JPH063934A - Development device - Google Patents

Abstract

PURPOSE:To sufficiently electrify a developer, to excellently supply the developer to an electrostatic latent image carrier, and to sharply and excellently make an image visualizable by sticking the developer to a developing roller via plural supplying rollers. CONSTITUTION:A storage tank 18 storing a one-component nonmagnetic developer as a powder developer is communicated with an opening part 20 by a narrow path 21 on the upper part of a housing 11. Supplying rollers 17-1 to 17-4 being freely rotatable developer supplying member supplying the developer to the periphery of a developing roller 12 are provided in the path 21, arranged so that the rotary shafts of the rollers 17-1 to 17-4 are in parallel with the rotary shaft of the roller 12 in the path 21, and connected so that the peripheries of the rollers 17-1 to 17-4 are brought into contact with each other. Further, a gap between the rollers 17 and the inside wall of the housing, is made vary small, and the developer is in the order of the rollers 17. Thus, the developer can be sufficiently triboelectrified in the path 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an electrostatic latent image on a photosensitive member as an electrostatic latent image holding member, which is uniformly charged, such as an electrophotographic copying machine or a laser printer, by optical scanning. Powder development for developing an electrostatic latent image formed on a photoconductor in an electrophotographic apparatus for developing an electrostatic latent image with a charged developer and transferring the resulting image to a recording medium such as paper for recording. The present invention relates to a developing device for supplying an agent.

[0002]

2. Description of the Related Art Conventionally, the colorization of printed matter has progressed, and the demand for color electrophotographic copying machines and color printers has increased accordingly. To obtain a color image by an electrophotographic method, for example, a plurality of photoconductors on which a color image of a different color is formed are conveyed on a paper conveyance belt horizontally stretched in an electrophotographic apparatus. It is known that the color images are arranged in parallel in the direction, and each color image formed on these photoconductors is sequentially transferred to a sheet conveyed by a sheet conveying belt to form a full-color image on the sheet. However, in such a device, a printing station including a charging device, an exposure device, a developing device, and the like must be provided for each photoconductor, which causes a problem that the device becomes large. Therefore, in order to solve such a problem, downsizing and flattening of the developing device are being promoted.

As this type of developing device, for example, the one disclosed in Japanese Patent Application Laid-Open No. 3-287184 is known. As shown in FIG. 6, the developing device 1 rotates a developing roller 4 arranged to face the photoconductor 3 in an opening formed on one lower side surface of a housing 2 vertically elongated. This is a device that can be freely attached to reduce the size and flatten the device. On the peripheral surface of the developing roller 4, a developer layer thickness regulating member 6 attached to the upper edge of the opening of the housing 2 via a spring 5, the housing 2
The recovery member 7 attached to the lower edge of the opening and the supply roller 8 rotatably attached below the housing 2 are in contact with each other with a predetermined nip amount.

A developer storage tank 9 for storing the developer supplied to the supply roller 8 is provided in the housing 2.
Are provided so as to be continuous from above in the vertical direction toward the peripheral surface of the supply roller 8. The one-component non-magnetic developer stored in the developer storage tank 9 is styrene-based,
It is generally known that an acrylic resin, a polyester resin, an epoxy resin or the like is used as a base material. In this device, in order to increase the amount of the developer stored in the developer storage tank 9, the inner side wall of the housing 2 is provided outside above the developer layer thickness regulating member 6 and the supply roller 8. It is expanded toward a predetermined angle α. This angle α
Is configured at an angle (70 degrees or more) where the developer stored in the developer storage tank 9 does not stick to the inner wall of the housing 2 but naturally falls by its own weight. Further, the inner wall of the lower portion of the housing 2 is formed in a shape along the peripheral surface of the developing roller 4 and the supply roller 8 while maintaining a minute gap therebetween.

