JP2001296747A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device and an image forming device capable of preventing liquid developer removed from a developer carrier by a cleaning member from being accumulated on the cleaning member. SOLUTION: This device is provided with an eccentric roller 26 and a driving source driving and rotating the roller 26 so as to prevent residual developer 13a on a cleaning blade 25 from being stuck and accumulated. By rotating the roller 26, the residual developer 13a on the blade 25 is removed by the rotational force of the roller 26. When the roller 26 is rotated, shearing force is given to the residual developer 13a, and the residual developer 13a has fluidity (thixotropy) because its viscosity is lowered, and then it flows on the surface of the blade 25 and drops to the liquid developer 13 in a developer storing tank 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus used for an image forming apparatus such as a copying machine, a facsimile, and a printer. The present invention relates to a developing device and an image forming device for visualizing an image using a liquid developer having a viscosity.

[0002]

2. Description of the Related Art Conventionally, there has been known an image forming apparatus provided with a liquid developing device for visualizing a latent image on a latent image carrier using a high-viscosity liquid developer. In this type of image forming apparatus,
For example, the surface of the latent image carrier is uniformly charged by charging means, and the surface of the latent image carrier is exposed by writing means in accordance with image data to form a latent image. Then, this electrostatic latent image is visualized by a liquid developing device.

In the above liquid developing apparatus, a liquid developer in which charged toner is dispersed in an insulating liquid is used. In a developing area where a developer carrying the liquid developer and a latent image carrying member are opposed to each other. Then, the charged toner moves in the insulating liquid by the electrostatic force, and an electrostatic latent image on the latent image carrier is visualized. Therefore, the shorter the moving distance in the insulating liquid, the faster the toner moves to the electrostatic latent image on the latent image carrier, and the faster the electrostatic latent image can be visualized. When the moving distance is short, the time required for visualization can be reduced as compared with the case where the moving distance is long, and the development efficiency is improved. Therefore, it is desirable that the liquid developer be thinned in the developer carrying member, and the thinned liquid developer be brought into contact with the latent image carrying member for development. The effect that the development efficiency is improved by this thinning is particularly 100 to 1000.
This is more noticeable when a high-viscosity liquid developer prepared at 0 mPa · s is used.

[0004] However, the liquid developer remains on the surface of the developer carrier that has passed through the developing area. In particular, since the toner does not move to the non-image portion where the latent image on the latent image carrier is not formed, the liquid developer remains on the surface of the developer carrier corresponding to the non-image portion. A gravure roller or the like in which the present applicant has engraved the surface as disclosed in Japanese Patent Application Laid-Open No. H11-265122 on a developer carrying member carrying the remaining liquid developer (hereinafter referred to as “residual developer”). When the liquid developer is newly applied by the application member, the residual developer may cause uneven application and a ghost image may be generated. In order to prevent such uneven application of the liquid developer, a cleaning member is brought into contact with the surface of the developer carrier to remove the residual developer from the surface, and then a new liquid developer is applied. There is a need. As the cleaning member, for example, a blade made of rubber or metal is used.

[0005]

In the non-image area, only the insulating liquid (carrier liquid) of the liquid developer on the developer carrier adheres to the latent image carrier and is consumed.
The ratio of the solid content in the liquid developer rises, and the liquid developer becomes more viscous, and the fluidity decreases. The high-viscosity liquid developer has a property that its viscosity changes due to a shearing force acting on the liquid developer, and a property that its viscosity changes depending on time. These properties are called thixotropy. FIG. 6A is a graph showing the relationship between the shear rate and the viscosity. As can be seen from this graph, the viscosity of the high-viscosity liquid developer decreases when a high shear force acts, and becomes high when no shear force acts. FIG. 6B is a graph showing the relationship between time and viscosity. It can be seen that the viscosity reduced by the shearing force increases with time.

