JPH0876585A - Developing device - Google Patents

Abstract

PURPOSE: To provide a developing device capable of removing the developer remaining on the developer carrier without contributing to the developing together with the foreign additive while maintaining the contact pressure with respect to the developer carrier of the developer supplying recovering rotary body at a value so as not to crush the developer. CONSTITUTION: In the developing device 4 provided with the toner container (developer container) 12 for containing the approximately spherical toner (one component developer) whose shape factor SFI is 100 to 110 and disposed with an opening part so as to oppose the outer periphery of the image carrier, the developing sleeve (developer carrier) 9 held in freely rotatably in the opening part of the toner container 12, the developing blade (developer thin layer forming member) 10 held in contact with the outer periphery of developer sleeve 9 by the tip part or the vicinity of the tip part of the blade, and the toner supplying recovering roller (developer supplying recovering rotary body) 11 disposed so as to come into contact with the outer periphery of the developing sleeve 9 at the part on the upstream side of the contact position of the developing blade 10 with the outer periphery of the developing sleeve 9 on the toner container 12 side in the rotary direction of the developing sleeve 9, the toner supplying recovering roller 11 is constituted of the brush type rotary body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in a color image forming apparatus adopting an electrophotographic system or the like, and a developing apparatus for visualizing an electrostatic latent image formed on an image bearing member, particularly by a polymerization method. The present invention relates to a developing device that uses a manufactured developer.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an intermediate transfer member as shown in FIG. 5 has been proposed for the purpose of obtaining a color image free from color misregistration.

In FIG. 5, reference numeral 101 denotes a photosensitive drum as a first image bearing member which is rotationally driven in the direction of the arrow in the figure, and its surface is first uniformly and negatively charged by a charging means 102. Next, depending on the first image information, ON / OF
The F-controlled exposure unit 103 performs scanning to form a first electrostatic latent image on the photosensitive drum 101. The first electrostatic latent image is developed by the first developing unit 104a containing the first color negatively charged developer, and is visualized as a first toner image.

The visualized first toner image is electrostatically transferred (primary transfer) onto the surface of the intermediate transfer member 105 at a portion facing the intermediate transfer member 105 as the second image carrier that is rotationally driven. ) Will be done.

Then, the above steps are repeated a plurality of times, and the second developing means 104b and the third developing means 104 are carried out each time.
c, the toner images formed by the developers of different colors contained in the fourth developing means 104d are sequentially electrostatically transferred onto the surface of the intermediate transfer member 105 to form a color image, and then the intermediate transfer member 105 is formed. And a color image is collectively transferred onto the surface of the transfer material 107 that is conveyed to the nip portion with the transfer roller 106 as a transfer unit that contacts and rotates.
Next transfer). The transfer residual toner remaining on the surface of the photosensitive drum 101 at the time of the primary transfer and the transfer residual toner remaining on the surface of the intermediate transfer member 105 at the time of the secondary transfer are cleaned by the cleaning means 109 and 110, respectively. It is removed from the surface of the transfer body 105.

Next, the developing means 104 (104a-1 to 104a-1)
04d) will be described.

As a developing system generally adopted in a color image forming apparatus, there are a non-magnetic one-component system and a non-magnetic two-component system. The latter is a developer prepared by mixing toner and carrier. Since it is used, it is necessary to control the mixing ratio of these in accordance with the consumption of toner, which causes a problem that the device configuration is complicated and the size is increased.

Therefore, in recent years, the former non-magnetic 1
Many component systems are used. And this non-magnetic 1
As a developing device suitable for the component system, a developing device as shown in FIG. 6 is widely used.

That is, in FIG. 6, reference numeral 111 is a developing sleeve as a developer carrying member, which is rotationally driven in the direction of the arrow shown in the drawing, and on its surface a developing blade 112 as a toner regulating member and a toner supply / collection roller. 113 is abutted.

The developing blade 112 is constructed by adhering an elastic member 112b such as urethane rubber to the surface of the supporting member 112a made of phosphor bronze or the like which faces the developing sleeve, and the elastic member 112b is made of toner on the surface of the developing sleeve 111. It has a function of forming a thin layer and imparting an electric charge to the toner.

Further, the toner supply / recovery roller 113 is
An outer peripheral surface of a cored bar 113a made of SUS or the like is covered with an elastic member 113b such as urethane foam, which supplies the toner stored in the toner container 114 to the surface of the developing sleeve 111 and also develops it. It has a function of scraping off the returned toner without contributing to the process from the surface of the developing sleeve 111.

