JP2001100532A - Development method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To form a stable image for a long period of time. A developing device includes a developing container holding a developer, a developer conveying screw disposed in a developer supply chamber in the developing container, and a developing device disposed in a developer receiving chamber. It has an agent conveying screw 7 and a photosensitive drum 20 as an image carrier that rotates in the direction of arrow a. Further, a developing sleeve 10 made of a non-magnetic material, which rotates in the direction of arrow b to convey the developer 12 in the developing container 2 toward the developing unit 13 facing the photosensitive drum 20, and a developing sleeve 1
0, a magnet roller 11 magnetized to S2 pole, N1 pole, S1 pole, N2 pole, and N3 pole from the most upstream portion 31 to the downstream side, and a developing sleeve 10
Regulates the transport amount of the developer 12 transported by the
There is a regulating blade 30 composed of a non-magnetic blade 30a and a magnetic plate 30b, which is arranged in the vicinity of the N3 pole opposing position of the magnet roller 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing method in an image forming apparatus using an electrostatic latent image.

The term "downstream" used in the present specification refers to the position of the surface of the developing sleeve facing the tip of the regulating member as a reference position, from which the rotational direction of the developer carrying member is defined. The “upstream” direction refers to a direction opposite to the rotation direction of the developer carrier. For example, in FIG. 1 described below, the reference position 31 is
The position indicated by the point c on the developing sleeve 10 is “downstream”.
The direction is the rotation direction of the developing sleeve 10 indicated by the arrow b, and the “upstream” direction is the opposite direction to the arrow b.

[0003]

2. Description of the Related Art FIG. 4 shows an example of a conventional developing device using a two-component developer.

This developing device includes a developing container 102 for holding a two-component developer 150 composed of a magnetic carrier and a non-magnetic toner, a photosensitive drum 120 serving as an image carrier rotating in the direction of arrow e, and a direction of arrow f. Rotate the developing container 10
2 and a developing sleeve 110 that conveys the developer 150 in the developing container 112 toward the developing unit 112 facing the photosensitive drum 120, and a developer sleeve 110 that conveys the developer 150 in the developing container 102 to the developing sleeve 110. And non-rotating coaxially provided inside the developing sleeve 110 with the developer conveying screws 104 and 106, and N1 pole, N2 pole, S2
A magnet roller 111 having five magnetic poles, i.e., a pole, an N3 pole, and an S1 pole, and a regulating blade 130 that regulates the amount of the developer 150 conveyed by the developing sleeve 110 at the position of the S2 pole of the magnet roller 111. Have.

The N1, N2 and N3 poles are N poles, and the S1 and S2 poles are S poles. The solid line drawn in the radial direction from the center of the magnet roller 111 indicates the position where the magnetic flux density of each magnetic pole in the normal direction with respect to the surface of the magnet roller 111 is maximum.
It shows the position where the magnetic flux density in the normal direction in the repulsion magnetic field formed by the single pole and the N2 pole is the smallest.

The two-component developer 150 generally has an average particle diameter of 30 to 80 μm and a saturation magnetization of 50 to 70 μm.
[Am ² / kg], volume resistance is 10 ⁷ to 10 ¹⁰ [Ωcm]
A magnetic carrier composed of a non-magnetic resin toner composed of a resin to which about ₂ % of a magnetic carrier and SiO ₂ or the like are externally added is used.

The developer 150 in the developing container 102 is pumped onto the developing sleeve 110 by the N2 pole of the magnet roller 111, and is rotated on the developing sleeve 110 to the S2 pole, N3 pole, and S1 pole with the rotation of the developing sleeve 110. Conveyed in order. In the course of the conveyance, the developer 150 is transferred to the developing sleeve 11 near the position where the magnetic flux density in the normal direction of the S2 pole is maximum.
The thickness of the developing sleeve 110 is regulated by a regulating blade 130 arranged in a non-contact manner with respect to the developing sleeve 110.
A thin layer of developer 150 is formed thereon. The S1 pole located in the developing section 112 of the magnet roller 111 is a main developing pole, and the developer 150 raised by the S1 pole, that is, the developer 150 extending toward the photosensitive drum 120,
Develops the latent image formed on the photosensitive drum 100. The developer is then removed from the developing sleeve 110 by the repelling magnetic field of the N1 pole and the N2 pole, and the developing container 102
Will fall back inside.