When the high-viscosity liquid developer is used for development, the residual developer removed from the developer carrier by the cleaning member becomes highly viscous and adheres to the surface of the cleaning member. If left unattended, the residual developer adhering to the surface of the cleaning member accumulates until it cannot withstand the adhesive force, and drops as a lump all at once. As described above, since the carrier liquid is consumed and the ratio of the solid content is increased and the concentration is increased as described above, when the lump of the residual developer falls into the liquid developer in the liquid developing device, the residual developer is removed. The concentration of the liquid developer changes rapidly. It is necessary to adjust the density in order to reuse the residual developer, but a sharp change in the liquid developer density is not desirable for the density adjustment. Therefore, it is not preferable that the residual developer is deposited on the cleaning member.

Further, in the case where the developer carrying member is disposed in a case of the liquid developing device so as to be movable on the surface, and the gap between the end portion of the developer carrying member and the inner wall surface of the case is narrow, When the residual developer deposited on the cleaning member is scattered and adheres to the inner wall surface of the case, the residual developer further adheres and deposits on the adhered residual developer, and the residual developer is deposited on the end surface of the developer carrier. There is a possibility that the agent may flow around. When the residual developer wraps around the end surface of the developer carrier in this way, the residual developer is gradually deposited upward between the end surface of the developer carrier and the inner wall surface of the case, and the latent image There is a possibility that the inside of the image forming apparatus may be stained by leaking from the case opening facing the carrier. In order to prevent the liquid leakage, it is sufficient to enlarge the case so as to widen the gap between the end of the developer carrier and the inner wall surface of the case. However, there is a problem that the liquid developing device becomes large.

The present invention has been made in view of the above background, and an object of the present invention is to provide a developing device capable of preventing a liquid developer cleaned by a cleaning member from a developer carrier from being deposited on the cleaning member. It is an object to provide an apparatus and an image forming apparatus.

[0009]

According to one aspect of the present invention, there is provided a developer carrying member for carrying a high-viscosity liquid developer in which a toner is dispersed in an insulating liquid; An application unit for applying the liquid developer to the developer carrier; and a cleaning unit for cleaning the liquid developer remaining on the surface of the developer carrier, the liquid developer carried on the developer carrier. A developing device for developing a latent image formed on a latent image carrier by using a cleaning member as the cleaning unit, and having a removing unit for removing the liquid developer attached to the cleaning member. Things.

In the developing device of the first aspect, the liquid developer adhered to the cleaning member of the cleaning means is removed by the removing means, and the liquid developer can be prevented from being deposited on the cleaning member. As a result, the lump of the liquid developer deposited on the cleaning member falls and rapidly changes the concentration of the liquid developer, or the deposited liquid developer adheres to the end surface of the developer carrier. Thus, it is possible to prevent the liquid developer from leaking.

According to a second aspect of the present invention, in the developing device of the first aspect, the removing means has an eccentric roller and a driving means for driving the eccentric roller to rotate. The eccentric roller is disposed so that the outer peripheral surface of the eccentric roller moves near the surface where the liquid developer cleaned by the cleaning member flows.

In the developing device according to the second aspect, as the eccentric roller rotates, the outer peripheral surface of the eccentric roller moves near the surface of the cleaning member through which the liquid developer flows, and the eccentric roller moves the liquid developing device. While removing the developer, a shearing force is applied to the liquid developer in a rotational direction. Further, when the eccentric roller rotates and the outer peripheral surface portion further away from the rotation axis approaches the cleaning member surface, the gap between the outer peripheral surface of the eccentric roller and the cleaning member surface gradually narrows. As a result, a shear force is generated such that the liquid developer is pressed against the surface of the cleaning member. In particular, when using a high-viscosity liquid developer,
By applying a shearing force, the viscosity of the liquid developer is reduced and the fluidity is improved, so that the removal of the liquid developer is promoted.

According to a third aspect of the present invention, in the developing device of the first aspect, the removing means has one or more wire members and a moving means for moving the wire members, and the cleaning member has a surface. Wherein the wire member is configured to move near a surface where the liquid developer cleaned by the cleaning member flows.

In the developing device according to the third aspect, the wire moves near the surface of the cleaning member through which the liquid developer flows, thereby removing the liquid developer flowing on the surface of the cleaning member and removing the liquid developer. A shear force can be applied to the developer. In particular, when a high-viscosity liquid developer is used, the shearing force reduces the viscosity and improves the fluidity, so that the removal of the liquid developer is promoted. In addition, since the wire has a small surface area, the liquid developer hardly adheres to the surface thereof, so that the removal performance can be maintained, and the liquid developer can be prevented from being scattered due to the movement of the wire.