By the way, in the toner container 114,
A toner manufactured by a polymerization method (hereinafter referred to as a polymerized toner) is stored. This polymerized toner has a substantially spherical shape (shape factor SFI is 100 to 110), and has a transfer efficiency higher than that of an irregular toner manufactured by a conventional crushing method (hereinafter referred to as crushed toner). It is possible to improve. This is largely to make the output image high in density and good in an image forming apparatus having two transfer steps of primary transfer and secondary transfer using the intermediate transfer member as described above. Have contributed.

Further, the polymerized toner contains paraffin wax, for example, inside the polymerized toner. When the polymerized toner is used, the offset is prevented in the fixing device provided in the image forming apparatus. The step of applying a large amount of silicone oil or the like to the fixing roller can be omitted.

[0014]

However, the developing device as shown in the above conventional example has the following problems.

That is, generally, a toner having a particle diameter smaller than that of the toner is externally added to the toner mainly for the purpose of increasing and stabilizing the charge. Also in the polymerized toner, for example, silica-based fine powder is externally added as an external additive, and the external additive is attached to the surface of each toner particle in a state of being sprinkled.

However, as described above, the polymerized toner has a substantially spherical shape, and therefore the adhesive force between the toner and the external additive tends to be weaker than that of the ground toner. When such a toner is used in the developing device having the above-mentioned configuration, as the developing sleeve continues to rotate, the external additive is gradually released from the toner surface, and the developing agent is not developed. Even if the toner that does not contribute is removed from the surface of the developing sleeve by the toner supply / collection roller, the toner can be removed, but the external additive released from the toner cannot be completely removed and remains on the surface of the developing sleeve. If such a phenomenon occurs continuously, a film of an external additive is formed on the surface of the developing sleeve, and the charge is originally imparted to the toner at the nip portion between the developing sleeve and the developing blade in contact with it. Although it should be, this is blocked by the film of the external additive, a sufficient charge is not applied to the toner, and furthermore, the insufficiently charged toner causes the nip portion between the developing sleeve and the developing blade. It slips through, and a phenomenon called "bottom dropping" occurs.

Further, as shown in the above-mentioned conventional example, in order to provide the toner supply / collection roller made of an elastic material such as rubber or sponge with a sufficient scraping ability, the toner supply / collection roller is subjected to a strong pressure against the developing sleeve. In the case of contact, in the case of polymerized toner in which wax or the like is contained inside and the strength of each toner is weaker than that of pulverized toner, the toner is crushed in the surface contact area between the toner supply / collection roller and the developing sleeve. There is also a problem that it becomes easier.

The present invention has been made in view of the above problems, and an object of the present invention is to set the contact pressure of the developer supply / recovery rotary member against the developer carrier so that the developer is not crushed. It is an object of the present invention to provide a developing device capable of removing the developer remaining on the surface of the developer carrier, which has not contributed to the development, together with the external additive, from the surface of the developer carrier while being held at the same time.

[0019]

In order to achieve the above object, in the invention according to claim 1, an opening is formed so as to face the outer peripheral surface of the image carrier, and the shape factor SFI is 100 to 110 inside. And a developer accommodating container for accommodating the substantially spherical one-component developer, a developer carrier rotatably held in an opening of the developer accommodating container, and an outer peripheral surface of the developer carrier. The direction of rotation of the developer carrier relative to the contact position of the developer thin layer forming member with which the tip portion or the vicinity of the tip portion abuts and the developer thin layer forming member on the outer peripheral surface of the developer carrier on the developer accommodating container side. In a developing device having a developer supply / recovery rotary member arranged so as to abut on the upstream side, the developer supply / recovery rotary member is constituted by a brush-shaped rotary member.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the developer is produced by a polymerization method.

Further, the invention according to claim 3 is the same as the invention according to claim 1 or 2, wherein the developer is 5
It is characterized by containing ~ 30 parts by weight of the low-softening substance.

[0022]

According to the present invention, since the developer supply / recovery rotary member is constituted by the brush-like rotary member, the contact pressure of the developer supply / recovery rotary member against the developer carrying member does not crush the developer. It is possible to remove the developer remaining on the surface of the developer carrier, which has not contributed to the development, from the surface of the developer carrier together with the external additive while maintaining the above value.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a block diagram of a main portion of an image forming apparatus including a developing device according to the present invention.

In FIG. 1, reference numeral 1 denotes a photosensitive drum as a first image bearing member, which is an OPC or amorphous S on the outer peripheral surface of a cylindrical substrate such as aluminum or nickel.
e, a photosensitive layer of amorphous Si or the like is formed.