[0008]

However, as shown in FIG. 4, in the conventional developing device, the developer 150 remaining after being regulated by the regulating blade 130 is formed on the back surface 131a side of the regulating blade 130 with the S2 pole. It is retained by the magnetic force generated by the N2 pole and accumulates in a large amount, so that a stagnant portion 151 is generated.

Further, the developer is conveyed one after another by the developing sleeve to the stagnation portion, so that a large pressure is applied. As a result, 2
When a large force is applied between the magnetic carrier of the component developer and the resin toner, a phenomenon that fine powder particles such as SiO ₂ externally added to the resin toner are embedded in the resin toner may occur. In addition, when used for a long time, the resin toner adheres to the surface of the magnetic carrier and cannot be removed.
A so-called spent phenomenon may occur.

When these phenomena occur, the charge amount of the resin toner is reduced, that is, a so-called tribo-down state occurs, the image density is changed, and the mechanical adhesion of the resin toner to the magnetic carrier and the photosensitive drum is increased, and the response to the electric field is increased. Development and transfer are difficult to be performed, and uneven development which is a partial lack of the resin toner occurs. That is, there is a case where the image becomes extremely impressive as compared with the initial image with use.

[0011] Even if the resin toner does not adhere to the surface of the carrier to prevent the tribodown, the external additive may be released from the toner due to durability, and the developer is replenished. It is conceivable that the tribodown occurs due to the increase of the external additive every time.

Accordingly, an object of the present invention is to provide a developing method capable of stably obtaining an image similar to an initial image for a long period of time.

[0013]

In order to achieve the above object, the present invention provides a developing method comprising: a developer container containing a developer therein; and a magnetic field generator having a plurality of magnetic poles for generating magnetic fields. A rotatable developer carrier that contains means for carrying and transporting the developer by a magnetic field generated by the magnetic field generator, and a developer carrier disposed at a predetermined interval between the developer carrier and the developer A regulating member that regulates the amount of the developer carried on the surface of the carrier, and a developing method using a developing device that develops a latent image formed on the developer carrier in a developing unit. When the side that advances in the rotation direction of the developer carrier is the downstream side, the position where the amount of the developer is regulated by the regulating member is the first magnetic pole formed downstream from the developing unit. Formed adjacent to the downstream side of the Outside the non-magnetic toner supplied to the developing device, which is located near the downstream side of the position where the magnetic flux density in the normal direction on the surface of the developer carrier of the second magnetic pole having the same polarity as the first magnetic pole is maximum. The amount of the additive is smaller than the amount of the external additive of the non-magnetic toner used before replenishing the developer.

According to the developing method of the present invention as described above, the position where the regulating member is disposed is a magnetic field formed by the first magnetic pole and the second magnetic pole having the same polarity as the first magnetic pole, that is, And the downstream of the second magnetic pole, where the magnetic flux density in the normal direction on the surface of the developer carrier is maximized, is located downstream of the region of the repulsive magnetic field having a small magnetic field strength. Use the device. In other words, after the developer not used for development is dropped from the developer carrier by passing through the area of the repelling magnetic field, the developer pumped up by the second magnetic pole is placed on the surface of the developer carrier. Before reaching the region where the developer is easily carried, the regulating member regulates the layer thickness of the developer. For this reason, it becomes difficult for the developer to accumulate on the rear surface side of the regulating member, and deterioration of the developer can be suppressed by reducing the force applied to the developer. In addition, by disposing the regulating member near the downstream side of the position where the magnetic flux density in the normal direction on the surface of the developer carrier of the second magnetic pole is maximum, immediately before the layer thickness is regulated by the regulating member. Forms a magnetic brush, a so-called spike, which extends in the radial direction from the surface of the developer carrier and has a height equal to or higher than the clearance between the regulating member and the surface of the developer carrier. As a result, since the accumulation of the developer on the rear surface side of the regulating member becomes too small, the layer thickness of the developer becomes uneven due to a layer thickness smaller than the clearance between the regulating member and the surface of the developer carrier. Can be prevented. Further, since the amount of the external additive of the non-magnetic toner of the developer to be replenished is smaller than the amount of the external additive of the non-magnetic toner used before the replenishment of the developer, the external additive is accumulated. The occurrence of the tribodown that occurs can be suppressed.

