JP2002139916A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more efficiently perform the replacement of a developer and promotion of its mixture in a developer housing part of a developing device which performs self-control of a toner density by loading toner by the movement of the developer. SOLUTION: The developing device is provided with a developing sleeve 2 which carries a two-component developer 3 including the toner and a magnetic carrier, a doctor 4 which regulates the amount of the developer, a developer housing part 5 which houses a scraped developer, and a toner hopper 6 which is adjacent to the developer housing part 5 and houses the toner. The developing device changes a load state of toner by changing the contact state of the developer and the toner on the basis of the change of the toner density of the developer on the developing sleeve, and the developer on the developing sleeve is peeled by surface movement of a peeling roller 8 toward the inside of the developer housing part 5 in the direction opposite to the developing sleeve 2. The surface roughness Rz of the peeling roller 8 satisfies the following relaition: (diameter of a magnetic carrier/5)<(surface roughness Rz of a peeling member)<(diameter of the magnetic carrier).

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 printer, a facsimile and the like and a developing apparatus used for the same. More specifically, the present invention relates to a two-component developer containing a toner and a magnetic carrier. The present invention relates to a developing device and an image forming apparatus that self-control the toner concentration by changing the state of toner taken into the developer based on a change in the toner concentration of the developer on the body and taking in the toner by the movement of the developer. .

[0002]

2. Description of the Related Art Conventionally, there has been known a developing device which takes in toner by the movement of a developer without requiring a toner density detecting means. However, in this type of developing device, the amount of toner taken in is different between a place where the movement of the developer is active and a place where the movement of the developer is not so, or a place where the amount of the developer is large and a place where the amount of the developer is small. Image density unevenness is likely to occur. Therefore, various proposals have been made. In Japanese Patent Application Laid-Open No. 9-197833, toner is developed by moving a developer in a developer accommodating portion for accommodating a developer whose progress has been prevented by a developer regulating member. There has been disclosed a developing device which takes in a developer on an agent carrier and self-controls the toner supply constantly and constantly. This developing device is downsized,
It is possible to easily adjust the toner density while reducing the cost, and it is effective for the above-mentioned problems.

[0003] The toner concentration self-control mechanism in the developing device will be described. In this type of developing device, when toner is supplied to the developer on the developer carrier and the toner concentration increases, the filling rate of the developer in the developer accommodating portion increases, and the developer on the developer carrier becomes On the other hand, the transport resistance given by the developer in the developer storage unit increases, the developer in the developer storage unit hardly moves, and the developer is accumulated at the toner replenishing position from the toner storage unit, and the toner intake stops. . Conversely, when the toner is consumed and the toner concentration decreases, the filling rate of the developer in the developer accommodating portion decreases, and the developer becomes easy to move. It becomes incorporated into the agent. The toner taken into the developer is
The developer is carried on the developer carrier, and is conveyed to a developing area, which is a portion facing the latent image carrier of the image forming apparatus, and is used for development. As described above, the toner concentration self-control mechanism controls the taking-in of the toner by the movement of the developer and keeps the toner concentration constant at all times.

According to this type of developing device, the toner can be automatically replenished directly to the developer on the developer carrier by the bulk of the developer which changes according to the toner concentration.
This eliminates the need for a toner density sensor and simplifies the toner supply device.

However, in this type of developing device,
Since the developer carried on the developer carrier and being transported is almost separated from the developer carrier and is carried around, it can be replaced with the remaining developer remaining in the developer accommodating portion. May be rarely done. If the developer is not replaced, the stress on the magnetic carrier in the developer carried on the developer carrying member becomes relatively high, and the remaining amount of the developer remaining in the developer accommodating portion in the developer accommodating portion is reduced. Deterioration may occur earlier than magnetic carriers. When the magnetic carrier deteriorates early, the charging ability of the magnetic carrier on the developer carrier that is actually engaged in image formation is reduced even if the developer as a whole is not so deteriorated. As a result, the developer is inevitably deteriorated, and the developer must be replaced at an early stage.

