carrier is provided with an airflow generating means for blowing an airflow from the downstream side in the moving direction of the latent image carrier.

In the image forming apparatus according to the fifth aspect, a one-component developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier. In the image forming apparatus for forming a developer image on the latent image carrier, transferring the developer image to a transfer material, and then fixing the developer image on the transfer material to form an image. The present invention is characterized in that an air flow generating means for blowing an air flow from the downstream side in the moving direction of the transfer material is provided to the unfixed developer image on the transfer material.

According to a sixth aspect of the present invention, in the method of using the developing device, a one-component developer externally supplemented with an auxiliary agent is charged to a desired polarity and carried on a developer carrier, and the developer carrier is then charged. Installation of a developing device for developing the latent image on the latent image bearing member using the above developer, and the start developing which has been put into the developing device containing the above developer bearing member before the start of use. The developer is consumed along with the developing operation, and when the remaining amount of the developer in the developing device decreases to a predetermined amount, a predetermined amount of new developer is charged into the developing device, and thereafter, similarly, In the method of using the developing device, in which a predetermined amount of new developer is charged into the developing device when the remaining amount of the developer in the developing device decreases to a predetermined amount due to the developing operation, As the developer, use a developer that has a smaller degree of aggregation than the developer that is subsequently put into the developing device. It is characterized in.

A method of using the developing device according to claim 7 is the method of using the developing device according to claim 6, wherein a lubricant is added as a developer for the start, rather than a developer to be subsequently charged into the developing device. This is characterized in that a large amount of developer is used.

According to the method of using the developing device of claim 8, if necessary, a one-component developer externally added with an auxiliary agent is charged to a desired polarity and carried on the developer carrying member, and the developer carrying member is carried. Installation of a developing device for developing the latent image on the latent image bearing member using the above developer, and the start developing which has been put into the developing device containing the above developer bearing member before the start of use. The developer is consumed along with the developing operation, and when the remaining amount of the developer in the developing device decreases to a predetermined amount, a predetermined amount of new developer is charged into the developing device, and thereafter, similarly, At the time when the remaining amount of the developer in the developing device decreases to the predetermined amount with the developing operation,
In a method of using a developing device for charging a predetermined amount of a new developer into the developing device, the degree of aggregation of the developer remaining in the developing device is a mixture of the developer and a newly charged developer. When a large amount of the developer remains, which is larger than the remaining amount of the developer corresponding to the time when the toner becomes defective, a new developer is added.

According to the image forming apparatus of claim 9, a one-component type developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier. In an image forming apparatus that forms a developer image on the latent image carrier, the remaining amount of the developer in the developing device that contains the developer carrier or the developer decreases to a predetermined amount with the developing operation. When a predetermined amount of a new developer is introduced into the developing device, a control means for driving at least a member that contributes to stirring the developer in the developing device for a predetermined time is provided. .

In the image forming apparatus according to the tenth aspect, a one-component type developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier. ,
In an image forming apparatus for forming a developer image on the latent image carrier, when the remaining amount of the developer in the developing device containing the developer carrier or the developer decreases to a predetermined amount with the developing operation. A control means is provided for executing an operation of causing a large amount of the developer charged to the desired polarity to adhere to the latent image carrier. (Hereinafter, margin)

The image forming apparatus of claim 11 charges a latent image on a latent image bearing member by charging a one-component type developer to which an auxiliary agent is externally added, if desired, to a desired polarity, thereby ,
In an image forming apparatus for forming a developer image on the latent image carrier, when the remaining amount of the developer in the developing device containing the developer carrier or the developer decreases to a predetermined amount with the developing operation. The control means is provided for executing the operation of adhering the developer charged with a polarity opposite to the desired polarity onto the latent image carrier.

[0023]

In the developing device according to the first aspect, between the conductive material portion of the developer transporting member in the developing device and the conductive material portion of the developing device wall which the transporting member contacts or approaches. By applying a voltage, an electric field is formed between the transport member and the developing device wall portion so as to push the developer charged to the opposite polarity to the desired polarity toward the developing device wall portion. . Due to this electric field, the developer charged to the opposite polarity is pushed and adsorbed on the wall portion of the developing device so that the developer is not conveyed to the developer carrier side.

In the developing device of the second aspect, a voltage is applied between the conductive material portion of the developer carrying member and the conductive material portion of the developing device wall with which the carrying member approaches or contacts, An electric field is formed between the carrier and the wall portion of the developing device to push the developer charged to the opposite polarity to the desired polarity toward the wall portion of the developing device. By this electric field, the developer charged to the opposite polarity is pushed against the wall portion of the developing device to be adsorbed and accumulated, so that the developer is not carried on the developer carrier.

According to another aspect of the developing device of the present invention, an air flow generating means is provided between the developer carried by the developer carrying member and conveyed toward the latent image carrying member, and the developing device wall portion approaching the developer. Generates an air flow in the direction opposite to the developer transport direction. By this air flow, the granular developer adhering to the surface layer of the developer layer on the developer carrying member is blown away to be removed, and the latent image carrying member has a stable electrostatic charge having an adsorbing power to the developer carrying member. Only the uniform developer layer can be transported.

According to another aspect of the image forming apparatus of the present invention, an air flow is generated in the upstream direction of the place where the developer image on the latent image carrier is transferred to the transfer material, in the direction opposite to the traveling direction of the image carrier. This air flow blows off and removes the granular background stain developer transferred to the non-image portion of the latent image carrier. Here, unlike the developer that adheres to the image area due to electrostatic force, this granular background smear developer is mechanically transferred to the non-image area, so it can be easily removed by the force of the air flow. . Then, the developer image is transferred with the latent image carrier facing the transfer material with the developer attached only to the image portion.