Further, even if the repulsion magnetic field formed by the first magnetic pole and the second magnetic pole has a magnetic field strength of 5 [mT] or less in the normal direction on the surface of the developer carrying member. Alternatively, when the developer carrier is cylindrical, the strength of the repulsion magnetic field in the tangential direction on the surface of the cylindrical developer carrier may be 5 [mT] or less. .

By setting the strength of the repelling magnetic field to 5 [mT] or less as described above, it is possible to promote removal of the developer from the surface of the developer carrier.

Furthermore, the maximum magnetic flux density in the normal direction on the surface of the developer carrying member by the second magnetic pole is 50 [mT] or more, and the magnetic flux density is 80 [%] or more of the maximum magnetic flux density in the normal direction. Range is 20 [°] or more in angle from the magnetic pole center of the second magnetic pole, and the range of the magnetic flux density of 50 [%] or more of the normal direction maximum magnetic flux density is 45 [°].
It may be as follows. By doing so, it is possible to prevent ghost images, white stripes, and the like from occurring. Also, in this case,
The regulating member may be arranged at a position facing the developer carrier in a range of a magnetic flux density of 80% or more of the normal direction maximum magnetic flux density. By arranging the regulating member in this manner, it is possible to ensure that the height of the developer spike before regulating the layer thickness by the regulating member is higher than the clearance between the regulating member and the surface of the developer carrier. it can.

Still further, the position where the developer carrying member pumps up the developer and the position where the regulating member is disposed may be below the developer carrying member. With such a configuration, the distance for transporting the developer pumped to the developer carrier to the regulating member while opposing gravity is shortened, and therefore, the transport time during which the developer may fall off the developer carrier. Therefore, the developer can be stably transported to the regulating member.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a side sectional view schematically illustrating a developing device according to a first embodiment of the present invention.

The developing device of this embodiment is provided in a developing container 2 for holding a two-component developer 12 composed of a non-magnetic toner such as a magnetic carrier and a resin toner, and a developer supply chamber 13 in the developing container 2. Also, a developer transport screw 6 that transports the developer 12 and a developer transport screw that transports the developer 12 to the developer transport screw 6 disposed in a developer receiving chamber 14 below the developer supply chamber 13. 7 and a photosensitive drum 20 as an image carrier that rotates in the direction of arrow a. The developing device further includes a non-rotating magnet roller 11 having S2, N1, S1, N2, and N3 magnetic poles from the reference position 31 toward the downstream side, and a hollow cylindrical shape made of a nonmagnetic material. And the magnet roller 11
And a regulating blade 30 that regulates the amount of the developer 12 conveyed by the developing sleeve 10. Note that N1
Pole, N2 pole, N3 pole is N pole, S1 pole, S2 pole is S
It is a pole. The solid line drawn in the radial direction from the center of the magnet roller 11 indicates the magnet roller 1 of each magnetic pole.
The magnetic flux density in the normal direction indicates the position where the magnetic flux density in the normal direction is the maximum with respect to the surface of No. 1, and the broken line indicates the position where the magnetic flux density in the normal direction in the repulsion magnetic field formed by the N2 pole and the N3 pole described later. It is shown.

The regulating blade 30 has a non-magnetic blade 30a, which is a non-magnetic plate member, and a magnetic magnetic plate 30b adhered to the back surface 30c of the non-magnetic blade 30a. Is provided on the downstream side of the position where the magnetic flux density of the developing sleeve 10 is the largest, with an interval from the surface of the developing sleeve 10. Note that, more specifically, the regulating blade 30
When a region of 80% or more of the maximum magnetic flux density in the normal direction of the three poles is expressed as X [°] by the magnetic pole center angle of the N3 pole, X / 2 [°] is downstream from the position of the maximum magnetic flux density. It is located at a position between:

The two-component developer 12 has a smaller average particle diameter and a smaller saturation magnetization than the magnetic carrier used in the conventional developing device described with reference to FIG. A magnetic carrier larger than the used magnetic carrier is used, and a resin toner using alumina as an external additive is used.

On the developing sleeve 10, between different poles, that is, between the N3 pole and the S2 pole, between the S2 pole and the N1 pole,
Between the first pole and the S1 pole and between the S1 pole and the N2 pole, the lines of magnetic force between the respective poles are directed in the circumferential direction of the developing sleeve 10, so that the developer 12 does not stand, that is, This is an area where the developer 12 is deposited on the surface of the developing sleeve 10 in a direction along the surface of the developing sleeve 10 without forming a magnetic brush directed in the radial direction on the surface of the developing sleeve 10. Further, between the same poles, that is, between the N2 pole and the N3 pole, a repelling magnetic field is formed.
2 is an area that does not accumulate in the direction along the surface of the developing sleeve 10 and easily falls off from the surface of the developing sleeve 10.

