JP2000221796A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high quality image by steadily supplying liquid developer to the developer carrier of a developing device. SOLUTION: In the image forming device, a developing device 10 having a developer storage tank 11 for storing highly viscous liquid developer 4, a developing sleeve 12 for applying the liquid developer to a photoreceptor 1, and a coating roller 14 for coating the developing sleeve with the liquid developer is provided with an accumulating part 40, situated below the coating roller 14, in which a portion of the liquid developer in the developer storage tank is accumulated. Thus, regardless of an amount of the liquid developer in the developer storage tank, the liquid developer can steadily be supplied to the coating roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
The present invention relates to an image forming apparatus for visualizing a latent image formed on an image carrier using a high-viscosity liquid developer.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No. 7-152254,
JP-A-7-209922, JP-A-7-21935
Japanese Patent Application Laid-Open No. 5 (1999) -2005 discloses an image forming apparatus that visualizes an electrostatic latent image using a high-viscosity liquid developer. In these image forming apparatuses, the surface of the photoreceptor is uniformly charged by charging means,
The surface of the photoreceptor is exposed by writing means according to image data to form an electrostatic latent image. Then, this electrostatic latent image is visualized by the liquid developing device. The liquid developer in the image forming apparatus is prepared by dispersing a toner at a high concentration in a carrier liquid composed of an insulating liquid such as dimethylpolysiloxane oil and has a high viscosity of 100 to 10,000 mPa · s. The liquid developer is stored in a developer storage tank of the liquid developing device.

In such an image forming apparatus, the liquid developer is applied to a surface of a developing roller or a developing sleeve in the liquid developing apparatus with a uniform thickness. The liquid developer applied to the developing roller or the like develops the electrostatic latent image on the photoconductor in a developing area as a liquid developer thin layer to form a toner image. At this time, the residual liquid developer remaining on the developing roller and the like that has passed through the developing area is removed by the scraping blade and collected in the developer storage tank. Then, the toner image formed on the photoreceptor is transferred to a transfer paper and fixed by a fixing unit to form an image. After the transfer step, the transfer residual developer remaining on the photoreceptor is removed by the cleaning unit, and the image forming step is completed.

In the above-described liquid developing apparatus, since it is necessary to supply the liquid developer to the developing roller and the like, a liquid developer is applied on the surface of the developing roller and the like to form a liquid developer layer. Developer application means is used. As the developer applying means, a roller-shaped applying roller conventionally used for ink application of a printing machine or the like is generally used. In order to form a uniform liquid developer thin layer on the developer carrying member, a sufficient amount of the liquid developer must be supplied to the developer applying unit.
In addition, as a modified example of the developer applying unit, a belt-shaped application belt, a hollow cylindrical application sleeve, and the like can be given.

As a method of supplying the liquid developer to the developer applying means such as the application roller as described above, for example, there is a method in which the liquid developer is pumped by a pump or the like and applied to the application roller or the like. According to this method, the liquid developer can be supplied to the application roller or the like without being greatly affected by the volume of the liquid developer in the developer storage tank. However, the amount of supply to the application roller or the like tends to be uneven, and the contact time between the application roller or the like and the liquid developer is short, so that sufficient supply of the liquid developer cannot be performed. On the other hand, as a method that does not cause such a problem, there is a method of directly immersing an application roller or the like in a liquid developer in a developer storage tank. According to this method, the liquid developer can be stably supplied to the coating roller and the like, and the mechanism is simple, so that the size of the apparatus can be reduced.

[0006]

However, conventionally, when the application roller or the like is simply immersed directly in the liquid developer in the developer accommodating tank, only the height of the immersion of the application roller or the like is equal to or less than the height of the application roller. There was a problem that the capacity of the tank could not be increased. Further, when the liquid developer is consumed and the liquid level of the liquid developer in the developer storage tank becomes lower than the lowermost portion of the application roller or the like, the liquid developer may remain even though the liquid developer still remains. However, at this point, it is not possible to form an image, which is uneconomical.

On the other hand, when a latent image is visualized using a high-viscosity liquid developer as described above, there is a specific problem with the high-viscosity liquid developer that does not occur when a normal liquid developer is used. . For example, in a developing area where an image carrier such as a photoconductor on which the latent image is formed and a developer carrier such as a developing roller for visualizing the latent image, a latent image on the image carrier from the developer carrier is formed. The toner moves to the image. At this time, if the carrier has a high viscosity, the moving speed of the toner is lower than that of a normal carrier, so that there is a problem that the developing time needs to be increased accordingly. This problem has traditionally been
This problem is solved by using a flexible developer carrier and increasing the nip width in the development area.