In the developing device 1 configured as described above, the developer stored in the developer storage tank 9 falls on the peripheral surface of the supply roller 8 due to its own weight, and the supply roller 8
Is conveyed to the nip portion with the developing roller 4 as the supply roller 8 rotates, and moves to the peripheral surface of the developing roller 4. Then, the developer that has moved to the peripheral surface of the developing roller 4 is first conveyed to the nip portion with the developer layer thickness regulating member 6 as the developing roller 4 rotates. At this nip portion, the developer layer thickness is regulated from the peripheral surface of the developing roller 4 so that the layer of the developer attached to the peripheral surface of the developing roller 4 has a uniform thickness in the axial direction of the developing roller 4. The member 6 scrapes off the excess developer.

The developer, which has a predetermined layer thickness suitable for development, is further rotated by the rotation of the developing roller 4, and further, the photosensitive member 3
The toner is conveyed to a developing unit that comes into contact with the electrostatic latent image formed on the photoconductor 3 by the developing unit, and electrostatically adheres to the electrostatic latent image to make the image visible. At this time, the developer that has returned to the inside of the housing 2 while remaining on the peripheral surface of the developing roller 4 without being electrostatically attached to a portion other than the electrostatic latent image of the photoconductor 3 by the supply roller 8. It is scraped off from the peripheral surface of 4 onto the lower inner wall of the housing 2 described above, and is conveyed again to the developer storage tank 9 as the supply roller 8 rotates.

[0007]

However, in the developing device 1 as described above, the developer is conveyed from the developer storage tank 9 while being charged by the friction between the supply roller 8, the developing roller 4 and the rollers. However, in the case of one-component non-magnetic development, the charging amount of the developer on the developing roller 4 is incomplete at such a charging frequency, and variations in the charging amount also occur. The density was lowered and the developer layer was peeled off. Further, the pressure generated by the weight of the developer in the developer storage tank 9 is directly applied to the contact portion between the developing roller 4 and the developer layer thickness regulating member 6, and the pressure from the contact weight causes the developer from the contact portion. There were adverse effects such as leakage and pressure contact of the developer with the developing roller. Further, when the amount of the developer consumed on the developing roller 4 is large, the supply of the developer from the supply roller 8 cannot catch up,
There is a problem that phenomena such as image blurring and unevenness occur.

The present invention has solved the above-mentioned problems. The developer is sufficiently charged in the developing device, and the developer having a sufficient charge is sufficiently supplied to the developing roller to prevent electrostatic discharge. The developer is stably attached to the electrostatic latent image on the photoconductor serving as the latent image holding member so that a clear and excellent visible image can be formed.

[0009]

According to a first aspect of the present invention, a storage tank for storing a powdery one-component non-magnetic developer that can be charged is formed at an upper end with an opening at the lower end, and the storage tank and the opening are provided. And a developing roller connected to each other through a narrow passage, a developing roller provided in an opening of the housing and arranged to face the electrostatic latent image holding member, and a plurality of the developing rollers arranged in series so that their peripheral surfaces are close to each other in the passage. A developer supply roller group that is provided and has a supply roller located at the lowermost end in contact with the developing roller, and a regulation that is provided close to the developing roller and that regulates the developer layer thickness on the developing roller. 3. A developing device for an electrophotographic apparatus, comprising: a member, which supplies the developer on the developing roller to the electrostatic latent image on the electrostatic latent image holder to develop the electrostatic latent image. Of the invention, the developer supply roller The rotation peripheral speed of people, is made larger than the rotary peripheral velocity of the developing roller.