Next, development by the developing device of the present embodiment and transport of the developer 12 will be described in detail.

First, the developer 12 in the developer supply chamber 13 in the developing container 2 is transported from the back side to the front side in FIG. 1 while being stirred by the developer transport screw 6, and at this time, a part of the developer is Numeral 12 is pumped to the surface of the developing sleeve 10 by the N3 pole of the magnet roller 11.

The developer 12 is conveyed to the developing sleeve 10 rotating in the direction of the arrow b, and the layer thickness is regulated by the sweeping of the tip of the regulating blade 30 and the suction of the magnetic plate 30b. First, the developer 12 on the surface of the developing sleeve 10 is brought into a state of standing near the maximum magnetic flux density in the normal direction of the N3 pole. That is, when regulating the layer thickness of the developer 12 by the regulating blade 30, if the layer thickness is less than the clearance between the surface of the developing sleeve 10 and the regulating blade 30, the tip of the regulating blade 30 12
The inability to touch the
There is a possibility that the thickness of the layer cannot be regulated by the sweeping, and the thickness of the layer becomes uneven. For this reason, the developer 12 is
Before being conveyed to the developer, the developer 12 is raised over the clearance between the surface of the developing sleeve 10 and the regulating blade 30.

As described above, while the developer 12 which has been raised is somewhat attracted to the magnetic plate 30b, the tip of the non-magnetic blade 30a sweeps the developer 12 to regulate the layer thickness to a desired thickness. .

The developer 12 regulated to a desired layer thickness contains S
In the vicinity of the S1 pole maximum magnetic flux density (developing unit 15), the photosensitive drum 2
Standing toward 0. Then, the latent image on the photosensitive drum 20 is developed by the developer 12 that has been raised.

After the developer 12 which has not been used for developing the latent image on the photosensitive drum 20 and has passed through the developing section 15 is conveyed to the N2 pole, the N2 and N3 poles of the same polarity are adjacent to each other. In the region of the repelling magnetic field formed by the above, the developer drops from above the developing sleeve 10 to the developer receiving portion 14. And
The developer 12 is conveyed while being stirred from the near side in FIG. 1 to the back by the developer conveying screw 7, and is then delivered to the developer conveying screw 6.

After the developer 12 is again pumped up from the developer conveying screw 6 to the surface of the developing sleeve 10 by the N3 pole of the magnet roller 11, the regulating blade 3
Although the layer thickness is regulated by 0, the position where the regulating blade 30 is provided is immediately downstream of the position where the magnetic flux density in the normal direction of the N3 pole located downstream of the N2 pole is the maximum. The developer 1 on the back surface 30 c side of the regulating blade 30.
2 is less likely to accumulate. This is for the reason described below.

In the developing device of this embodiment, the N2 pole and the N3
The repelling magnetic field formed because the poles have the same polarity, that is, repelling each other, and therefore passing through a region where the magnetic field lines are not formed along the circumferential direction on the surface on the developing sleeve 12 formed between the different poles After that, the layer thickness of the developer 12 is regulated by the regulating blade 30. Since the regulating blade 30 is provided immediately after the region in which the developer 12 is less likely to be deposited on the surface of the developing sleeve 10, the developer 12 is less likely to accumulate on the back surface 30c.

On the other hand, in the conventional developing device shown in FIG.
The regulating blade 130 is provided at a position facing the S2 pole, but with such a configuration, the N2 pole
Since magnetic lines of force are present along the circumferential direction on the surface of the developing sleeve 120 between the poles, the developer 150 tends to deposit on the surface of the developing sleeve 120 along the circumferential direction. The developer 150 tends to accumulate on the back surface 131a side.