When the liquid developer is highly viscous, for example, when the liquid developer is applied to the developer carrier using an application roller, the liquid surface of the liquid developer 4 is applied as shown in FIG. A phenomenon called hanging back which cannot follow the rotation of the roller 14 occurs. This hanging back phenomenon is caused by the difference between the surface of the application roller and the liquid level of the liquid developer on the upstream side in the rotation direction of the application roller from the deepest part of the application roller 14 immersed in the liquid developer 4 in FIG. This means that a gap G is formed therebetween. Accordingly, the contact time between the application roller 14 and the liquid developer 4 is shortened, and there is a problem that the liquid developer cannot be sufficiently supplied to the application roller.

The present invention has been made in view of the above problems, and a first object is to form a high quality image by stably supplying a liquid developer to a developer carrier. It is an object of the present invention to provide an image forming apparatus capable of performing the above. Also,
A second object is to provide an image forming apparatus capable of forming a high-quality image by solving a problem caused by the viscosity of a liquid developer that adversely affects image formation.

[0010]

In order to achieve the first object, the invention according to claim 1 has a feature that the present invention is applied to a method for manufacturing a medium having a pressure of 100 to 10000 mP.
An image forming apparatus that visualizes a latent image formed on an image carrier using a liquid developer having a viscosity of a · s,
A developer accommodating tank for accommodating the liquid developer; a developer carrier for carrying the liquid developer for applying the liquid developer to the image carrier; and a liquid developer for carrying the liquid developer on the developer carrier. An image forming apparatus provided with a developing means having a developer applying means for applying a developer, wherein the reservoir is located below the developer applying means and stores a part of the liquid developer in the developer storing tank. And a developer conveying means for conveying the liquid developer to the reservoir.

In this image forming apparatus, a reservoir for storing a part of the liquid developer in the developer accommodating tank is provided below the developer applying means. If the developer is filled, a sufficient amount of the liquid developer can be supplied to the developer applying means. That is, the liquid developer can be stably supplied to the developer applying unit regardless of the amount of the liquid developer in the developer storage tank. Therefore, the shape and dimensions of the developer storage tank can be freely set, and the capacity of the developer storage tank can be increased. Also,
In this image forming apparatus, since the liquid developer can be transported to the reservoir by the developer transporting means, even when the amount of the liquid developer is reduced and its bulk is reduced, the developer is applied to the developer applying means. A sufficient amount of liquid developer can be supplied stably.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, there is provided a backflow preventing means for preventing the liquid developer accumulated in the reservoir from flowing out of the inlet of the reservoir. It is characterized by having been provided. In the image forming apparatus of the first aspect, in order to sufficiently supply the liquid developer to the developer application unit, the liquid developer is transported to the reservoir by the developer transport unit. However, depending on the specific configuration of the image forming apparatus of the first aspect,
When the image forming apparatus or the developer conveying unit is stopped, the liquid developer in the reservoir flows out through the inflow port, and there is a possibility that the liquid developer does not remain in the reservoir. At this time, when the image forming apparatus or the developer transport unit is operated again, it is necessary to transport the liquid developer by the developer transport unit until the reservoir is filled with a sufficient amount of the liquid developer. Nature occurs.

Therefore, the image forming apparatus according to the present invention is provided with a backflow preventing means for preventing the liquid developer accumulated in the reservoir from flowing out from the inlet of the reservoir. By this backflow prevention means, it is possible to prevent the liquid developer accumulated in the reservoir from flowing backward from the inlet of the reservoir, and it is possible to prevent the liquid developer from stopping when the image forming apparatus or the developer transporting means stops. Even if there is, the liquid developer in the reservoir does not flow out from the inflow port, and the liquid developer can be held in the reservoir. Therefore, it is possible to shorten the preparation time when the image forming apparatus or the developer transport unit is operated again to perform the development. still,
As the backflow prevention means, a check valve or the like can be used. Further, the developer conveying means may be provided with a function as a backflow preventing means.

According to a third aspect of the present invention, there is provided the first or second aspect.
In the above image forming apparatus, the developer application means is constituted by an application roller. Examples of the developer applying means include those using an applying member having a roller shape, a belt shape, a sleeve shape, or the like. Further, for example, a liquid developing device disclosed in Japanese Patent Application Laid-Open No. 7-209922, in which a liquid developer is applied to the developer carrier by a pump without using the above-described coating member, is also available. Are known. However, among these,
By using an application roller that is a roller-shaped application member as in the image forming apparatus of the present invention, the liquid developer can be stably applied to the developer carrier, and the developer can be applied thinly. And the mechanism can be simplified.