According to a fourth aspect of the present invention, in the developing device of the first, second or third aspect, the surface of the removing member for removing the liquid developer adhered to the cleaning member is subjected to an oil-repellent treatment. It is.

According to the fourth aspect of the present invention, since the surface of the removing member is subjected to oil-repellent treatment, the liquid developer hardly adheres to the surface, and the removing performance can be maintained. The scattering of the liquid developer from the removing member can be prevented.

According to a fifth aspect of the present invention, in the developing device of the first, second, third or fourth aspect, the control means for operating the removing means at least at one of timings when starting or ending the developing operation is provided. It is characterized by having.

In the developing device according to the fifth aspect, by operating the removing means when the developing operation is started, the liquid developer adhered and deposited on the cleaning member can be removed while the operation is stopped. . This makes it possible to prevent the liquid developer removed by cleaning from the developer carrying member during the developing operation from flowing smoothly on the surface of the cleaning member, and to prevent the liquid developer from being attached and deposited. By operating the removing means when the developing operation is completed, the liquid developer adhering to the cleaning member can be removed, and the liquid developer adheres and accumulates on the cleaning member while the operation is stopped. Never do.

According to another aspect of the present invention, there is provided a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a latent image on the latent image carrier. 6. An image forming apparatus comprising: a developing unit for developing a latent image; and a transfer unit for transferring a visible image on the latent image carrier to a transfer material, wherein the developing device according to claim 1 is used as the developing unit. It is characterized by having been.

In the image forming apparatus of the present invention, it is possible to prevent the liquid developer from adhering and depositing on the cleaning member provided in the developing device for visualizing the latent image on the latent image carrier. it can. As a result, the lump of the liquid developer deposited on the cleaning member falls and rapidly changes the concentration of the liquid developer, or the deposited liquid developer adheres to the end surface of the developer carrier. Thus, it is possible to prevent the liquid developer from leaking and to form a high quality image.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as "copier") as an image forming apparatus will be described. First, the configuration and operation of the entire copying machine according to the embodiment will be described. FIG. 1 is a schematic diagram illustrating the configuration of the entire copying machine according to the embodiment. The copying machine includes a charging roller 1 as a charging unit around a photoreceptor 10 as an image carrier.
1, an exposure device 12 as a writing unit, and a liquid developer 1
Developing device 20 as a developing means for accommodating the inside 3
And a transfer device 14 as a transfer unit and a photoconductor cleaning device 15. The latent image forming means for forming a latent image on the photoreceptor 10 includes the charging roller 11 and the exposure device 12
Etc. Further, the copying machine is provided with a paper supply unit 17 for storing transfer paper 16 as a transfer material, and a fixing device 18 as a fixing unit.

After the photoreceptor 10 is charged by the charging roller 11, the exposure device 12 irradiates light corresponding to an image to form an electrostatic latent image. This electrostatic latent image is
The liquid is developed by the liquid developer 13 and visualized by the liquid developing device 20. The liquid developer 13 used in the copying machine according to the present embodiment is obtained by dispersing a toner at a high concentration in a carrier liquid composed of an insulating liquid.
It is prepared to have a high viscosity of Pa · s. The toner image formed on the photoreceptor 10 by the liquid developer 13 is transferred by the transfer device 14 onto transfer paper 16 conveyed from the paper supply unit 17. Then, the toner transferred to the transfer paper 16 is sent to the fixing device 18 and is fixed on the transfer paper 16 under the action of heat and pressure. The transfer residual developer remaining on the photoconductor 10 is
After being removed by the cleaning device 15, the image forming process is completed, and thereafter, the above process is repeated.

