JP2001075344A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developing device where back ground soiling and unevenness in image density due to attachment of carrier generated by aggregation of toner or excessive feeding of the toner can be prevented by carrying out agitation of the toner in the developing device provided with a toner concentration self control mechanism before starting of toner replenishing. SOLUTION: In this device, driving of a toner agitator 9 as the toner agitating member is started for warming up after a power source of the device is turned on and returning to operation from a standby state of the device but the drive is stopped while the toner is replenished. Thus, the toner with good fluidity is in a state of contact with the developer even without carrying out agitation by a toner agitator when developing is carried out and the toner is fetched into the developer with its own weight and fluidity. Therefore, a flexible toner replenishment corresponding to consumed quantity of the toner is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, a printer, and the like, and a developing device used in the image forming apparatus. The present invention relates to a developing device having a toner concentration self-control system for replenishing developer, and an image forming apparatus using the developing device.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, a first regulating member regulates the amount of a two-component developer carried and carried by a developer carrier having a magnetic field generating means therein. A developing device that accommodates the developed developer in a developer accommodating portion and replenishes toner from the toner accommodating portion adjacent to the developer accommodating portion to the developer on the developer carrying member. A second regulating member provided on the upstream side in the transport direction of the developer on the developer carrier regulates the layer thickness of the developer on the developer carrier, and the regulated developer controls the intake of toner. Therefore, a developing device that adjusts the toner density is known.

[0003] In this type of developing device, the bulk of the developer in the developer accommodating portion changes in accordance with the change in the toner concentration.
In accordance with this change, the bulk of the developer stagnation portion that stagnates on the upstream side of the second regulating member also changes. Then, when the toner concentration decreases due to consumption of the toner and the bulk of the developer in the developer accommodating portion decreases, the bulk of the developer retaining portion also decreases. At this time, the developer carried on the surface of the developer carrier and the developer in the developer accumulating portion come into contact with the developer and come up from the toner accommodating portion at a position where the developer is wound up (hereinafter referred to as a toner intake port). When the toner comes in contact,
The toner is taken into the developer, and is conveyed to the developer container. On the other hand, when the toner concentration of the developer in the developer accommodating portion is high and the bulk of the developer is large, the bulk of the developer that is regulated by the second regulating member and stagnates on the upstream side also increases, The toner supply port, which is a communication port between the storage section and the developer carrying member, is closed, so that the toner cannot contact the toner intake port, and the toner intake stops.

[0004] Further, the toner taken into the developer accommodating section is charged together with the magnetic particles by the internal pressure of the developer accommodating section and the movement of the developer in the developer accommodating section. According to this type of developing device, the amount of toner supplied to the carrier adhered to the developer carrier can be controlled according to the bulk of the developer that changes according to the toner concentration. This eliminates the need and simplifies the toner supply device. Further, the number of magnetic particles can be reduced as compared with the conventional two-component developing method. For these reasons, the size and cost of the device can be reduced.

In the developing device having the above structure, since there is no toner concentration sensor and the amount of magnetic particles is small, it is important how to stably supply toner to the developer on the developer carrier. Conventionally, as a toner replenishment method, toner in a toner container is agitated by an agitator as a toner agitating member, and is moved to a toner intake port by a pressure due to the agitation, thereby replenishing the developer. Was.

[0006]

However, in a developing apparatus using a method in which toner is moved to a toner intake port by agitating pressure of an agitator and taken into a developer, unevenness in image density or the like is formed on a formed image. It was found that a problem occurred.

[0007] When the present inventor investigated the cause of the problem, the following was found. In the above configuration, even when the toner concentration is not so reduced, for example, when an image with a small toner consumption is developed, the toner is actively sent by the agitator. For this reason,
In some cases, the toner may agglomerate partially in the width direction due to the pressure of the agitator in front of the toner intake port, and if the agglomeration occurs, the toner will not move smoothly in that part, and the development corresponding to that part will occur. Insufficient toner supply to the developer results in uneven image density in the width direction of the image (the direction orthogonal to the developer transport direction).