[0015] In particular, the invention of claim 4 is the image forming apparatus of claim 3, wherein the coating roller is a gravure roller. In this image forming apparatus, it is possible to accurately control the amount of the liquid developer applied on the developer carrier, and to form a liquid developer thin layer having a uniform thickness on the developer carrier. be able to.
The gravure roller is a roller-shaped coating member whose surface is engraved. When applying a liquid developer to the developer carrier using this gravure roller,
An excess liquid developer on the surface of the gravure roller is removed by contacting a regulating member for regulating the amount of the liquid developer attached to the surface of the gravure roller. At this time, the amount of the liquid developer on the surface of the gravure roller is accurately measured by the effect of the unevenness due to the engraving, so that the amount of the liquid developer applied can be easily controlled.

According to a fifth aspect of the present invention, there is provided an image forming apparatus according to the third or fourth aspect.
The inlet of the liquid developer in the reservoir is more than the deepest part of the application roller immersed in the liquid developer.
The coating roller is arranged on the upstream side in the rotation direction of the coating roller. In the above-described image forming apparatus, since the liquid developer has a high viscosity, the hanging back phenomenon described above occurs when the application roller rotates. As a result, the time during which the application roller is immersed in the liquid developer is shortened, so that a sufficient amount of the liquid developer cannot be supplied to the application roller. Further, when the liquid developer is supplied to the developer applying unit, the liquid developer is pumped up by the developer conveying unit to a height at which the developer applying unit is arranged.
At this time, the phenomenon that the liquid level of the liquid developer rises near the supply port for supplying the liquid developer conveyed by the developer conveying means to the reservoir due to the pumping of the developer conveying means. Occur.

According to the image forming apparatus of the present invention, based on such characteristics of the high-viscosity liquid developer, an inflow port through which the liquid developer conveyed by the developer conveying means flows into the reservoir is provided. The application roller is arranged upstream of the deepest part of the part immersed in the liquid developer accumulated in the reservoir in the rotation direction of the application roller (hereinafter referred to as the roller rotation direction). . The portion where the inflow port is arranged is a portion where the above-mentioned hanging back phenomenon occurs. Then, the liquid level of the liquid developer at that portion rises due to the liquid developer flowing out from the inflow port. Thereby, the gap formed by the hanging back phenomenon between the surface of the application roller and the liquid developer surface at the deepest portion on the upstream side in the roller rotation direction can be filled. Therefore, the hanging back phenomenon can be suppressed, and the liquid developer can be uniformly supplied to the application roller.

According to a sixth aspect of the present invention, in the image forming apparatus of the third, fourth or fifth aspect, the developer conveying means is provided with:
A developer transport member having a dimension smaller than the axial length of the application roller, and a liquid developer dispersed in the axial direction of the application roller between an outlet of the developer transport member and an inlet of the reservoir. And a developer dispersing means.

If the liquid developer used has a high viscosity, there is a problem that it is difficult to make the toner concentration of the liquid developer carried on the developer carrier uniform. This problem can be solved by devising the supply of the liquid developer to the application roller at least in the circumferential direction of the application roller (hereinafter, referred to as
It is called the vertical direction. ) Can be solved. However, as a developer transport member constituting the developer transport means, a pump or a screw is usually used, so that in order to disperse the liquid developer in the entire axial direction of the application roller using these, An outlet of a pump or the like must be arranged in the entire area of the coating roller in the axial direction. However, it is very difficult to manufacture a developer conveying member such as a pump having an outlet in the entire region in the axial direction of the application roller. Even if such a developer conveying member can be manufactured, the apparatus is large. It will be. Further, if a plurality of developer conveying members are arranged in the axial direction of the application roller, the liquid developer can be ejected to the whole area in the lateral direction, but the cost increases. Further, even in an image forming apparatus in which a liquid developer is circulated using a pump or the like as described above, since the liquid developer has a high viscosity, the liquid developer is traversed during circulation. Is hardly dispersed. Therefore,
It is most preferable that the developer conveying means is narrower than the axial length of the application roller and can uniform the toner concentration in the horizontal direction.

