JPH11167279A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of obtaining an image more stable in quality and uniform in toner density by circulating developer in a developer storing part more vigorously. SOLUTION: In a developing sleeve 1, a magnetic pole P1 is arranged opposite to a photoreceptor drum 12, and magnetic poles P2 and P3 are arranged counterclockwise with the magnetic pole P1 as a reference, besides, a magnetic pole P4 is arranged facing the developer storing part 4. In this case, a doctor 2 is positioned above the developing sleeve 1 in a nearly vertical direction, and also, an angle θ1 formed by a direction showing the peak value of the magnetic pole P4 facing the developer storing part 4 and a vertical line is set to >=25 deg.. Thus, an attraction force by the magnetic force of the magnetic pole P4, a reaction force reverse to the attraction force and received from the surface of the developing sleeve 1 and a gravity working with inclination with reference to the aforesaid forces are applied on the developer 3, then, the staying developer 3 begins to fall downwards, then, the circulation speed of the developer 3 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device that uses a two-component developer in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like. The present invention relates to a developing device which does not require the configured toner density detecting means.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, a developer carrier for carrying a developer composed of toner and magnetic particles on the surface thereof and transporting the developer, and a magnetic field for carrying the developer on the surface of the developer carrier Magnetic field generating means, a developer regulating member for regulating the amount of developer carried on the developer carrying member, and a developer accommodating portion for accommodating the developer whose conveyance is prevented by the developer regulating member There is known a developing device having a toner storing section for storing the toner.

[0003] However, in such a developing device, the developer contained in the developer accommodating portion has the active part and the inactive part where the movement of the developer is active, or the developing part in the part where the amount of the developer is large and the part where the movement is small. Since the amount of toner taken into the developer is different, the toner concentration of the developer conveyed by the developer carrier becomes unstable, and density unevenness and background fouling (toner fog) occur in the developed image. There was a problem that it was easy to do.

In order to solve such a problem, in a developing device disclosed in Japanese Patent Application Laid-Open No. 63-4282, two toner supply members are disposed in a toner storage section, and each toner supply member is formed by each toner supply member. By passing the developer through the path, unevenness in the concentration of the developer in the machine length direction and fogging of the toner are eliminated.

[0005]

However, the conventional developing device disclosed in Japanese Patent Application Laid-Open No. 63-4282 uses two toner supply members, so that the size and cost of the developing device main body are increased. There is a problem that leads to up. Therefore, the present applicant aims to provide a developing apparatus capable of stabilizing image quality while reducing the size and cost by reducing the number of parts and integrating functions. As shown in FIG. 1, a developer carrier 15 that carries and transports a two-component developer 22 containing a toner 18 and a magnetic carrier 22a, a first regulating member 17 that regulates the amount of the developer 22, and a developer Developer storage unit 1 that stores storage 22
6a, and a toner container 19 for supplying the developer 18 with the toner 18 to the developer carrier 15. The developer container 16a is disposed upstream of the first regulating member 17 in the transport direction of the developer 22. When the toner concentration of the developer 22 on the developer carrier 15 increases and the layer thickness of the developer 22 increases, a gap between the developer carrier 15 and the developer carrier 15 is set to restrict the passage of the increase. A developing device 13 having a second regulating member 23 has been proposed (Japanese Patent Application Laid-Open No. 9-197833).

In the developing device disclosed in Japanese Patent Application Laid-Open No. Hei 9-197833, the developer 22 in the developer accommodating portion 16a for accommodating the developer 22 whose progress has been prevented by the first regulating member 17 is controlled. By the circulation operation, the developer 22 that has passed through the first regulating member 17 or the developing area and the developer 22 in the developer accommodating portion 16a are gradually replaced, so that the developer 22 is set in the developer accommodating portion 16a. Developer 22 is used. And by such a change of the developer 22 being performed smoothly,
The stress applied to the developer 22 is dispersed, and the progress of scraping of the film of the magnetic carrier 22a and spent of the toner is delayed,
The life of the developer 22 is extended, and the image quality is stabilized.