[0010]

According to the first aspect of the invention, a plurality of rotatable developer supply rollers are arranged in series in a narrow passage provided between the storage tank and the opening, and a gap between the supply roller and the inner wall of the housing is provided. Since the developer is made minute, the developer is conveyed in sequence through the supply roller, so that the developer is sufficiently frictionally charged along the path. Further, the pressure of the developer in the storage tank is relieved, the developer is not spilled from the developing roller, and a clear visible image without density unevenness can be obtained. Further, in the invention of claim 2, since the rotational peripheral speed of each supply roller and the rotational peripheral speed of the developing roller are made different from each other, the amount of developer conveyed can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional side view showing a schematic internal configuration of an embodiment according to the present invention. This developing device 10
In the same manner as the developing device 1 described above, the developing roller 12 is rotatably arranged in the opening 20 formed in one lower side surface of the housing 11 whose shape is vertically long in the vertical direction. The developing roller 12 is mainly composed of urethane rubber, ethylene-propylene-diene rubber (EPDM), nitrile rubber (NBR), silicon rubber, chloroprene rubber (CR), or a foamed elastic body thereof, preferably 10 ⁹ Ωcm. It is made of the following conductive rubber, and on the surface thereof, a conductive layer mixed with a conductive substance in a resin such as polyurethane, polyester, polypropylene, nylon and acrylic to have a low resistance is used.

In this embodiment, a urethane rubber roller coated with a coating material of conductive carbon in polyurethane elastomer by spray coating or dipping method is used. Further, the developing roller 12
A part of the peripheral surface of the is exposed to the outside from the opening over the entire length in the longitudinal direction, and is arranged to face a drum-shaped photosensitive member 13 rotatably arranged in an electrophotographic apparatus (not shown). .
Further, on the peripheral surface of the developing roller 12, a developer layer thickness regulating member 15 made of silicon rubber, urethane rubber, or the like attached to the upper edge of the opening of the housing 11 via a spring 14, and the opening of the housing 11. The recovery members 16 attached to the lower edges of the parts are in contact with each other with a predetermined nip amount.

A storage tank 18 for storing a one-component non-magnetic developer as a powdery developer and the opening 20 are connected to the upper portion of the housing 11 by a narrow passage 21. In the passage 21, supply rollers 17-1, 17-2, 17-3, and 17-4 (developer), which are rotatable developer supply members for supplying the developer to the peripheral surface of the developing roller 12, are provided. Supply roller group), a developer storage tank 18 for storing the developer supplied to the peripheral surfaces of the supply rollers 17-1 to 17-4,
An agitating roller 19 which is a rotatable developer agitating member for agitating the developer stored in the developer storage tank 18 is arranged. The supply rollers 17-1 to 17-4 are
The passage 21 in the housing 11 is arranged such that its rotation axis is parallel to the rotation axis of the developing roller 12 and is connected so that its peripheral surfaces are in contact with each other. The supply rollers 17-1 to 17-4 are rotatable roller members made of a conductive sponge member obtained by impregnating conductive carbon into, for example, urethane foam, and the supply rollers 17-1 to 17-4. The developing roller 12 is in contact with the peripheral surface with a predetermined nip amount (here, 2 mm). The supply rollers 17-1 to 17-4 do not have to be brought into contact with each other as long as the developers attached to the peripheral surfaces are brought close to each other by friction and charging.

The developer storage tank 18 is supplied from the opening 22 provided on the upper surface of the housing 11 to the supply roller 1.
It has a vertically elongated shape that extends vertically toward the peripheral surfaces of 7-1 to 17-4, and is located above the supply rollers 17-1 to 17-4 in the vertical direction. The inner side wall of the housing 11, which is the side wall of the developer storage tank 18, expands outward from the passage 21 at a predetermined angle to increase the volume for storing the developer. Further, the lower inner walls 24 and 25 of the housing 11 forming the bottom surface of the developer storage tank 18 are arranged along the peripheral surfaces of the developing roller 12 and the supply roller 17-1 while maintaining a minute gap therebetween. It is formed in a shape. The opening 22 provided on the upper surface of the housing 11 serves as a replenishment port for replenishing the developer storage tank 18 with the developer, and the opening 22 has an openable / closable lid 23.
Is provided.

The stirring roller 19 is located in the developer storage tank 18 and vertically above the supply roller 17-4, and its rotation axis is the supply rollers 17-1 to 17-.
It is parallel to the rotation axis of No. 4. The distance between the stirring roller 19 and the side wall of the developer storage tank 18 is such that, even when the stirring roller 19 is not rotating, a part of the developer stored above the stirring roller 19 is
The weight is such that it falls below the stirring roller 19 under its own weight. Further, the supply rollers 17-1 to 17-1
A diameter d1 of 17-4, a width d2 of the lower portion of the developer storage tank 18,
And the maximum diameter d3 of the stirring roller 19 is d1 <d2 <d
3, the stirring roller 19 receives most of the load from the developer stored above the stirring roller 19 and is stored between the supply rollers 17-1 to 17-4 and the stirring roller 19. Developer and supply rollers 17-1 to 17-1
No extra load is applied to 7-4.

FIG. 2 is an external perspective view of the developing device according to the present invention. The drive transmission means for the developing roller 12, the supply rollers 17-1 to 17-4, and the stirring roller 19 will be described with reference to this drawing. First, the drive gear 26 that transmits the driving force
Is attached to the rotary shaft of the supply roller 17-1 and is directly connected to the rotary shaft 17a of the motor (not shown). Further, the drive gear 26 is provided on the rotary shaft 12 of the developing roller 12.
The developing roller gear 27 is driven by being engaged with the developing roller idler gear 28 for transmitting the driving force to the developing roller gear 27 attached to a. Further, the drive gear 26 is a supply roller for transmitting a driving force to the supply roller gears 29-2 to 29-4 attached to the rotary shafts 17b, 17c and 17d of the supply rollers 17-2 to 17-4. The supply roller gears 29-2 to 29-4 are driven by meshing with each other through the idler gears 30-2 to 30-4. The drive gear 26 drives the stirring roller gear 31 by meshing with a stirring roller idler gear 32 for transmitting a driving force to the stirring roller gear 31 attached to the rotating shaft 19a of the stirring roller 19. And
The agitating roller 19 rotates in synchronism with the rotation of the developing roller 12 and the supply rollers 17-1 to 17-4 by the rotation of the motor of the drive transmitting means configured as described above.

In the developing device 10 configured as described above, for example, a one-component non-magnetic developer is stored in the developer storage tank 18, and the developer is electrically charged in the device to the photoconductor 13. The image is visualized by electrostatically attaching it to the formed electrostatic latent image. That is, the developer stored in the developer storage tank 18 is agitated by the agitating roller 19 which rotates in synchronization with the rotation of the developing roller 12 and the supply rollers 17-1 to 17-4, while being agitated. Fall towards.

The developer captured on the peripheral surface of the supply roller 17-4 is conveyed to the nip portion with the supply roller 17-3 as the supply roller 17-4 rotates, and the rollers in the nip portion are separated from each other. It is precharged by friction and friction between each roller and the developer, and adheres to the peripheral surface of the supply roller 17-3. Similarly, the developer adhering to the peripheral surface of the supply roller 17-3 is conveyed to the nip portion with the supply roller 17-2 as the supply roller 17-3 rotates, and the friction between the rollers at this nip portion. And the charging roller 17-2 is precharged by friction between each roller and the developer,
Adheres to the peripheral surface of. Similarly, the developer is supplied to the supply roller 1.
7-2 to 17-1 is conveyed while being pre-charged by friction, and similarly, the developer conveyed to the supply roller 17-1 is attached to the peripheral surface of the developing roller 12. As described above, the developer is pre-charged (primarily charged) by the supply rollers 17-1 to 17-4 and the developing roller 12 and adheres to the developing roller 12.

The developer attached to the peripheral surface of the developing roller 12 is further conveyed to the nip portion with the developer layer thickness regulating member 15 as the developing roller 12 rotates. At the nip portion between the developing roller 12 and the developer layer thickness regulating member 15,
The developer layer thickness regulating member 15 regulates the developer layer attached to the peripheral surface of the developing roller 12 so that the developer layer 12 has a uniform thickness in the axial direction of the developing roller 12.
Excess developer is scraped off from the peripheral surface of the. The developer layer thickness regulating member 15 regulates the layer thickness of the developer in this way, and at the same time, imparts electric charge to the developer by frictional charging with the developing roller 12 (secondary charging), and the developer is the developing roller. Helps to adhere to 12.

The developing agent having a predetermined layer thickness suitable for development is rotated by the developing roller 12 and the photosensitive member 1 is rotated.
3 is conveyed to the developing unit which is in contact with the photosensitive member 1, and the photosensitive member 1 is conveyed in this developing unit.
It electrostatically adheres to the electrostatic latent image formed in 3 to make the image visible. At this time, the developer that has returned to the inside of the housing 11 while remaining on the peripheral surface of the developing roller 12 without being electrostatically attached to a portion other than the electrostatic latent image on the photoconductor 13 is supplied to the supply roller 17. -1 is scraped off on the bottom surface of the developer storage tank 18 described above.

Here, in the developing device 10, as described above, it is below the inside of the developer storage tank 18 and at the supply roller 17.
Since the rotatable stirring roller 19 is provided at the upper position in the vertical direction of, the fluidity of the developer stored between the supply roller 17-4 and the stirring roller 19 is kept good, and the developer is supplied to the supply roller 17-4. Since it falls well on the peripheral surface of 17, it is possible to obtain an image without uneven density.

Further, as in this embodiment, the housing 1
The lower part of 1 is made narrow, and the supply rollers 17-1 to 17-4
Since the gap between the peripheral surface of the developer and the inner wall of the housing 11 is made minute, the load due to the weight of the developer in the developer storage tank 18 is received by the supply roller 17-4, so that the supply rollers 17-1 to 17- 3 and the developing roller are not directly applied, and the developer is supplied to the supplying roller 17-as described above.
4 to 17-3, 17-2, 17-1, 1 to developing roller
It is conveyed in sequence with 2. Therefore, since only the developer that has passed through the above-mentioned transport path is attached to the developing roller 12, a uniformly and stably charged developer can be obtained.
In the vicinity of the nip portion between the developer layer thickness regulating member 15 and the developer layer thickness regulating member 15, the convective fluidity of the developer is kept good.

Further, the diameter of the supply roller is 12 mm and the length of the supply roller is 216 mm in common. As shown in FIG. 3, the charge amount of the developer is measured by changing the number of the supply rollers as described above. It was found that the number increased as the number of supply rollers increased. Therefore, by providing the supply rollers in multiple stages, the triboelectrification of the developer is sufficiently performed, and the development failure due to the insufficient charge amount of the developer and the developer peeled from the development roller 12 and spilled to the outside of the developing device are caused. It can be expected to be hard to happen. In FIG.
Since the number of supply rollers is almost saturated in four stages, in this example, when the supply rollers were connected in four stages, good images could be obtained.

Further, the same supply roller and developing roller as those described above having a roller diameter of 18 mm, a roller length of 222 mm, and a peripheral speed of 78.5 mm / s were used, and four stages were connected.
7-1 to 17-4 Development is performed by setting the rotation direction of each supply roller and the development roller 12 to be the same direction (the opposite direction on the contact surface) and changing the peripheral speed ratio of the supply roller and the peripheral speed of the development roller 12. When the supply amount of the developer is measured, as shown in FIG. 4, as the peripheral speed of the supply roller with respect to the developing roller increases, the amount of developer conveyed through the supply roller to the developing roller increases. It was found that it saturates at about 3 times. Further, when the charge amount of the developer is measured in the same manner, as shown in FIG. 5, the charge amount of the developer on the developing roller is proportional to the increase in the peripheral speed of the supply roller with respect to the developing roller. I found that it increased a little. Therefore, for each roller diameter in this embodiment, it is considered appropriate that the peripheral speed ratio between the supply roller and the developing roller is about 3 times. As a result of printing in this manner, it was possible to obtain a good image without white spots or blurring of the image even when a large amount of developer was consumed such as continuous black solid printing.

In this embodiment, the number of supply rollers is four, and the peripheral speed ratio with the developing roller is three times, but the number of supply rollers is not limited to this, and the number of supply rollers and the number of supply rollers may be increased. The diameter of the developing roller may be changed, and the peripheral speed ratio with the developing roller may be adjusted to a value equal to or less than the same value or may be adjustable.

[0026]

The present invention is configured as described above in an electrophotographic apparatus or the like provided with a photosensitive member, and the developer is attached to the developing roller via a plurality of supply rollers.
The developer is sufficiently charged, and the developer is satisfactorily supplied to the electrostatic latent image bearing member, so that a clear and visible image can be formed. Further, it is possible to eliminate the problem that the developer peels off from the developing roller and spills out of the developing device.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a developing device of the present invention.

FIG. 2 is a perspective view showing an embodiment of a power transmission means relating to the developing device of the present invention.

FIG. 3 is a graph showing a relationship between the number of supply rollers and a charge amount of a developer according to the developing device of the present invention.

FIG. 4 is a graph showing the relationship between the speed ratio between the peripheral speed of the supply roller and the peripheral speed of the developing roller and the amount of developer conveyed in the developing device of the present invention.

FIG. 5 is a graph showing the relationship between the speed ratio between the peripheral speed of the supply roller and the peripheral speed of the developing roller and the charge amount of the developer in the developing device of the present invention.

FIG. 6 is a vertical sectional side view showing a conventional developing device.

[Explanation of symbols]

 10 Developing Device 11 Housing 12 Developing Roller 13 Photoreceptor 15 Developer Layer Thickness Controlling Member 17 Supply Roller 18 Developer Reservoir Tank 19 Stirring Roller 20 Opening 21 Passage 22 Opening 23 Lid 24 Lower Inner Wall 25 Lower Inner Wall

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[Procedure amendment]

[Submission date] October 15, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

Further, the same supply roller and developing roller as those described above have a roller diameter Φ18 mm, a roller length of 222 mm,
Using a peripheral speed of 78.5 mm / s, the four supply rollers 17-1 to 17-4 are supplied in such a manner that the supply rollers and the developing roller 12 rotate in opposite directions (the contact surfaces are in the same direction). When the supply amount of the developer is measured while changing the peripheral speed ratio of the roller common peripheral speed and the peripheral speed of the developing roller 12, as shown in FIG. 4, the peripheral speed of the supply roller relative to the developing roller is proportional to the increase. It has been found that the amount of developer conveyed through the supply roller to the developing roller increases and becomes saturated at about 3 times. Further, when the charge amount of the developer is measured in the same manner, as shown in FIG. 5, the charge amount of the developer on the developing roller is proportional to the increase in the peripheral speed of the supply roller with respect to the developing roller. I found that it increased a little. Therefore, for each roller diameter in this embodiment, it is considered appropriate that the peripheral speed ratio between the supply roller and the developing roller is about 3 times.
As a result of printing in this manner, it was possible to obtain a good image without white spots or blurring of the image even when a large amount of developer was consumed such as continuous black solid printing.

Claims (2)

[Claims] 1. A housing, which has an opening at a lower end of a storage tank for storing a chargeable powdery one-component non-magnetic developer on an upper portion, and connects the storage tank and the opening with a narrow passage. A developing roller provided in an opening of the housing and arranged to face the electrostatic latent image holding member, and a plurality of developing rollers arranged in series in the passage with their peripheral surfaces being close to each other and at the bottom end. A developer supply roller group in which a roller is in contact with the developing roller, and a restricting member that is provided in the vicinity of the developing roller and restricts the developer layer thickness on the developing roller. A developing device for an electrophotographic apparatus, which supplies an agent to the electrostatic latent image on the electrostatic latent image holding member to develop the electrostatic latent image. 2. The developing device according to claim 1, wherein the rotational peripheral speed of each of the developer supply rollers is set higher than the rotational peripheral speed of the developing roller.