Furthermore, when a toner having a high degree of aggregation is used, a large aggregation toner is generated. At this time, when the toner having a high image area ratio is continuously developed and the toner is rapidly consumed, the bulk of the developer on the developer carrier is rapidly reduced, and the On the upstream side, a gap is formed between the developer and the aggregated toner. FIG. 5 is an explanatory diagram of the developing device in a state where the gap G has occurred. In this figure, between an upstream side of a developer accommodating case 7 as a second regulating member and a toner hopper 8 as a toner accommodating portion,
The aggregated toner forms a bridge 11, and a gap G is formed between the bridge 11 and the developer 3.
When such a gap occurs, toner replenishment is stopped, the toner concentration is reduced, and finally carrier adhesion occurs on the transfer paper.

On the other hand, when a toner having a small degree of aggregation is used, aggregation of the toner is unlikely to occur, but the toner is excessively taken into the developer due to the pressure caused by the stirring of the toner stirring member. In addition, the intake of the toner tends to cause a deviation in the width direction of the image without corresponding to the toner consumption. Therefore, the toner density becomes higher than the set value, or the toner density becomes partially high in the width direction of the image, so that a black band-shaped background stain occurs on the white portion of the image, or the image density unevenness due to the deviation of the toner density. Will occur.

Conventionally, in order to prevent deterioration of an image due to aggregation of toner, Japanese Patent Application Laid-Open No. Hei 10-239966 discloses a method in which a toner container and a toner layer regulating member in a developer accommodating container accommodating a magnetic toner. A developing device has been proposed in which a flat toner flow regulating member is disposed so as to partially cut off the flow of the magnetic toner in the flow path of the magnetic toner moving toward the gap that regulates the thickness of the toner layer. I have. Accordingly, when the stirring action of the toner stirring member is strong, the movement of the magnetic toner is prevented by the toner flow regulating member, which is a flat plate, and the magnetic toner is excessively retained on the front side of the toner layer regulating member. It is possible to apply the above configuration to a developing device having the toner concentration self-control system of the present invention.

However, it is difficult to control the flow of a fluid such as toner by a flat plate unless the cohesion of the toner is constant, and the effect of the toner flow regulating member also depends on the pressure of the toner stirring member. May be uneven. Therefore, even if the above configuration is applied to the developing device of the present invention, it is considered that the effect of preventing the image from being deteriorated due to the aggregation of the toner is not sufficiently obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to reduce unevenness in image density and carrier adhesion caused by aggregation of toner and to reduce the amount of toner by a toner agitating means. It is an object of the present invention to provide a developing device and an image forming apparatus which can obtain a good image by preventing background contamination and image density unevenness caused by excessive supply of toner.

[0013]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a developing device having a magnetic field generating means therein and carrying a developer comprising toner and magnetic particles; A developer carrier that transports the developer to a region facing the latent image carrier, a first regulating member that regulates the amount of developer carried and transported by the developer carrier, and a first regulation A developer accommodating section for accommodating the developer whose passage is regulated by the member, and a developer accommodating section disposed upstream of the first regulating member in a conveying direction of the developer on the developer carrying member and conveyed to the developer accommodating section. A second regulating member that regulates the amount of developer to be supplied, a toner accommodating section that is provided in connection with the developer accommodating section and accommodates toner therein, and a toner stirring unit that agitates the toner in the toner accommodating section. And a change in toner concentration of the developer on the developer carrier. A developing device having a toner concentration self-control system that controls the amount of toner supplied in the developer by changing the contact state of the toner with the developer carried on the developer carrier in accordance with the The toner in the toner container is movable by its own weight to a contact area where the toner comes into contact with the developer, and the toner is stirred by the toner stirring means before the development is started to perform the development. It is characterized in that it is sometimes not performed.

According to the first aspect of the present invention, the toner in the toner container is agitated by the toner agitating means before the development is started to increase the fluidity of the toner in the toner container. Various timings before the development may be considered before the start of the development, including, for example, a warm-up immediately after the power is turned on and a return operation from the standby state. During the development, the driving of the toner stirring means is stopped. Thereby, when the toner concentration is reduced during the development and the toner is supplied to the developer, the toner having good fluidity moves from the toner storage unit to the toner intake port which is a contact area with the developer by its own weight, It is taken into the developer. Therefore, at the time of toner replenishment, the pressure by the developer stirring means is not applied to the toner, and as a result,
Partial aggregation of toner and formation of bridges can be avoided. Also, there is no excessive supply of toner due to the toner stirring pressure.