Next, the configuration of the liquid developing device 20 of the copying machine will be described. FIG. 2 is an explanatory diagram showing the configuration of the liquid developing device 20. The liquid developing device 20 has a developer storage tank 21 that stores the liquid developer 13. Inside the developer accommodating tank 21, a developing roller 22 as a developer carrier and an application roller 2 as an application member are provided.
3, a metering blade 24 as metering means for measuring the amount of the liquid developer 13 applied, a cleaning blade 25 as a cleaning member for collecting the residual developer remaining on the developing roller 22, An eccentric roller 26 described below as a removing unit for removing the residual developer attached to the blade 25, and a pair of stirring screws 27a and 27b as a developer circulating / stirring unit for circulating and stirring the liquid developer 13 are provided. Have been. A carrier liquid storage tank 28 and a liquid developer storage tank 29 are connected to the developer storage tank 21 via a carrier liquid supply pump 30 and a liquid developer supply pump 31, respectively.

The application roller 23 is partially immersed in the liquid developer 13 in the developer storage tank 21, and the liquid developer 13 attached to the application roller 23 is measured by a metering blade 24. Is applied on the developing roller 22 to form a thin layer of the liquid developer 13. The latent image on the photoreceptor 10 is developed by the liquid developer 13 applied on the developing roller 22 in a thin layer, and the liquid developer 1 after the development is developed.
Reference numeral 3 denotes a developing roller 22 by a cleaning blade 25.
Removed from above. In addition, a pair of screws 27a, 2
7b, the liquid developer 1 in the developer storage tank 21
By circulating and stirring the liquid developer 3, the state, the viscosity and the dispersion state of the liquid developer 13 can always be kept the same. Further, the density of the liquid developer 13 is detected, and the density is adjusted based on the detection result. The liquid developer 13 is supplied into the developer storage tank 21 from the liquid developer storage tank 29 and the carrier liquid is supplied from the carrier liquid storage tank 28 as needed. The agent 13 is filled.

In the liquid developing apparatus 20 having the above-described structure, a cleaning member that contacts the developing roller 22 as a cleaning member that removes an undeveloped residual developer remaining on the developing roller 22 after developing the latent image on the photosensitive member 10. Since the blade 25 is used, the residual developer can be stably removed from the surface of the developing roller 22.

Here, the residual developer removed from the developing roller 22 by the cleaning blade 25 is
It may adhere and deposit on the surface of the cleaning blade 25. Therefore, in the copying machine according to the present embodiment, the eccentric roller 26 and a drive source (not shown) for rotating the eccentric roller 26 are provided to prevent the residual developer adhered on the cleaning blade 25 from being deposited. are doing.

FIGS. 3A and 3B are diagrams for explaining the operation of the eccentric roller 26. FIG. As shown in FIG. 3A, the residual developer 1 on the surface of the cleaning blade 25
3a is the gravity and the residual developer 1 which is cleaned later.
With the pushing force (shearing force) 3a, the cleaning blade 25 flows downward in the drawing on the surface. However, the viscosity of the residual developer 13a increases with time due to the thixotropy, and the residual developer 13a stops flowing and the cleaning blade 2
5 There is a tendency to adhere to the surface. If the printing operation is stopped in this state, the pushing force (shearing force) does not act on the residual developer 13 on the surface of the cleaning blade 25, and this tendency is promoted. While such a process is repeated, the residual developer 13a accumulates on the cleaning blade 25. As shown in FIG. 3B, the residual developer 13a adheres and accumulates by rotating the eccentric roller 26. The residual developer 13a can be removed.

The eccentric roller 26 is attached to the residual developer 13a.
Shear force in the rotational movement direction. Further, when the eccentric roller 26 rotates and the outer peripheral surface portion further away from the rotation axis approaches the surface of the cleaning blade 25, the gap with the surface of the cleaning blade 25 gradually narrows, and the residual developer 13a Is applied to the surface of the cleaning blade 25. In this way, by applying a shearing force to the residual developer 13a, the viscosity thereof is reduced and the residual developer 13a becomes fluid, so that the residual developer 13a can be prevented from flowing on the surface of the cleaning blade 25 and accumulating. Then, the residual developer 13a falls to the liquid developer 13 in the developer storage tank 21.

Here, the surface of the eccentric roller 26 is subjected to an oil-repellent treatment to prevent the residual developer 13a from adhering to the eccentric roller 26. This allows
The removal performance of the eccentric roller 26 is maintained, and the scatter of the residual developer 13a from the eccentric roller 26 can be prevented. In addition, as the oil repellent for performing the oil repellent treatment, a fluorine-based coating agent or the like can be used.