As described above, the developing device of this embodiment is
Due to the repelling magnetic field formed by the N2 pole and the N3 pole, the developer 12 drops from above the developing sleeve 10 to the developer receiving portion 14, and the developer formed by the N2 pole and the N3 pole having the same polarity. Since the regulating blade 30 is provided on the downstream side of the N3 pole immediately after passing the region in which the developer 12 hardly deposits on the developing sleeve 10, the developer 12 hardly accumulates on the back surface 30c side of the regulating blade 30. I have. Therefore, the pressure applied to the developer 12 caused by the successive conveyance and accumulation of the developer 12 is reduced. Further, since the saturation magnetization of the developer 12 used in the developing device of the present embodiment is smaller than the saturation magnetization of the developer 150 shown as an example of the related art, the force of attracting the developer 12 to the magnet roller 11 is small. The force applied to the developer 12 is reduced. Thus, the embedding of the external additive in the resin toner is suppressed.

Although the embedding of the external additive is suppressed as described above, the durability of the external additive is improved. However, the tribodown due to the accumulation of the external additive every time the developer 12 is replenished. It is necessary to make the amount of the external additive of the developer at the time of replenishment smaller than the amount of the external additive of the developer 12 used at the beginning in order to prevent the occurrence of the above.

Further, before the regulating blade 30 regulates the layer thickness, the developer 12 is raised by the magnetic force of the N3 pole, so that the layer thickness of the developer 12 is reduced between the surface of the developing sleeve 10 and the regulating blade 30. Can be prevented from being generated when the thickness is less than the clearance.

As described above, according to the developing device of the present embodiment, the deterioration of the developer 12 is suppressed, so that an image similar to the initial image can be stably obtained for a long period of time. (Second Embodiment) Next, FIG. 2 is a side sectional view for schematically explaining a developing device according to a second embodiment of the present invention.

The developing device of this embodiment includes a photosensitive drum 50 for carrying a latent image, a developing sleeve 40 rotating in the direction of arrow B which is the same as the rotating direction of the photosensitive drum 50, a developing sleeve 40 and a magnet roller. A regulating blade 60 disposed below 41, a developer conveying screw 36 for stirring and conveying the developer 42 and supplying the developer 42 to the developing sleeve 40, and a developer conveying for stirring and conveying the developer 42. Screw 37 and developer conveying screw 36
A developer supply chamber 43 holding the developer and a developer stirring chamber 44 holding the developer conveying screw 37 are formed, and a developing container holding the developing sleeve 40 and the non-magnetic regulating blade 60 32.

The above-described developer supply chamber 43 and developer stirring chamber 4
4 is communicated with a communication portion (not shown), and the developer 42 is exchanged at this communication portion.

The photosensitive drum 50 and the developing sleeve 40
In the developing unit 43, the photosensitive drum 50 and the developing sleeve 40 are rotating in the counter direction.

Further, the magnet roller 41 is moved from the reference position 61 to the downstream side (the direction of arrow B),
, S2, N2, and N3.

The regulating blade 60 of the present embodiment does not include the magnetic plate 30b provided on the regulating blade 30 of the first embodiment. It is arranged near the lowest point.

The configuration of the developing device of this embodiment other than the above is basically the same as that of the developing device shown in the first embodiment, and a detailed description thereof will be omitted. The physical properties of the developer 42 used in the present embodiment are the same as those of the developer 12 used in the first embodiment.

In the case of this embodiment, since the regulating blade 60 is disposed near the lowermost point of the developing sleeve 40,
The distance that the developer 42 pumped onto the developing sleeve 40 is conveyed to the regulating blade 60 while opposing gravity is reduced. Thereby, even if the developer 42 has a smaller saturation magnetization than the developer 42 shown as an example of the conventionally used developer such as the developer 42 used in the present embodiment, the developer 42 Since the transport time during which the developer 42 may fall is shortened, the developer 42 can be transported stably to the regulating blade 60.

Also, in the present embodiment, similarly to the first embodiment, an N2 pole and an N3 pole having the same polarity are formed.
Immediately after passing the region where the developer 42 hardly accumulates on the developing sleeve 10, the regulating blade 60 is located downstream of the N3 pole.
Is provided, the back surface 60c of the regulating blade 60 is provided.
The developer 42 is less likely to accumulate on the side. For this reason,
The pressure applied to the developer 42 caused by the successive conveyance and accumulation of the developer 42 is reduced.

Further, since the saturation magnetization of the developer 42 used in the developing device of the present embodiment is smaller than the saturation magnetization of the developer 150 shown as an example of the related art, the force at which the developer 42 is attracted to the magnet roller 41 is reduced. Is small, the force applied to the developer 42 is small. Thus, the embedding of the external additive in the resin toner is suppressed.