Therefore, in the image forming apparatus according to the present invention, the developer conveying member such as a pump is configured to be narrower than the axial length of the application roller, and the distance between the developer conveying member and the inflow port of the reservoir is adjusted. In between, a developer dispersing means for dispersing the liquid developer in the horizontal direction is provided. By this developer dispersing means, the liquid developer discharged from the developer conveying member can be laterally dispersed before the liquid developer is conveyed to the inlet of the reservoir. This makes it possible to equalize the toner concentration in the horizontal direction of the liquid developer supplied to the application roller. In addition, as the developer dispersing means, for example, a passage having the same width as the axial length of the coating roller is provided between the outlet of the developer conveying member and the inlet of the reservoir, and this passage is provided. An example is one in which a plurality of bent portions are formed and diffused in the lateral direction by flow resistance in the bent portions. Instead of the bent portion, a portion in which a cross section having a different size is formed in the passage, and the portion is diffused in a lateral direction by a flow resistance in a portion where the cross section changes can be used. Further, a structure in which the passage is branched in the lateral direction and a plurality of inlets for the reservoir are provided in the lateral direction may be used.

According to a seventh aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, or sixth aspect, the image forming apparatus is provided near the outlet of the developer carrying member constituting the developer carrying means. It is characterized in that a developer stirring means for stirring the liquid developer is provided. The developer transport member includes:
Since the high-viscosity liquid developer must be conveyed to at least the reservoir, the liquid developer is vigorously ejected from the outlet. As in the present invention, if a developer stirring means for stirring the liquid developer is provided near the outlet of the developer conveying member, the liquid flow of the liquid developer flowing out from the outlet can be used. The stirring effect is greater than when the liquid developer is stirred in a portion where the flow of the liquid developer is small. Therefore, before the liquid developer is transported to the reservoir, the liquid developer can be sufficiently stirred. As the developer stirring means, a propeller, a rotor, a static mixer, or the like can be used. In particular, when a passing-type developer stirring means such as a static mixer is used, it is advantageous because the mechanism can be simplified and the size of the apparatus can be reduced.

According to an eighth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, or seventh aspect, the image forming apparatus is provided near the entrance of the developer conveying member constituting the developer conveying means. And a foreign matter removing means. In this image forming apparatus, foreign matter removing means is provided near the entrance of the developer conveying member. Since the foreign matter removing means can remove foreign matter mixed in the liquid developer before the liquid developer enters the developer transport member, it is possible to prevent failure of the developer transport member due to the foreign matter. it can. Further, by removing the foreign matter, the liquid developer thin layer on the developer carrier can be made uniform. In addition, as the foreign matter removing means, a net-like thing, a thing composed of a plurality of meshes, or the like can be used.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter, referred to as a copying machine) as an image forming apparatus will be described. First, the configuration and operation of the entire copying machine according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic diagram showing the configuration of the entire copying machine according to the first embodiment. This copying machine has a photoconductor 1 as an image carrier.
And a charging roller 2 as a charging unit, an exposure device 3 as a writing unit, a liquid developing device 10 as a developing unit, a transfer device 5 as a transfer unit, and a cleaning device 6 as a cleaning unit. Having. The transfer paper 8 on which the toner image is transferred by the transfer device 5 is
From the paper supply unit 7 through the paper supply path, through the transfer device,
The sheet is conveyed to a fixing device 9 as a fixing unit.

After the photosensitive member 1 is charged by the charging roller 2, the exposure device 3 irradiates light corresponding to the image to form an electrostatic latent image. The electrostatic latent image is developed by the liquid developing device 10 with the liquid developer 4 and is visualized. The liquid developer 4 used in the present embodiment is:
For example, a toner is dispersed at a high concentration in a carrier liquid composed of an insulating liquid such as dimethylpolysiloxane oil,
It is prepared to have a high viscosity of 0 to 10000 mPa · s. The toner image formed on the photoreceptor 1 by the liquid developer 4 is transferred by the transfer device 5 onto transfer paper 8 conveyed from the paper supply unit 7. And
The toner transferred to the transfer sheet 8 is sent to the fixing device 9 and is fixed on the transfer sheet under the action of heat and pressure. Further, the transfer residual developer remaining on the photoconductor 1 is removed by the cleaning device 6, and the image forming process is completed. Thereafter, the above-described process is repeated.