By providing a removing means such as an eccentric roller 26 for the cleaning blade 25 for removing the undeveloped residual developer 13a remaining on the developing roller 22, the residual developer 13a Can be prevented from adhering and depositing.

The eccentric roller 26 is used as the removing means.
Has been described, but this roller can apply a shearing force to the residual developer 13a even if it is not eccentric. However, the roller that is not eccentric has a small shearing force that presses the residual developer 13 a against the cleaning blade 25, and thus the shearing force is slightly inferior to the eccentric roller 26. The same effect can be obtained by rotating the blade-shaped member or by a knurled roller as the removing means. However, when these complicated shapes of the removing means are used, the residual developer 13a adheres to the removing means. Once the residual developer 13a has adhered, removing it is troublesome. On the other hand, since the eccentric roller 26 has a simple shape, the residual developer 13a does not easily adhere thereto.

[Modification 1] In the first embodiment, the configuration using the eccentric roller 26 as the removing means has been described. However, a configuration using a wire as the removing means may be adopted. Since the eccentric roller 26 has a simple shape, the residual developer 13a does not easily adhere thereto. However, since the surface area is large, it is difficult to completely prevent the adhesion. When the residual developer 13a adheres to the eccentric roller 26, the residual developer 13a gradually accumulates, and the removal performance is reduced, or the accumulated residual developer 13a is scattered. Therefore, the removing means according to the present modification is configured to use a wire having a small surface area.

FIG. 4 is a perspective view of a wire removing member 32 using a wire according to the first modification. The wire removing member 32 includes a rotating shaft 33, a pair of flanges 34, and four wires 35. Four wires 35 are parallel to the rotating shaft 33 between the pair of flanges 34 and are on the same circumference. 35 is configured to be stretched. Note that the number of wires 35 is not limited to the above four wires, and one or more wires may be used. The wire removing member 32 is rotated by a driving source (not shown).

FIG. 5 shows a wire removing member 3 according to this modification.
It is an enlarged view of 2 vicinity. The rotation of the wire removing member 32 in the direction of the arrow in FIG.
5 passes and drops the residual developer 13a attached to the cleaning blade 25. In addition, a shearing force can be applied to the residual developer 13a, and its viscosity can be reduced to improve fluidity. Here, the wire 35
Has a small surface area, so the residual developer 1
3a hardly adheres. Accordingly, it is possible to prevent the residual developer 13 a from depositing on the wire 35 and from scattering the residual developer 13 a from the wire 35 due to the rotation of the wire removing member 32. Further, by performing the oil-repellent treatment on the surface of the wire 35, the residual developer 13 on the wire 35 is further increased.
a can be prevented from adhering.

[Modification 2] Embodiment 1 and Modification 1
In the copier described above, the removing means of the eccentric roller 26 and the wire removing member 32 is not always operated during the printing operation, but is performed at least at one timing when the printing operation is started or ended. Is performed.

In the copying machine according to this modification, the removing means does not always operate during the printing operation, but performs the removing operation at least at one timing when the printing operation is started or ended. . This not only prevents wasteful energy consumption, but also extends the mechanical life of the removing means.

In FIG. 3A, during the copying operation of the copying machine, the cleaning blade 25 causes the developing roller 22 to move.
The residual developer 13a continuously removed from above applies an extruding force (shear force) to the residual developer 13a on the cleaning blade 25. Thereby, the residual developer 1
The viscosity of the cleaning blade 25a is reduced, and the fluidity is improved.
If the mounting angle is set close to the vertical direction, there is almost no accumulation. However, when the copying machine is in a stopped state after printing, the residual developer 13 on the cleaning blade 25 is removed.
The pushing force does not act on a, its viscosity increases, and it remains attached. Then, when the next printing operation is performed, the residual developer 13a flows thereon. By repeating such an operation, the deposition is gradually performed. Once the deposition is performed, the deposition blocks the flow of the residual developer 13a, and the deposition is accelerated. As described above, when the residual developer 13a adheres and accumulates on the cleaning blade 25, the residual developer 13a that adheres and accumulates when the next printing operation is performed, or the residual developer 1a
3a is deposited. Therefore, the eccentric roller 26
Is operated for a predetermined time after the copying operation of the copier to remove the residual developer 13a on the cleaning blade 25, so that the cleaning blade 25 is stopped when it is stopped.
The residual developer 13a does not adhere to and accumulate on the substrate.