As described above, since the embedding of the external additive is suppressed, the durability of the external additive is improved. However, the tribodown due to the accumulation of the external additive every time the developer 42 is replenished. It is necessary to make the amount of the external additive of the developer at the time of replenishment smaller than the amount of the external additive of the developer 42 used initially.

Further, before regulating the layer thickness by the regulating blade 60, the developer 42 is raised by the magnetic force of the N3 pole, so that the layer thickness of the developer 42 is set between the surface of the developing sleeve 40 and the regulating blade 60. Can be prevented from being generated when the thickness is less than the clearance.

As described above, the developing device of this embodiment is the first type.
As in the embodiment, the deterioration of the developer 42 is suppressed, and an image similar to the initial image can be stably obtained for a long period of time.

[0049]

EXAMPLES Next, specific examples of the present invention will be described, but the present invention is not limited to these examples. (First Example) First, an example of the first embodiment of the present invention will be described below.

In this embodiment, the developing device of the first embodiment shown in FIG. 1 was used as the developing device.

The material of the developing sleeve 10 is SUS
A non-magnetic material such as 316 was used.

The regulating blade 30 is provided 5 [deg.] Downstream from the position where the magnetic flux density in the normal direction on the surface of the developing sleeve 10 is maximized due to the N3 pole.
Is a non-magnetic blade 30a having a thickness of 0.3 [mm].
Was used by being adhered to the side wall.

The maximum magnetic flux density in the normal direction on the surface of the developing sleeve 10 due to the N3 pole of the magnet roller 11 is 60.
[MT].

The strength of the repulsive magnetic field in the direction normal to the surface of the developing sleeve 10 between the N2 pole and the N3 pole is 5 [mT].
And the intensity of the magnetic field in the tangential direction is also 5 [mT] or less.

In this embodiment, the average particle diameter is 40 [μm] or more, the saturation magnetization is 30 [Am ² / kg], and the volume resistance is 10
^A two-component developer 12 comprising a magnetic carrier of ¹¹ [Ωcm] and a non-magnetic resin toner externally added with 1 [%] of alumina as an initial agent was used. As described above, in the present embodiment, the average particle size shown as an example of the conventional example is 50 to 80 [μ].
m], a magnetic carrier having a saturation magnetization of 60 to 70 [Am ² / kg] and a volume resistance of about 10 ⁷ to 10 ⁸ [Ωcm];
The saturation magnetization is smaller than that of the developer 150 made of a nonmagnetic resin toner made of a resin externally added with iO ₂ or the like. The amount of magnetization of the magnetic carrier was determined to be 7.75 [kA / by using an oscillating magnetic field type magnetic characteristic automatic recording device manufactured by Riken Denshi Co., Ltd.
m] in an external magnetic field.

Using the developing device having the above-described configuration, the magnetic flux density distribution on the surface of the developing sleeve 10 as a parameter as shown in Table 1 is used as a parameter to determine the distance between the developing sleeve 10 and the tip of the regulating blade 30. The maximum value of the distance between SBs, which is the distance, was measured, and the occurrence of ghosts was observed.

[0057]

[Table 1] The 80 [%] width in Table 1 is 6 times the maximum magnetic flux density in the normal direction.
A region in which the magnetic flux density in the normal direction is 48 [mT] or more with respect to 0 [mT] is represented by an angle from the center of the N3 pole. The same applies to the width of 50 [%], and the area where the magnetic flux density in the normal direction is 30 [mT] or more is represented by an angle from the center of the N3 pole magnetic pole. For example, under the condition (a), the magnetic flux density in the normal direction on the surface of the developing sleeve 10 due to the N3 pole is 48 [mT] or more in the range of 25 [°] from the center of the N3 pole magnetic pole. Within the range of 40 [°], the magnetic flux density in the normal direction is 3
0 [mT] or more.

The positional relationship between the regulating blade 30 and the N3 pole is such that the regulating blade 30 is located 5 ° downstream from the position where the magnetic flux density in the normal direction on the surface of the developing sleeve 10 is maximum due to the N3 pole. Are provided. The area of 80% or more of the maximum magnetic flux density in the normal direction of the N3 pole of 60 mT is 25 [°] from the center of the N3 pole magnetic pole. That is, when the range of the region of 80% or more of the normal direction maximum magnetic flux density is X [°], X / 2 [°] or less downstream from the position where the normal direction magnetic flux density is maximum. It is arranged in a position between them.