Next, the configuration of the liquid developing device 10 of the copying machine will be described. FIG. 2 is an enlarged view of the liquid developing device 10 of the copying machine, and FIG.
0 is a side view. The liquid developing device 10 has a developer storage tank 11 that stores the liquid developer 4. Inside the developer accommodating tank 11, a developing sleeve 12 as a developer carrier, a driving roller 13 as driving means for driving the developing sleeve, an application roller 14 as developer applying means, A metering blade 15 as a regulating member for regulating the application amount of the developer 4 and a collecting blade 16 for collecting the residual developer remaining on the developing sleeve 12 are provided.

The developer storage tank 11 has a storage section 30 for storing the liquid developer 4 and a storage section 40 for storing a part of the liquid developer 4. This reservoir 4
Numeral 0 is formed on an upper part of a reservoir forming part 41 integrally formed with the developer storage tank so as to occupy a part of the developer storage tank 11.
1 is located below the application roller 14 arranged above. In other words, the reservoir 40 is provided over the entire area of the application roller 14 in the axial direction.
1 extends from the inner wall through the area below the metering blade 15 so as to cover the lower part of the application roller 14.

The gear pump 17 as a developer carrying member which constitutes a developer carrying means for carrying the liquid developer 4 to the reservoir 40 is arranged inside the reservoir forming section 41. The suction port 17a of the gear pump 17 is open at the lowest position of the housing section 30. The suction port 17a is provided with a net 18 as foreign matter removing means for removing foreign matter mixed in the liquid developer 4.

On the other hand, the spout 17b of the gear pump 17
As shown in FIG. 2, a plurality of bent portions (A, B,
A passage 19 constituting a developer dispersing means having C) is provided. As shown in FIG. 3, the passage 19 extends so as to gradually expand from the lateral width of the ejection port 17 b of the gear pump 17 to the inflow port 40 a having the same width as the axial length of the application roller 14.

By the way, in order to form a high-quality image using the copying machine according to the present embodiment, the developing sleeve 1
The liquid developer thin layer formed on the surface of No. 2 needs to be formed with a uniform toner concentration and a constant layer thickness. However, usually, as the developer applying means, an applying roller composed of a roller-shaped member having a smooth surface, which is also used in an ink applying step of a printing press, is used. When the liquid developer is applied to the developing sleeve 12 using the application roller having a smooth surface as described above, when the liquid developer sandwiched between the application roller and the developing sleeve is opened, the liquid developer is formed into two layers. Separating liquid separation may occur. In this case, on the surface of the liquid developer thin layer, by cavitation,
Fine irregularities such as voids (mottle irregularities) and ribs (circular irregularities in the circumferential direction) occur. It is difficult to form a completely uniform flat surface because the minute unevenness depends on conditions such as the linear velocity of the application roller and the belt-shaped member and the contact pressure thereof, in addition to the viscosity and surface tension of the liquid. It is.

Therefore, in the present embodiment, a gravure roller having an uneven engraved portion on the surface is used as the application roller 14. The metering blade 15 is attached to the inner wall of the developer storage tank 11 facing the application roller 14. Generally, the amount of liquid developer applied to the surface of the developing sleeve 12 is controlled by the contact pressure and the relative speed between the application roller 14 and the developing sleeve. Therefore, when an ordinary application roller having a smooth surface is used, in order to accurately control the liquid developer thin layer in units of micrometers, it is necessary to sufficiently manage the axis deviation and the pressing force against the developing sleeve 12. There is. In this case, it is necessary to further process the application roller with high accuracy in terms of roundness, circumferential contact, surface roughness, and the like, which makes machining difficult and leads to an increase in cost. However, when the application roller is a gravure roller as in the present embodiment, the liquid applied to the surface of the application roller can be obtained simply by contacting the metering blade 15 with the surface to remove excess liquid developer. The developer amount can be controlled accurately.

In this embodiment, by rotating the coating roller 14 in the counter direction with respect to the rotation direction of the developing sleeve 12, voids and ribs generated after the coating roller is separated from the developing sleeve are formed. Such fine unevenness is prevented. Further, by setting the linear velocity of the application roller 14 higher than the linear velocity of the developing sleeve 12, the thickness unevenness of the liquid developer thin layer generated by the engraved portion formed on the surface of the application roller 14 is improved. Has been prevented. With such a configuration, a liquid developer thin layer having a uniform thickness is formed on the surface of the developing sleeve 12.

The gear pump 17 has two gears (17
c, 17d) are engaged with each other. These gears (17c, 17d) are driven by an electric motor (not shown). In addition, as the developer conveying member, in addition to the above gear pump, a piston pump, a gear pump,
A pump using other pumps such as a vane pump, a monopump, and a tube pump, and a pump using a screw or the like can be used.