According to a second aspect of the present invention, in the developing device according to the first aspect, the toner is agitated by the toner agitating means when the power of the developing device is turned on and when the device returns from a standby state. And development is not performed during development.

In the developing device according to the present invention, the toner in the toner container is agitated when the power of the device is turned on and when the device returns from the standby state. These timings are because the developing operation is considered to have been reliably stopped for a certain period of time, and there is a possibility that the toner in the toner container may be aggregated. In this way, before the toner is replenished to the developer, the fluidity of the toner in the toner storage unit is increased, and the toner is replenished during the toner replenishment is actually performed, such as during development. By stopping the stirring, the natural flow of the toner and the soft toner replenishment by its own weight are performed according to the toner consumption.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, the toner agitating means includes a toner agitating member located in the toner accommodating portion and a toner agitating member for driving the toner agitating member. The toner stirring member is driven by the toner stirring member driving unit to stir the toner in the toner storage unit. When the stirring of the toner is stopped, the weight of the toner in the toner storage unit is reduced. The stop position of the toner stirring member by the toner stirring member driving means is controlled so that the toner stirring member stops at a position where the movement of the toner stirring member does not prevent the toner from being replenished. It is assumed that.

In the developing device according to the third aspect, when the stirring of the toner is stopped, the toner stirring member is stopped at a position where the movement of the toner in the toner container due to its own weight does not prevent the toner from being replenished into the developer. As a result, as the toner that comes into contact with the developer at the toner intake port is taken into the developer, new toner can be moved to the toner intake port, and into the developer in a state where stirring by the toner stirring member is stopped. Is supplied smoothly. Further, depending on the stop position of the toner stirring member, it is possible to regulate the moving direction of the toner in the toner storage unit.

Further, the developing device according to claim 4 is characterized in that:
In the developing device according to item 2 or 3, the aggregation degree (%) of the toner is 15.0 or less.

In the developing device according to the present invention, the toner is used in a state where the toner is agitated by the toner agitating means by setting the agglomeration degree of the toner to be 15.0% or less. It can flow naturally by its own weight without being used.

According to a fifth aspect of the present invention, there is provided an image forming apparatus, comprising: a latent image carrier; a latent image forming means for forming a latent image on the latent image carrier;
An image forming apparatus comprising: a developing unit that develops a latent image on the latent image carrier;
It is characterized by using 2, 3, or 4 developing devices.

In the image forming apparatus according to the fifth aspect, the developing device can perform development without causing trouble in taking in toner due to aggregation of toner and formation of a bridge, and excessive supply of toner due to pressure of toner stirring. Do.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment to which the developing device of the present invention is applied will be described below. FIG. 1 is a sectional view showing a schematic configuration of a developing device to which the present invention can be applied. The developing device is provided on a side of a photosensitive drum 1 used as a latent image carrier of a copying machine, and has a casing 2 having an opening formed toward the photosensitive drum 1, and a part thereof is exposed from the opening. A developing sleeve 4 as a developer carrier for carrying a developer 3 comprising toner 3a and magnetic particles (hereinafter referred to as “carrier”) on the surface, and a fixing as a magnetic field generating means fixedly disposed inside the developing sleeve 4 A magnet roller 5 composed of a group of magnets and a first regulation position at a first regulation position for regulating the amount of the developer 3 carried and conveyed on the developing sleeve 4.
, A developer storage case 7 as a cover member provided so as to form a developer storage portion A of the developer 3 above the developing sleeve 4 and the surface of the sleeve, and a toner storage case. The printer includes a toner hopper 8 as a unit. Further, a region of the developer storage case close to the development sleeve serves as a second restriction member 7a for restricting the amount of the developer conveyed to the developer storage section.