Next, FIG. 3 shows the distribution of the magnetic flux density in the normal direction of the developing sleeve surface with respect to the angle from the center of the N3 magnetic pole. (A) to (d) in FIG. 3 are (a) to (d) in Table 1.
(D).

Incidentally, if it is attempted to mechanically sweep the regulating blade 30 to achieve 45 dg / m ^2, which is the amount of the developer 12 that is appropriate for the developing device of this embodiment, SB
The distance between them is 200 to 400 [μm]. However, if an image is formed for a long period of time at 400 [μm] or less, the developer may be clumped between the developing sleeve 10 and the regulating blade 30, which may cause white streaks. From the above, the layer thickness of the developer 12 which is appropriate for the developing device of this embodiment is 45 [dg / m ² ].
It is necessary to regulate the developer 12 on the other hand, but on the other hand, the distance between SBs is set to 400 [μ] in order to prevent the developer clogging.
m] or more.

Therefore, when an experiment was conducted under the conditions shown in Table 1, the distance between SBs could be made 400 [μm] or more under the conditions (a), (b) and (d). That is, in order to set the distance between SBs to 400 [μm] or more, N3
Of the maximum magnetic flux density in the normal direction on the surface of the developing sleeve.
It is necessary to set the range of [%] or more to 20 [°] or more.

Further, as shown in (a) to (c) in Table 1, the area of 50% or more of the maximum magnetic flux density in the normal direction on the surface of the N3 pole developing sleeve is set to 45 ° or less. If not, a ghost image has occurred.

Therefore, the appropriate layer thickness of the developer 12 of 4
In order to secure 5 [dg / m ² ] and to prevent the occurrence of ghost, (a) or (b), that is, N
The maximum magnetic flux density in the normal direction on the surface of the three-pole developing sleeve is 8
It has been found that it is necessary to set the range of 0% or more to 20 ° or more and to set the range of 50% or more to 45 ° or less. In the condition (b), the distance between SBs is 420 [μm] and the margin from 400 [μm] is 20 [μm], whereas in the condition (a), the distance between SBs is 550. [Μm] and 400 [μm].
m] is 150 [μm],
The condition (a), in which the distance between SBs can be made wider than the condition (b), is less likely to cause development blockage and is more preferable.

Further, in this embodiment, a non-magnetic resin toner externally added with 1% of alumina is used as an initializing agent.
A non-magnetic resin toner externally added with 0.8 [%] of alumina was used as a replenishing toner. Conventionally, since the force applied to the developer is large, the apparent tribodown is small when the external additive is embedded in the non-magnetic resin toner, but in the present embodiment, the force applied to the developer 12 is small. The amount of the external additive embedded in the non-magnetic resin toner is reduced,
Accumulation of the external additive makes it easier for tribodown to occur. Therefore, when replenishing the non-magnetic resin toner, a non-magnetic resin toner having less external additives than the initial non-magnetic resin toner was supplied.

Further, the developer deterioration level in the developing device of this embodiment was compared with the developer deterioration level in the conventional developing device shown in FIG. 4 using the developer 12 used in this embodiment. As a result, when judging from the obtained image quality, the developer deterioration level in the developing device of this embodiment is about 6%.
With twice the idle rotation time, the developer deteriorated almost the same as the developer deterioration level in the conventional developing device, and an image similar to the initial image could be stably obtained for a long period of time. (Second Embodiment) Next, an embodiment of the second embodiment of the present invention will be described below.

In this example, the developing device of the second embodiment shown in FIG. 2 was used as the developing device.

The maximum magnetic flux density in the direction perpendicular to the normal direction on the developing sleeve 40 of this embodiment is also 60 [m] as in the first embodiment.
T], and the range of the area of 80% or more of the maximum magnetic flux density in the normal direction is 25 °, and the area of 50% or more is 40%.
[°].

The regulating blade 60 is arranged at 10 ° downstream of the rotation direction of the developing sleeve 40 from the position of the maximum magnetic flux density in the normal direction of the N3 pole. That is, when the range of the region of 80% or more of the normal direction maximum magnetic flux density is X [°], X / 2 [°] or less downstream from the position where the normal direction magnetic flux density is maximum. It is arranged in a position between them.