[0026] The photosensitive drum 1 is rotated in the direction indicated by an arrow at a predetermined peripheral speed, first, the surface of the dark portion potential V _D by a charging roller 2 as a charging device -700
It is uniformly charged to [V]. Next, the surface of the photosensitive drum 1 is subjected to scanning exposure by the laser beam 3 whose ON / OFF is controlled according to the first image information, and the bright portion _VL
The first electrostatic latent image of −100 [V] is the photosensitive drum 1.
Formed on top.

The first electrostatic latent image thus formed is developed and visualized by the developing device 4. The developing device 4 contains the first toner containing the yellow toner as the first color toner. No. 1 developing device 4a, and second developing device 4 containing magenta toner as the second color toner.
b, a third developing device 4c containing cyan toner as the third color toner, and a fourth developing device 4d containing black toner as the fourth color toner are integrated. First, the first electrostatic latent image is developed by the first developing device 4a containing the yellow toner as the first color toner, and is visualized as the first toner image. As a developing method, image exposure and reversal development are often used in combination.

Thus, the visualized first toner image is
It is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and comes into contact with an intermediate transfer member 5 as a second image carrier which is rotationally driven in the direction of the arrow in the drawing at a speed substantially equal to the peripheral speed of the photosensitive drum 1. Electrostatic transfer (primary transfer) is performed on the surface of the intermediate transfer member 5 at the first transfer portion 6a. Here, the intermediate transfer body 5 has a peripheral length slightly longer than the length of the transfer material, and the toner image formed on the surface of the photosensitive drum 1 is transferred to the intermediate transfer body 5 from a high-voltage power source (not shown). By applying a voltage having a polarity opposite to the charging polarity, electrostatic transfer (primary transfer) is performed on the surface of the intermediate transfer member 5. Incidentally, a small amount of toner remaining on the surface of the photosensitive drum 1 after the primary transfer is removed by the cleaning device 7a.

Then, the above steps are repeated three times, and each time, the second toner image developed with magenta toner,
The third toner image developed with the cyan toner and the fourth toner image developed with the black toner are sequentially transferred onto the surface of the intermediate transfer member 5 and laminated to form a color image.

After that, the transfer roller 8 as a transfer means, which is in a state of being separated from the surface of the intermediate transfer body 5, is pressed against the surface of the intermediate transfer body 5 with a predetermined pressing force and driven or driven to rotate, and the transfer roller 8 is rotated. By applying a voltage having a polarity opposite to the charging polarity of the toner from a high voltage power source (not shown), the color images are collectively transferred onto the surface of the transfer material P which is conveyed to the second transfer portion 6b at a predetermined timing ( After the secondary transfer), the transfer material P is conveyed to a fixing device (not shown), where a color image is fixed as a permanent image and then discharged to the outside of the apparatus. Incidentally, a small amount of toner remaining on the surface of the intermediate transfer body 5 after the secondary transfer is removed by the cleaning device 7b which is in operation on the surface of the intermediate transfer body 5 at a predetermined timing.

Here, the developing device 4 (4
The details of the configurations a to 4d) will be described with reference to FIG.

The developing device 4 according to the present invention comprises a developing sleeve 9, a developing blade 10, a toner supply / collection roller 11, a toner container 12 and a stirring blade 13.

The developing sleeve 9 has an outer diameter of 16 mm.
Of aluminum and is driven to rotate in the direction of the arrow at a peripheral speed of 90 [mm / sec], and its outer peripheral surface is roughened by # 800 abrasive grains to a roughness R _Z = 3 [μm]. Then, on the surface of the developing sleeve 9,
The developing blade 10 and the toner supply / collection roller 11 are in contact with each other.

The developing blade 10 has a thickness of 0.2 [m
m] phosphor bronze plate 10a is bonded with urethane rubber 10b having a thickness of 1 [mm], and the urethane rubber 10b portion is about 10 [g / g with respect to the surface of the developing sleeve 9.
[cm] is applied with a linear pressure of [cm].

Further, the toner supply / recovery roller 11 is provided on the outer peripheral surface of a core metal 11a made of SUS having an outer diameter of 6 mm.
Hair length 5 [mm], fineness 16 [Dener / Filament]
(Hereinafter referred to as [D / F]), the density is 48000 [F /
inch ² ] of polypropylene 11b is planted. This toner supply / collection roller 11
Has a penetration amount δ of the tip of the brush 11b with respect to the developing sleeve 9 set to 1.5 [mm].
At the contact portion with the developing sleeve 9 in the direction opposite to the rotating direction of the developing sleeve 9 is higher than the peripheral speed of the developing sleeve 9 by 150 [mm
/ Sec].

On the other hand, the toner container 12 contains a non-magnetic polymerized toner having a particle size of about 6 [μm] manufactured by a polymerization method. This polymerized toner has a particle size of about 0.
1 [μm] of silica is externally added at a weight ratio of 1.5%.

Thus, the above-mentioned polymerized toner is used in the toner container 1.
2 is conveyed to and supplied to the toner supply / collection roller 11 by the stirring blade 13 rotating at a rotation speed of 20 [rpm] in the direction of the arrow shown in FIG. Supplied with.

The experimental results regarding the toner supply / recovery roller are shown below.

First, Table 1 shows the experimental results on the influence of the flocking density of the toner supply / collection roller on the coating state of the toner on the surface of the developing sleeve.

As an experimental method, a developing sleeve, a toner supply / collection roller, and a developing sleeve shown in FIG.
The stirring blade was idled at a predetermined peripheral speed, and the coating state of the toner on the surface of the developing sleeve was observed with time.

The toner supply / recovery roller used in the experiment has a core metal outer diameter of 6 [mm] and a roller outer diameter of 16 [mm].
Then, a polypropylene brush having a fineness of 16 [D / F] is used.

[0042]

[Table 1] In Table 1, "Ref." Shown in the rightmost column means a conventional toner supply / collection roller, that is, 90 cells, hardness 20 [K.
g] consisting of urethane foam.

In the case of using the conventional toner supply / recovery roller, "fluttering" occurs within a few minutes after the start of idling. At this time, when the amount of charge of the toner that has fallen off is measured, it is almost 0 [μC / g], which means that almost no charge is held. Further, when the toner adhering to the surface of the developing sleeve in this state was removed by air blowing, a white powder layer, that is, silica as an external additive, was present under the toner layer. It was confirmed.

On the other hand, in the case where the toner supply / collection roller is of the brush type, when the flocking density is small, no "fluttering" occurs, but the toner layer coated on the surface of the developing sleeve. A remarkable coat unevenness has occurred. It is considered that this is due to the fact that the amount of toner supplied to the surface of the developing sleeve by the toner supply / collection roller is partially uneven due to the small flocking density. On the other hand, when the flocking density was high, neither “fluttering” nor uneven coating occurred even after 1 hour of idle rotation. Then, when the toner adhering to the surface of the developing sleeve was removed by air blowing, no phenomenon such as a silica layer was formed under the toner layer was confirmed.

Next, Table 2 shows the experimental results on the influence of the fineness of the brush of the toner supply / collection roller and the penetration amount δ of the brush into the developing sleeve on the coating state of the toner on the surface of the developing sleeve. The experimental method is the same as that described above.

[0046]

[Table 2] According to the results shown in Table 2, when the fineness is small, that is, when the brush is soft, even if the penetration amount δ of the brush into the developing sleeve is set to be large, the toner is scraped from the developing sleeve surface together with the external additive. The ability to drop it was weak, and I had a drop in idle rotation.

On the other hand, even if the fineness is large, that is, as the brush becomes harder and the amount of penetration δ of the brush into the developing sleeve is small, the ability to scrape the toner together with the external additive from the developing sleeve surface is strong, Although the dripping did not occur even during idling, if the intrusion amount δ is set too large, the contact torque between the developing sleeve and the brush roller will be strong, and the rotating torque between the developing sleeve and the brush roller will increase. The strong pressure causes the toner to be crushed, and the crushed toner adheres to the surface of the developing sleeve, so-called “sleeve fusion” occurs.

From the above, as a structure capable of sufficiently ensuring the ability to scrape the toner from the surface of the developing sleeve without causing problems such as increase in rotational torque and fusion of the sleeve, the fineness is 16 [D / F]. ] Above, intrusion amount δ
Is preferably 0.5 [mm] to 2.0 [mm].

Modified examples of the present invention will be described below. Since the structure of the developing device in each modified example is the same as that of the first embodiment, the description thereof will be omitted.

<Embodiment 2> This embodiment is characterized in that the toner supply / recovery roller is not in a linear brush shape but in a loop shape as shown in FIG.

As described above, by constructing the toner supply / recovery roller with the loop-shaped fiber, it is possible to further enhance the ability to scrape off the toner adhering to the surface of the developing sleeve together with the external additive.

Here, the fineness of the brush with respect to the toner supply / collection roller and the amount of penetration of the brush into the developing sleeve δ
Table 3 shows the experimental results regarding the influence of the above on the coating state of the toner on the surface of the developing sleeve. The experimental method is the same as that described above. The flocking density of the loop-shaped fibers used in this experiment was 3 of the linear fibers shown in Example 1 above.
It was set to the same level as 3000 (F / In ² ).