The developing sleeve 12 is formed of a cylindrical elastic member having flexibility, and is disposed so as to be in contact with the coating roller 14 and the photosensitive member 1. The developing sleeve 12 is rotated by the driving roller 13 in the same direction as the photosensitive member 1 at the same surface speed. The collection blade 16 is disposed above the storage unit 30 in the developer storage tank 11 and is in contact with the surface of the development sleeve 12. This collection blade 16
The inner wall of the developing sleeve 12 in the area where
The drive roller 13 is configured to abut.
That is, the drive roller 13 and the collection blade 16
Thus, a part of the developing sleeve 12 is sandwiched therebetween. As the developer carrier, in addition to the above-described developing sleeve, a developing roller whose surface is covered with an elastic body such as rubber, or which has a soft member such as a sponge inside, or an endless roller A developing belt constituted by a belt can be used.

Next, the structure of the liquid developing device 10 will be described in more detail, and its operation will be described. In the liquid developing device 10 configured as described above, the liquid developer 4 stored in the developer storage tank 11 is:
The suction force generated by the driving of the gear pump 17 causes the net 1 provided at the suction port 17a of the gear pump to operate.
Go through 8. The liquid developer 4 that has passed through the net 18
Is taken into the space formed between the teeth of the gears (17c, 17d) of the gear pump 17 and the inner wall of the reservoir forming portion 41, and as the gears rotate, the spout of the gear pump 17 17b.
Then, the liquid developer 4 is ejected from the ejection port 17b and sent out into the passage 19 communicating with the inlet 40a of the reservoir 40.

In the passage 19, a flow velocity is generated by the gear pump 17, and the liquid developer 4 is stored in the reservoir 4.
It is transported toward zero. At this time, the liquid developer 4
Is highly viscous and the spout 1 of the gear pump 17
The liquid developer hardly disperses in the lateral direction because 7b is opened at the central portion in the lateral direction of the passage 19. Therefore, in the present embodiment, a plurality of bent portions (A, B, C) are provided in the passage 19 in order to disperse the liquid developer in the lateral direction.

The liquid developer 4 discharged from the jet port 17b
When it reaches the first bent portion A, it collides with the wall surface in the traveling direction of the liquid developer. The liquid developer 4 colliding with the wall is
Since the traveling direction can be rapidly changed, the light is diffused not only in the vertical direction but also in the horizontal direction, that is, the width direction of the passage 19 at the bent portion A. Similarly, in the remaining bent portions (B, C) provided up to the reservoir 40, diffusion in the horizontal direction occurs, and the liquid developer 4 conveyed to the reservoir is in the horizontal direction. Is sufficiently diffused.

The liquid developer 4 passing through the passage 19 is
The water flows into the reservoir through an inlet 40a provided in the reservoir 40. As a result, the liquid developer 4 is stored in the reservoir 40 to such an extent that a part of the application roller 14 is immersed. The excess liquid developer 4 in the reservoir 40 is
The water is spilled from the reservoir, falls into the storage section 30, is taken into the gear pump 17 again, and is reused. on the other hand,
In the reservoir 40, the liquid developer 4 that is pumped up by the coating roller 14 and adheres to the coating roller is
The toner is regulated on the metering blade 15 and applied to the surface of the developing sleeve 12. The liquid developer 4 applied on the developing sleeve 12 forms a thin layer of the liquid developer thin layer, and forms a toner image in the developing area according to the electrostatic latent image on the photoconductor 1. The residual developer remaining on the surface of the developing sleeve 12 after passing through the developing area is scraped off by the collection blade 16, falls into the storage section 30 in the developer storage tank 11, and is reused. You.

When the copying machine or the gear pump 17 is stopped, the liquid developer 4 in the reservoir 40 may return to the container 30 through the inlet 40a. Since the gear pump 17 also functions as backflow prevention means for preventing backflow of the liquid developer, there is no problem. However, when a developer transporting unit having no function as a backflow preventing unit is used, there is a possibility that the developer flows backward. In this case, for example, as shown in FIG. 4, a check valve 2 serving as a backflow prevention means is provided at the inlet 40a of the reservoir.
If 0 is provided, the liquid developer 4 can be stored in the storage section 40 even when the copying machine or the gear pump 17 is stopped, and the time loss at the time of restarting is reduced. can do.