Further, in the developing device having such a configuration, the toner and the magnetic carrier are sufficiently stirred and mixed by the circulation operation of the developer in the developer accommodating portion for accommodating the developer whose progress has been prevented by the regulating member. As a result, the toner concentration of the developer is made uniform and the toner is sufficiently charged, thereby preventing image density unevenness and occurrence of background fog due to insufficiently charged toner. Therefore, in this type of developing device, the image quality can be further improved by making the circulation operation of the developer in the developer accommodating portion more smoothly.

The present invention has been made in view of the above problems, and an object of the present invention is to further enhance the circulation of the developer in the developer accommodating section to obtain a more stable and uniform image quality. An object of the present invention is to provide a developing device capable of obtaining an image having a toner density.

[0009]

In order to achieve the above object, the present invention is directed to a developer carrying member which carries a developer comprising toner and magnetic particles on a surface thereof and transports the developer. A magnetic field generating means for generating a magnetic field for carrying the developer on the surface of the body, a developer regulating member for regulating the amount of the developer carried on the developer carrying member, and a conveyance blocked by the developer regulating member In a developing device having a developer accommodating section for accommodating the developed developer and a toner accommodating section for accommodating the toner, the developer regulating member is positioned substantially vertically above the developer carrying member, and The angle between the vertical direction and the direction of the magnetic field generating means, which faces the agent container, indicating the peak value of the magnetic pole is set to 25 ° or more.

In this developing device, the angle between the direction indicating the peak value of the magnetic pole of the magnetic field generating means and the vertical line is 2 degrees.
When the angle is set to 5 ° or more, the developer is attracted by the magnetic force of the magnetic pole generating means, the drag received from the surface of the developer carrier in the opposite direction to this force, and the angle between these forces is Acting with gravity and receiving. As a result, the developer to be retained collapses downward, and the circulation speed of the developer is increased.

According to a second aspect of the present invention, there is provided a developer carrying member for carrying a developer composed of toner and magnetic particles on a surface thereof, and generating a magnetic field for carrying the developer on the surface of the developer carrying member. A magnetic field generating means, a developer regulating member for regulating the amount of developer carried on the developer carrying member, a developer accommodating portion for accommodating the developer whose conveyance has been prevented by the developer regulating member, and In a developing device having a toner storage portion for storing toner, a surface of the developer restricting member or a member provided on the developer restricting member for preventing advance of the developer is formed by extending the surface of the developer restricting member and the developer. It is characterized by being inclined to the upstream side in the traveling direction of the developer with the contact point with the surface of the carrier as a base point.

In this developing device, the surface of the developer regulating member or a member provided on the developer regulating member for preventing the progress of the developer is formed by extending the surface of the developer regulating member and the surface of the developer carrying member. The inclined surface is inclined to the upstream side in the traveling direction of the developer with the contact point as a base point. The developer stopped by the developer regulating member rises along the inclined surface. However, as the developer moves away from the developer carrier, the binding force on the developer by the magnetic force of the magnetic field generating means becomes weaker. The inclination of the surface breaks the balance with the gravity. As a result, the developer collapses downward and is conveyed again by the developer carrier and circulated.

According to a third aspect of the present invention, there is provided a developer carrier for carrying a developer comprising toner and magnetic particles on a surface thereof, and generating a magnetic field for carrying the developer on the surface of the developer carrier. A magnetic field generating means, a developer regulating member for regulating the amount of developer carried on the developer carrying member, a developer accommodating portion for accommodating the developer whose conveyance has been prevented by the developer regulating member, and In a developing device having a toner storage portion for storing toner, a surface of the developer regulating member that prevents the progress of the developer, and a developer advancing direction at an intersection of an extended surface of the surface and the surface of the developer carrier. An angle between the downstream tangent and the tangent is less than 90 °.