[0038]

According to the first to sixth aspects of the present invention, there is an excellent effect that the liquid developer cleaned by the cleaning member from the developer carrier can be prevented from being deposited on the cleaning member. By preventing the accumulation, the circulation of the liquid developer in the developing device can be smoothly performed, and there is also an excellent effect that the concentration of the liquid developer can be easily controlled. Also,
Since the problem such as the liquid leakage due to the accumulation of the liquid developer in the developing device can be prevented, there is also an excellent effect that the size of the device can be reduced.

In particular, the invention according to claim 2 has an excellent effect that the accumulation of the liquid developer adhering to the cleaning member can be prevented with a simple structure.

In particular, according to the third aspect of the present invention, since the liquid developer hardly adheres to the wire of the removing means, the capability of the removing means can be maintained and the liquid developer can be removed from the wire. There is an excellent effect that scattering can be prevented.

In particular, in the invention of claim 4, since the removing means is subjected to an oil-repellent treatment, the liquid developer is prevented from adhering to the removing means, and the ability of the removing means can be maintained. There is an excellent effect that the liquid developer can be prevented from scattering from the removing means.

In particular, according to the invention of claim 5, by performing the operation of the removing means at a necessary timing, not only the wasteful consumption of energy can be prevented, but also the mechanical life of the removing means is prolonged. There is an excellent effect that you can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment.

FIG. 2 is a schematic configuration diagram of a liquid developing device of the copying machine.

FIGS. 3A and 3B are diagrams for explaining the operation of an eccentric roller 26. FIGS.

FIG. 4 is a perspective view of a wire removing member according to a modification.

FIG. 5 is an enlarged view of the vicinity of a wire removing member of a copying machine according to a modification.

FIGS. 6A and 6B are graphs for explaining the properties (thixotropy) of a high-viscosity liquid developer.

[Explanation of symbols]

 Reference Signs List 10 photoconductor 11 charging roller 12 exposure device 13 liquid developer 13a residual developer 14 transfer device 16 transfer paper 20 liquid development device 21 developer storage tank 22 developing roller 23 application roller 24 metering blade 25 cleaning blade 26 eccentric roller 27a 27b Stirring screw 28 Carrier liquid storage tank 29 Developer storage tank 32 Wire removing member 35 Wire

Claims (6)

[Claims] 1. A developer carrying member for carrying a high-viscosity liquid developer in which a toner is dispersed in an insulating liquid; an application means for applying the liquid developer to the developer carrying member; Cleaning means for cleaning the liquid developer remaining on the surface of the body, a developing device for developing a latent image formed on the latent image carrier by the liquid developer carried on the developer carrier, A developing device comprising: a cleaning member as the cleaning means; and a removing means for removing the liquid developer attached to the cleaning member. 2. The developing device according to claim 1, wherein said removing means has an eccentric roller and a driving means for driving said eccentric roller to rotate, said cleaning means being provided on said cleaning member surface and being cleaned by said cleaning member. A developing device, wherein the eccentric roller is disposed so that the outer peripheral surface of the eccentric roller moves in the vicinity of the surface on which the liquid developer flows. 3. The developing device according to claim 1, wherein said removing means has one or more wire members and moving means for moving said wire members. A developing device characterized in that the wire member is configured to move near a surface where the liquid developer cleaned by the cleaning member flows. 4. The developing device according to claim 1, wherein:
A developing device, wherein a surface of a removing member for removing the liquid developer attached to the cleaning member is subjected to an oil-repellent treatment. 5. The developing device according to claim 1, further comprising control means for operating said removing means at least at one of timings when starting or ending the developing operation. Developing device. 6. A latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, a developing means for developing a latent image on the latent image carrier, and a latent image carrier 6. An image forming apparatus comprising: a transfer unit for transferring a visible image on a body onto a transfer material, wherein the developing unit according to claim 1 is used as the developing unit.