[0006] Further, unless the developer is retained in the developer accommodating portion and replaced with the developer whose toner concentration is always kept at a certain concentration or less, the magnetic carrier on the developer carrier almost remains on the developer carrier. Alone, the toner corresponding to the consumption amount is supplied and mixed, and a predetermined charge amount must be obtained. However, since the surface moving speed of the developer carrier is high (in the case of the developing roller, the rotation speed is several hundred rpm. ), Charging may not be performed in time, and charging failure may be caused. In particular, if there is a portion where the toner consumption is large, the image quality is deteriorated such that a difference in shading appears remarkably as compared with a portion where the toner consumption is small.

In order to solve the above-mentioned problem, the present applicant has disclosed in Japanese Patent Application No. 11-188219 a provision of a peeling member for peeling off a developer on a developer carrying member in a developer accommodating portion. Promotes the replacement and mixing of the developer and the developer in the developer accommodating section, thereby preventing the early deterioration of the developer due to a decrease in the charging ability of the magnetic carrier in the developer and making the toner distribution more uniform. Thus, a developing device capable of performing favorable development without image density unevenness has been proposed.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and it is an object of the present invention to use a two-component developer containing a toner and a magnetic carrier and develop the toner on a developer carrier. A developing device that changes the state of toner taken into the developer based on a change in the toner concentration of the developer, and self-controls the toner concentration by taking in the toner with the movement of the developer. It is an object of the present invention to provide a developing device and an image forming apparatus capable of realizing higher image quality by more efficiently performing replacement and mixing of images.

[0009]

According to a first aspect of the present invention, there is provided a magnetic recording medium having a magnetic field generating means therein for carrying and transporting a two-component developer containing a toner and a magnetic carrier. A developer carrying member, a regulating member that regulates the amount of the developer carried and conveyed by the developer carrying member, and a developer accommodating portion that accommodates the developer scraped by the regulating member,
A toner container adjacent to the developer accommodating portion and accommodating toner so as to be taken in contact with the developer on the developer carrier; and a toner for the developer on the developer carrier. In a developing device for changing the state of contact between the developer and the toner in the toner storage unit by changing the concentration to change the state of taking in the toner into the developer, the developer may be stored in the developer storage unit. A peeling member is provided for moving the surface in the opposite direction to the surface of the carrier and peeling the developer on the developer carrier, and the surface roughness Rz of the peeling member is (magnetic carrier diameter / 5) <(surface of the peeling member). (Roughness Rz) <(magnetic carrier diameter).

According to the first aspect of the present invention, the developer on the developer carrier is dammed by the peeling member which moves in the predetermined direction in the developer accommodating portion. The developer on the developer carrier that has been blocked is accompanied by the surface movement of the peeling member, and moves away from the developer carrier. Thereby, the developer on the developer carrier is peeled. Next, the developer is conveyed to the peeling member in the developer accommodating portion and is sufficiently stirred. This agitation promotes replacement and mixing with the developer contained in the developer containing section, and also makes the developer uniform. Part of the developer conveyed by the peeling member is carried on the developer carrying member by magnetic force in the vicinity of a junction where the developer carried by the developer carrying member merges. In order to more efficiently exchange and mix the developer in the developer accommodating section by such a process, the amount of the developer separated and conveyed by the surface of the separating member may be an appropriate amount. desired. The amount of the developer separated and conveyed by the surface of the peeling member is affected by the relationship between the surface roughness of the peeling member and the size of the developer. Here, in a general two-component developer, 20 to 50
[Μm] of the magnetic carrier and 4 to 15 [μm] of the toner are frictionally charged, and the surface of the magnetic carrier is covered with the toner. Thus, it can be said that the relationship between the surface roughness of the peeling member and the diameter of the magnetic carrier affects the amount of the developer peeled and conveyed by the surface of the peeling member. Specifically, when the surface roughness of the peeling member is small, the amount of the developer peeled and conveyed decreases due to the surface irregularities.
When the amount of the developer peeled off from the developer carrier and conveyed is reduced, sufficient replacement and mixing are not performed in the developer accommodating chamber. The present inventor has experimentally found that when the surface roughness Rz of the peeling member is smaller than 1/5 of the diameter of the magnetic carrier, poor charging is caused, and background smear, image density reduction, and density unevenness occur. On the other hand, if the surface roughness of the peeling member is rough, the amount of the developer that is peeled and conveyed increases due to the surface irregularities. When the amount of the developer peeled off from the developer carrier and conveyed is too large, the amount of the developer conveyed to the vicinity of the confluence by the peeling member becomes too large, and the regulating member downstream of the confluence and the confluence point The developer agglomerates between the times. Therefore, even if the developer replaced and mixed by the peeling member is transported to the junction, the developer carrier cannot carry a sufficient amount of the developer due to the aggregation of the developer, which is a so-called pumping failure. The phenomenon occurs. For this reason, it becomes impossible to obtain an appropriate amount of the developer conveyed to the developing area after passing through the regulating member, and image density decreases and density unevenness occurs. The inventor has experimentally determined that when the surface roughness Rz of the peeling member is larger than the magnetic carrier diameter,
It has been found that image density reduction and density unevenness occur.
From the above, when the surface roughness Rz of the peeling member satisfies the relationship of (magnetic carrier diameter / 5) <(peeling member surface roughness Rz) <(magnetic carrier diameter), the peeling member is placed on the developer carrier. The developer can be peeled off as a thin layer and transported, and replacement of the developer in the developer accommodating portion and promotion of mixing can be performed more efficiently.

According to a second aspect of the present invention, in the developing device of the first aspect, the outer peripheral surface of the peeling member has a circular cross-sectional shape.

According to the second aspect of the present invention, since the cross-sectional shape of the peeling member is circular, the gap between the peeling member and the developer carrier is constant even if the peeling member is rotated. The developer can be peeled off evenly.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, the toner is supplied from the toner accommodating portion and regulates the amount of the developer that is going to progress toward the inside of the developer accommodating portion. A supply-side regulating member is provided.

According to the third aspect of the present invention, when the toner concentration of the developer on the developer carrier rises due to the regulation member on the toner supply side and the layer thickness of the developer increases,
The passage of the increased amount of the developer is regulated. By regulating the increase in the amount of developer, excessive toner intake into the developer on the developer carrier on the toner replenishing side is suppressed, and the toner concentration of the developer on the developer carrier is stabilized to a certain level or less. Can be maintained. Then, the developer in which the toner concentration of the developer on the developer carrier has become equal to or less than a certain concentration is peeled off by the peeling member of the developer accommodating section, and exchange and mixing with the developer in the developer accommodating section are performed. At the same time, uniformity of the developer and promotion of toner charging are performed,
The developer is again carried on the developer carrying member by magnetic force and transported.

According to a fourth aspect of the present invention, in the developing device of the third aspect, the gap G between the surface of the developer carrier and the surface of the peeling member is provided.
h, a gap Gd between the surface of the developer carrier and the regulating member
1 and a gap Gd2 between the surface of the developer carrying member and the regulating member on the toner supply side satisfies the relationship of Gh <Gd1 <Gd2.

According to the fourth aspect of the present invention, when the distances Gh and Gd1 satisfy the predetermined relationship, the distance Gh and Gd1 pass between the developer carrier and the peeling member and are conveyed to the junction. The amount of the developer should not be larger than the developer that can pass through the regulating member. This prevents the amount of the developer between the junction and the regulating member from becoming too large, and makes it difficult to cause aggregation of the developer and poor pumping due to the aggregation. In addition, the intervals Gd1 and Gd
2 satisfies the above-mentioned predetermined relationship, thereby suppressing excessive incorporation of toner into the developer on the developer carrier on the toner supply side, and reducing the toner concentration of the developer on the developer carrier to a certain concentration or less. The changed developer is replaced and mixed with the developer in the developer accommodating portion by the peeling member in the developer accommodating portion, and the uniformity of the developer and the promotion of toner charging are performed.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising an image carrier for carrying an electrostatic latent image and a developing device for visualizing the electrostatic latent image. The present invention is characterized in that the developing device of item 1, 2, 3, or 4 is adopted.

In the image forming apparatus according to the fifth aspect, by using the developing device according to any one of the first to fourth aspects,
The replacement of the developer in the developer accommodating portion and the promotion of the mixing are more efficiently performed, the early deterioration of the developer is prevented, and the developer can be made uniform and the development can be performed using the well-charged toner. . As a result, a higher quality image can be obtained.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic printer (hereinafter, referred to as a printer) which is an electrophotographic image forming apparatus will be described below. First,
A basic configuration of the printer according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. In FIG. 1, a photosensitive drum 1 serving as an image carrier is uniformly charged by a charging charger 20 serving as a uniform charging unit while being rotationally driven in a direction indicated by an arrow A by a driving unit (not shown). Scanning exposure is performed by the optical device 30 based on image information, and an electrostatic latent image is formed on the surface. The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing device 40 with toner as a developer, whereby an image is formed on the photosensitive drum 1. The image formed on the photoconductor 1 is transferred by the transfer charger 50 onto transfer paper (not shown) conveyed to a transfer unit from a paper feed cassette (not shown) or a manual paper feed tray. After completion of the transfer, the transfer paper is fixed to an image by a fixing device (not shown) and discharged outside the apparatus. Note that the toner on the photoconductor drum 1 that has not been transferred onto the transfer paper is removed from the photoconductor 1 by the cleaning device 60.

Next, the developing device 40 will be described in detail. The developing device 40 includes a developing sleeve 2 made of a non-magnetic material as a developer carrier that carries a two-component developer (hereinafter, referred to as a “developer”) 3 containing a toner T and a magnetic carrier. 2, a magnet roller (not shown) composed of a group of fixed magnets as magnetic field generating means fixedly disposed inside the developing device 2, a doctor 4 as a regulating member for regulating the amount of developer carried and conveyed on the developing sleeve 2, and a developing sleeve An eaves member 9 provided to form a developer container 5 for developer between the surface of the sleeve 2 and the doctor 4 and a toner hopper 6 as a toner container. The toner hopper 6 has a toner supply port 6 a adjacent to the upstream side of the developer accommodating section 5 in the developer conveying direction on the developing sleeve 2 and facing the surface of the developing sleeve 2. Further, inside the toner hopper 6, a toner agitator 7 as a stirring member for sending out the toner T while stirring it toward the toner supply port 6a is disposed.

The tip of the eaves member 9 in the vicinity of the developing sleeve 2 is supplied with the toner T from the toner hopper 6 and the developer 3 which is going to enter the developer accommodating section 5.
Of the toner supply side that regulates the amount of toner. The pre-doctor 9a has a gap G larger than the gap Gd1 between the doctor 4 and the developing sleeve 2.
The developer 3 is disposed so as to face the developing sleeve 2 via d2, and regulates the layer thickness of the developer 3 to be thicker than the doctor 4. Further, the developer accommodating portion 5 formed by the eaves member 9 and the like accommodates the developer 3 which is not supplied to the developing position of the portion facing the photosensitive drum 1 and is prevented from proceeding by the doctor 4. . Two magnetic poles of the same polarity are provided between the main pole (P1) formed opposite to the developing position and the position opposite to the pre-doctor 9a so that the magnetic force of the magnetic field reaches the developer accommodating portion 5.
As shown, a magnetic pole is formed on a magnet roller (not shown). In addition, a transport magnetic pole is formed on the magnet roller so that the developer 3 can be transported while being continuously carried on the developing sleeve 2 as in a general developing device.

In the developing device 40 having the above-described structure, the developer 3 on the developing sleeve 2 is conveyed with the rotation of the sleeve 2 in the direction of arrow B in the figure, and is regulated by the doctor 4 to be thinned. The thinned developer 3 is conveyed to a developing position facing the photosensitive drum 1 rotating in the direction of arrow A in the figure. At this developing position, the toner T is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is visualized. The developer on the developing sleeve 2 that has passed the developing position is further transported as the sleeve 2 rotates, and reaches a position facing the toner supply port 6a. The toner T in the toner hopper 6 is sent out by the agitator 7 and stays in the toner supply port 6 a so as to be in contact with the developer on the developing sleeve 2. Toner T and developer container 5
After the new toner T is taken in at the contact portion with the developer, the process returns to the developer accommodating portion 5. Then, the internal pressure of the developer 3 containing the new toner T increases in the regulating section by the doctor 4. The toner is charged by the magnetic carrier in the developer having the increased internal pressure. On the other hand, a part of the developer 3 which is not supplied to the developing position and is prevented from proceeding by the doctor 4,
The developer 3 moves toward the toner supply port 6a in the developer container 5 due to the internal pressure and gravity of the developer 3 itself. The developer 3 that has moved to the vicinity of the toner supply port 6a
Is transported so as to circulate toward the doctor 4 with the rotation of the developing sleeve 2.

In the developing device 40 having the above-described structure, when the amount of toner supplied to the developer 3 increases and the toner concentration increases, the bulk of the developer 3 increases accordingly. The toner stays in the opening 6a and covers the opening of the toner supply opening 6a. Therefore, the amount of toner taken into the developer 3 on the developing sleeve 2 is reduced. Due to this decrease in the amount of toner taken in, the toner density of the developer 3 is always kept below a certain density. Conversely, when the toner concentration of the developer 3 decreases, the bulk of the developer 3 decreases, so that the developer 3 does not block the toner supply port 6a.
A predetermined amount of toner is taken into the developer 3 on the developing sleeve 2, and the toner density of the developer 3 is always kept at a certain level or more. Since the toner density can be controlled within a substantially constant range in this manner, a toner density sensor and an optical image density sensor for detecting the image density of a reference toner image formed on the photosensitive drum 1 in order to know the developing ability of the developer. This eliminates the need for a complicated toner density control mechanism using a toner supply member or the like. In the developing device 40 of the present embodiment, a toner T having a particle size of 4 to 15 [μm]
A toner containing a magnetic carrier having a low resistance of [μm] was used, and the toner concentration was controlled so as to maintain the toner coverage of the magnetic carrier in the developer accommodating section 5 at about 100%.

Further, in the developing device 40 of the present embodiment, a substantially straight bar having a circular cross section is formed in almost the entire longitudinal direction (direction along the rotation axis of the developing sleeve) in the developer accommodating portion 5.
A peeling roller 8 as a peeling member for peeling the developer 3 on the developing sleeve 2 is provided. The peeling roller 8 is rotated by a driving unit (not shown) in the same counterclockwise direction (the direction of arrow C in FIG. 2) as the rotation direction of the developing sleeve 2 (the direction of arrow B in FIG. 2). The surface of the peeling roller 8 is moved in a direction opposite to the surface of the sleeve. The developer 3 on the developing sleeve 2 is dammed by the peeling roller 8. The developer 3 on the development sleeve 2 that has been dammed follows the surface movement of the peeling roller 8 and moves away from the development sleeve 2.
As a result, the developer 3 on the developing sleeve 2 is peeled off. Next, the peeling roller 8 is stirred while transporting the developer 3 in the developer accommodating section 5. By this stirring, replacement and mixing with the developer 3 contained in the developer containing section 5 are promoted, and the developer 3 is also made uniform. Then, a part of the developer 3 mixed and replaced is
It is carried on the developing sleeve 2 by a magnetic force between the doctor 4 and the junction where it joins the developing sleeve 2 again.

Further, since the surface of the developing sleeve 2 and the peeling roller 8 oppose each other so that the conveying directions of the developer 3 are opposite to each other, the gap between the peeling roller 8 and the developing sleeve 2 is changed. The developer 3 that passes through the developing sleeve 2
And the transfer force by the peeling roller 8
The frictional charging between the developers is promoted.

In order to efficiently exchange and mix with the developer contained in the developer accommodating portion 5 by such a process, the developer separated and conveyed by the surface of the peeling roller 8 is required. Is desired to be in an appropriate range. The amount of the developer that is peeled off and conveyed by the surface of the peeling roller 8 is affected by the relationship between the surface roughness of the peeling roller 8 and the size of the developer. Here, the developer 3 is in a state where the surface of the magnetic carrier is covered with the toner. Therefore, it can be said that the relationship between the surface roughness of the peeling roller 8 and the diameter of the magnetic carrier affects the amount of the developer peeled and conveyed by the surface of the peeling roller 8.

Specifically, if the surface roughness of the peeling roller 8 is small, the amount of the developer peeled and conveyed is reduced due to the surface irregularities. If the amount of the developer peeled off from the developing sleeve 2 and conveyed is reduced, sufficient replacement and mixing in the developer accommodating chamber 5 cannot be performed. The present inventors have experimentally found that when the surface roughness Rz of the peeling roller 8 is smaller than 1/5 of the diameter of the magnetic carrier, charging failure is caused, and background stain, image density reduction, and density unevenness occur. .

On the other hand, if the surface roughness of the peeling roller 8 is rough,
Due to the surface irregularities, the amount of the separated and conveyed developer increases. If the amount of the developer peeled off from the developing sleeve 2 and conveyed becomes too large, the amount of the developer conveyed to the vicinity of the junction by the separation roller 8 becomes too large, and the doctor 4 downstream of the junction and the junction. In between, the developer 3 aggregates. Therefore, even if the developer 3 that has been replaced and mixed by the peeling roller 8 is conveyed to the junction, a sufficient amount of the developer 3 is formed due to the aggregation of the developer 3.
Cannot be carried, so-called poor pumping occurs. For this reason, an appropriate amount of the developer 3 conveyed to the development area after passing through the doctor 4 cannot be obtained, and
Image density reduction and density unevenness occur. The present inventor has experimentally found that when the surface roughness Rz of the peeling roller 8 is larger than the diameter of the magnetic carrier, image density reduction and density unevenness occur.

From the above, the surface roughness Rz of the peeling roller 8 is (magnetic carrier diameter / 5) <(peeling member surface roughness R
z) <(magnetic carrier diameter)
It can be said that the peeling roller 8 can peel and transport the developer from the developing sleeve 2 as a thin layer, and the replacement of the developer in the developer accommodating section 5 and the promotion of mixing can be more efficiently performed. . As a result, early deterioration of the developer can be prevented, and the toner distribution can be made more uniform, so that good development without background smear, density unevenness, and image density reduction can be performed.

Further, the surface roughness Rz of the peeling roller 8 is:
It is desirable that the surface roughness be smaller than the surface roughness of the developing sleeve 2. This is because, when the surface roughness Rz of the peeling roller 8 becomes larger than the surface roughness of the current sleeve, the developer 3 is transported in a direction opposite to the transport direction of the developing sleeve 2, that is, in the transport direction of the peeling roller 8. This is because there is a possibility that an appropriate amount of the developer conveyed to the developing area after passing through may not be obtained.

Further, the peeling roller 8 is connected to the developing sleeve 2.
The gap Gh between the surface and the surface of the peeling roller 8 is arranged to be smaller than the gap Gd1 between the surface of the developing sleeve 2 and the doctor 4. Therefore, the amount of the developer 3 that passes between the developing sleeve 2 and the peeling roller 8 and is conveyed to the junction does not become larger than the amount of the developer that can pass through the doctor 4.
As a result, the amount of the developer between the junction and the doctor 4 is not excessively increased, and the aggregation of the developer and poor pumping due to the aggregation are less likely to occur. Developing sleeve 2
Carries an appropriate amount of the developer 3 whose toner charge is promoted,
Since the sheet can be transported to the developing area, higher image quality can be realized.

Example Next, a more specific example of the developing device according to the present embodiment will be described. In the developing device 40 shown in FIG. 1, an image was formed under the following developing conditions. The distance Gh between the peeling roller 8 and the developing sleeve 2 is 0.3 mm. The distance Gd1 between the peeling roller 8 and the doctor 9 a is 0.4 mm. The distance Gd2 between the peeling roller 8 and the pre-doctor 9 a is 1.0 mm. Developer Magnetic carrier diameter 50 μm Toner diameter 9 μm And the peeling roller 8, the surface roughness Rz is 20 to
The thing of 30 [μm] was used. First, an image is formed on a document by using a chart composed of black and white alternately with different toner consumption in the longitudinal direction of the developing sleeve 2, and after forming 20 images, the image is again formed by a chart composed of uniform halftone over the entire surface. The formation was performed. As a result of this experiment, it was possible to obtain a good image free from background stain and density unevenness. Further, in the developing device 40 of the present embodiment, a good quality image without a decrease in image density could be obtained by configuring so as to satisfy the relationship of Gh <Gd1 <Gd2.

[Comparative Example] On the other hand, as a comparative example of the present embodiment, an image was formed in the same manner as described above using a peeling roller 8 having a surface roughness Rz of 10 [μm] or less. Density unevenness occurred in the halftone image. Also, the surface roughness Rz of the peeling roller 8
Of 50 [μm] or more, and the same image formation as above was performed. As a result, image density reduction and density unevenness occurred.

As described above, according to the present embodiment, the exchange and mixing of the developer on the developing sleeve 2 and the developer in the developer accommodating section 5 are promoted, thereby lowering the charging ability of the magnetic carrier in the developer. This can prevent the developer from being deteriorated at an early stage. Moreover, even when toner supply unevenness occurs in the longitudinal direction of the developing sleeve 2, the uniformized developer can be transported to the developing area, so that development without image density unevenness is possible.

[0035]

According to the first to fifth aspects of the present invention, a two-component developer containing a toner and a magnetic carrier is used, and the toner is transferred to the developer based on a change in the toner concentration of the developer on the developer carrier. A developing device that self-controls the toner concentration by changing the take-in state and taking in the toner with the movement of the developer. Further, there is an excellent effect that higher image quality can be realized.

In particular, according to the second aspect of the present invention, there is an excellent effect that the developer can be uniformly removed from the developer carrying member and uneven charging of the toner in the developer can be prevented.

In particular, according to the third aspect of the present invention, it is possible to stably maintain the toner concentration of the developer at a certain concentration or less. Moreover, since the developer having excessively taken in the toner is not carried / conveyed by the developer carrier and reaches the peeling member, the replacement and mixing of the developer by peeling the developer can be stably performed. There is an excellent effect that can be.

In particular, according to the fourth aspect of the present invention, there is an excellent effect that it is difficult for the developer carrying defect of the developer carrying member to occur.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a rotation direction of a developing sleeve and a peeling member of the developing device.

FIG. 3 is an explanatory diagram of intervals between components in the developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 developing sleeve 3 developer 4 doctor 5 developer container 6 toner hopper 6 a toner supply port 7 toner agitator 8 peeling roller 9 eaves member 9 a predoctor 20 charging charger 30 laser optical device 40 developing device 50 transfer charger 60 cleaning device

Claims (5)

[Claims] 1. A developer carrier having a magnetic field generating means therein for carrying and transporting a two-component developer containing a toner and a magnetic carrier, and a developer carrier carried and transported by the developer carrier. A regulating member for regulating the amount of the developer, a developer accommodating portion for accommodating the developer scraped by the regulating member, and the developer on the developer carrying member adjacent to the developer accommodating portion and on the developer carrying member And a toner storage portion for storing toner so as to be taken in contact with the toner, and a contact state between the developer and the toner in the toner storage portion due to a change in the toner concentration of the developer on the developer carrying member. In the developing device that changes the state of taking the toner into the developer by changing the surface of the developer carrier, the surface of the developer carrier moves in the opposite direction to the surface of the developer carrier, and A release member for releasing the developer is provided, and the surface roughness of the release member is provided. A developing device, wherein Rz satisfies a relationship of (magnetic carrier diameter / 5) <(peeling member surface roughness Rz) <(magnetic carrier diameter). 2. A developing device according to claim 1, wherein said peeling member has a circular cross section on the outer peripheral surface. 3. The toner supply side regulating member according to claim 1, wherein the toner is supplied from said toner storage section and the amount of said developer which tends to advance toward said developer storage section is regulated. A developing device comprising: 4. The developing device according to claim 3, wherein a gap Gh between the surface of the developer carrier and the surface of the peeling member, a gap Gd1 between the surface of the developer carrier and the regulating member, Gap G between body surface and regulating member on toner supply side
d2 satisfies the relationship of Gh <Gd1 <Gd2. 5. An image forming apparatus comprising: an image carrier for carrying an electrostatic latent image; and a developing device for visualizing the electrostatic latent image, wherein the developing device is used as the developing device. 3 or 4
An image forming apparatus comprising the developing device.