In this developing device, a surface of the developer regulating member for preventing the progress of the developer, and a tangent line at the intersection of the extended surface of the surface and the surface of the developer carrier in the developer advancing direction are provided. Is set to be less than 90 °. Therefore, in this developing device, the component force of the developer carrying force of the developer carrying member in the direction perpendicular to the surface of the developer regulating member is below the developer which is prevented from progressing by the developer regulating member. It acts as a force for squeezing the subsequent developer, and the component force of the developer carrying force of the developer carrier in the direction parallel to the surface of the developer regulating member is prevented from progressing by the developer regulating member. It acts as a force to push up the developed developer by the subsequent developer. Thus, the circulation of the developer, which has been prevented from proceeding by the developer regulating member, is activated by the subsequent developer.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device of a printer as an image forming apparatus will be described below. FIG. 1 shows a first configuration example of the developing device according to the present embodiment. In FIG. 1, a developing sleeve 1 as a developer carrier is formed of a rotatable cylindrical sleeve.
Inside, four magnetic poles P1, P as magnetic field generating means are provided.
A permanent magnet having 2, P3 and P4 is fixedly arranged. A doctor 2 as a developer regulating member for regulating the layer thickness of the developer 3 carried and transported by the developing sleeve 1 is disposed substantially vertically above the developing sleeve 1. Further, a developer storage case 5 having a developer storage portion 4 for storing the developer 3 whose progress has been prevented by the doctor 2 is provided upstream of the doctor 2 in the rotation direction of the developing sleeve.
Are arranged. Further, a toner hopper 7 serving as a toner storage unit for storing the toner 6 is provided at a position adjacent to the upstream side of the developer storage case 5. The toner storage section of the toner hopper 7 communicates with the developer storage section 4 via a toner supply path 8 formed at the upstream end of the developer storage case 5. Inside the toner hopper 7, there is provided an agitator 9 as a toner supply and stirring member for feeding the toner 6 stored in the toner storage section toward the toner supply path 8 while stirring. Further, at the upstream end of the developer storage case 5,
A pre-doctor 5 a as a second developer regulating member is formed close to the developing sleeve 1.

In the developing device configured as described above, when the toner concentration of the developer 3 (weight percentage of the toner 6 in the developer 3) is within an appropriate range, as shown in FIG.
A stagnant portion 10 of the developer 3 is formed on the upstream side of the pre-doctor 5a to prevent contact between the developer on the developing sleeve 1 and the toner, and to prevent the toner from being taken in from the toner hopper 7. When the toner on the developing sleeve 1 is consumed by forming an image on the photosensitive drum 12 as an image carrier, the bulk of the developer on the developing sleeve 1 is reduced. Thereby, the developer stagnation portion 10
Becomes small, and the developer on the developing sleeve 1 and the toner can come into contact with each other, so that the toner hopper 7 acts to take in the toner.

By the way, in this type of developing apparatus, as described above, the image quality is further improved by making the circulation operation of the developer 3 in the developer accommodating section 4 smoother. Can be done. Therefore, in the developing device according to the present embodiment, as shown in FIG. 1, the magnetic pole facing the photosensitive drum 12 is set to P1 inside the developing sleeve 1, and the magnetic pole is turned counterclockwise with respect to the magnetic pole P1. P2 and P3 are arranged, and a magnetic pole P4 is arranged at a position facing the developer accommodating section 4. At this time, the doctor 2 is positioned substantially vertically above the developing sleeve 1, and the magnetic pole P 4 opposing the developer accommodating section 4.
The angle θ1 between the direction indicating the peak value of
Set above.

As described above, an experiment was conducted by setting the angle .theta.1 between the direction indicating the peak value of the magnetic pole P4 facing the developer accommodating section 4 and the vertical line at 25 ° or more and less than 45 °. It was observed that the circulation speed of the developer 3 in the developer container 4 was increased. According to this experiment, the angle θ1
As the value of is increased, the circulation speed of the developer 3 increases, and the occurrence of image density unevenness due to toner density unevenness in the rotation axis direction of the developing sleeve 1 is eliminated.
Here, when the angle θ1 is set to 45 ° or more, P
There is a concern that the angle between the first pole and the P4 pole becomes too large, and the conveying force of the developer 3 during this time is reduced, and the operation of the developer 3 is changed. Therefore, the angle θ1 is 25 °
Although it is desirable to set the angle in the range of about 45 °, even if the angle θ1 is 45 ° or more, if the condition can be set so as not to hinder the operation of the developer 3, the effect is not exceeded even if the angle exceeds this range. Can demonstrate.