The developer accommodating portion A is not supplied to the developing position opposite to the photosensitive drum 1 between the developer accommodating case 7 and the developing sleeve 4 and the development is stopped by the doctor 6. This is a space where the agent 3 stays. Further, the toner hopper 8 has a toner supply port 8a adjacent to the upstream side of the developer accommodating portion A in the developer transport direction and facing the surface of the developing sleeve 4, and has a space adjacent to the toner supply port 8a. The toner 3a in the hopper 8 into the toner supply port 8a.
A toner agitator 9 is provided as a toner stirring member that feeds the toner while stirring the toner. The toner agitator 9 includes a shaft portion 9a and a blade portion 9b made of mylar, and is rotationally driven by toner stirring member driving means (not shown). As shown by a broken line in the drawing, the position of the shaft 9a and the length of the blade 9b are set so that the outermost track of the blade 9b does not touch the developer 3.

In the developing device having the above structure, the developer 3 on the developing sleeve 4 is conveyed with the rotation of the sleeve, and is regulated by the doctor 6 to be thinned. The thinned developer 3 is conveyed to a development area facing the photosensitive drum 1 rotating in the direction of the arrow. Then, in the developing area, the toner 3a is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is visualized. The developer 3 not used for the visualization is conveyed with the rotation of the developing sleeve 4 and the second regulating member 7
The developer reaches the contact area with the developer in the developer stagnant portion B, the passage of which is regulated at a. Here, from above the contact area, the developer in the developer stagnation portion is taken up by moving along with the developer on the developing sleeve 4, and the toner 3a in contact with this contact area is The toner is taken up together with the developer so that the developer is supplied into the developer.

The developer that has been sent out by the toner agitator 9 and has passed through the toner supply port 8a and has taken in new toner 3a from the toner intake port C returns to the developer accommodating section A by transporting the developing sleeve. The internal pressure of the developer 3 containing the new toner 3a increases due to the regulation by the doctor 6, whereby the toner 3a of the developer 3 is charged. In this manner, the toner 3a in the developer on the developing sleeve 4 can be charged by the internal pressure of the developer 3 on the doctor 6 side of the developer accommodating portion A, so that the developer 3 such as a paddle or a screw can be charged or A complicated stirring mechanism for stirring is not required.

On the other hand, a part of the developer 3 which is not supplied to the developing area and is prevented from proceeding by the doctor 6 is moved to the vicinity of the toner supply port 8a by the internal pressure and gravity of the developer in the developer accommodating section A. Moving. The developer 3 that has moved to the toner supply port 8a is drawn to the developing sleeve 4 side by the magnetic force of the magnet, and is conveyed to the doctor 6 side as the developing sleeve 4 rotates, so that the inside of the developer accommodating portion A is moved. Circulate. When the toner 3a supplied to the developer 3 increases and the toner concentration increases, the developer 3a
Because the volume of the developer increases, the volume of the developer whose passage is restricted by the second restricting member 7a increases, and the volume of the developer retaining portion B increases to close the toner supply port 8a. For this reason, the toner cannot contact the developer in the toner intake port C,
The intake of the toner 3a is stopped. As a result, the toner concentration in the developer 3 is always kept at a certain concentration or less.
Conversely, when the toner concentration in the developer 3 decreases, the bulk of the developer 3 in the developer accommodating portion A decreases, and the volume of the developer retaining portion B also decreases, so that the toner supply port 8a is not blocked. A predetermined amount of toner 3a is taken into the developer. As a result, the toner density in the developer 3 is maintained at a certain level or higher.

According to the developing device having the above structure, the volume of the developer accumulating portion B changes in accordance with the volume of the developer 3 in the developer accommodating portion A which changes in accordance with the toner concentration. Therefore, the toner concentration of the developer 3 is always kept within a substantially constant range. Therefore, a complicated toner density control mechanism such as a toner density sensor, a P sensor, and a toner supply member is not required.

However, in the developing device having the above configuration, if the image is left unused for a long time, or if an image having a small image area is continuously developed, the moving amount of the toner 3a itself near the toner supply port 8a is reduced. Is reduced.
In this state, if the toner agitator 9 continues to apply the toner sending pressure, the toner 3 a
Agglomeration may occur near a. When this state progresses, the bridge 11 may be formed near the toner supply port 8a.

FIG. 5 is an explanatory view of the developing device when the bridge 11 is formed. As described above, in a situation where the toner 3a is frequently consumed such that an image having a large image area is continuously developed while the bridge 11 is formed, the toner 3a cannot be smoothly taken in from the toner intake port C. As a result, the volume of the developer retaining portion B is reduced. Then, the bridge 11 of the aggregated toner 3a is formed.
A gap G is created between the toner 3 and the toner intake port C.
a Supply stops. As a result, the supply of the toner to the developer 3 is stopped, the toner density of the image is reduced, and finally, the carrier adheres to the transfer paper.

Even if the bridge 11 is not formed, if the toner 3a is partially aggregated in the vicinity of the toner replenishing port 8a due to the toner sending pressure by the toner agitator 9, the toner 3a in the aggregated portion will not be formed.
Movement is not performed smoothly, and toner supply to the developer 3 corresponding to the portion is insufficient, and as a result, image density unevenness in the width direction of the image (a direction orthogonal to the developer transport direction) is caused. Sometimes it happens.

The above-mentioned stopped state of the supply of the toner 3a is more remarkable for the toner 3a which is easily aggregated. This cannot be completely eliminated only by the pressure of toner agitation by the toner agitator 9, resulting in carrier adhesion and image density unevenness over a long period of time.

On the other hand, when the toner 3a having a small degree of aggregation is used, the toner 3a is easily affected by the pressure of the toner agitation by the toner agitator 9. For this reason, by driving the toner agitator 9, the toner 3a is taken into the developer accommodating case 7 more than necessary, and the toner density increases to a set density or more, and as a result, the background image May occur or image density unevenness may occur due to a deviation in toner density.

In view of the above, the developing device of the present embodiment is capable of reducing unevenness in image density and carrier adhesion caused by agglomeration of the toner 3a and background contamination caused by excessive supply of the toner 3a to the developer 3 due to the toner sending pressure of the toner agitator 9. It has a configuration that can prevent image density unevenness and obtain a good image.

Hereinafter, an embodiment to which the developing device of the present invention is applied will be described. In the developing device of the present invention,
The bottom of the toner hopper 8 has a round bottom so that the toner 3a in the toner hopper 8 can reach the toner intake port C by its own weight. Supply port 8a
Is provided.

In this embodiment, the toner agitator 9 is driven only at the time of warm-up after the power is turned on before the development is started, or only at the time of the operation of returning the apparatus from the standby state. It stops during replenishment. As a result, immediately before the developing operation is performed, the toner 3a is sufficiently stirred by the toner agitator 9, and the fluidity is increased.

As described above, by increasing the fluidity of the toner 3a in the toner hopper 8 before the development, the toner 3a having a good fluidity moves to the toner inlet C by its own weight during the development. The developer comes into contact with the developer to be taken into the developer 3. Therefore, even if the toner is not stirred by the agitator 9, the toner is sequentially taken into the developer 3 by the fluidity of the toner itself. In this way, at the time of toner replenishment, soft toner replenishment by the natural flow of the toner 3a is performed according to the toner consumption amount without applying pressure by the toner agitator 9 to the toner 3a. Therefore, aggregation of the toner 3a and formation of the bridge 11 can be avoided, and uneven image density and carrier adhesion caused by the aggregation of the toner 3a can be prevented. Also, the toner agitator 9
And the image density unevenness caused by the excessive supply of the toner 3a to the developer 3 due to the toner sending pressure can be prevented, and a good image can be obtained.

Here, when the driving of the toner agitator 9 is stopped, if the stop position of the blade 9b is at a position where the flow of the toner 3a in the toner hopper 8 is prevented, the toner Supply will also be affected.
FIGS. 4A and 4B are explanatory diagrams of positions where the toner agitator 9 is not preferable as a stop position. The blade 9b of the toner agitator 9 in the stopped state is obstructing the flow of the toner 3a. It is shown.

In FIG. 4A, the blade 9b is stopped so as to lie almost horizontally above the toner supply port 8a. If development is performed while stopped at this position, when toner is replenished due to consumption of toner 3a,
Of the toner 3a in the toner hopper 8, the toner 3a located above the blade portion 9b falls downward by its own weight.
It is obstructed by the blade portion 9b and cannot be dropped in the direction of the toner supply port 8a (arrow D in the figure). FIG.
In (b), the tip of the blade 9b is connected to the toner supply port 8a.
Stopped at the bottom. If development is performed while stopped at this position, during toner supply, of the toner 3 a in the toner hopper 8, it passes through the bottom from the side along the inner wall of the toner hopper 8, and the toner supply port 8
a, the path of the toner 3a that is to be moved in the direction (arrow E in the figure) to be lifted
It will not be supplied in the direction a.

If the movement path of the replenishment toner 3a is blocked or obstructed in this way, the amount of toner 3a supplied to the toner supply port 8a becomes insufficient, and the amount of toner supplied into the developer 3 becomes insufficient. There is fear. Therefore, it is necessary to sufficiently consider the stop position of the toner agitator 9.

FIG. 2 is an explanatory diagram of the stop position of the toner agitator 9 which does not hinder the movement path of the supply toner 3a. In this figure, the toner agitator 9 is stopped at a position where the tip of the blade 9b is rotated by 180 degrees with respect to the lowermost part of the toner supply port 8a. By stopping at this position, of the toner 3a in the toner hopper 8, the toner 3a which is about to move from above to the toner supply port 8a side by its own weight and the toner 3a which is lifted toward the toner supply port 8a along the inner wall of the toner hopper 8 Neither route D nor route E will be blocked.

As described above, the blade 9 of the toner agitator 9
By controlling the stop position of b, as the toner 3a in contact with the developer 3 is taken into the developer, the new toner 3a can move to the toner supply port 8a by its own weight, and from the contact position with the developer 3 It is taken into the developer one after another. As a result, while the blade 9b of the toner agitator 9 is stopped, the toner 3a
Supply is performed smoothly. Therefore, with the simple configuration of controlling the stop position of the blade portion 9b of the toner agitator 9, it is possible to prevent background contamination and image density unevenness caused by excessive supply of the toner 3a to the developer 3 due to the toner sending pressure of the toner agitator 9. And a good image can be obtained.

Here, the blade portion 9b of the toner agitator 9
Is not limited to the position shown in FIG. In the case of the present embodiment, as shown in FIG. 3G, the stop range of the blade portion 9b of the agitator 9 is a rotation angle of 120 degrees upward from a position that becomes horizontal toward the side opposite to the toner supply port 8a. May be anywhere within the range. Depending on the stop position, the moving direction of the toner 3a is
It is also possible to specify by b.

Further, in the developing device of the present embodiment,
The toner 3a having a degree of aggregation of 3.0 to 15.0% is used. Here, the toner aggregation degree is measured as follows using a powder tester PT-N type manufactured by Hosokawa Micron. First, sieves composed of meshes (75 μm, 45 μm, 22 μm) having different openings are arranged in order from the top with the largest opening. 2 g of the toner 3a is put into the uppermost 75 μm sieve, and a vibration having an amplitude of 1 mm is applied to the whole for 30 seconds. After stopping, the weight of the toner 3a remaining on each screen is measured, and the weight of the toner 3a remaining on each screen is weighted in order from the top, 0.5, 0.3, and 0.1, and all are added. The resulting value is expressed as a percentage. The product obtained in this manner is defined as a toner aggregation degree.

When the toner aggregation degree is larger than 15.0%,
Even if the toner 3a is dispersed, the toner itself has poor fluidity, and when developing an image having a large image area ratio, the toner supply may not catch up. Then, there is a possibility that a problem such as a decrease in image density due to insufficient toner supply may occur. In the present embodiment, since the toner aggregation degree is 15.0% or less, even when an image having a large image area ratio is being developed, the toner 3a does not aggregate and moves to the toner supply port 8a by its own weight for development. It is taken into the agent. Therefore, there is no possibility that the toner density cannot be reduced and the image density is not reduced.

Even when the toner agitator 9 is stopped, the natural flow of the toner 3a can be maintained.
Since the toner 3a can be brought into uniform contact with the developer 3, uneven toner replenishment due to aggregation of the toner 3a does not occur, and a good image can be formed more reliably.

Further, when an image is formed by a copying machine using the developing device having the above-described configuration, uneven image density and carrier adhesion caused by toner aggregation, and excessive supply of toner to the developer due to the toner sending pressure of the toner agitator 9 are provided. It is possible to form a good image free from background contamination and uneven image density.

[0048]

According to the developing device of the first and second aspects, it is possible to avoid the aggregation of toner and the formation of a bridge, so that it is possible to prevent uneven image density and carrier adhesion caused by the aggregation of toner and to prevent the toner from being aggregated. Since soft toner replenishment is performed by natural flow and self-weight, it is possible to prevent background contamination and image density unevenness caused by excessive supply of toner to the developer due to the toner sending pressure of the toner stirring means, and to obtain a good image. There is an excellent effect that it can be obtained.

According to the developing device of the third aspect, the position at which the toner stirring member is stopped can be easily controlled.
There is an excellent effect that the image density unevenness and background stain can be prevented. Further, if the stop position of the toner stirring member is set so that the toner moves in a desired direction, there is also an excellent effect that a better image can be surely obtained.

According to the fourth aspect of the present invention, even if the stirring of the toner in the toner container by the toner stirring means is stopped during the replenishment of the toner into the developer, the toner can maintain the natural flow. As a result, since the toner can be uniformly contacted with the developer, there is an excellent effect that a good image can be formed more reliably.

According to the image forming apparatus of the present invention, uneven image density and carrier adhesion caused by agglomeration of toner, background contamination and image density caused by excessive supply of toner to the developer due to toner sending pressure of the toner stirring means. There is an excellent effect that a good image free from unevenness can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a developing device to which the present invention can be applied.

FIG. 2 is an explanatory diagram of a toner agitator stop position that does not obstruct a movement path of a supply toner.

FIG. 3 is an explanatory diagram of a stoppable range of a blade of an agitator.

FIGS. 4A and 4B are explanatory diagrams of positions that are not preferable as a stop position of the toner agitator.

FIG. 5 is an explanatory diagram of the developing device when a bridge is formed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 casing 3 developer 3a toner 4 developing sleeve 5 magnet roller 6 doctor 7 developer storage case 7a second regulating member 8 toner hopper 8a toner supply port 9 toner agitator 9a blade 11 bridge A developer storage B Developer retention section C Toner intake

Claims (5)

[Claims] A developer carrying member having a magnetic field generating means therein, carrying a developer comprising toner and magnetic particles, and transporting the developer to a region facing the latent image carrying member of the image forming apparatus; A first regulating member for regulating an amount of the developer carried and conveyed by the developer carrying member; a developer accommodating portion for accommodating the developer whose passage is regulated by the first regulating member;
A second regulating member which is disposed upstream of the regulating member in the direction of transport of the developer on the developer carrying member and regulates the amount of developer transported to the developer accommodating portion; A toner accommodating portion provided in connection with the toner accommodating portion and accommodating the toner therein; and a toner stirring means for agitating the toner in the toner accommodating portion. A developing device having a toner concentration self-control system that controls the amount of toner supplied in the developer by changing the contact state of the toner with the developer carried on the developer carrier in accordance with the The toner in the toner container is movable by its own weight to a contact area where the toner comes into contact with the developer, and the toner is stirred by the toner stirring means before the development is started to perform the development. Sometimes A developing device characterized in that the developing is not performed. 2. The developing device according to claim 1, wherein the toner is stirred by the toner stirring means when the power of the developing device is turned on and when the developing device is returned from a standby state. A developing device characterized in that the developing is not performed. 3. The developing device according to claim 1, wherein the toner stirring means comprises a toner stirring member located in the toner storage portion, and a toner stirring member driving means for driving the toner stirring member. The toner agitating member is driven by the toner agitating member driving means to agitate the toner in the toner accommodating portion. When the toner agitation is stopped, the toner in the toner accommodating portion moves by its own weight and the toner is contained in the developer. A toner stirring member driving unit that controls a stop position of the toner stirring member such that the toner stirring member stops at a position where the toner stirring member is not prevented from being supplied. 4. The developing device according to claim 1, wherein the degree of aggregation (%) of the toner is 15.0 or less. 5. An image forming apparatus comprising: a latent image carrier; a latent image forming unit for forming a latent image on the latent image carrier; and a developing unit for developing the latent image on the latent image carrier. 5. An image forming apparatus according to claim 1, wherein the developing device is the developing device according to claim 1, 2, 3, or 4.