According to another aspect of the image forming apparatus of the present invention, in the upstream area of the place where the developer image is fixed on the transfer material on which the developer image is transferred from the latent image carrier, the direction opposite to the moving direction of the transfer material is set. Generates a directional air flow. With this air flow, the granular background stain developer adhering to the transfer material is blown off and removed. Here, unlike the developer that is attracted onto the transfer material from the image portion of the latent image carrier by the electrostatic force, the granular background stain developer is mechanically transferred by contact with the transfer material. , Easily removed by the force of the air flow. Then, the developer image is fixed on the transfer material in a state where the developer is attached only to the image portion.

In the method of using the developing device according to the sixth or seventh aspect, the cohesion degree gradually increases due to the stress from the agitator or the like during the developing operation, and is subsequently charged into the developing device as a developer for starting. Since there is a developer having a smaller degree of agglomeration than the developer to be used, a developer having an agglomeration degree equivalent to that of the developer to be put into the developing device thereafter is used as compared with the case where the developer for start is used. The difference in the degree of cohesion between the residual developer in the developing device and the newly added developer at the time of introducing the new developer into the developing device becomes small. Therefore, compared to the above case, the developer layer forming characteristics of the residual developer in the developing device and the newly added developer are similar, and the new developer is adsorbed on the surface of the developing roller immediately after the new developer is added. Thus, the old developer does not appear in the form of particles on the surface of the developer layer, and a uniform developer layer in which the old and new developers are well mixed can be obtained.

Particularly, in the method of using the developing device according to the seventh aspect, since the amount of the lubricant added at the start is larger than that of the developer to be put into the developing device after that, the developer for the start is used. The progress of the degree of aggregation of the developer during the development with the developer is compared to the case where the developer with the same lubricant addition amount as the developer to be put into the developing device later is used as the developer for start. Can be kept low. Therefore, it is possible to further reduce the difference in the degree of aggregation between the residual developer in the developing device and the newly added developer when the new developer is introduced into the developing device.

In the method of using the developing device according to the eighth aspect, the degree of aggregation of the developer remaining in the developing device is so large that the mixing of the developer and the newly added developer is defective. Before that, add a new developer. As a result, immediately after the introduction of a new developer, due to the difference in the degree of aggregation between the developer remaining in the developing device before the introduction and the introduced developer, in the developing layer on the developer carrier, the old and new Prevents poor mixing of the developer such that the developer is separated into the lower layer and the surface layer.

According to another aspect of the image forming apparatus of the present invention, the remaining amount of the developer in the developing device decreases to a predetermined amount with the developing operation, and a predetermined amount of new developer is introduced into the developing device. At this time, at least a member that contributes to stirring the developer in the developing device is driven for a predetermined time. This sufficiently diffuses and mixes the introduced new developer and the old developer remaining in the developing device to prevent the old and new developers from separating into the lower layer and the surface layer in the developer layer, and to evenly distribute them. Allows a developer layer to be formed.

In the image forming apparatus of the tenth aspect, the image forming operation is stopped when the remaining amount of the developer in the developer carrying member or the developer accommodating the developer decreases to a predetermined amount in association with the developing operation. Then, the operation of depositing a large amount of the developer charged to the desired polarity on the latent image carrier is performed. As a result, the amount of developer in the developing device is rapidly reduced to make the inside of the developing device almost empty, and then the developer is charged. Here, when a large amount of the developer is attached to the latent image carrier, the poorly charged developer and the like in the developing device are also transferred to the latent image carrier side while being aggregated. Therefore, when the developer is added, the same state as at the start is obtained.

In the image forming apparatus of the eleventh aspect, when the remaining amount of the developer in the developer carrying member or the developer accommodating the developer decreases to a predetermined amount due to the developing operation, or when the non-image forming is performed, The operation of depositing the developer charged to the opposite polarity to the desired polarity on the latent image carrier is executed. As a result, the developer charged to the opposite polarity is consumed.

[0034]

FIG. 2 is a schematic view of an electrophotographic image forming apparatus to which the present invention can be applied, FIG. 3 (a) is a schematic cross-sectional view of a non-magnetic one-component developing device used in the apparatus, and FIG. 3 (b). Shows an explanatory view of toner replenishment to the developing device. In FIG. 2, the image forming apparatus charges the photoconductor 1 as the latent image carrier by the charger 21 and then writes the electrostatic latent image by the exposure device 22. After that, development is performed by the developing device 23 to form a toner image on the photoconductor. After this, the toner image is transferred
Transferred on the transfer paper as a transfer material by the transport member 24,
The toner image on the transfer paper is fixed on the transfer paper by heat or pressure of the fixing device 25. The transfer paper on which the toner image is fixed is
The paper is discharged onto the paper discharge tray 26. Then, the toner remaining on the photosensitive member after transfer is scraped off by the cleaning member 27 and used again for image formation.

In FIG. 3A, the developing device 23 is
A hopper 6 as a toner storage is formed inside. Toner 7 in this hopper 6 is agitator 5
The toner is agitated by and is passed over a supply roller 4 as a developer supply means. The supply roller rotates in contact with the developing roller 2 as a developer carrying member to rotate the toner,
Also, the dielectric portion 52 of the developing roller is triboelectrically charged. That is, the developing roller 2 of this example has a surface in which the grounded conductive portion 51 and the dielectric portion 52 made of a dielectric material are regularly distributed in a small area, as in the developing roller shown in FIG. And a minute electric field is formed on the surface. Here, the charged toner is held in multiple layers on the roller by a minute closed electric field on the roller. Then, the toner is adjusted to an appropriate toner layer thickness by the elastic regulating member (thinning blade) 3 and conveyed to the developing area. And photoconductor 1
Development is performed by transferring the toner to.

In FIG. 3B, when the remaining amount of toner in the developing device 23 has decreased to a predetermined amount, the lid 6a above the hopper 6 is opened to open the toner replenishment port, and the toner for replenishment is placed here. The toner cartridge 8 containing 9 is set and the toner is replenished at one time. After the replenishment, the toner cartridge 8 is removed, the lid 6a is closed, and the image forming operation can be restarted.

[Embodiment 1] An embodiment in which the present invention is applied to such an image forming apparatus and a developing device will be described below. First, a first embodiment will be described with reference to FIG. In this embodiment, the agitator 5 in the hopper 6 of the developing device is provided with a wing-shaped member 11. The wing-shaped member 11 is made of a conductive mylar and is electrically connected to the shaft of the agitator 5. When the toner used for development has a negative polarity, the bottom of the hopper 6 is made of aluminum sheet metal and grounded. Then, by applying a positive polarity bias to the agitator shaft, the positive toner generated as the opposite polarity toner is transferred to the Mylar blade 11 of the agitator.
The supply roller 4 is attracted to the bottom of the hopper 6 and
It is prevented from being conveyed to a contact portion (hereinafter, referred to as a toner layer forming area) between the developing roller 2 and the developing roller 2. By doing so, even if the toner of the opposite polarity increases in the hopper 6, the toner is accumulated at the bottom of the hopper 6 and the occurrence of background stain is prevented. When the toner used has a positive polarity, the bias applied to the agitator shaft has a negative polarity.

[Embodiment 2] Next, another embodiment will be described with reference to FIG. In this embodiment, as the supply roller 4, a roller provided with a semiconductive layer of polyurethane foam or rubber on a cored bar is used. The bottom of the hopper 6 is made of aluminum sheet metal so that the gap between the surface of the supply roller 4 and the bottom of the hopper 6 is about 1 mm or less.
When the toner used at the time of development has a negative polarity, a bias deviated from the bias applied to the supply roller 4 by 300 to 500 V and a negative polarity is applied to the bottom of the hopper 6. By doing so, the reverse polarity toner adhering to the supply roller 4 is adsorbed to the bottom of the hopper 6 so as not to be conveyed to the toner layer forming region. Therefore, even if the toner of the opposite polarity increases in the hopper 6, the toner is accumulated at the bottom of the hopper 6 and the occurrence of background stain is prevented. When the toner used has a positive polarity, the bias applied to the bottom of the hopper 6 is reversed.

[Third Embodiment] Next, still another embodiment will be described with reference to FIG. In this embodiment, the adjoining portion of the developing roller 2 in the hopper 6 or an extended portion of the hopper 6 is made of an aluminum material. When the toner used in the development has a negative polarity, the bias applied to the development roller 2 during development is 300 to 500 V, which is biased to the negative polarity and is adjacent to the development roller 2 at the bottom of the hopper 6 or an extension of the hopper 6. Apply to the member.
By doing so, the reverse polarity toner adhering to the developing roller 2 is adsorbed and accumulated on the bottom of the hopper 6 or an extended portion of the hopper 6, thereby preventing the occurrence of background stains. When the toner used has a positive polarity, the bias applied to the bottom of the hopper 6 or its extension is reversed.

[Fourth Embodiment] Next, still another embodiment will be described with reference to FIG. In this embodiment, the suction fan 12 as an air flow generating means for generating an air flow in the direction opposite to the rotating direction of the developing roller 2 on the upstream side of the developing area facing the photoconductor 1 in the developing roller rotating direction. Is provided. Even if the amount of the toner with unstable charging and the increased amount of toner increases in the hopper 6 with time and becomes granular and adheres to the surface layer of the roller, the fan 12 creates an air flow against the laminar flow of the surface layer of the toner layer. Then, the granular toner can be blown off and removed. Then, development can be performed only with a uniform toner layer which has an attractive force and is stable against the roller. Therefore, the occurrence of background stain is prevented and a good image can be obtained.

[Fifth Embodiment] Next, still another embodiment will be described with reference to FIG. In this embodiment, a suction fan 13 is provided as an air flow generating means for generating an air flow in the direction opposite to the traveling direction of the photoconductor 1 in the upstream region of the place where the toner image on the photoconductor 1 is transferred onto the transfer paper. Even if the agglomerated toner having unstable charging is transferred to the non-image portion of the photoconductor 1, the granular smear toner can be blown off and removed by the rapid flow against the laminar flow on the surface of the photoconductor. This is because, unlike the toner that adheres to the image area by electrostatic force, the granular background toner is mechanically transferred to the non-image area.
This is because it can be easily removed by the force of the air flow. Then, by transferring the toner image onto the transfer paper in a state where the toner is attached only to the image portion, a good image without background stain can be obtained.

[Sixth Embodiment] Next, still another embodiment will be described with reference to FIG. In this embodiment, after the toner image on the photoconductor 1 is transferred to the transfer paper, an air flow is generated in the upstream area of the place where the toner image on the transfer paper is fixed, in the direction opposite to the moving direction of the transfer paper. Suction fan 14 as a means
Is provided. Even if the toner having unstable charging is transferred to the non-image portion of the photoconductor 1 and is transferred onto the transfer paper, the toner can be blown off and removed by the air flow against the laminar flow on the surface of the transfer paper. This is because the granular background stain toner is mechanically transferred by contact with the transfer paper, unlike the toner that is attracted onto the transfer paper from the image portion of the photoconductor by electrostatic force. Because it can be removed. Then, by fixing the toner image on the transfer paper on which the toner is attached only to the image portion, a good image without background stain can be obtained.