On the other hand, if the angle θ1 is made smaller than 25 °, the developer 3
Stays on the upstream side of the doctor 2 and its gravity and the magnetic force of the P4 pole act in substantially the same direction, but the developer 3 comes to a standstill in balance with the drag force from the surface of the developing sleeve 1. As a result, in this case, the toner 6 taken in from the toner supply path 8 and the developer 3 in the developer accommodating section 4 are hardly mixed, and the toner density and the image density of the developer 3 become uneven. There has occurred.

Therefore, in this developing device, by setting the angle between the direction of the peak value of the magnetic pole P4 as the magnetic field generating means and the vertical line to be equal to or greater than 25 °, the developer 3 is transferred to the magnetic pole P4. The force attracted by the magnetic force of P4, the opposing force from the surface of the developing sleeve 1 in the opposite direction to the force, and the gravitational force acting at an angle. As a result, the developer 3 to be retained
Begins to crumble downward. Such behavior of the developer 3 is considered to be a mechanism for increasing the circulation speed of the developer 3.

FIG. 2 shows a second example of the developing device according to this embodiment.
An example of the configuration will be described. As shown in FIG. 2, the developing device includes a surface 11 of the doctor 2 or a member provided on the doctor 2 for preventing the developer 3 from advancing, and an extended surface of the surface 11 and a surface of the developing sleeve 1. With respect to the vertical point, the angle is inclined by an angle θ2 to the upstream side in the traveling direction of the developer 3 with the contact point with the base point as a base point.

In this developing device, the surface 11 is
The inclined surface is inclined toward the upstream side in the traveling direction of the developer 3 from the contact point between the extended surface of the surface 11 and the surface of the developing sleeve 1 as a base point. In FIG. 2, the developer 3, which has been prevented from moving by the doctor 2, rises along the inclined surface 11, but as the distance from the developing sleeve 1 increases, the magnetic pole P
The binding force of the magnetic force of the developer 4 against the developer 3 is weakened, and the inclination of the surface 11 breaks the balance with the gravity. As a result, the developer 3 collapses downward, is conveyed again by the developing sleeve 1 and circulated, and the toner taken in by the circulation action of the developer 3 and the developer 3 are sufficiently stirred. By sufficient stirring of the developer 3, the toner concentration of the developer 3 is made uniform, and the image density unevenness is improved.

FIG. 3 shows a third example of the developing device according to this embodiment.
An example of the configuration will be described. This developing measure is performed by setting an angle θ3 between a surface of the doctor 2 for preventing the developer 3 from advancing and a tangent on the downstream side in the developer advancing direction at the intersection of the extended surface of the surface and the surface of the developing sleeve 1. , Less than 90 °. Therefore, in this developing device, as shown in FIG.
The component force F1h of the developer conveying force F1 of the developing sleeve 1 in the direction perpendicular to the surface of the doctor 2 acts as a force for squeezing the subsequent developer under the developer blocked by the doctor 2. Further, a component force F1v of the developer conveying force F1 of the developing sleeve 1 in a direction parallel to the surface of the doctor 2 is given by:
The developer, which has been prevented from proceeding by the doctor 2, acts as a force for pushing up the developer by the subsequent developer. As a result, the circulation of the developer that has been prevented from proceeding by the doctor 2 is activated by the subsequent developer. By activating the circulation of the developer 3, the stirring of the toner taken into the developer 3 and the developer is promoted, the toner density is made uniform, and the image density unevenness is improved.

[0024]

According to the first aspect of the present invention, by setting the angle between the direction of the peak value of the magnetic pole as the magnetic field generating means and the vertical line to be equal to or greater than 25 °, the developer can be used for the magnetic pole. By receiving the force attracted by the magnetic force, the drag received from the surface of the developer carrier opposite to the force, and the gravity acting at an angle with the force, the developer that is about to stay Begins to crumble. Due to the behavior of the developer, the circulation speed of the developer is increased, and the activation of the circulation of the developer promotes agitation of the toner and the developer taken in the developer, thereby making the toner concentration uniform. ,
There is an excellent effect that image density unevenness is improved.

