JPH11174816A - Developing device, process cartridge, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high quality image having no density decrease, etc., by easily restoring the change of the characteristic of developer even in the case an addition agent added to developer is selectively consumed. SOLUTION: The process cartridge freely detachably set in the image forming device has a developing device 8, and the inside of the developing container 7 of the developing device 8 is divided into, in order from the one nearest to the developing sleeve 9, a first compartment 7a, a second compartment 7b, and a third compartment 7c. The compartments 7a and 7b and the compartments 7b and 7c are separated with sealing members 18 and 19, respectively, each of which can be pulled out. In the first compartment 7a, the developing sleeve 9, a developing blade 11, etc., are disposed, in the second compartment 7b, an agitator 16 and the developer T1 with addition-agent concentration A1, are stored, and in the third compartment 7c, an addition agent T2 with addition- agent concentration A2, A1<A2, is stored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 9 shows an electrophotographic printer as an example of a conventional electrophotographic image forming apparatus. This electrophotographic printer is a process cartridge type image forming apparatus in which a magnetic one-component developing device is integrally provided on an electrophotographic photosensitive member or the like.

As shown in FIG. 9, the image forming apparatus has a process cartridge 20 which is detachably mounted via a locking member 40. The process cartridge 20 integrally includes a photosensitive drum 2 serving as an image carrier that rotates in the direction of arrow A, a developing device 28, and the like. The photosensitive drum 2 is installed substantially at the center of the cartridge 20, and the developing device 28 is installed on the right side thereof.

[0004] The developing device 28 has a developing container 7 having an opening facing the photosensitive drum 2, and a developing sleeve 9 as a developer carrier is installed in this opening. In FIG. 9, the developing sleeve 9 protrudes into the developing container 7 with a substantially right half circumferential surface into the developing container 7 and exposes a substantially left half circumferential surface outside the developing container 7. In addition, the substantially left half circumferential surface of the developing sleeve 9 faces the surface of the photosensitive drum 2 with a slight gap C therebetween.

[0005] The developing sleeve 9 is made of a metal material such as aluminum, for example. In order to increase the probability of rubbing with the developer on the surface and to improve the transportability of the developer, the developing sleeve 9 has an appropriate surface. It has irregularities.

A magnet roller 1 is provided in a developing sleeve 9.
The magnet roller 10 is disposed coaxially with the developing sleeve 9 and non-rotatably. The developing sleeve 9 is driven to rotate around the magnet roller 10 in the direction of arrow B by a driving source of the printer body.

A developing blade 11 serving as a developer regulating member is provided above the developing sleeve 9 and is in contact with the surface of the developing sleeve 9. The developing blade 11 uses a soft elastic rubber material such as silicone rubber or urethane rubber having a JIS hardness of 40 to 80 mm, a metal thin plate such as stainless steel or phosphor bronze, or a soft elastic rubber material and a metal thin plate. A member composed of two layers is used. Developing blade 11
Is pressed against the developing sleeve 9 at a predetermined pressure so that a part of the surface facing the developing sleeve 9 comes into surface contact.

The developing container 7 is filled with a magnetic one-component developer T. The magnetic one-component developer T is a magnetic toner having a certain particle size distribution by dispersing a pigment or a magnetic material in various thermoplastic resins such as a styrene resin, an acrylic resin, and a polyethylene resin. It is. An external additive such as silica is added to the developer T, and the external additive adheres to the surface of the developer and floats between the developers to control the lubricity and chargeability of the developer. Is what you do. Usually, the external additive is added to the developer T so that the existing ratio of the developer T and the external additive becomes constant.

In the developing container 7, an agitator 16 as a developer stirring member is rotatably provided. The agitator 16 is composed of a rotatable plate-shaped support and a flexible sheet provided on the support.
The developer T filled in the developing container 7 is uniformly supplied to the developing sleeve 9 in the longitudinal direction while being stirred without uneven distribution in the developing container 7 by the rotation in the direction of the arrow.