The maximum magnetic flux density in the normal direction is 80%.
Even when the range of the above region is set to 20 ° or more, the developing sleeve 40 within the range of 80% or more is used.
By placing the regulating blade 60 at a position facing the SB, the SB
The distance between them could be 400 [μm] or more.

In the present embodiment, hydrophobic silica is used as an external additive to the resin toner, and 1.
5% and 1.2% with respect to the replenishment toner, an image similar to the initial image could be stably obtained over a long period of time as in the first embodiment.

[0071]

As described above, according to the present invention, after the developer not used for development is dropped and removed from the developer carrier by passing through the area of the repelling magnetic field, the surface of the developer carrier is removed. Before reaching the region where the developer is easily carried, the regulating member regulates the layer thickness of the developer. For this reason, it becomes difficult for the developer to accumulate on the rear surface side of the regulating member, and deterioration of the developer can be suppressed by reducing the force applied to the developer. In addition, the regulation member is disposed in the vicinity of the downstream side of the position where the magnetic flux density in the normal direction on the surface of the developer carrier of the second magnetic pole is maximized, thereby preventing the uneven thickness of the developer. it can.

Further, since the amount of the external additive of the non-magnetic toner for replenishment is smaller than the amount of the external additive of the non-magnetic toner of the developer used before the replenishment, the occurrence of tribodown can be suppressed.

As described above, an image having a sufficient density can be stably obtained for a long period of time, like the initial image.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically illustrating a developing device according to a first embodiment of the present invention.

FIG. 2 is a side sectional view schematically illustrating the developing device according to the first embodiment of the present invention.

FIG. 3 is a distribution of magnetic flux density in a normal direction of a developing sleeve surface with respect to an angle from an N3 pole magnetic pole center.

FIG. 4 is a side sectional view schematically illustrating a conventional developing device.

[Explanation of symbols]

 2, 32 developing container 6, 7, 36, 37 developer conveying screw 10, 40 developing sleeve 11, 41 magnet roller 12 developer 13, 43 developer supplying chamber 14 developer receiving chamber 15 developing unit 20, 50 photosensitive drum 30 , 60 regulating blade 30a non-magnetic blade 30b magnetic plate 31 reference position 44 developer stirring chamber

Claims (6)

[Claims] 1. A developer container for housing a developer therein,
A magnetic field generating means in which a plurality of magnetic poles each generating a magnetic field are formed, and a rotatable developer carrier incorporating the magnetic field generating means, and carrying and transporting the developer by a magnetic field generated by the magnetic field generating means. And a regulating member arranged at a predetermined interval on the developer carrier and regulating an amount of the developer carried on a surface of the developer carrier, wherein the developer carrier In a developing method using a developing device for developing a latent image formed in a developing unit, when a side of the developer carrier that advances in a rotation direction is a downstream side, the amount of the developer is regulated by the regulating member. The position at which the second magnetic pole is formed adjacent to the downstream side of the first magnetic pole formed downstream of the developing unit and has the same polarity as the first magnetic pole. The magnetic flux density in the normal direction on the surface of the That the amount of the external additive of the non-magnetic toner supplied to the developing device near the downstream side of the developing device is smaller than the amount of the external additive of the non-magnetic toner used before replenishing the developer. Characteristic development method. 2. The repulsion magnetic field formed by the first magnetic pole and the second magnetic pole, which has a normal magnetic field strength of 5 [mT] or less on the surface of the developer carrying member. The developing method according to claim 1. 3. The tangential magnetic field strength of the repelling magnetic field on the surface of the cylindrical developer carrier is 5 [mT].
The developing method according to claim 2, wherein: 4. The maximum magnetic flux density in the normal direction on the surface of the developer carrier by the second magnetic pole is 50 [mT] or more, and is 80 [%] or more of the maximum magnetic flux density in the normal direction. The range of the magnetic flux density region is 20 [°] or more in angle from the magnetic pole center of the second magnetic pole, and the range of the magnetic flux density region of 50% or more of the normal direction maximum magnetic flux density is The developing method according to any one of claims 1 to 3, wherein the temperature is 45 [°] or less. 5. A normal magnetic field maximum magnetic flux density of 80%.
The developing method according to claim 4, wherein the regulating member is disposed at a position facing the developer carrier in the range of the magnetic flux density. 6. The apparatus according to claim 1, wherein a position at which the developer carrying member pumps up the developer and a position at which the regulating member is disposed are below the developer carrying member.
The developing method according to the above item.