According to the second aspect of the present invention, the developer stopped by the developer regulating member rises along the inclined surface of the developer regulating member. The restraining force on the developer by the magnetic force of the magnetic pole as the magnetic field generating means is weakened, and the balance with the gravity is lost due to the inclination of the surface. This allows
The developer collapses downward, is again conveyed and circulated by the developer carrier, and the toner and the developer taken in by the circulation action of the developer are sufficiently stirred. By sufficiently stirring the developer, there is an excellent effect that the toner concentration of the developer is made uniform and the image density unevenness is improved.

According to the third aspect of the present invention, the component of the developer carrying force of the developer carrying member in the direction perpendicular to the surface of the developer regulating member is prevented from developing by the developer crisis member. Works as a force to squeeze the following developer below the developer,
Further, the component force of the developer carrying force of the developer carrying member in the direction parallel to the surface of the developer regulating member is a force for pushing up the developer, the progress of which is prevented by the developer regulating member, by the subsequent developer. Work as As a result, the circulation of the developer that has been prevented from proceeding by the developer regulating member is activated by the subsequent developer, and the activation of the circulation of the developer causes the toner taken in the developer and the developer to be circulated. There is an excellent effect that the agitation is promoted, the toner density is made uniform, and the image density unevenness is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a first configuration example of a developing device according to an embodiment.

FIG. 2 is a schematic configuration diagram illustrating a second configuration example of the developing device according to the embodiment.

FIG. 3 is a schematic configuration diagram illustrating a third configuration example of the developing device according to the embodiment.

FIG. 4 is a schematic view of a main part of a developer regulating member in the third configuration example.

FIG. 5 is a schematic configuration diagram of a conventional developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing sleeve 2 doctor 3 developer 4 developer accommodating section 5 developer accommodating case 6 toner 7 toner hopper 8 toner replenishing path 9 agitator 10 developer accumulating section 11 doctor developer blocking surface 12 photoconductor drums P1, P2, P3 , P4 Magnetic pole F1 Developer transport force FIh, F1v Component force of developer transport force

Claims (3)

[Claims] A developer carrying member for carrying a developer comprising toner and magnetic particles on a surface thereof; a magnetic field generating means for generating a magnetic field for carrying the developer on the surface of the developer carrying member; A developer regulating member for regulating the amount of the developer carried on the developer carrying member, a developer accommodating portion for accommodating the developer blocked from being conveyed by the developer regulating member, and a toner accommodating the toner In the developing device having an accommodating portion, the developer regulating member is positioned substantially vertically above the developer carrying member, and a direction indicating a peak value of a magnetic pole of the magnetic field generating means facing the developer accommodating portion. An angle between the vertical line and the vertical line is set to 25 ° or more. 2. A developer carrier for carrying a developer comprising toner and magnetic particles on the surface thereof, and a magnetic field generating means for generating a magnetic field for carrying the developer on the surface of the developer carrier. A developer regulating member for regulating the amount of the developer carried on the developer carrying member, a developer accommodating portion for accommodating the developer blocked from being conveyed by the developer regulating member, and a toner accommodating the toner In the developing device having an accommodating portion, a surface of the developer restricting member or a member provided on the developer restricting member for preventing the progress of the developer, an extended surface of the surface and a surface of the developer carrying member. Wherein the contact point is a base point and is inclined upstream in the direction of travel of the developer. 3. A developer carrier for carrying and transporting a developer comprising toner and magnetic particles on a surface thereof; a magnetic field generating means for generating a magnetic field for carrying the developer on the surface of the developer carrier; A developer regulating member for regulating the amount of the developer carried on the developer carrying member, a developer accommodating portion for accommodating the developer blocked from being conveyed by the developer regulating member, and a toner accommodating the toner In the developing device having an accommodating portion, a surface of the developer regulating member for preventing the progress of the developer, and a tangent line at the intersection of an extended surface of the surface and the surface of the developer carrier at a downstream side in the developer advancing direction. A developing angle of less than 90 °.