[Embodiment 7] Next, still another embodiment will be described. In this embodiment, the toner replenished into the hopper 6 is characterized in that the start-time replenishment toner and the second and subsequent replenishment toners have different aggregation degrees of the one-component toner, and the start-time toner has a different aggregation degree. It is low. In this way, the difference in the degree of cohesion between the toner that remains in the hopper 6 from the start and continues to be stressed by the agitator and the toner that has been newly replenished is small, and the toner layer forming characteristics are similar. For this reason, the new toner is not adsorbed on the surface of the developing roller immediately after the toner is replenished, and the old toner does not appear in the form of particles on the surface of the toner layer, and the old and new toner are well mixed to form a uniform toner layer. . Therefore, it is possible to obtain a good image with no background stain even after the toner is replenished.

[Embodiment 8] Next, still another embodiment will be described. In this embodiment, hydrophobic silica is externally added as a fluidizing agent to the one-component toner to be replenished in the hopper 6, and the replenishment toner at the start has a larger amount of addition of the hydrophobic silica than the second and subsequent replenishment toners. Therefore, the liquidity is high. By doing so, the progress of the aggregation of the toner remaining in the hopper 6 until the toner end is suppressed to a low level, and the toner layer forming characteristics of the old and new toners can be made similar. For this reason, the new toner is not adsorbed on the surface of the developing roller immediately after the toner is replenished, and the old toner does not appear in the form of particles on the surface of the toner layer, and the old and new toner are well mixed to form a uniform toner layer. . Therefore, it is possible to obtain a good image with no background stain even after the toner is replenished.

[Ninth Embodiment] Next, still another embodiment will be described. In this embodiment, the amount of toner remaining in the hopper 6 is larger than the amount of toner replenished in the hopper 6 after the second start. This is to prevent a large amount of toner from remaining in the hopper 6 at the time of toner end, so that stress from an agitator or the like is applied to a small amount of toner and the progress of aggregation is suppressed. As a result, the newly replenished toner is diffused and mixed into the toner already in the hopper 6, and the old and new toners in the toner layer are not separated into the lower layer and the surface layer to cause background stain. A good image can be obtained. In this example, the amount of toner replenished to the hopper 6 after the second time after the start is adjusted so that the newly replenished toner is well dispersed and mixed in the toner already in the hopper 6. Although the amount of toner remaining in the hopper 6 is larger, the amount of toner to be replenished and the amount of residual toner at the time of toner end are determined depending on the fluidity of the toner used and the progress of the degree of aggregation due to stress. Is set appropriately.

[Embodiment 10] Next, still another embodiment will be described. In this embodiment, when a predetermined amount of toner is replenished into the hopper 6 at one time, when new toner is replenished into the hopper 6, a rotation operation is performed for a predetermined time before image formation. By doing this, new toner and old toner remaining in the hopper 6 are sufficiently dispersed,
By mixing, the new and old toners in the toner layer are prevented from separating into a lower layer and a surface layer, and a uniform toner layer is formed.
A good image can be obtained without causing scumming after toner replenishment.

[Embodiment 11] Next, still another embodiment will be described. In this embodiment, when the amount of toner in the hopper 6 becomes smaller than a predetermined amount, it is determined that the toner has run out, the image forming operation is stopped, and solid development is performed in the non-image forming area to rapidly reduce the amount of toner in the hopper 6. The inside of the hopper 6 is made almost empty, and then the toner is replenished. In this way, the solid development causes the uncharged toner and the like in the hopper 6 to be transferred to the photosensitive member side while being aggregated, and the toner replenishment is always in the same state as at the start. Therefore, there is almost no change in the image density, and a good image is maintained with no background stain after replenishment.

[Embodiment 12] Next, still another embodiment will be described. In this embodiment, when the amount of toner in the hopper 6 becomes smaller than a predetermined amount, a bias for positively consuming toner of opposite polarity is applied to the developing roller 2 during non-image formation to operate the developing device. There is. This is because by applying a bias to the developing roller 2 so as to be opposite to the normal developing potential difference with respect to the photoconductor before and after image formation, during paper interval, etc., the reverse polarity toner in the hopper 6 is consumed, It is possible to prevent the reverse charge field toner from appearing on the surface of the toner layer and causing the background stain after replenishing with new toner. (Hereinafter, margin)

Next, an example of another developing device applicable to the image forming apparatus of FIG. 2 will be described with reference to FIG.
In FIG. 10, the speed of the photoconductor 1 is 200 mm / se.
c, which is rotating in the direction of the arrow. In this developing device, the toner in the hopper 6 is stored in the first agitator 5a,
And it is stirred and conveyed by the second agitator 5b.
A 0.2 mm thick polyethylene terephthalate (PET) mylar blade is attached to the metal shafts of both agitators, and the length of the mylar blade is such that it contacts the bottom of the hopper. The developing roller 2 rotates in the direction indicated by the arrow and contacts the supply roller 4. The supply roller 4 bites about 1 mm at the contact portion with the developing roller 2 and rotates in the same direction (forward rotation) at about 1.5 times the speed of the developing roller 2 to give a triboelectric charge to the developing roller 2 and the toner.
FIG. 11A is an explanatory view of the surface structure of the developing roller 2, FIG.
1 (b) is an enlarged view of the surface. Electric charges having a polarity opposite to that of the toner are accumulated in the dielectric portion 52 of the developing roller 2, and a minute closed electric field (microfield) is formed between the dielectric portion 52 and the grounded conductive portion 51, so that the charged toner is electrostatically charged in multiple layers. Hold. Then, as the developing roller 2 rotates, the elastic regulation blade comes into surface contact with the roller from the trailing direction to make the toner layer thickness uniform. Then, in the developing area, the photoconductor and the developing roller 2 are rotated at substantially the same speed to perform development.

