JP2011164257A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing fixation with low thermal energy through the use of a liquid developer containing toner dispersed in high-volatile carrier liquid, simultaneously, and capable of preventing the toner from firmly adhering onto the developer carrier due to volatilization, during the stopping period of the apparatus, of the carrier liquid components in the liquid developer remaining on the developer carrier after finishing the image formation. <P>SOLUTION: The image forming apparatus includes an applying means configured to apply the liquid having volatility lower than the carrier liquid, on the surface of the developer carrier which carries and conveys the liquid developer. The low-volatile liquid is applied by the applying means all over the surface, on which the liquid developer of the developer carrier is carried at a prescribed timing except the image formation period. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a developing device that carries and transports a liquid developer in which toner is dispersed in a carrier liquid, using a developer carrier, and develops a latent image formed on the image carrier.

  2. Description of the Related Art An electrophotographic image forming apparatus that forms an electrostatic latent image on a photoconductor (image carrier), adheres toner to the image, and transfers and fixes the image on paper or the like is widely used. In particular, in an image forming apparatus that requires higher image quality and higher resolution, such as an office printer for large-scale printing and an on-demand printing apparatus, a wet process using a liquid developer that has a small toner particle diameter and is less likely to cause toner image disturbance. Development methods are being used.

  In recent years, an image using a high-viscosity, high-concentration liquid developer composed of high-concentration dispersion of a solid toner composed of a resin and a pigment in an insulating liquid “carrier liquid” such as silicone oil. Forming devices have been proposed.

  When developing using this liquid developer, a thin layer of developer is formed on a developer carrier such as a developing roller, and the thinned developer is brought into contact with the photoreceptor. It is common to develop. However, even after the latent image on the photosensitive member is developed, the liquid developer remains on the developer carrying member such as a developing roller, which adversely affects the next image formation or the like.

  In order to cope with such a problem, a technique has been developed in which a developer on a developer carrier such as a developing roller remaining after image formation is removed using a cleaning member such as a blade. In addition, a technique has been proposed in which the developer thus removed can be recovered and reused.

  On the other hand, the developed liquid developer is transferred onto a recording medium such as paper as a toner image (including a carrier liquid) on the photoreceptor, and then heated by a fixing device to be fixed on the recording medium.

  It is the toner image that is fixed, and the carrier liquid contained therein is required to volatilize during the process (especially during heating by fixing). If the carrier liquid remains in the fixed toner image, the fixing strength is lowered, and the fixing quality such as back-faced is adversely affected.

  Accordingly, sufficient heat energy for volatilizing the carrier liquid is required (during fixing), but in order to suppress the heat energy during fixing as much as possible, it is desirable that the carrier liquid has high volatility.

  However, when a highly volatile liquid that easily volatilizes at room temperature (environment during use) is used as the carrier liquid, the following problems occur. That is, immediately after the image formation, the liquid developer remains on the developer carrying surface of each developer carrying body carrying and transporting the liquid developer. If the apparatus is stopped in this state, Then, the carrier liquid is volatilized and the toner solid content ratio in the residual developer is increased. If the toner is left for a long time, the toner sticks to the developer carrying member, causing a problem in image quality during the next image formation.

  The residual developer on each developer carrier is removed by the cleaning member described above, but a small part of the toner passes through the blade and the like and remains on the developer carrier, and if left for a long time, Causes sticking.

  In order to solve such problems caused by using a highly volatile carrier liquid, a technique for supplying a low volatile liquid to a developer carrying body carrying and transporting a liquid developer has been developed (for example, Patent Document 1).

  Patent Document 1 discloses a method for preventing toner fixation by supplying a non-volatile liquid onto a developer carrying member after completion of image formation.

Japanese Patent Laid-Open No. 3-118579

  According to the technique described in Patent Document 1, it is possible to prevent toner sticking from occurring on the developer carrier by supplying a non-volatile liquid onto the developer carrier after completion of image formation.

  However, the following problems occur only by supplying a non-volatile liquid onto the developer carrying member.

  That is, since the non-volatile liquid is removed by the cleaning member for removing the residual developer, as a result, the non-volatile liquid is formed on the downstream side of the cleaning member with respect to the moving direction of the developer carrier. It will not be supplied.

  The cleaning member is for removing the liquid developer from the developer carrying member, and can thereby provide an image free from defects such as fogging. However, it is difficult to completely remove the toner from the developer carrying member.

  As described above, there is a toner that passes through between the cleaning member and the developer carrying member, though only a small part. In this way, when only a part of the toner remains on the developer carrying member and the non-volatile liquid is not supplied to the downstream side of the cleaning member, the toner is still fixed.

  The present invention has been made in view of the above technical problems.

  An object of the present invention is to enable fixing at low heat energy using a liquid developer in which toner is dispersed in a carrier liquid that is volatile at room temperature, and at the same time, the liquid remaining on the developer carrier after the completion of image formation. An object of the present invention is to provide an image forming apparatus capable of preventing the carrier liquid component of the developer from volatilizing while the apparatus is stopped and the toner from sticking to the developer carrying member.