[0053]

[Table 3] According to the results shown in Table 3, even though the fineness of the linear fibers shown in Example 1 is smaller and the penetration amount δ into the developing sleeve is also smaller, the toner has a sufficient toner scraping ability. I understand. This can reduce the stress on the toner and also reduce the rotational torque of the developing sleeve and the toner supply / collection roller.

<Third Embodiment> In the first embodiment, the brush material of the toner supply / collection roller is polypropylene. However, in the present embodiment, the brush material is one that negatively charges the toner. Characterized by being made of nylon.

With this structure, the toner conveyed from the toner container to the toner supply / collection roller by the stirring blade is rubbed or the like in the nip portion between the toner supply / collection roller and the developing sleeve and in the vicinity thereof. It is possible to uniformly charge a large amount of the toner, and it is possible to solve the problem that the toner having almost no electric charge slips through the nip portion between the developing sleeve and the developing blade. .

<Fourth Embodiment> FIG. 4 shows a fourth embodiment of the present invention. In FIG. 4, the same members as those in the practical example 1 are designated by the same reference numerals.

The present embodiment is characterized in that a flicker member 14 for scraping off the toner adhering to the brush 11b is provided at a position of the toner supply / collection roller 11 in the toner container 12 in contact with the brush 11b. And

With this configuration, it is possible to reliably shake off the toner collected from the developing sleeve 9 by the toner supply / collection roller 11 and adhered to the brush 11b, whereby the toner is newly conveyed from the toner container 12. The new toner thus collected is taken into the toner supply / collection roller 11 sufficiently and uniformly, so that a uniform thin layer coating of toner can be realized on the surface of the developing sleeve 9.

[0059]

As is apparent from the above description, according to the present invention, the opening is formed so as to face the outer peripheral surface of the image carrier, and the inside of the opening has a substantially spherical shape factor SFI of 100 to 110. , A developer accommodating container accommodating the one-component developer, a developer carrying member rotatably held in the opening of the developer accommodating container, and a tip or a tip thereof on the outer peripheral surface of the developer carrying member. And a developer thin layer forming member with which the vicinity of the portion abuts,
A developer supply / recovery rotary member arranged so as to abut on an outer peripheral surface of the developer carrier on the side of the developer accommodating container on the upstream side in the rotational direction of the developer carrier with respect to the abutting position of the developer thin layer forming member; In the developing device having the above, since the developer supply / recovery rotator is composed of a brush-like rotator, the contact pressure of the developer supply / recovery rotator with respect to the developer carrier is set to a value that does not crush the developer. It is possible to obtain the effect that the developer remaining on the surface of the developer carrier, which has not contributed to the development, can be removed from the surface of the developer carrier together with the external additive while being held.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus including a developing device according to the present invention.

FIG. 2 is a sectional view of a developing device according to the present invention.

FIG. 3 is a diagram showing a brush form (loop-shaped brush) of a toner supply / collection roller according to a modified embodiment of the present invention.

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

FIG. 5 is a configuration diagram of a main part of a conventional image forming apparatus.

FIG. 6 is a sectional view of a conventional developing device.

[Explanation of symbols]

1 Photosensitive Drum (Image Carrier) 4 Developing Device 9 Developing Sleeve (Developer Carrier) 10 Developing Blade (Developer Thin Layer Forming Member) 11 Toner Supply and Recovery Roller (Developer Supply and Recovery Rotation Body) 12 Toner Container (Developer) (Storage container)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 9/08 9/087 G03G 9/08 384 (72) Inventor Kazuhisa Kuramo 3 Shimomaruko Ota-ku, Tokyo In the 30th-2nd Canon Co., Ltd. (72) Inventor Osamu Iwasaki 3-30th-2 Shimomaruko, Ota-ku, Tokyo In the Canon Co., Ltd.

Claims (3)

[Claims] 1. An opening is formed so as to face the outer peripheral surface of the image carrier, and the shape factor SFI is 100 to 11 inside the opening.
A substantially spherical one-component developer containing 0, a developer container, a developer carrier rotatably held in an opening of the developer container, and an outer peripheral surface of the developer carrier. Rotation of the developer carrier relative to the contact position of the developer thin layer forming member with which the tip portion or the vicinity of the tip portion abuts and the developer thin layer forming member on the outer peripheral surface of the developer carrier on the developer accommodating container side. A developing device having a developer supply / recovery rotator arranged so as to abut on the upstream side in the direction, wherein the developer supply / recovery rotator is a brush-like rotator. 2. The developing device according to claim 1, wherein the developer is a developer manufactured by a polymerization method. 3. The developing device according to claim 1, wherein the developer contains 5 to 30 parts by weight of a low-softening substance therein.