When 60 g of toner was replenished to such a developing device at the time of start, M / A (toner mass per unit area) was 1.3 mg / cm ² , Q / M on the developing roller.
A toner layer having optimum characteristics for development of (-12 μc / g of toner charge amount per unit mass) was obtained. In the developing area, the toner layer and the electrostatic latent image were opposed to each other in a non-contact manner, and development was performed to obtain a good image.

Specific developing part characteristics and developing conditions are as follows. Elasticity regulation blade 3 ・ Material urethane rubber ・ Thickness 2 mm ・ Blade length to free end 11 mm ・ Blade biting amount to roller 0.6 mm ・ Protrusion amount from blade abutting part to free end 0.5
mm Developing roller 2 (creation method) FIG. 10 shows a schematic view.・ Knurled type, roller diameter is 20mm, 0.3mm pitch on aluminum core metal, depth 0.1mm, groove width 0.2mm
Iris knurling is performed at an angle of 45 degrees.・ Electric modified silicone resin (Toray SR
2115) and dried at 50 ° C. for about 90 minutes. -Cutting the roller surface to expose the aluminum surface 51 and the dielectric surface 52 at a ratio of 3: 7. Supply roller 4 ・ Material: Carbon kneaded foamed polyurethane sponge roller Diameter 16 mm Agitator member 5 ・ Aluminum shaft with 0.2 mm thick Mylar (polyethylene terephthalate material) attached Development gap ・ 150 μm (photoreceptor is drum type) ) Development bias-DC-750V Photoreceptor 1-Photoreceptor type: OPC-Surface potential: Background part -850V, writing part (image part)
-100V Toner 7 ・ Negatively charged toner using non-magnetic styrene acrylic resin + polyester resin Volume average particle diameter: 10 μm External additive: Hydrophobic silica fine powder

By using the above developing device, image formation is continued, the toner in the hopper 6 is reduced, and the decrease in toner amount to a predetermined amount is indicated by the piezoelectric sensor 1 below the hopper 6.
When it was continuously detected as 0, it was determined that the toner was out, and the image forming operation was stopped. At this time, the amount of toner remaining in the hopper 6 was 25 g, and the degree of aggregation was 20%. Further, the M / A on the developing roller 2 was lowered to 0.9 mg / cm ² , and the image density was also lowered. And the lid 11 on the ceiling of the hopper 6
Opened and refilled with 60 g of new toner using the cartridge, M / A on the roller was 1.3 mg / cm ²
And the image density was restored. This new toner is the same as the starting toner and has a cohesion of 11%.

Here, the cohesion degree of the toner was measured using the apparatus shown in FIG. This device is mounted on a vibrating table 101 of a powder tester manufactured by Hosokawa Micron Co., Ltd., which has accessory parts such as a vibro chute 102 and a packing 10.
3, space ring 104, three types of filters 105, 1
06, 107, set the restraining bar 108 in this order,
Although the vibrating table 101 is not vibrated by the vibrating device 100, the vibrating table 101 is measured under the following measurement conditions. -Opening of the lower filter 105 is 22 μm-Opening of the middle filter 106 is 45 μm-Opening of the upper filter 107 is 75 μm-Amplitude scale of the vibration table 101 is 1 mm-Amount of toner collected as the sample T is 10 g- The vibration time was 30 seconds, and the degree of aggregation was determined by the following calculation. [(Toner mass of upper filter) / (Sample collection amount)] × 100 (a) [(Toner mass of middle filter) / (Sample collection amount)] × 100 × (3/5) (b) [( Toner mass of lower filter) / (sample amount)] × 100 × (1/5) (c) (a) + (b) + (c) = coagulation degree (unit:%)

However, in the image formation after replenishing the toner, the toner aggregated on the surface layer of the toner layer appeared in the form of particles and appeared as a background stain on the image. An embodiment in which the present invention is applied to the above specific developing device will be described below. In addition, each embodiment applies the same invention as in the above-described first to twelfth embodiments, and in order to clarify the correspondence, the embodiment numbers in parentheses at the beginning of the description of each embodiment are as follows: The numbers with "-2" added to the above-described Examples 1 to 12 are used.

[Embodiment 1-2] In this embodiment, the Mylar blades of the agitator 5a and the agitator 5b of the above-described concrete developing device are subjected to the conductive treatment by carbon dispersion.
It was changed to an ET film and +300 V was applied from the agitator shaft. The bottom of the hopper 6 was made of metal and grounded. Other than that, image formation was performed under the same conditions as described above. At this time, the potential of the wing portion was +250 V, but it did not leak to the bottom of the hopper due to the semiconductive material.
Even after the same toner replenishment was performed at the time of toner end, a uniform negatively charged toner layer was formed, and a good image was continuously obtained without generation of granular background stain on the image.

[Embodiment 2-2] In this embodiment, the same developing device and developing conditions as those of the above-mentioned Embodiment 1-2 are used, and -750 V is applied to the developing roller 2 and the supply roller 4 shaft during the development. . A carbon dispersed polyurethane resin is used for the supply roller 4, and the surface of the supply roller 4 and the developing roller 2 are
Are set to have the same potential. Supply roller 4
To the grounded metal hopper bottom 6 of 0.
6 mm, and -100 at the bottom of the hopper during development.
0V was applied. The image formation is continued in such a state, and even after the toner is replenished at the time of the toner end, a uniform negatively charged toner layer is formed, and the image does not have a granular background stain, which is excellent. Images were continuously acquired.

[Embodiment 3-2] In this embodiment, the same developing device and developing conditions as those of the above-mentioned Embodiment 1-2 are used, and -750 V is applied to the developing roller 2 and the supply roller 4 shaft during development. . At the time of development, −1000 V was applied to the bottom portion 6 of the hopper and to the aluminum toner receiving portion 15 arranged in contact with the hopper and in the vicinity of the developing roller 2. The toner receiving member 15 is for preventing the toner on the surface layer of the toner layer from scattering outside the developing device due to the rotation of the developing roller 2, and is arranged with a gap of 0.7 mm from the developing roller 2. . The gap between the developing roller 2 and the bottom of the hopper is set to 0.6 mm. Even after the image formation was continued in this state and the toner was replenished at the toner end, a uniform negatively charged toner layer was formed and no granular background stain was generated on the image. After the 10,000 sheets of images were formed, the toner having the opposite polarity was laminated on the surface of the toner receiving portion facing the developing roller 2, but a good image was continuously obtained.

[Embodiment 4-2] In this embodiment, the same developing device and developing conditions as those in Embodiment 1-2 are used, and
Similar to the device shown in FIG. 7, the exhaust fan 12 is arranged above the developing device, and the elastic blade 3 and the upper scattering prevention member 16 are provided.
It is set so as to draw out the airflow between and. The image formation was continued in such a state, and even after the toner was replenished at the time of the toner end, a good image was continuously obtained without the occurrence of granular background stain on the image.

[Embodiment 5-2] In this embodiment, the same developing device and developing conditions as in Embodiment 1-2 are used, and
Similar to the device shown in FIG. 8 described above, the exhaust fan 13 is set so as to extract the air flow from the photoconductor 1. The image formation was continued in such a state, and even after the toner was replenished at the time of the toner end, a good image was continuously obtained without the occurrence of granular background stain on the image.

[Embodiment 6-2] In this embodiment, the same developing device and developing conditions as in Embodiment 1-2 are used, and
The transfer / conveyance body 2 of the image forming apparatus is similar to the apparatus shown in FIG.
4 the exhaust fan 14 from the toner image transferred to the recording medium on 4.
Is set so that the air flow is withdrawn in the direction opposite to the transport direction. The image formation was continued in such a state, and even after the toner was replenished at the time of the toner end, a good image was continuously obtained without the occurrence of granular background stain on the image.

[Embodiments 7-2, 8-2] In this embodiment, the same developing device and developing conditions as the above specific developing device are used, and the amount of silica added is 0. A toner having an aggregation degree of 5% of 9 wt% was used, and 60 g of this toner was replenished. At the time of toner end, the amount of toner remaining in the hopper 6 was 23 g, and the degree of aggregation was 13%. In this state, 60 g of a new toner having an agglomeration degree of 11% and an externally added amount of silica of 0.5 wt% was replenished. As a result, a uniform toner layer was formed even after the replenishment, and scumming did not occur.

[Embodiment 9-2] In this embodiment, the same developing device and developing conditions as in Embodiments 7-2 and 8-2 above are used.
In addition, the piezoelectric sensor for detecting the toner end is attached to the upper side or the side plate of the hopper. Then, at the start, after replenishing 120 g of toner having a cohesion of 11%, the image formation is continued and about 70 g of toner is left in the hopper to stop the image formation as a toner end. At this time, the aggregation degree of the toner in the hopper was 15%. Then, when 60 g of toner similar to that used at the start is replenished to form an image,
A good image was formed and obtained without the occurrence of scumming.

[Embodiment 10-2] In this embodiment, the same developing device and developing conditions as in Embodiments 7-2 and 8-2 are used. Then, at the start, 60% of toner with an aggregation degree of 11%
After replenishing with g, the image formation is continued and 25 g is added to the hopper.
A certain amount of toner remains, and the image formation is stopped as the toner end. At this time, the aggregation degree of the toner in the hopper was 21%. Then, after replenishing 60 g of the same toner as at the start, the agitator was rotated for about 2 minutes to stir and mix the toner before performing the image forming operation. After that, when the developing roller 2 was rotated, granular aggregated toner did not appear on the surface of the toner layer, and a uniform toner layer was formed. A good image was continuously obtained without the occurrence of scumming.

[Embodiment 11-2] In this embodiment, the same developing device and developing conditions as in Embodiments 7-2 and 8-2 are used. Then, at the start, 60% of toner with an aggregation degree of 11%
After replenishing with g, the image formation is continued and 25 g is added to the hopper.
A certain amount of toner remains, and the image formation is stopped as the toner end. M / A on the roller at this time is 0.9 mg / cm
It had dropped to ² . Then, while exposing the entire surface of the photosensitive member, a bias of -1000 V is applied to the developing roller 2 to
When the developing device was driven for about a minute, only about 5 g of toner remained on the wall surface of the hopper. After that, when the image formation was performed after replenishing 60 g of the same toner as at the time of start, a good image was continuously obtained without generation of background stain.

[Embodiment 12-2] In this embodiment, the same developing device and developing conditions as those in Embodiments 7-2 and 8-2 are used. Then, at the start, 60% of toner with an aggregation degree of 11%
After replenishing, the image formation is continued. At this time, the driving of the developing device is stopped except during image formation. Then, the operation timing of the image forming apparatus is changed at the time when the toner end detection sensor under the hopper issues a toner-less signal, and the charging potential of the photoconductor is set to −850 V before and after the image formation or between the sheets, to the developing roller 2. Applied bias of + 150V
And driving the developing device to positively consume the positive polarity toner in the toner layer. Then 10
The image forming operation was stopped as toner end and toner replenishment was performed at the time when the toner end detection sensor continuously emitted a toner absence signal after image formation of 0 sheets, but after that, the roller surface also has a reverse polarity. The toner did not appear and did not cause background stains, and good images were continuously obtained.

[0065]

According to the developing device of the first aspect, between the developer conveying member and the developing device wall portion in the developing device,
An electric field is formed that pushes the developer charged to the opposite polarity to the desired polarity toward the wall portion of the developing device, and the developer charged to the opposite polarity is adsorbed to the wall portion of the developing device. Let me
Since the developer is not conveyed to the developer carrying member side, even if the developer of the opposite polarity is increased in the developing device, it is possible to prevent the occurrence of background stain due to the developer of the opposite polarity.

According to the developing device of the second aspect, between the developer carrier and the wall portion of the developing device, the developer charged to the opposite polarity to the desired polarity is applied to the wall portion of the developing device. An electric field in the direction of pushing is formed, and the developer charged to the opposite polarity is adsorbed to the wall portion of the developing device so as not to be carried on the developer carrier, so that the developer having the opposite polarity is developed in the developing device. Even if the amount of the developer is increased, it is possible to prevent the background stain from being caused by the developer having the opposite polarity.

According to the developing device of the third aspect, the granular developer adhering to the surface layer of the developing layer carried by the developer carrying member and conveyed toward the latent image carrying member is blown off by an air stream to be removed. However, since it is possible to convey only to the latent image carrier a uniform developer layer that has an adsorbing force to the developer carrier and is stable in charging, it is possible to prevent scumming due to the granular developer. Images can be obtained.

According to the image forming apparatus of claim 4, in the upstream region of the place where the developer image of the latent image carrier is transferred to the transfer material,
The granular background stain developer transferred to the non-image area of the latent image carrier is removed by blowing it off with an air stream, and the latent image carrier is made to face the transfer material with the developer attached only to the image area. Since the developer image is transferred, a good image free of background stain due to the granular developer can be obtained.

According to the image forming apparatus of the fifth aspect, in the upstream region of the place where the developer image is fixed, the granular background adhered on the transfer material onto which the developer image is transferred from the latent image carrier. The stain developer is blown away with an air stream to remove it, and the developer image is fixed on the transfer material with the developer attached only to the image area.
A good image without background stains due to the granular developer can be obtained.

According to the method of using the developing device of claim 6 or 7, a developer having a smaller degree of agglomeration than a developer to be put into the developing device later is used as the developer for start-up, and the developing is performed. The difference in the degree of cohesion between the residual developer in the developing device and the newly charged developer at the time of charging the new developer into the device is reduced so that the new developer will be developed even immediately after the new developer is charged. Since the old developer is adsorbed on the surface and does not appear in the form of particles on the surface of the developer layer, a good image free from background stains due to the granular developer can be obtained even after the introduction of the developer.

In particular, according to the method of using the developing device of claim 7, as the developer for the start, a developer in which the amount of the lubricant added is larger than that of the developer to be put into the developing device thereafter is used. , To suppress the progress of the degree of aggregation of the developer during development to further reduce the difference in the degree of aggregation between the residual developer in the developing device and the newly added developer when the new developer is introduced into the developing device. Therefore, the background stain due to the granular developer after the developer is added can be prevented more effectively.

According to the method of using the developing device of claim 8,
A new developer is charged before a new developer is charged before the agglomeration degree of the developer remaining in the developing unit becomes large to such an extent that the mixing of the developer and the newly charged developer becomes poor. Since the separation of the old and new developer layers in the developing layer on the developer carrier is prevented due to the difference in the degree of aggregation between the old and new developers immediately after the developer is charged, the development is performed after the developer is charged. In the developer layer on the agent-carrying member, a good image can be obtained in which there is no background stain due to separation of the old and new developers into the lower layer and the surface layer.

According to the image forming apparatus of claim 9, when a predetermined amount of new developer is charged into the developing device, at least a member that contributes to stirring the developer in the developing device is driven for a predetermined time. , The new developer and the old developer remaining in the developing unit are sufficiently diffused and mixed to prevent the old and new developers from separating into the lower layer and the surface layer in the developer layer. Later, in the developer layer on the developer carrying member, a good image is obtained which is free from background stains due to separation of old and new developers into a lower layer and a surface layer.

According to the image forming apparatus of the tenth aspect, when the remaining amount of the developer in the developer carrier or the developer containing the developer is reduced to a predetermined amount, the image forming operation is stopped and the desired amount of the developer is stopped. The developer is charged in a large amount on the latent image bearing member, and the operation is performed to transfer the developer including the poorly charged developer to the latent image bearing member side. Since the state is the same as when starting the developer, the state is similar to that at the time of starting, and there is almost no change in the image density, and it is possible to maintain a state in which a good image can be formed with no background stain after the developing.

According to the image forming apparatus of the eleventh aspect, when the remaining amount of the developer in the developer carrying member or the developer containing the developer is reduced to a predetermined amount, the above-mentioned desired polarity is maintained during non-image formation. Causes the developer charged with the opposite polarity to adhere to the latent image carrier, thereby consuming the developer charged with the opposite polarity. It is possible to prevent the oppositely charged developer from appearing on the surface of the developer layer on the developing carrier and causing the background stain after the agent is added.

As described above, according to the invention of each claim,
In particular, when placed in an image forming apparatus using a non-magnetic one-component developing device, it is possible to prevent deterioration of the image quality level such as scumming due to defective formation of the toner layer and maintain a good image for a long period of time. Further, it is possible to prevent the image quality level such as background stain from fluctuating before and after the toner is put into the developing device, and maintain a good image for a long time.

[Brief description of drawings]

1A and 1B are explanatory views of a developing roller according to a conventional example.

FIG. 2 is a schematic configuration diagram of an image forming apparatus to which the present invention can be applied.

3A and 3B are explanatory views of a developing device of the image forming apparatus.

FIG. 4 is an explanatory diagram of a developing device according to an embodiment.

FIG. 5 is an explanatory view of a developing device according to another embodiment.

FIG. 6 is an explanatory view of a developing device according to still another embodiment.

FIG. 7 is an explanatory view of a developing device according to still another embodiment.

FIG. 8 is an explanatory view of a developing device according to still another embodiment.