  In order to solve the above problems, the present invention has the following features.

1. An image forming apparatus for developing a latent image with a liquid developer in which toner is dispersed in a carrier liquid to form a toner image,
A developer carrier for carrying and transporting the liquid developer to the surface for use in another member;
Cleaning means for removing the remaining liquid developer provided to another member from the surface of the developer carrier;
Application means for applying a liquid having a lower volatility than the carrier liquid to the surface of the developer carrying member from which the liquid developer is removed by the cleaning means;
The application means includes
The low-volatile liquid is applied to the entire surface of the at least one developer carrying member carrying the liquid developer at a predetermined timing other than during image formation. .

2. 2. The image forming apparatus according to 1, wherein the predetermined timing is after completion of image formation.

3. 2. The image forming apparatus according to 1, wherein the predetermined timing is a case where an image forming operation has not been performed for a predetermined time.

4). The image forming apparatus according to 1, wherein the predetermined timing is immediately before the apparatus power is turned off.

5. 5. The image forming apparatus according to claim 1, wherein when the low-volatile liquid is applied by the applying unit, the cleaning unit is separated from the developer carrying member.

6). 5. The image formation according to claim 1, wherein the developer carrying member rotates in a direction opposite to that during image formation during application of the low-volatile liquid by the application unit. apparatus.

7). The image forming apparatus according to any one of 1 to 6, wherein the low-volatile liquid has a flash point of 120 ° C. or higher.

  According to the image forming apparatus of the present invention, a liquid having a lower volatility than the carrier liquid is applied to the surface of the developer carrier that carries and conveys the liquid developer in which the toner is dispersed in the highly volatile carrier liquid. The coating means applies a low-volatile liquid over the entire surface of the developer carrying member carrying the liquid developer at a predetermined timing other than during image formation.

  This enables fixing with low thermal energy, and at the same time, the carrier liquid component of the liquid developer remaining on the developer carrier after the completion of image formation volatilizes while the apparatus is stopped, and the toner sticks to the developer carrier. This can be prevented.

1 is a diagram illustrating a schematic configuration example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration example 1 of a developing device used in the image forming apparatus of FIG. 1. FIG. 3 is a diagram illustrating a schematic configuration example 2 of a developing device used in the image forming apparatus of FIG. 1. It is a figure which shows one structural example of the cleaning apparatus of a developing agent carrier. It is the schematic for demonstrating the structural example 1 of the application | coating means of a low-volatile liquid. It is the schematic for demonstrating the structural example 2 of the application | coating means of a low-volatile liquid. It is the schematic for demonstrating the structural example 3 of the application | coating means of a low-volatile liquid. It is the schematic for demonstrating the structural example 4 of the application | coating means of a low-volatile liquid. It is the schematic for demonstrating the structural example 5 of the application | coating means of a low-volatile liquid. It is a flowchart which shows the process sequence example of the process of apply | coating a non-volatile liquid on a developing roller. 6 is a flowchart illustrating an example of a processing procedure of a coating process when the developer carrying member is a photosensitive member or an intermediate transfer member.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

(Schematic configuration and operation of image forming apparatus)
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  Around the photosensitive member 1 as an image carrier, a charging device 2, an exposure device 3, liquid developing devices 4Y, 4M, 4C, and 4K, an intermediate transfer member 5, and a photosensitive member cleaning device 6 are sequentially arranged in a rotation direction indicated by an arrow. And a transfer roller 7 and an intermediate transfer member cleaning device 10 are provided around the intermediate transfer member 5.

  The transfer material (paper) 8 passes between the intermediate transfer member 5 and the transfer roller 7 and is discharged through the fixing device 9.

  Each of the four sets of liquid developing devices 4Y, 4M, 4C, and 4K is provided so as to be detachable from the photoreceptor 1, and carries a liquid developer on the surface, respectively, A developing roller 41 for developing the image is provided.

  Here, the toner of the liquid developing device 4Y is yellow toner, the toner of the liquid developing device 4M is magenta toner, the toner of the liquid developing device 4C is cyan toner, and the toner of the liquid developing device 4K is black toner. A corresponding color toner image is formed, superimposed on the surface of the intermediate transfer member 5, and then transferred onto the transfer material 8 at a time to form a full color image.

  The operation of the image forming apparatus in FIG. 1 will be described step by step.

  The photoreceptor 1 rotates in the direction indicated by the arrow. First, the surface of the photoconductor 1 is uniformly charged to a predetermined surface potential by the charging device 2, and then image information is exposed by the exposure device 3 to form an electrostatic latent image on the surface of the photoconductor 1. .

  Next, the liquid developing device 4Y is opposed to the photoconductor 1, and the liquid developer carried on the surface of the developing roller 41 is brought into contact with the photoconductor 1 to develop the electrostatic latent image, whereby the surface of the photoconductor 1 is yellow. The toner image is formed.

  When the photosensitive member 1 further rotates, the toner image on the surface moves to a primary transfer region where the photosensitive member 1 and the intermediate transfer member 5 are in contact with each other.

  A negative voltage is applied to the intermediate transfer member 5 by a power source (not shown), and the toner moves by the electric field generated by the applied voltage, so that the toner image on the surface of the photoreceptor 1 is primarily applied to the surface of the intermediate transfer member 5. Transcribed.

  After the primary transfer, the liquid developer remaining on the photoconductor 1 is removed by the photoconductor cleaning device 6, and the surface of the photoconductor 1 is again uniformly charged to a predetermined surface potential by the charging device 2.

  Subsequently, an electrostatic latent image is formed again on the surface of the photoconductor 1 and developed by the liquid developing device 4M, so that a magenta toner image is formed on the surface of the photoconductor 1.

  Thereafter, the magenta toner image is primarily transferred onto the surface of the intermediate transfer member 5, and the yellow toner image and the magenta toner image are superimposed on the surface of the intermediate transfer member 5.

  Similarly, a cyan toner image developed by the liquid developing device 4C and a black toner image developed by the liquid developing device 4K are superimposed to form a full-color toner image on the surface of the intermediate transfer member 5. .

  The full-color toner image formed on the surface of the intermediate transfer member 5 moves to the secondary transfer region where the intermediate transfer member and the transfer material 8 are in contact with each other as the intermediate transfer member 5 rotates in the direction of the arrow.

  In the secondary transfer region, a linear pressure is applied between the intermediate transfer member 5 and the transfer material 8 by the transfer roller 7 on the back surface of the transfer material 8, while the transfer roller 7 is negatively charged by a power source (not shown). A voltage is applied. By applying this voltage, the toner image is attracted to the surface of the transfer material 8 and secondarily transferred.

  The transfer material 8 onto which the toner image has been transferred is subjected to a fixing process by the fixing device 9 to complete image output.

(About liquid developer)
The liquid developer used in the liquid developing devices 4Y, 4M, 4C, and 4K is obtained by dispersing toner particles in a carrier liquid that is an organic solvent such as isoparaffin, and further providing functions such as a charge control agent and a dispersant. An agent may be contained.

  Regarding the concentration and viscosity of the liquid developer, a liquid developer in which solid components such as toner particles are dispersed at a ratio of 10 to 50% by mass and the viscosity at 25 ° C. is in the range of 1 mPa · s to 10,000 mPa · s. Especially suitable for use.

  If the volatility of the carrier liquid is too low, the heat energy required for fixing becomes too high. In order to suppress the heat energy at the time of fixing, the carrier liquid should have high volatility. However, when a volatile liquid at room temperature is used, another problem described later arises due to this.

(Schematic configuration and operation of the liquid developing device)
2 and 3 are diagrams showing different examples (configuration examples 1 and 2) of the schematic configuration of the developing device 4 used in the image forming apparatus of FIG.

<Developing device configuration example 1>
A configuration example 1 of the developing device 4 used in the image forming apparatus shown in FIG. 1 will be described with reference to FIG. However, the application means is not shown because it will be described with reference to FIG.

  In FIG. 2, a liquid developer supply nozzle 42 for supplying the liquid developer is installed in the developer tank 49, and the liquid developer is supplied from a liquid developer storage tank (not shown) via a pipe.

  A part of the supply roller 47 is immersed in the liquid developer in the developer tank 49, and as the supply roller 47 rotates, the liquid developer is attached to the surface of the supply roller 47 and pumped up.

  The developer thin layer regulating blade 44 is in contact with the upper part of the pumping-up portion, or is close to it with an appropriate gap, where excess liquid developer is scraped off and only an appropriate amount of liquid developer passes. .

  The liquid developer regulated to an appropriate amount is transferred onto the developing roller 41 that rotates in contact with the supply roller 47 and is carried on the developing roller 41 as a thin liquid developer layer.

  A corona charger 45 to which a toner charging voltage is applied from a voltage application device (not shown) applies a charge to the thin liquid developer layer formed and supported on the developing roller 41, and thereby, in the thin layer. The toner is charged, and the charge amount of the toner makes the electrostatic latent image development and toner image transfer smoother and more reliable. Note that the charger 45 can be omitted if the toner has sufficient charge.

  For developing the electrostatic latent image, a developing bias voltage is applied to the developing roller 41 from a voltage applying device (not shown).

  Thus, the toner in the developer thin layer on the developing roller 41 is used for developing the electrostatic latent image on the photoreceptor 1, and a visible toner image is formed as described above.

  The liquid developer that has not been consumed by the development on the developing roller 41 is scraped off from the developing roller 41 by the cleaning device 46.

  The supply roller 47 may be an elastic roller or a metal roller. However, a recess capable of holding and transporting the liquid developer is provided on the surface, and the amount of the liquid developer transported can be stably regulated by the volume of the recess. An anilox roller is preferably used.

  As the developing roller 41, a conductive roller having a surface of an elastic body such as urethane rubber or NBR rubber and having a hardness of about 30 degrees to 80 degrees is preferably used.

<Developer configuration example 2>
A configuration example 2 of the developing device 4 used in the image forming apparatus shown in FIG. 1 will be described with reference to FIG. Again, the application means will be described with reference to FIG.

  The only difference from the apparatus of FIG. 2 is how to supply the liquid developer to the supply roller 47.

  A developer supply blade 43 is installed so as to form a liquid developer reservoir that contacts the supply roller 47. A developer supply nozzle 42 is installed in the vicinity of the end opposite to the end facing the supply roller 47 of the developer supply blade 43.

  The developer supply blade 43 has an appropriate angle such that the side close to the supply roller 47 is lowered, and the leading end is in contact with the supply roller 47 or close to the supply roller 47 with an appropriate gap.

  The liquid developer reservoir is formed in a substantially wedge-shaped region formed by the developer supply blade 43 and the supply roller 47.

  The advantage of using the developing device of Configuration Example 2 in FIG. 3 is that the size can be reduced as compared with Configuration Example 1 in FIG.

(Schematic configuration of the cleaning device)
In the present invention, a member such as a developing roller, a photosensitive member, and an intermediate transfer member that carries and transports a thin layer of a liquid developer or a liquid developer image for use in another member, that is, a developer carrier. All the members that function as are called developer carriers.

  In the image forming apparatus described with reference to FIGS. 1 to 3, a developer carrier such as the developing roller 41, the photosensitive member 1, and the intermediate transfer member 5 is not used for image formation or is not transferred. A cleaning device (functioning as a cleaning unit) is provided for removing the remaining liquid developer from the developer carrying member.

  FIG. 4 shows a configuration example of a cleaning device used in the developing roller cleaning device 46, the photosensitive member cleaning device 6, the intermediate transfer member cleaning device 10, and the like.

  The cleaning device is generally a device that scrapes off the liquid developer on the developer carrier 13 by pressing the edge of the cleaning blade 12 made of rubber or resin having a thickness of about 0.5 mm to 10 mm.

  The liquid developer scraped from the developer carrier 13 is temporarily stored in the cleaning box 14 and then collected in a liquid developer tank (not shown).

  In addition to the cleaning member, a sponge roller having a sponge-like contact surface with the developer carrying member can be used. As the sponge, polyurethane foam such as maltoprene or color foam can be used. Further, both a sponge roller and a cleaning blade may be used.

  In the following description, a case where a cleaning blade is used as the cleaning member will be described, but the present invention is not limited to this.

(Regarding residual developer on developer carrier)
In the image forming apparatus as described above, a part of the liquid developer remains on the developer carrying member immediately after the end of image formation.

  By rotating the developer carrier, most of the liquid developer on the developer carrier can be removed by the cleaning device, but only a small part of the liquid developer passes between the cleaning blade and the developer carrier. Since it slips through, it is difficult to completely remove the liquid developer from the developer carrier.

<Toner sticking due to volatilization of carrier liquid>
When using a highly volatile carrier liquid that volatilizes at room temperature to suppress fixing energy, if the liquid developer remains on the developer carrier, the carrier liquid will gradually evaporate while the device is stopped. To do. If left as it is for a long time, the toner adheres to the developer carrying member, causing a problem in image quality during the next image formation.

  Before the apparatus is stopped, a volatile liquid lower than the carrier liquid (a non-volatile liquid at normal temperature is desirable. In the following description, this low-volatile liquid is referred to as a non-volatile liquid) is supplied onto the developer carrier. In this case, the surface of the developer carrying member is kept wet by the non-volatile liquid, so that even if the carrier liquid is volatilized, occurrence of sticking of the toner to the developer carrying member is suppressed.

  However, when the cleaning member for removing the liquid developer from the developer carrying member is used, the non-volatile liquid is also removed by the cleaning member, so that the cleaning member is viewed from the rotation direction of the developer carrying member. The non-volatile liquid is not supplied to the downstream side.

  As described above, part of the liquid developer slips between the cleaning blade and the developer carrying member, so that the toner remaining on the downstream side of the cleaning member as viewed from the rotation direction of the developer carrying member is stopped. There is a risk of sticking to the developer carrier.

(Application and method of non-volatile liquid)
In order to completely prevent the toner from adhering to the developer carrying member, the surface of the developer carrying member carrying the liquid developer as in the application means in this embodiment (details will be described later). It is necessary to apply the nonvolatile liquid over the entire surface.

There are the following methods for applying the non-volatile liquid over the entire surface of the developer carrying member carrying the liquid developer.
(1) When the non-volatile liquid is applied, the non-volatile liquid can be applied over the entire surface of the developer carrying body carrying the liquid developer by separating the cleaning member from the developer carrying body. . Or
(2) During the application of the non-volatile liquid, the non-volatile liquid can be applied over the entire surface of the developer carrying body carrying the liquid developer by rotating the developer carrying body in the opposite direction. Is possible.

(Non-volatile liquid at room temperature)
The liquid having a lower volatility than the carrier liquid used in the present invention can be judged by the length of the period until the liquid does not actually volatilize in a thin layer state. As described above, the low-volatile liquid is preferably a non-volatile liquid at room temperature. As the non-volatile liquid at room temperature, a liquid that does not evaporate for at least several days in a thin layer state is preferable.

As a measure of volatility, a liquid having a flash point of 120 degrees or more is preferable. Moreover, in order to apply as uniformly as possible on the developer carrying member, the viscosity should not be too high, and the kinematic viscosity is preferably 50 mm ² / s (40 ° C.) or less.

  For example, Moresco White P40, P70, P120, P200 (all manufactured by Matsumura Oil Research Co., Ltd.) can be used as the liquid that satisfies these conditions.

  Further, the normal temperature referred to in the present invention means not the room temperature at the place where the image forming apparatus is installed, but the temperature around which the developing apparatus and the temperature of the members of the developing apparatus can be normally taken. Depending on the configuration of the apparatus, the surroundings of the developing apparatus may be extremely hot or cold. A liquid with a higher flash point is preferable when the temperature around the developing device is high, and a liquid with a low flash point can also be used when the temperature around the developing device is low.

(Non-volatile liquid application means)
<Application means configuration example 1>
FIG. 5 is a schematic diagram for explaining a configuration example 1 of an application unit for applying the nonvolatile liquid over the entire surface of the developer carrier. FIG. 5a shows a case where the cleaning blade is not separated from the developer carrier when supplying the non-volatile liquid as a conventional example, and FIG. 5b is a case where the cleaning blade is separated.

  The non-volatile liquid sent from the non-illustrated non-volatile liquid storage tank through the non-illustrated liquid supply path is discharged from the non-volatile liquid supply nozzle 15. The discharged non-volatile liquid 16 is supplied onto the application roller 17 and applied onto the developer carrier 13 as the application roller 17 rotates.

  If the cleaning blade 12 remains pressed against the developer carrier 13 as shown in FIG. 5a, the non-volatile liquid applied on the developer carrier 13 is removed by the cleaning blade 12 as described above. It will be removed from the carrier 13. Accordingly, the non-volatile liquid is not applied to the downstream side of the cleaning blade 12 when viewed from the rotation direction of the developer carrier 13.

  On the other hand, when the cleaning blade 12 is separated from the developer carrier 13 and the non-volatile liquid supply nozzle 15 and the application roller 17 are operated as shown in FIG. 5b, the entire surface of the developer carrier 13 of the developer carrier 13 is operated. A non-volatile liquid can be applied.

  Thus, the non-volatile liquid supply nozzle 15, the application roller 17, and the cleaning blade 12 that is separated from the developer carrier 13 during application function as application means.

  As the application roller 17, in addition to a metal roller and a rubber roller, a sponge roller or a brush roller whose contact surface with the developer carrying member is a sponge shape or a brush shape can be used. In the case of a rubber roller, urethane rubber or silicone rubber can be used, and in the case of a sponge, polyurethane foam such as maltoprene or color foam can be used.

<Application means configuration example 2>
FIG. 6 is a schematic diagram for explaining another configuration example 2 of the coating unit, and after supplying the non-volatile liquid without separating the cleaning blade 12 to obtain the developer carrier shown in FIG. 13 is configured to rotate in the direction opposite to the normal direction.

  The non-volatile liquid supplied from the application roller 17 is also supplied to the portion not supplied in FIG. 5 a as the developer carrying member 13 rotates in the reverse direction.

  On the other hand, the non-volatile liquid damped to the tip of the cleaning blade 12 in FIG. 5a is again stretched and spread on the developer carrier as the developer carrier 13 rotates in the reverse direction.

  Thus, the non-volatile liquid can be applied over the entire surface of the developer carrying surface of the developer carrying body 13 by rotating the developer carrying body 13 in the reverse direction during the application.

  The non-volatile liquid supply nozzle 15, the application roller 17, and the developer carrier 13 that rotates in the reverse direction during application function as application means.

<Application example 3>
FIG. 7 is a schematic diagram for explaining another configuration example 3 of the coating unit, and the developer carrying member is a developing roller.

  In the developing device configured as shown in FIG. 2, the non-volatile liquid is first supplied onto the supply roller 47, and then moves from the supply roller 47 to the development roller 41. In this way, the non-volatile liquid is applied to the entire developer carrying surfaces of the supply roller 47 and the developing roller 41.

  Here, it is desirable to perform the non-volatile liquid application in a state where the supply roller 47 is not immersed in the liquid developer in the developer tank 49. When the supply roller 47 is immersed in the liquid developer in the developer tank 49, the non-volatile liquid on the supply roller 47 spreads into the developer tank 49, or a new liquid is applied to the supply roller 47 and the development roller 41. Since the developer is supplied, it is difficult to cover the supply roller 47 and the developing roller 41 with a non-volatile liquid.

  In order to prevent the supply roller 47 from being immersed in the liquid developer in the developer tank 49, each roller is stopped in a state where the supply of the liquid developer from the developer supply nozzle 42 is stopped prior to the non-volatile liquid application process. Rotate. Then, as the liquid developer in the developer tank 49 is pumped up to the supply roller 47, the liquid level in the developer tank 49 decreases, and the supply roller 47 is eventually separated from the liquid level in the developer tank 49. .

  Further, a liquid developer discharge port may be provided in the developer tank 49, and the liquid developer in the developer tank 49 may be discharged by the negative pressure of the pump.

  Further, the developer tank 49 may be moved away from the supply roller 47.

  The developer thin layer regulating blade 44 is a blade for scraping off excess liquid developer from the supply roller 47 and allowing only an appropriate amount of liquid developer to pass therethrough. Since it can pass between the layer regulating blade 44 and the supply roller 47, it may or may not be separated when the nonvolatile liquid is applied.

  Thus, the non-volatile liquid supply nozzle 15, the application roller 17, the developing roller cleaning device 46, and the supply roller 47 function as application means.

<Application Example Configuration Example 4>
FIG. 8 is a schematic diagram for explaining another configuration example 4 of the coating unit, and the developer carrier is also a developing roller.

  In the developing device configured as shown in FIG. 3, the non-volatile liquid is supplied onto the supply roller 47. Regarding the application of the nonvolatile liquid, there is no significant difference from the apparatus of FIG.

  Again, the non-volatile liquid supply nozzle 15, the application roller 17, the developing roller cleaning device 46, and the supply roller 47 function as application means.

<Application means configuration example 5>
FIG. 9 is a schematic diagram for explaining another configuration example 5 of the coating unit, and the developer carrier is also a developing roller.

  The difference from the configuration example of FIG. 8 is how the non-volatile liquid is supplied to the supply roller 47.

  That is, the non-volatile liquid is supplied from the same nozzle as the developer supply nozzle 42 or the non-volatile liquid is supplied from the non-volatile liquid supply nozzle 15 installed in the vicinity of the developer supply nozzle 42.

  As in the case of supplying a normal liquid developer, the non-volatile liquid is applied by forming a non-volatile liquid reservoir in a wedge-shaped area between the developer supply blade 43 and the supply roller 47.

  As described above, the non-volatile liquid supply nozzle 15 (42), the developer supply blade 43, the developing roller cleaning device 46, and the supply roller 47 function as an application unit.

  The advantage of using the configuration example of FIG. 9 is that the application roller 17 and the pressure contact / separation mechanism thereof as in the apparatus of FIGS. 5 to 8 are not required, and the apparatus can be downsized.

(Nonvolatile liquid application process)
FIG. 10 is a flowchart illustrating an example of a processing procedure of a process of applying a non-volatile liquid onto the developing roller 41. FIG. 11 is a flowchart showing a processing procedure example of the coating process when the developer carrying member is a photosensitive member or an intermediate transfer member.

  The timing of starting the non-volatile liquid application process may be set to start the non-volatile liquid application process immediately after the image formation is finished and the next image formation instruction is not given. It may be set to start after a lapse of a certain time from the end, or may be performed immediately before the apparatus is turned off, or in response to an input operation from the panel by the user.

  In the case of starting the non-volatile liquid application process after a lapse of a certain time from the end of image formation, for example, the non-volatile liquid application process is started when the next image formation instruction is not given for 5 minutes or more from the end of the most recent image formation. It should be set so that.

  In the case of starting the non-volatile liquid application process immediately before turning off the power of the apparatus, for example, when the user inputs a panel to turn off the power, the non-volatile liquid application process is performed and the power of the apparatus is automatically It can be set so that

  In the case of performing an input operation from the panel by the user, for example, when there is no plan to output an image for several hours, the user directly instructs the non-volatile liquid application and waits until the next image output. Can be used.

<Procedure example 1>
A processing procedure example 1 of a process of applying a non-volatile liquid on the developing roller 41 will be described with reference to FIG. The application means illustrates the case of the configuration example of FIG.

  When the nonvolatile liquid application process start signal is received (S11), first, when the liquid developer is being supplied from the developer supply nozzle 42, the supply is stopped (S12). Thereafter, the liquid developer is discharged from the developer tank 49 (S12) to prevent the supply roller 47 from being immersed in the liquid developer.

  Thereafter, each roller is rotated for a predetermined time, and most of the liquid developer on the supply roller 47 and the developing roller 41 is removed by the cleaning blade (S13). Next, a non-volatile liquid is supplied from the non-volatile liquid supply nozzle 15 (S14), then the application roller 17 is rotated (S15), and is brought into pressure contact with the supply roller 47 (S16). Thereafter, the cleaning blade 46 is separated from the developing roller 41 (S17). After rotating for a certain time, each roller is stopped (S18).

  Note that this flowchart is an example, and it is not necessary to strictly follow this order. For example, the supply of the nonvolatile liquid may be started after the cleaning blade is separated.

<Procedure example 2>
When a photosensitive member or an intermediate transfer member is assumed as the developer carrying member, the flowchart is as shown in FIG.

  10 is different from the procedure example in FIG. 10 because the supply of the non-volatile liquid to the supply roller 47 is not performed, so that the procedure for stopping the supply of the liquid developer and discharging the liquid developer from the developer tank 49 becomes unnecessary. And the application roller 17 is directly pressed against the developer carrier.

Example 1
The image forming apparatus shown in FIG. 1 is configured using the developing device shown in FIG.

  As a liquid developer, 75 parts of IP solvent 2028 (Idemitsu Kosan Co., Ltd.), 25 parts of pulverized toner, and 0.8 part of V220 (manufactured by ISP) as a dispersant were mixed and wet pulverized.

  The system speed is 400 mm / sec.

As the developing roller, a conductive rubber roller as shown below was used.
Diameter: 40mm
Material: NBR + carbon black Volume resistivity: 1.0 × 10 ⁶ Ω · cm
Rubber hardness: 40 °.

As the supply roller, an anilox roller as shown below was used.
Diameter: 40mm
Shape: 200 grid lines / inch
Volume: 20 ml / m ²
Push amount to developing roller: 0.1 mm.

  As the developer thin layer regulating blade, a SUS 0.3 mm blade was used.

  As a cleaning device for the developing roller, the photosensitive member, and the intermediate transfer member, a device using a cleaning blade as shown in FIG. 4 was used.

The cleaning blade (common conditions for the developing roller, photoconductor and intermediate transfer member) was set as follows.
Material: Silicon rubber Thickness: 3mm
Pressure contact angle: An angle pressure contact force of 20 degrees from a tangent to the member to be cleaned: 30 N / m to 50 N / m.

  As the nonvolatile liquid, Moresco White P120 (manufactured by Matsumura Oil Research Co., Ltd.) was used.

The application roller (common conditions for the developing roller, the photosensitive member, and the intermediate transfer member) was set as follows.
Material: Urethane sponge roller Density 30kg / m ³
Rotational speed: 400mm / sec (followed by developer carrier)
Diameter: 26 mm.

  Using a coating apparatus using the coating roller as described above, the non-volatile liquid can be applied to the developing roller, the photosensitive member, and the intermediate transfer member.

  For the developing device, the non-volatile liquid was applied with the configuration of the application means as shown in FIG.

  Immediately before the power of the apparatus was turned off, the nonvolatile liquid application operation was set to be performed according to the flow of FIGS.

  That is, after stopping the supply of the developer, the liquid developer is discharged from the developer tank, and then each roller is rotated for about 5 seconds to remove the liquid developer on the developer carrying member to some extent by the cleaning blade. While supplying the non-volatile liquid from the non-volatile liquid supply nozzle, the application roller was rotated.

  After that, the application roller is brought into pressure contact with the supply roller, and the cleaning blade is separated from the development roller and rotated at a peripheral speed of 50 mm / sec for 5 seconds to apply a non-volatile liquid to the supply roller and the development roller, and the apparatus is stopped. did.

  Similarly, the non-volatile liquid was applied to the photosensitive member and the intermediate transfer member in a state where the cleaning blade was separated from the developer carrying member.

  With the above settings, a reliability test was performed assuming actual usage. After performing an image forming operation using the apparatus, the power supply was turned off and left for 2 weeks. As described above, the non-volatile liquid application operation was performed immediately before the power was turned off.

  Two weeks later, the apparatus was turned on and image formation was performed. However, image defects caused by toner sticking to the developer carrying member did not occur, and high image quality could be maintained.

(Comparative Example 1)
(Same apparatus configuration as Example 1, but without blade separation)
As in Example 1, the non-volatile liquid application operation was performed immediately before the apparatus was turned off, but the cleaning blade was kept in pressure contact with the developer carrier during application of the non-volatile liquid. Except this point, the second embodiment is the same as the first embodiment.

  With the above settings, long-term tests were conducted assuming actual usage. After performing an image forming operation using the apparatus, the power supply was turned off and left for 2 weeks. As described above, the non-volatile liquid application operation was performed immediately before the power was turned off.

  Two weeks later, the apparatus was turned on and image formation was performed, but image density unevenness occurred. When the cause was examined, toner stuck to the developing roller was found.

  When the test was further continued with the above settings, toner sticking occurred on the photosensitive member and the intermediate transfer member after about one month, and image density unevenness was observed.

(Example 2)
(Same configuration as in Example 1, but reverse rotation instead of blade separation)
As in Example 1, the non-volatile liquid application operation was performed immediately before the apparatus was turned off. At the time of non-volatile liquid application, the developer carrier was rotated while the cleaning blade was kept in pressure contact with the developer carrier. After rotating in the same direction as the image formation at a speed of 50 mm / sec for about 5 seconds, it was further rotated in the reverse direction at a rotational speed of 50 mm / sec for about 5 seconds and then stopped. Except this point, the second embodiment is the same as the first embodiment.

  With the above settings, a neglect test was conducted assuming actual usage. After performing an image forming operation using the apparatus, the power supply was turned off and left for 2 weeks. As described above, the non-volatile liquid application operation was performed immediately before the power was turned off.

  Two weeks later, the apparatus was turned on and image formation was performed. However, image defects caused by toner sticking to the developer carrying member did not occur, and high image quality could be maintained.

(Example 3)
(Configuration using supply blade, supply of non-volatile liquid from developer supply nozzle)
The image forming apparatus shown in FIG. 1 is configured using the developing device shown in FIG.

  For the developing device, the nonvolatile liquid was applied with the configuration of the application means as shown in FIG. That is, at the time of applying the non-volatile liquid, the non-volatile liquid is supplied from the liquid developer supply nozzle instead of the liquid developer. Except for these points, the second embodiment is the same as the first embodiment.

  As in Example 1, a non-volatile liquid application operation was performed immediately before the apparatus was turned off.

  At the time of applying the non-volatile liquid, the cleaning blade of the developing roller is separated from the developer carrier.

  With the above settings, a neglect test was conducted assuming actual usage. After performing an image forming operation using the apparatus, the power supply was turned off and left for 2 weeks. As described above, the non-volatile liquid application operation to the developing roller was performed immediately before the power was turned off.

  Two weeks later, the apparatus was turned on and image formation was performed. However, image defects caused by toner sticking to the developer carrying member did not occur, and high image quality could be maintained.

  As described above, according to the image forming apparatus of the present embodiment, the surface of the developer carrier that carries and conveys the liquid developer in which the toner is dispersed in the highly volatile carrier liquid is lower than the carrier liquid. A coating means for applying a volatile liquid is provided, and the coating means applies a low-volatile liquid over the entire surface of the developer carrier carrying the liquid developer at a predetermined timing other than during image formation. Put it in a state.

  This enables fixing with low thermal energy, and at the same time, the carrier liquid component of the liquid developer remaining on the developer carrier after the completion of image formation volatilizes while the apparatus is stopped, and the toner sticks to the developer carrier. This can be prevented.

  In addition, the above-mentioned embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Photoconductor (image carrier) (developer carrier)
2 Charging device 3 Exposure device 4 Liquid developing device 5 Intermediate transfer member (developer carrier)
6 Photoconductor cleaning device 7 Transfer roller 8 Transfer object (paper)
DESCRIPTION OF SYMBOLS 9 Fixing device 10 Intermediate transfer body cleaning device 12 Cleaning blade 13 Developer carrier 14 Cleaning box 15 Non-volatile liquid supply nozzle 16 Non-volatile liquid 17 Application roller 41 Developing roller (developer carrier)
42 Developer Supply Nozzle 43 Developer Supply Blade 44 Developer Thin Layer Regulating Blade 45 Charger 46 Developing Roller Cleaning Device 47 Supply Roller 49 Developer Tank

Claims (7)

An image forming apparatus for developing a latent image with a liquid developer in which toner is dispersed in a carrier liquid to form a toner image,
A developer carrier for carrying and transporting the liquid developer to the surface for use in another member;
Cleaning means for removing the remaining liquid developer provided to another member from the surface of the developer carrier;
Application means for applying a liquid having a lower volatility than the carrier liquid to the surface of the developer carrying member from which the liquid developer is removed by the cleaning means;
The application means includes
The low-volatile liquid is applied to the entire surface of the at least one developer carrying member carrying the liquid developer at a predetermined timing other than during image formation. . The image forming apparatus according to claim 1, wherein the predetermined timing is after completion of image formation. The image forming apparatus according to claim 1, wherein the predetermined timing is a case where an image forming operation has not been performed for a predetermined time. The image forming apparatus according to claim 1, wherein the predetermined timing is immediately before the apparatus power is turned off. 5. The image forming apparatus according to claim 1, wherein when the low-volatile liquid is applied by the applying unit, the cleaning unit is separated from the developer carrier. 6. 5. The image according to claim 1, wherein the developer carrying member rotates in a direction opposite to that during image formation during application of the low-volatile liquid by the application unit. Forming equipment. The image forming apparatus according to claim 1, wherein the low-volatile liquid has a flash point of 120 ° C. or higher.

Images