In the reservoir 40, the application roller 14 supplies the liquid developer to the application roller by rotating and pumping up the liquid developer 4 in the reservoir. At this time, since the liquid developer 4 has high viscosity, a hanging back phenomenon occurs. In order to suppress this, in the present embodiment, as shown in FIG. 5A, the inflow port 40 a of the reservoir is set to be deeper than the deepest part where the application roller 14 is immersed in the liquid developer 4. It is arranged on the upstream side in the roller rotation direction. If the inflow port 40a is provided on the downstream side in the roller rotation direction, as shown in FIG. 5B, unlike the present embodiment, the influence of the hanging back phenomenon increases. That is, as in the present embodiment, if the inflow port 40a is provided upstream of the deepest part of the application roller in the roller rotation direction, the liquid developer 4 whose flow velocity is generated by the gear pump allows the liquid developer 4 to flow from the inflow port 40a through the inflow port 40a. When flowing into the reservoir 40, the liquid level of the liquid developer near the inflow port is raised, and the gap G between the liquid level of the liquid developer 4 and the surface of the coating roller 21 formed by the hanging back phenomenon is increased. Buried. Thus, the above-mentioned hanging back phenomenon can be effectively suppressed.

The liquid developer 4 used in the present embodiment is
Is obtained by dispersing toner in a carrier liquid which is an insulating liquid.
If the toner is left in the container for a long time, the toner may settle, and the toner concentration may be non-uniform in the upper and lower parts of the container. In the system for circulating the liquid developer as in the present embodiment, there is an effect that the liquid developer is agitated to some extent during the circulation, but when the liquid developer is used after being left for a long time, the liquid developer is used for a while. Can only be used after circulation.

Therefore, in the present embodiment, a static mixer 24 as a developer stirring means is provided at the ejection port 17b of the gear pump 17. FIG. 6 is an explanatory diagram of the static mixer 24. The static mixer 24 is disposed in the passage 19 between the outlet 17b of the gear pump 17 and the first bent portion. The static mixer 24 is configured such that a plurality of fins having a shape obtained by twisting a flat member are arranged in the transport direction of the liquid developer, and the angles of the fins are shifted. The number of fins in this embodiment is three.
With such a configuration, the liquid developer 4 ejected from the ejection port 17b is branched into two flows by the first fin 24a, moves along the twisted surface of the first fin, and moves to the next second fin 24b. Is further branched into two streams. At this time, at the same time as the two branches, half of each of the first branched streams are combined and mixed. Then, branching and merging are similarly repeated by the next third fin 24c, and when the liquid developer 4 passes through the static mixer 24, the liquid developer 4 can be brought into a sufficiently stirred state.

As described above, if the developer agitating means such as the static mixer 24 is provided at the ejection port 17b of the gear pump 17, the liquid pump is left for a long time by utilizing the flow rate of the liquid developer ejected from the gear pump. Even after use, the liquid developer ejected from the gear pump can be immediately stirred to form a uniform image.

Next, a second embodiment of the present invention will be described. FIG. 7 is an enlarged view showing a schematic configuration around a reservoir in the second embodiment. The copying machine of this embodiment is almost the same as the first embodiment, but differs from the first embodiment in that the developer dispersing means is different.
Note that the image forming operation of the copying machine in the present embodiment is basically the same as that in the first embodiment, so that the configuration is the same as that of the first embodiment, and the description of the operating parts is omitted. I do.

In the present embodiment, as the developer dispersing means, between the jet port 17b of the gear pump 17 and the inlet port 40a of the reservoir, the width of the jet port of the gear pump is determined from the lateral width of the coating roller 14. A damper portion 11 extending so as to gradually spread to an inlet 40a having the same width as the axial length and having a different cross-sectional size from other passage portions.
A passage 119 having 9a is used.

The liquid developer 4 flowing into the passage 119
Is moved toward the reservoir 40 with its flow velocity increased by the gear pump 17. The liquid developer 4 coming out of the gear pump 17 enters the damper portion 119a having a large cross section. And this damper part 119
When trying to exit a, it again enters the narrow part of the cross section.
At this time, the liquid developer 4 collides with the wall surface in the traveling direction, moves along the wall surface, and enters the narrow portion of the cross section. At this time, the liquid developer 4 also diffuses in the horizontal direction, that is, in the width direction of the passage 119. Accordingly, the liquid developer 4 transported to the reservoir 40 is in a state of being sufficiently diffused in the lateral direction. If a plurality of bent portions described in the above embodiment are provided in the passage 119,
Further, the diffusion in the lateral direction can be performed more effectively.