The developer T supplied to the developing sleeve 9 is
It is carried on the developing sleeve 9 by the magnetic force of the magnet roller 10, enters the contact portion between the developing blade 11 and the developing sleeve 9 with the rotation of the developing sleeve 9, and passes through the surface of the developing sleeve 9 while passing therethrough. And developing blade 1
It is rubbed on both sides of the surface of No. 1 and sufficiently receives triboelectric charge of negative polarity. In this way, the developer T to which the triboelectric charge has been applied is formed as a thin developer layer on the developing sleeve 9 by exiting the above-mentioned contact portion, and the developing area facing the photosensitive drum 2 is formed. Transported to

The photosensitive drum 2 receives a uniform charge of negative polarity by a charging device 3 during the rotation process in the direction of arrow A, and then receives an exposure 5 of an original image by a laser beam output from an exposure device 4, and An electrostatic latent image corresponding to the document image is formed on the surface of the drum 2.

The developing sleeve 9 and the photosensitive drum 2 have a minute gap C of 100 to 300 μm in the developing section, and a DC voltage or a DC voltage supplied from the developing bias power supply 12 is applied between the two. When the superimposed voltage is applied, the thin-layered developer T on the developing sleeve 9 is transferred in accordance with the electrostatic latent image on the photosensitive drum 2 to visualize the latent image.

On the other hand, the developer remaining on the developing sleeve 9 that has not been consumed for the development is collected into the developing container 7 from below the developing sleeve 9 with the rotation of the developing sleeve 9. A lower seal 17, which is a developer leakage preventing member, is provided in the collecting portion to allow the remaining developer to pass into the developing container 7 and to prevent the developer from leaking from the developing container 7. I do.

The visible image formed on the photosensitive drum 2 is then transferred onto the transfer material P by the operation of the transfer device 13. The transfer material P to which the visible image has been transferred is separated from the photosensitive drum 2 and introduced into the fixing device 14, where the visible image is fixed, and then, as a printed matter (print), the printed material is printed outside the image forming apparatus. Is discharged.

After the transfer of the visible image, the photosensitive drum 2 from which the transfer residual developer remaining on the surface is removed by the cleaning device 15 is subjected to the following image forming process.
The above operation is repeated.

[0016]

By the way, the developing container 7
The developer T inside is consumed as printing by the image forming apparatus proceeds. At this time, the silica externally added to the developer T is selectively consumed at an early stage of consumption of the developer T due to its polarity. To go.

Then, as the consumption of the developer T progresses,
The properties of the developer T are deteriorated, and as a result, the developer T
However, there has been a problem that the development characteristics of the image are changed and the density of an image obtained by development is reduced.

An object of the present invention is to easily recover a change in the characteristics of a developer even when an external additive added to the developer is selectively consumed, and to obtain a high-quality image without a decrease in density. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus which enable the above.

[0019]

The above object is achieved by a developing device, a process cartridge and an image forming apparatus according to the present invention. In summary, the present invention provides a developing device in which a developer stirring member is provided in a developer container containing a developer, and the developer carrier is provided in an opening of the developer container facing the image carrier. The interior of the developing container is divided into first, second, and third chambers in order from the side closer to the developer carrier, and the space between the first and second chambers and the space between the second and third chambers are respectively defined. Is closed by a releasable seal member, a developer is accommodated in the second and third chambers, a developer carrier is installed in the first chamber, a developer stirring member is installed in the second chamber, and A developing device characterized by satisfying the relationship of A1 <A2 when the external additive concentrations of the developers contained in the second and third chambers are A1 and A2, respectively.

According to another aspect of the present invention, the inside of the developing container is divided into a first chamber and a second chamber in order from a side closer to the developer carrier, and a space between the first chamber and the second chamber is provided. Is closed by a partition wall whose lower end is open to form a gap at the bottom,
The developer is contained in the first and second chambers, the developer carrying member and the developer stirring member are installed in the first chamber, and the first and second chambers pass through the gap at the lower end of the partition wall to the second chamber. A developer conveying means for conveying the stored developer to the first chamber is provided, and when the external additive concentrations of the developers stored in the first chamber and the second chamber are A1 and A2, a relationship of A1 <A2 is satisfied. Can be satisfied.

According to still another aspect of the present invention, a developer stirring member is provided in a developer container containing a developer, and the developer carrier is placed in an opening of the developer container facing the image carrier. In the installed developing device, the inside of the developing container is divided into first, second, and third chambers in order from a side closer to the developer carrier, and a seal that can be pulled out between the first chamber and the second chamber is provided. The second chamber and the third chamber are closed by a member, and are partitioned by an opening / closing door that can swing in the direction of the second chamber with the upper end serving as a fulcrum. The developer is stored in the second chamber and the third chamber. When the developer carrier is installed in the chamber, the developer stirring member is installed in the second chamber, and the external additive concentrations of the developers housed in the second chamber and the third chamber are A1 and A2, respectively, A1 <A2 can be satisfied.

According to still another aspect of the present invention, the inside of the developing container is fixed by a cylindrical container having an opening at the bottom, so that the first chamber outside the cylindrical container and the second chamber inside the cylindrical container are formed. The first chamber and the second chamber contain a developer, and the first chamber is provided with a developer carrier and a developer stirring means. The developer stirring means is rotatable around the cylindrical container. It is fitted and rotated, and has an opening of a size corresponding to the opening of the cylindrical container in one place around the fitting, and the external additive concentration of the developer contained in the first chamber and the second chamber is set to A1 respectively. And A2, it is possible to satisfy the relationship of A1 <A2.

According to the present invention, there is provided a process cartridge in which at least an electrophotographic photosensitive member and a developing device are integrally incorporated, and the developing device is detachably provided in an image forming apparatus main body. A process cartridge comprising a developing device.

Further, the present invention relates to an image forming apparatus having at least an electrophotographic photosensitive member and a developing device.
An image forming apparatus, wherein the developing device comprises any of the developing devices described above.

[0025]

Embodiments of the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a cross-sectional view showing an image forming apparatus in which a developing device according to an embodiment of the present invention is installed. It is an electrophotographic laser beam printer.

As shown in FIG. 1, the image forming apparatus has a process cartridge 1 which is detachably mounted via a locking member 40. The process cartridge 1 integrally includes a photosensitive drum 2 serving as an image carrier and a developing device 8. The photosensitive drum 2 is installed substantially at the center of the cartridge 1, and the developing device 8 is installed on the right side thereof.

The present invention is characterized by the developing device 8, particularly the developing container 7 and the developer T accommodated therein. In FIG. 1, the reference numerals given in FIG. 9 indicate the same members.

The developing container 7 has an opening facing the photosensitive drum 2, and a developing sleeve 9 as a developer carrying member is installed in this opening.

The photosensitive drum 2 rotates in the direction of arrow A. In this rotation process, the photosensitive drum 2 is uniformly charged with negative polarity by the charging device 3. , A scanning exposure 5 of the original image is performed, and an electrostatic latent image is formed on the surface of the photosensitive drum 2.

Next, the magnetic one-component developer T accommodated in the developing container 7 of the developing device 8 has a developing sleeve 9 rotatably supported in the developing container 7 by a bearing (not shown).
Is attracted and carried by the magnetic force of the magnet roller 10 in the developing sleeve 9. Developing sleeve 9
Is opposed to the photosensitive drum 2 with a predetermined developing gap C, and in this embodiment, the developing gap C is set to 300 μm. The developing sleeve 9 has a peripheral speed of 42 mm / sec.
Driving direction.

Subsequently, with the rotation of the developing sleeve 9, the developer T enters between the developing sleeve 9 and the developing blade 11 which is in contact with the antinode, and is rubbed there and frictionally charged to a negative polarity. At the same time, after being coated on the developing sleeve 9 in a thin layer, it is conveyed to a developing area facing the photosensitive drum 2.

The charged developer T is supplied from the developing sleeve 9 to the photosensitive drum 2 in the developing area, and is used for developing the electrostatic latent image on the photosensitive drum 2. At this time, a predetermined developing bias is applied to the developing sleeve 9 by the developing bias power supply 12, and in this example, the peak-to-peak voltage V
A voltage obtained by superimposing an AC voltage of pp = 1200 V and a frequency f = 1800 Hz and a DC voltage of Vdc = −425 V is applied, whereby the latent image is reverse developed and visualized.

The obtained visible image is transferred onto the transfer material P by the operation of the transfer device 13. The transfer material P to which the visible image has been transferred is separated from the photosensitive drum 2 and
After the visible image is fixed there, it is discharged outside the image forming apparatus as a printing unit (print).

After the transfer of the visible image, the developer remaining on the surface of the photosensitive drum 2 after transfer of the visible image is removed by the cleaning device 15, and the photosensitive drum 2 is subjected to the next image forming process.
The above operation is repeated.

Next, the developing device 8 of this embodiment will be described in detail. The present developing device 8 is a non-contact type developing device using a non-magnetic one-component developer, but the present invention relates to a developing device using another developer, for example, a developer such as a non-magnetic one-component developer. Can also be applied.

As shown in FIG. 2, in the present developing device 8, the conventional single developing container 7 is sequentially replaced with the first chamber 7a, the second chamber 7b, and the third chamber 7c from the vicinity of the developing sleeve 9. And are separated by seal members 18 and 19 therebetween. The developing sleeve 9 including the magnet roller 10 and the developing blade 11 are installed in the first chamber 7a, and the agitator 16 is installed in the second chamber 7b. The agitator 16 includes a rotatable plate-like support and a flexible sheet provided on the support.

In the second chamber 7b, as a developer T,
Developer T externally added with finely divided silica such as dry-processed silica
Similarly, the third chamber 7c contains a developer T2 to which finely divided silica is externally added. This developer T1
And the silica concentrations A1 and A2 externally added to T2 satisfy the condition of A1 <A2.

According to this embodiment, when the user mounts the process cartridge 1 in the image forming apparatus main body, first, the seal member 18 of the developing device 8 is pulled out to open the second chamber 7b. Then, as shown in FIG. 3A, the second chamber 7b communicates with the first chamber 7a, and the developer T1 in the second chamber 7b flows into the first chamber 7a by its own weight and is supplied. The user can print by attaching the process cartridge 1 to the image forming apparatus main body in this state.

Thereafter, the developer T1 is stirred by the agitator 16 in the second chamber 7b without being unevenly distributed in the first chamber 7a and the second chamber 7b by the rotation of the agitator 16 in the direction of the arrow. It is supplied uniformly in the longitudinal direction.

The developer T1 is consumed as printing by the image forming apparatus proceeds. At this time, the silica externally added to the developer T1 is selectively consumed depending on its polarity, and the characteristics of the developer T1 Is being spoiled. As the consumption further proceeds, the developer T1 is not sufficiently coated on the developing sleeve 9, and uneven coating of the developer T1 occurs. As a result, unevenness (white spots) that is not printed but white appears on the image.

At this time, conventionally, at most, it is necessary to take out the process cartridge 1 from the image forming apparatus and shake the process cartridge 1 to try to use up all the developer in the developing device 8. Met.

On the other hand, in the present embodiment, after the process cartridge 1 is removed from the image forming apparatus, the seal member 19 is pulled out to open the third chamber 7c, and the second chamber 7b and the third chamber 7c are communicated. . As a result, as shown in FIG. 3B, the developer T2 in the third chamber 7c flows into the first chamber 7a via the second chamber 7b by its own weight, and the agitator 1
Due to the rotation of 6, the developer T2 is mixed with the developer T1 remaining in the first chamber 7a.

In the developer obtained by mixing the developer T1 with the developer T2, the silica concentration A2 of the developer T2 is higher than the silica concentration A1 of the developer T1, so that the lack of silica in the developer T1 due to the selective consumption of silica. The developer having the required silica concentration is supplemented by the mixing of the developer T2. Therefore, stable printing with low image density can be performed. The user may start printing by mounting the process cartridge 1 in this state again on the image forming apparatus main body.

In the above embodiment, the third chamber 7c is opened when a white spot occurs on the image. However, the image forming apparatus is provided with a remaining amount detecting means for detecting the remaining amount of the developer. In this case, the remaining amount detecting means may detect a decrease in the remaining amount of the developer and prompt the user to open the third chamber 7c, whereby the operation and effect of the present embodiment can be achieved. it can.

In this embodiment, silica was used as an external additive. However, a metal oxide such as strontium titanate or a mixture of this metal oxide and silica can be used.

In the developing container 7, two chambers for accommodating the developer are provided: the second chamber 7b and the third chamber 7c. The number of n chambers is n, and the silica of the developer accommodated in each chamber is n. When the concentrations are A1, A2, A3,..., An, the effects of the present invention can be achieved by satisfying the following condition: A1 <A2 <A3 <.

Embodiment 2 Another embodiment of the present invention will be described with reference to FIG. In this embodiment, the process cartridge 1 of the image forming apparatus of FIG.
Then, the developing device 8 shown in FIG. 4 was incorporated in place of the developing device 8 shown in FIG. 4, the same elements as those shown in FIG. 2 are denoted by the same reference numerals.

In the developing device 8, the developing container 7 is divided into a first chamber 7a and a second chamber 7b in order from the vicinity of the developing sleeve 9, and the space therebetween is partitioned by a partition wall 22 having an open lower end. A gap 23 image is formed between the lower end of the partition wall 22 and the developing container 7. In the first room 7a,
A developing sleeve 9 having a built-in magnet roller 10 and a developing blade 11 are provided.
4 are installed.

The developer conveying means 24 is provided on the swing arm 2
A transport plate 24a is attached to the tip of 4b, and the transport plate 24a passes through the gap 23 at the lower end of the partition wall 22. When the swing arm 24b is swung, the transport plate 24a reciprocates along the bottom of the developing container 7, whereby the second
The developer T2 in the chamber 7b can be transported to the first chamber 7a. The main body of the developer conveying means 24 is provided in the second chamber 7b.
It can also be installed inside.

The first chamber 7a contains a developer T1 externally added with finely divided silica such as dry-processed silica, and the second chamber 7b similarly contains a developer T1 externally added with finely divided silica.
2, and the silica concentrations A1 and A2 externally added to the developers T1 and T2 satisfy the condition of A1 <A2.

The developer T1 in the first chamber 7a is uniformly supplied to the developing sleeve 9 in the longitudinal direction while being stirred by the rotation of the agitator 16 without being unevenly distributed in the first chamber 7a. The developer T1 is consumed as printing by the image forming apparatus proceeds. At this time, the silica externally added to the developer T1 is selectively consumed depending on its polarity, and the characteristics of the developer T1 are reduced. It is being damaged.

However, according to the present embodiment, at this time, the developer conveying means 24 is operated to reciprocate the conveying plate 24 a passing through the gap 23 below the partition plate 22, whereby the second
The developer T2 in the room is gradually conveyed into the first chamber 7a through the gap 23, and the developer T2 is rotated by the rotation of the agitator 16.
2 is mixed with the developer T1 remaining in the first chamber 7a.

Therefore, also in this embodiment, the developer T1
The developer obtained by mixing the developer T2 with the developer T2 becomes the developer having the required silica concentration, as in Example 1, because the insufficient silica in the developer T1 due to the selective consumption of silica is compensated by the mixing of the developer T2. Thus, stable printing with a low image density can be performed.

Further, in this embodiment, since the developer conveying means 24 is used to supply the developer T2, the process cartridge 1 is removed from the image forming apparatus to remove the seal member as in the first embodiment. There is also an advantage that printing is not required and printing can be continued without interruption.

In this embodiment, in addition to silica, a metal oxide such as strontium titanate or a mixture thereof with silica can be used as an external additive. Further, assuming that the number of chambers for storing the developer in the developing container 21 is n, the silica concentrations A1, A2, and A of the developer stored in the respective chambers
The effects of the present invention can be achieved by satisfying the following condition: A1, <A2 <A3 <... <An.

Embodiment 3 Still another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the developing device 8 shown in FIG. 5 is incorporated in the process cartridge 1 of the image forming apparatus shown in FIG. 5, the same elements as those shown in FIG. 2 are denoted by the same reference numerals.

In the developing device 8, the developing container 7 is divided into a first chamber 7a, a second chamber 7b and a third chamber 7c in order from the vicinity of the developing sleeve 9, and the first chamber 7a and the second chamber 7b are separated from each other. The second chamber 7b and the third chamber 7c are separated by an opening / closing door 25 between them. In the first room 7a,
A developing sleeve 9 and a developing blade 11 having a built-in magnet roller 10 are provided, and an agitator 16 is provided in the second chamber 7b.

The opening / closing door 25 is attached to the top plate in the developing container 7 with a hinge 27a at the upper end, and is provided to be openable and closable in the direction of the first chamber 7a with the upper end serving as a fulcrum. 7 is pressed against a step 27 provided on a bottom plate and is locked by a stopper 26 provided there.

The second chamber 7b contains a developer T1 externally added with finely divided silica such as dry-processed silica, and the third chamber 7c similarly contains a developer T1 externally added with finely divided silica.
2 are contained, and the silica concentrations A1 and A2 contained in the image agents T1 and T2 satisfy the condition of A1 <A2.

According to the present embodiment, similarly to the first embodiment, when the user mounts the process cartridge 1 in the image forming apparatus main body, first, the user pulls out the seal member 18 and the second
The chamber 7b is opened, and as shown in FIG.
Is communicated with the first chamber 7a, and the developer T1 in the second chamber 7b is
Is poured into the first chamber 7a by its own weight. And
If the process cartridge 1 is mounted on the image forming apparatus main body in this state, printing can be performed.

The developer T1 in the first chamber 7a is uniformly supplied to the developing sleeve 9 in the longitudinal direction while being stirred by the rotation of the agitator 16 without being unevenly distributed in the first chamber 7a. The developer T1 is consumed as printing by the image forming apparatus proceeds. At this time, the silica externally added to the developer T1 is selectively consumed depending on its polarity, and the characteristics of the developer T1 are reduced. It is being damaged.

However, according to the present embodiment, if the stopper 26 that locks the lower end of the opening / closing door 25 is removed at this time, as the developer T1 in the second chamber 7b is consumed, the opening / closing is stopped. The pressure of the developer T1 pressing the door 25 decreases, and as shown in FIGS.
Is pushed by the weight of the developer T2 in the third chamber 7c and the opening and closing door 25 opens in the direction of the second chamber 7b, and the developer T2 in the third chamber 7c enters the second chamber 7b. To go. Second
The developer T2 entering the chamber 7b is stirred by the agitator 16 and mixed with the developer T1 remaining in the first chamber 7a and the second chamber 7b.

Therefore, also in this embodiment, the developer T1
The developer obtained by mixing the developer T2 with the developer T2 becomes the developer having the required silica concentration, as in Example 1, because the insufficient silica in the developer T1 due to the selective consumption of silica is compensated by the mixing of the developer T2. Thus, stable printing with a low image density can be performed.

In this embodiment, the developer T2 is supplied by using the weight of the opening / closing door 25 and the pressing force of the developer T2. It is not necessary to drive the developer conveying device as described above. Further, similarly to the second embodiment, there is no need to remove the process cartridge 1 from the image forming apparatus and interrupt printing.

In this embodiment, in addition to silica, a metal oxide such as strontium titanate or a mixture thereof with silica can be used as an external additive. Further, assuming that the number of chambers for storing the developer in the developing container 21 is n, the silica concentrations A1, A2, and A of the developer stored in the respective chambers
The effects of the present invention can be achieved by satisfying the following condition: A1, <A2 <A3 <... <An.

Embodiment 4 Another embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the developing device 8 shown in FIG. 7 is incorporated in the process cartridge 1 of the image forming apparatus shown in FIG. FIG.
, The same elements as those shown in FIG. 2 are denoted by the same reference numerals.

In the developing device 8, the cylindrical container 30 is installed in the developing container 7, and the developing container 7 is the first container other than the container 30.
It is partitioned into a chamber 7a and a second chamber 7b in the container 30.
A developing sleeve 9 having a built-in magnet roller 10 and a blade 11 are provided in the first chamber 7a.

The cylindrical container 30 extends in the same direction as the developing sleeve 9, and a slit-shaped or mesh-shaped opening 30 a is provided at the bottom of the cylindrical container 30 in the longitudinal direction. Around the cylindrical container 30, a cylindrical stirring means 31 is rotatably fitted, and the stirring means 31 is rotated in the direction of the arrow. The stirring means 31 has a plurality of fins 31b around it, and the opening 30
An opening 31a having the same size as a is provided.

The first chamber 7a contains a developer T1 to which finely divided silica such as dry-processed silica is externally added, and the second chamber 7b similarly has a developer T1 to which finely divided silica is externally added.
2, and the silica concentrations A1 and A2 externally added to the developers T1 and T2 satisfy the condition of A1 <A2.

The developer T1 in the first chamber 7a is
By the rotation of 1, the developer is uniformly supplied to the developing sleeve 9 in the longitudinal direction while being stirred without uneven distribution in the first chamber 7a. The developer T1 is consumed as printing by the image forming apparatus proceeds.
The silica externally added to No. 1 is selectively consumed depending on its polarity, and the characteristics of the developer T1 are deteriorated.

However, according to the present embodiment, as shown in FIGS. 8A and 8B, each time the stirring means 31 rotates, the opening 31a of the stirring means 31 comes to the lower side every time the stirring means 31 rotates. It matches the opening 30a at the bottom of the container 30. When this coincides, the developer T2 in the second chamber 7b flows into the first chamber 7a by its own weight through the opening 30a of the cylindrical container 30 and the opening 31a of the stirring means 31. When the consumption of the developer T1 in the chamber 30a is small and the upper surface of the developer T1 is above the lower opening 30a of the stirring means 31, there is almost no inflow due to its own weight. When the developer T1 in the first chamber 30a is consumed in a large amount and the upper surface of the developer T1 is lowered to approach the lower opening 30a of the stirring means 31, the developer T2 gradually flows into the first chamber 30a, The mixture is stirred by the fins 31b of the stirring means 31 and mixed with the developer T1 remaining in the first chamber 30a.

Therefore, also in this embodiment, the developer T1
The developer obtained by mixing the developer T2 with the developer T2 becomes the developer having the required silica concentration, as in Example 1, because the insufficient silica in the developer T1 due to the selective consumption of silica is compensated by the mixing of the developer T2. Thus, stable printing with a low image density can be performed.

Further, according to the present embodiment, as in the case of the second embodiment, the printing is not interrupted by removing the process cartridge 1 from the image forming apparatus. In addition, the cylindrical container 30
In particular, when the opening 30a is formed into a mesh, the aggregates of the external additives, which are generally easily formed when the concentration of the external additive is high, can be removed by the openings 30a, and the streaks or spots on the image due to the influence of the aggregates can be removed. Image defects can be prevented from occurring.

In this embodiment, in addition to silica, a metal oxide such as strontium titanate or a mixture thereof with silica can be used as an external additive.

[0076]

As described above, according to the present invention,
A chamber for accommodating the developer in the developing container of the developing device is divided into two sections from the side closer to the developer carrying member, and the developer having the external additive concentration A1 satisfying A1 <A2 is divided into two sections. The developer having the external additive concentration A2 is housed in a chamber far from the developer carrier, and the space between these chambers is separated by a pullable seal member, and the seal member is pulled out. By means, it is possible to supply the developer contained in the chamber far from the developer carrier to the chamber closer to the developer carrier. Even if the added external additive is selectively consumed with consumption, by supplying the developer housed in a chamber far from the developer carrier, the shortage of the external additive is compensated for. To easily recover the characteristic change of the image and obtain a high-quality image without density reduction etc. It can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a developing device installed in the image forming apparatus of FIG.

FIG. 3 is a cross-sectional view illustrating an operation of the developing device of FIG. 2;

FIG. 4 is a cross-sectional view illustrating a configuration and operation of a developing device according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a developing device according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating an operation of the developing device of FIG. 5;

FIG. 7 is a cross-sectional view illustrating a configuration of a developing device according to still another embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating an operation of the developing device of FIG. 7;

FIG. 9 is a schematic configuration diagram illustrating a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Process cartridge 2 Photosensitive drum 7 Developing container 7a, 7b, 7c Chamber 8 Developing device 9 Developing sleeve 16 Agitator 18, 19 Seal member 24 Developer conveying means 25 Opening / closing door 30 Stirring means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (6)

[Claims] 1. A developing device in which a developer agitating member is provided in a developing container containing a developer and a developer carrying member is provided in an opening of the developing container facing the image carrier. Are, in order from the side closer to the developer carrying member,
The chamber is divided into a second chamber and a third chamber, and a space between the first chamber and the second chamber and a space between the second chamber and the third chamber are closed by a pull-out seal member. , A developer carrier is installed in the first chamber, a developer stirring member is installed in the second chamber, and the second chamber and the third
A developing device characterized by satisfying a relationship of A1 <A2 when the external additive concentrations of the developer contained in the chamber are A1 and A2, respectively. 2. A developing device in which a developer stirring member is provided in a developing container containing a developer and a developer carrying member is provided in an opening of the developing container facing the image carrier. Are partitioned into a first chamber and a second chamber in order from the side closer to the developer carrying member, and a lower end between the first chamber and the second chamber forming a gap at a lower portion is closed by an open partition wall, The first and second chambers contain developer, the first chamber is provided with a developer carrier and a developer stirring member, and the first or second chamber passes through the gap at the lower end of the partition wall to form the second chamber. A developer conveying means for conveying the developer housed in the first chamber to the first chamber is provided, and when the external additive concentrations of the developers housed in the first chamber and the second chamber are A1 and A2, A1 <A2 A developing device characterized by satisfying the relationship. 3. A developing device in which a developer stirring member is provided in a developer container containing a developer and a developer carrier is provided in an opening of the developer container facing the image carrier. Are, in order from the side closer to the developer carrying member,
The chamber is divided into a second chamber and a third chamber, and the space between the first chamber and the second chamber is closed by a releasable seal member. Partitioned by a swingable opening / closing door, a developer is accommodated in the second and third chambers, a developer carrier is installed in the first chamber, a developer stirring member is installed in the second chamber, and The external additive concentrations of the developers contained in the second and third chambers were set to A1 and A2, respectively.
The developing device satisfies the following relationship: A1 <A2. 4. A developing device in which a developer stirring member is provided in a developer container containing a developer and a developer carrier is provided in an opening of the developer container facing the image carrier. Is divided into a first chamber outside the cylindrical container and a second chamber inside the cylindrical container by a fixedly installed cylindrical container having an opening at the bottom, and a developer is contained in the first and second chambers. A developer carrier and a developer stirring means are installed in the chamber, and the developer stirring means is rotatably fitted around the cylindrical container and rotated, and has an opening of the cylindrical container at one location around the cylindrical container. Wherein the external additive concentration of the developer accommodated in the first chamber and the second chamber is A1 and A2, respectively, wherein the relationship of A1 <A2 is satisfied. apparatus. 5. The process cartridge according to claim 1, wherein at least an electrophotographic photosensitive member and a developing device are integrated and integrated, and the process cartridge is detachably provided in an image forming apparatus main body. A process cartridge comprising any one of the developing devices. 6. An image forming apparatus having at least an electrophotographic photosensitive member and a developing device, wherein the developing device comprises the developing device according to claim 1.