FIG. 9 is an explanatory view of a developing device according to still another embodiment.

FIG. 10 is an explanatory diagram of another developing device that can be used in the image forming apparatus.

11A and 11B are explanatory views of a developing roller of the same developing device.

FIG. 12 is an explanatory diagram of a device for measuring toner cohesion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Development roller 4 Supply roller 5 Agitator 6 Hopper 6a Lid 7 Toner 8 Toner cartridge 9 Replenishment toner 23 Developer

Claims (11)

[Claims] 1. A one-component developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and carried on a developer carrier, and the developer on the developer carrier is used. In a developing device for developing a latent image on an image carrier, a carrying member for carrying a developer toward the developer carrier in the developer carrier or a developing device containing the developer, and At least a part of each wall of the developing device, which is brought into contact with or close to the carrying member, is made of a conductive material, and the developing portion is charged to a position opposite to or opposite to the desired polarity at a position where they come in contact with or close to each other A developing device, wherein a voltage is applied between portions made of respective conductive materials so as to form an electric field in a direction of pushing the agent toward the wall portion of the developing device. 2. A one-component developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and carried on a developer carrier, and the latent image is formed using the developer on the developer carrier. In a developing device for developing a latent image on an image bearing member, at least a part of each of the developer bearing member and a developing device wall with which the bearing member approaches or contacts is formed of a conductive material, and contact between the two At a location close to each other, so as to form an electric field in a direction in which the developer charged to the opposite polarity to the desired polarity is pushed to the developing device wall portion side,
A developing device characterized in that a voltage is applied between portions made of respective conductive materials. 3. A one-component developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and carried on a developer carrier, and the latent image is formed using the developer on the developer carrier. In a developing device for developing a latent image on an image bearing member, a developer carried by the developer bearing member and conveyed, and a developing device wall portion approaching before facing the latent image bearing member,
A developing device, characterized in that an air flow generating means for generating an air flow in a direction opposite to a developer carrying direction is provided between the developer carrying member and the developer carrying member. 4. A one-component type developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier, whereby the latent image carrier is In the image forming apparatus, which forms a developer image on the latent image carrier and transfers the developer image to a transfer material to form an image, the developer image on the latent image carrier is downstream of the moving direction of the latent image carrier. An image forming apparatus comprising an air flow generating means for blowing an air flow from the side. 5. A one-component type developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and adhered to the latent image on the latent image bearing member, whereby the latent image bearing member is charged. In the image forming apparatus, a developer image is formed on a transfer material, the developer image is transferred to a transfer material, and then the developer image is fixed on the transfer material to form an image. An image forming apparatus, comprising: an airflow generating means for blowing an airflow from a downstream side in a moving direction of the transfer material to the developer image. 6. A one-component developer to which an auxiliary agent is externally added, if necessary, is charged to a desired polarity and carried on a developer carrier, and the latent image is formed by using the developer on the developer carrier. Installation of a developing device that develops the latent image on the image bearing member Before the start of use, the developer for starting that was put in the developing device containing the developer bearing member is consumed with the developing operation. Then, when the remaining amount of the developer in the developing device decreases to a predetermined amount, a predetermined amount of new developer is charged into the developing device, and thereafter, similarly,
A method of using the developing device, wherein a predetermined amount of new developer is charged into the developing device when the remaining amount of the developer in the developing device decreases to a predetermined amount due to the developing operation. A method of using a developing device, characterized in that, as a developer, a developer having a smaller degree of aggregation than a developer to be subsequently charged into the developing device is used. 7. The method of using the developing device according to claim 6, wherein a developer having a larger amount of lubricant added than the developer to be subsequently introduced into the developing device is used as the developer for the start. How to use the developing device. 8. A one-component developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and carried on a developer carrier, and the developer on the developer carrier is used. Installation of a developing device that develops the latent image on the image bearing member Before the start of use, the developer for starting that was put in the developing device containing the developer bearing member is consumed with the developing operation. Then, when the remaining amount of the developer in the developing device decreases to a predetermined amount, a predetermined amount of new developer is charged into the developing device, and thereafter, similarly,
A method of using a developing device, wherein a predetermined amount of a new developer is charged into the developing device when the remaining amount of the developer in the developing device decreases to the predetermined amount with the developing operation. There is more developer remaining than the remaining amount of developer corresponding to the time when the degree of aggregation of the remaining developer becomes large enough to cause poor mixing of the developer and newly added developer. A method of using a developing device, characterized in that a new developer is added at a time point. 9. A one-component developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier, whereby the latent image carrier is In an image forming apparatus for forming a developer image on a developing device, the remaining amount of the developer in the developer carrying member or the developer containing the developer is reduced to a predetermined amount with the developing operation, and An image forming apparatus comprising: a control unit that drives at least a member that contributes to stirring of a developer in a developing device for a predetermined time when a fixed amount of a new developer is charged. 10. A one-component developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and attached to the latent image on the latent image carrier, whereby the latent image carrier is formed. In an image forming apparatus for forming a developer image on a sheet, when the remaining amount of the developer in the developer carrying member or the developer containing the developer is reduced to a predetermined amount due to the developing operation, the desired polarity is obtained. An image forming apparatus comprising: a control unit that performs an operation of causing a large amount of charged developer to adhere to the latent image carrier. 11. A one-component type developer, to which an auxiliary agent is externally added if necessary, is charged to a desired polarity and adhered to the latent image on the latent image carrier, whereby the latent image carrier is In an image forming apparatus for forming a developer image on a sheet, when the remaining amount of the developer in the developer carrying member or the developer containing the developer is reduced to a predetermined amount with the development operation, Is an image forming apparatus characterized in that it is provided with a control means for executing an operation of depositing the developer charged to the opposite polarity on the latent image carrier.