As a modification of the developer dispersing means, as shown in FIG.
A passage 21 having a plurality of branching points branching in the lateral direction between the inlet 7a and the inlet 40a of the reservoir, and having a plurality of laterally arranged outlets communicating with the inlet of the reservoir.
9 may be provided.

[0047]

According to the present invention, there is provided an image forming apparatus capable of forming a high quality image by stably supplying a liquid developer to a developer carrier. There is an excellent effect that you can.

In particular, according to the second aspect of the present invention, even when the image forming apparatus or the developer conveying means is stopped, an excellent effect that the preparation time for re-operating can be reduced. is there.

According to the third aspect of the present invention, the mechanism of the developer applying means can be simplified, and the liquid developer can be more stably applied to the developer carrier, thereby improving the image quality. There is an excellent effect that you can. In particular,
According to the fourth aspect of the invention, there is an excellent effect that a thin liquid developer layer having a uniform thickness can be easily formed on the developer carrier, and the image quality can be improved.

According to the fifth to seventh aspects of the present invention, it is possible to solve the problem due to the viscosity of the liquid developer, such as the hanging back phenomenon, and to supply the liquid developer uniformly to the developer applying means, thereby achieving high quality. There is an excellent effect that an image forming apparatus capable of forming an image can be provided.

In particular, according to the invention of claim 6, there is an excellent effect that the liquid developer can be more uniformly supplied to the developer applying means.

Further, according to the invention of claim 7, there is an excellent effect that the liquid developer can be more uniformly supplied to the developer applying means without making the apparatus complicated and large.

According to the eighth aspect of the present invention, there is an excellent effect that the reliability of the apparatus can be improved and the image quality can be prevented from deteriorating due to foreign matter.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view showing a schematic configuration of a liquid developing device according to the first embodiment.

FIG. 3 is a side view showing a schematic configuration of the liquid developing device according to the first embodiment.

FIG. 4 is a partially enlarged view of the liquid developing device in the first embodiment showing a modification of the backflow prevention unit.

FIGS. 5A and 5B are partially enlarged views of the liquid developing device according to the first embodiment.

FIG. 6 is an explanatory diagram of a static mixer of the liquid developing device according to the first embodiment.

FIG. 7 is a partially enlarged view showing a schematic configuration of a liquid developing device of a copying machine according to a second embodiment.

FIG. 8 is a schematic diagram illustrating a modified example of the developer dispersing unit according to the second embodiment.

FIG. 9 is an explanatory diagram of a hanging back phenomenon.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 4 liquid developer 10 liquid developing device 11 developer storage tank 12 developing sleeve 14 application roller 15 metering blade 17 gear pump 18 net 19 119 219 passage 20 check valve

Claims (8)

[Claims] 1. An image forming apparatus for visualizing an electrostatic latent image formed on an image carrier using a liquid developer having a viscosity of 100 to 10000 mPa · s, wherein the liquid developer is stored. A developer accommodating tank, a developer carrier for carrying the liquid developer to apply the liquid developer to the image carrier, and a developer application for applying the liquid developer to the developer carrier. An image forming apparatus provided with a developing means having means for storing a part of the liquid developer in the developer storage tank, which is located below the developer applying means; and An image forming apparatus, comprising: a developer transport unit configured to transport the liquid developer. 2. An image forming apparatus according to claim 1, further comprising backflow preventing means for preventing liquid developer accumulated in said reservoir from flowing out from an inlet of said reservoir. Forming equipment. 3. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the developer applying means is constituted by an applying roller. 4. An image forming apparatus according to claim 3, wherein said coating roller is a gravure roller. 5. The image forming apparatus according to claim 3, wherein
The inlet of the liquid developer in the reservoir is more than the deepest part of the application roller immersed in the liquid developer.
An image forming apparatus, which is arranged on the upstream side in the rotation direction of the coating roller. 6. An image forming apparatus according to claim 3, wherein said developer conveying means comprises: a developer conveying member having a dimension smaller than an axial length of said coating roller; and an outlet of said developer conveying member. And a developer dispersing means for dispersing the liquid developer in the axial direction of the coating roller between the liquid developer and the inlet of the reservoir. 7. The developer according to claim 1, wherein the liquid developer is agitated near an outlet of a developer carrying member constituting the developer carrying means. An image forming apparatus provided with stirring means. 8. An image forming apparatus according to claim 1, wherein a foreign matter removing means is provided near an entrance of a developer carrying member constituting said developer carrying means. An image forming apparatus comprising: