JP2003091161A - Liquid image forming apparatus and method for regulating liquid film of developed image in liquid image forming apparatus - Google Patents

Abstract

(57) Abstract: A liquid image forming apparatus capable of favorably forming images on various transfer materials when a liquid developer having a higher viscosity and a higher concentration than a conventional liquid developer is used. Provided is a method for regulating a liquid film of a developed image in a liquid image forming apparatus. A sweep roller as a surplus liquid removing member that contacts a photosensitive drum and moves in the same direction at substantially the same speed as the surface of the photosensitive drum.
And a control unit 118 for controlling the eccentric cam 113 and the like based on the properties of the transfer paper P, for making the liquid removing force of the sweep roller 110 variable. The liquid removing force of the sweep roller 110 is switched based on the properties of the transfer paper P, and the liquid film is regulated by removing the excess liquid developer by an amount to be removed. Since the sweep roller 110 is in contact with the photosensitive drum 1, high-viscosity and high-concentration liquid developer, which is difficult to remove, can be easily removed, and the mechanical accuracy of the sweep roller 110 and the photosensitive drum 1 is maintained. Becomes easier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid image forming apparatus such as a copying machine, a facsimile and a printer and a liquid film regulating method for a developed image in the liquid image forming apparatus. A latent image forming unit that forms a latent image on the latent image carrier and a high-viscosity and high-concentration liquid developer in which toner is dispersed in a carrier liquid are used to form the latent image formed on the latent image carrier. Developing means for developing the image to make it visible, excess liquid removing means for removing the excess liquid developer on the latent image carrier to regulate the liquid film after the developing, and developing means on the latent image carrier. The present invention relates to a liquid image forming apparatus having a transfer unit that transfers an image to a transfer material, and a liquid film regulating method for a developed image in the liquid image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a latent image formed on a latent image carrier is formed into a developed image by a developing means using a developing solution in which toner is dispersed in a carrier solution, and the developed image is directly transferred to a transfer material. Alternatively, a liquid image forming apparatus is known which transfers to a transfer material via an intermediate transfer member. The case of directly transferring the latent image formed on the latent image carrier to the transfer material will be described below. As a method for transferring the developed image, a method is generally used in which a transfer material is brought into contact with a developed image formed by using the developing solution by a transfer roller, and a transfer bias having a polarity opposite to that of the toner is applied to the transfer roller to perform the transfer. Target.

In such a liquid image forming apparatus,
A developer layer is formed on the surface of the latent image carrier that has passed through the developing area. If this developer layer is too thick, that is, if the carrier liquid or toner is too much, the adhesiveness between the developer layer and the transfer material will be poor even if the transfer material is transferred onto the surface of the latent image carrier, and sufficient toner will not be obtained. The transfer rate may not be obtained, or image drift or thick characters may occur. In addition, the consumption amount of the carrier liquid is increased and the running cost is increased. On the other hand, when the amount of the carrier liquid is too small, the transfer by electrophoresis becomes difficult and the image density is lowered, or the image density is lowered and the white spots are generated only in a portion of the transfer material corresponding to the concave and convex portions of the surface. Therefore, an appropriate amount of carrier liquid that does not cause such a problem is left, and excess carrier liquid is swept (removed) by using a surplus liquid removing unit composed of a sweep roller or the like.

In recent years, the types of paper used as a transfer material have been increasing. In particular, in order to form a full-color image, the use of coated paper coated with a coating agent to improve whiteness and smoothness has also been studied. In the case of forming an image on such various types of paper, various process conditions for liquid image formation such as the removing power of the excess liquid removing unit and the developing amount of the developing unit are fixedly set as in the conventional case. Then, depending on the paper, the above-mentioned problem may appear remarkably.

That is, when an image is formed on a paper which does not easily absorb the carrier liquid, a paper having a smooth surface, or a paper having a high degree of surface coating (a large amount of coating agent is applied), various conditions are required. However, if the conventional setting values were set assuming normal plain paper for copying, which belongs to a paper that is rough and easily absorbs the carrier liquid, thickening of the character portion and image blurring at the trailing edge of the solid portion are remarkable. In order to form a good image without thickening of characters on such paper, changing some setting values of the above various process conditions makes it easier to absorb carrier liquid, paper with rough surface or surface coating. When forming an image on paper with a low level of work, the image density may be partially reduced or the white spots may be lost due to the recesses on the paper surface.
Alternatively, a uniform decrease in image density was noticeable.

Therefore, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 8-29741.
In Japanese Patent Laid-Open No. 8 (1999), the excess developing solution removing means is configured to have a variable solution removing force, and the liquid removing force is switched based on the property of the transfer material to regulate the liquid film. A method for controlling the liquid film of an image was proposed. In this method of controlling the liquid film of the developed image, the excess developer removing means is
The latent image carrier may be constituted by a squeeze roller that is arranged to face the surface of the latent image carrier at a predetermined interval and rotates in the same direction as the latent image carrier, or may be spaced from the surface of the latent image carrier at a predetermined interval. For example, the slit nozzles are arranged so as to face each other and eject compressed air.

[0007]

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention
The liquid film regulation method of the developed image proposed in Japanese Patent No. 418 discloses a low-viscosity and low-concentration developer, for example, 1 to 2 in an insulating liquid carrier manufactured by Exxon Co. known under the trade name of Isopar.
1 [mPa · containing a toner having a concentration of about [wt%]
This is an effective method when a developer having a viscosity of about [s] is used. However, in recent years, use of a high-viscosity and high-concentration developing solution has been studied as compared with the low-viscosity and low-concentration developing solution. The high-viscosity and high-concentration developer is, for example, about 5 to 40 [wt%] in an insulating liquid carrier such as silicone oil, normal paraffin, IsoparM (trade name: manufactured by Exxon), vegetable oil, or mineral oil. The developing solution has a viscosity of about 50 to 10000 [mPa · s] and contains a toner having a concentration of. When this high-viscosity and high-concentration developer is used, it has a high viscosity and a small amount is attached to the latent image carrier. Therefore, in the liquid film regulation method proposed in JP-A-8-297418, etc. Will be difficult to regulate. For example, because of its high viscosity, it is not easy to remove it by ejecting compressed air from a slit nozzle. In addition, because of the high concentration, the liquid film that adheres to the latent image carrier after development is thin, so in a squeeze roller that is placed facing each other at a predetermined interval, the squeeze roller contacts the carrier liquid layer on the latent image carrier. It is difficult in terms of mechanical accuracy to configure the structure.

The present invention has been made in view of the above background, and it is an object of the present invention to perform various transfer operations when a liquid developer having a high viscosity and a high concentration is used as compared with a conventional liquid developer. A liquid image forming apparatus capable of forming an image on a material satisfactorily, and a method for regulating a liquid film of a developed image in the liquid image forming apparatus.

[0009]

In order to achieve the above-mentioned object, the invention of claim 1 provides a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a carrier liquid. Using a high-viscosity and high-concentration liquid developer in which toner is dispersed in
Developing means for developing the latent image formed on the latent image carrier to make it visible, and excess liquid for removing the excess liquid developer on the latent image carrier after the development to regulate the liquid film. In a liquid image forming apparatus having a removing means and a transferring means for transferring a visible image on the latent image carrier to a transfer material, the surplus liquid removing means comprises:
A surplus liquid removing member which comes into contact with the latent image carrier and moves in the same direction as the surface of the latent image carrier in the same direction, and a liquid removing device for varying the liquid removing force of the surplus liquid removing member. It is characterized by having a force varying means and a control means for controlling the liquid removing force varying means based on the property of the transfer material.

In order to achieve the above object, the invention of claim 7 is a high-viscosity and high-concentration liquid developing method in which toner is dispersed in a carrier liquid on the surface of a latent image carrier on which a latent image is formed. Development in a liquid image forming apparatus that supplies a developing agent to develop the latent image, and then removes the excess liquid developer on the latent image carrier by the excess liquid removing unit to regulate the liquid film and transfer it to a transfer material. In the image liquid film regulation method, the surplus liquid removing member is configured by using a surplus liquid removing member that comes into contact with the latent image carrier and moves in the same direction as the surface of the latent image carrier in the same direction. In addition, the excess liquid removing means is configured to have a variable liquid removing force, and the liquid removing force is switched based on the property of the transfer material to regulate the liquid film.

A liquid image forming apparatus according to claim 1 and claim 7
In the liquid film regulation method for the developed image in the liquid image forming apparatus, the liquid removing force of the excess liquid removing member that contacts the latent image carrier is switched based on the property of the transfer material, and the amount to be removed according to the transfer material. Only the excess liquid developer is removed to regulate the liquid film. Since the excess liquid removing member is in contact with the latent image carrier, it is possible to easily remove the high-viscosity and high-concentration liquid developer which is difficult to remove by, for example, ejecting compressed air from the slit nozzle. Further, since the excess liquid removing member is brought into contact with the latent image carrier, the mechanical precision is maintained at a higher precision than the conventional structure in which the squeeze roller is opposed to the latent image carrier at a predetermined interval. You don't have to. In addition,
The surplus liquid removing member moves in the same direction as the surface of the latent image carrier in the same direction, and therefore does not disturb the developed image on the latent image carrier. Switching the liquid removal force based on the properties of the transfer material can be performed, for example, for a transfer material that does not easily absorb the carrier liquid, a transfer material with a smooth surface, or a transfer material with a high degree of surface coating, that is, a surface coating amount is large. When forming an image, switching is performed so that the removal force is increased. On the other hand, when the image is formed on a transfer material that easily absorbs carrier liquid, a transfer material with a rough surface, or a transfer material with a low surface coating amount, that is, a surface coating amount is small, the removal power becomes smaller. To switch.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A printer using an electrophotographic liquid developer as an image forming apparatus according to the present invention (hereinafter, referred to as
An embodiment applied to a printer) will be described.

First, the basic construction of this printer will be described. FIG. 1 is a schematic configuration diagram of a main part of the printer according to the present embodiment. In the figure, this printer includes a charger 2 around a photosensitive drum 1 as a latent image carrier.
0, an exposure device (not shown) for irradiating the photosensitive drum 1 with the exposure light L, a liquid developing device 100, a transfer device including an intermediate transfer belt 31, a transfer roller 32, a charge eliminating lamp 40, a drum cleaning device 50, and the like. There is.

The surface of the photosensitive drum 1 is formed of amorphous silicon (a-Si), and is rotated in the direction of the arrow in the figure by a driving means (not shown) during printing.

The charger 20 uniformly charges the surface of the photosensitive drum 1 which is rotationally driven in the dark by corona discharge. In this embodiment, it is charged to about 600V. As the charging device 20, in addition to a device that realizes charging by corona discharge in this way, a device that applies a predetermined charging bias to a charging member such as a charging roller brought into contact with the photosensitive drum 1 may be used. Good.

The above-mentioned exposure apparatus is provided with a scanning optical system, and the photosensitive drum 1 uniformly charged by the charger 20.
An image data light image L is exposed to the surface of the image data LED light or laser light based on the image information to carry an electrostatic latent image.

The liquid developing device (hereinafter, simply referred to as developing device) 100 develops the electrostatic latent image by attaching charged toner to the electrostatic latent image. As a result, a toner image is formed on the photosensitive drum 1.

The transfer device has an intermediate transfer belt 31 shown in FIG. 1, a transfer roller 32 for stretching the intermediate transfer belt 31, a plurality of stretching rollers 33, and a polarity opposite to the charging polarity of the toner on the transfer roller 32. A power supply (not shown) for applying a transfer bias is provided, and the intermediate transfer belt 31 is endlessly moved in the direction of the arrow in the drawing during printing. Further, the intermediate transfer belt 31 is pressed by the transfer roller 32 toward the photoconductor drum 1 to form a transfer nip. In the transfer nip, a transfer electric field is formed by the potential difference between the transfer roller 32 to which the transfer bias is applied and the surface of the photosensitive drum 1. The toner image that has entered the transfer nip with the rotation of the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 31 under the action of the transfer electric field and the nip pressure. As the transfer device, it is possible to use a transfer device that uses such a transfer roller, or a device that transfers a toner image by corona discharge, adhesion, heat, or the like.

The toner image primarily transferred in this manner is secondarily transferred to the transfer paper P by the secondary transfer roller 34 and then subjected to heat pressure fixing, solvent fixing, UV fixing or the like in an area (not shown). It is fixed by a fixing device using a fixing method. The transfer sheet on which the toner image has been fixed is discharged from the fixing device to the outside of the apparatus via the discharge path.

The discharging lamp 40 discharges the residual charge on the surface of the photosensitive drum 1 which has passed through the transfer nip.

In the drum cleaning device 50, the cleaning blade 51 removes the liquid developer remaining on the surface of the photosensitive drum 1 that has been neutralized by the static elimination lamp 40.
Scrape off with. By this removal, the surface of the photoconductor drum 1 is initialized and the next image formation can be realized.

Next, the structure of the developing device 100 will be described. The developing device 100 includes a developing unit 109 and a sweep unit 112. This developing unit 109 is
Tank part 101, a pair of stirring screws 102, 10
3, Anilox roller 104, doctor blade 10
5, developing roller 106, cleaning blade 107,
The feedback unit 108 and the like are provided. In addition, the sweep unit 1
Reference numeral 12 includes a sweep roller 110, a cleaning blade 111, a carrier collecting device, and the like.

A liquid developer 60 containing toner and a liquid carrier is stored in the tank portion 101.
The liquid developer 60 is not a low-viscosity and low-concentration agent that is widely used in general liquid developing apparatuses, but a high-viscosity and high-concentration agent. The low-viscosity and low-concentration liquid developer is, for example, Iso that is widely available on the market.
This is a liquid developer having a viscosity of about 1 [mPa · s] containing a toner having a concentration of about 1 [wt%] in an insulating liquid carrier called par (trade name: manufactured by Exxon Corporation).
Further, the high-viscosity and high-concentration liquid developer means, for example, 5 to 40 [wt% in an insulating liquid carrier such as silicone oil, normal paraffin, IsoparM (trade name: manufactured by Exxon), vegetable oil, or mineral oil. ] A liquid developer having a viscosity of about 50 to 10,000 [mPa · s] containing a toner having a concentration of about []. The volatility or nonvolatility of the high-viscosity and high-concentration liquid developer 60 used in the developing device 100 is adjusted according to the developing performance of the developing device 100 and the image forming performance of the printer. Here, when the liquid developer is volatile, it is more advantageous for fixing as compared with the case where it is non-volatile, but if the device is not used for a while, the toner sticks in the device and the load on the device when restarted. May increase. On the other hand, when the liquid developer is non-volatile, the toner does not stick to the inside of the device even if the device is not used for a while, and there is no possibility that the burden on the device at the time of restarting will increase. Further, the particle diameter of the toner in the liquid developer 60 is also adjusted in the range from submicron to about 10 [μm] according to the developing performance and the image forming performance.

The pair of stirring screws 102 and 103
Are arranged in parallel with each other so as to be immersed in the liquid developer 60 in the tank portion 101, and are rotationally driven in opposite directions by a driving means (not shown) as indicated by an arrow in the figure. When the developing device 100 starts the developing operation, the screws 102 and 103 rotate in the opposite directions as described above,
The liquid developer 60 in the tank portion 101 is agitated. By this stirring, the liquid developer 60 has uniform toner concentration and viscosity. Also, the screws 102, 10
When 3 rotates in opposite directions, the liquid level of the liquid developer 60 rises between the two as shown in the figure, and adheres to the anilox roller 104 disposed above it.

The anilox roller 104 as an application roller pumps up the liquid developer 60 thus attached while being rotationally driven in the direction of the arrow in the figure by a driving means (not shown). This anilox roller 10
A plurality of concave portions (not shown) are formed on the peripheral surface of No. 4. A part of the liquid developer 60 drawn up by the anilox roller 104 is accommodated in this recess.

The doctor blade 105 as a regulating blade is formed of metal such as stainless steel, and scrapes off the liquid developer 60 on the anilox roller 104 by contacting the rotating anilox roller 104. By this scraping, the liquid developer 6 on the anilox roller 104 is
The amount of 0 is accurately measured to a value corresponding to the capacity of the plurality of recesses.

As shown in FIG. 1, the developing roller 106 is in contact with the surface of the anilox roller 104 that has passed through the contact portion with the doctor blade 105, and the surface thereof is different from the anilox roller 104 at the contact portion. Rotate to move in the opposite direction.

Developing roller 106 and anilox roller 10
At the application nip, which is the contact position with 4, the rollers contact each other while moving in the counter direction, and the liquid developer 60 on the anilox roller 104 is accurately measured regardless of its viscosity. , Developing roller 10
It is possible to form a thin developer layer having a uniform thickness in 6-shape.

Further, at the exit side of the coating nip, the developing roller 1
While the supply of the liquid developer to 06 is started, the liquid developer transferred onto the developing roller 106 moves in the direction opposite to the supply direction. With such a configuration, if the maximum pressure in the coating nip is a certain value or more, the thickness of the thin developer layer on the developing roller 106 does not depend on the maximum pressure value. Therefore, it is possible to suppress the uneven thickness of the thin developer layer due to the uneven pressure in the coating nip.

As a result, such application forms a thin developer layer of the uniform thickness of the liquid developer 60 on the surface of the developing roller 106.

The developing roller 106 is provided with a conductive elastic layer made of conductive urethane rubber or the like on its peripheral surface.
While rotating at the same speed as the photoconductor drum 1, it contacts the photoconductor drum 1 to form a developing nip. A developing electric field is formed in the developing nip by a potential difference between the developing roller 106 to which a developing bias having the same polarity as the toner charging polarity is applied from a power source (not shown) and the photosensitive drum 1. Specifically, in the developing nip, the developing roller 106, the background portion of the photosensitive drum 1 and the electrostatic latent image each have a potential of the same polarity as the toner, and the values thereof are the background portion, the developing roller 106 and the electrostatic latent image. It becomes lower in order. Therefore, an electric field that electrostatically moves the toner toward the developing roller 106 having a lower potential is formed between the background portion and the developing roller 106. Further, between the developing roller 106 and the electrostatic latent image,
An electric field is formed which moves the toner towards the lower potential electrostatic latent image. In the developing nip in which such a developing electric field is formed, the toner in the developer thin layer is electrophoresed and collected between the developing roller 106 and the background portion toward the surface of the developing roller 106, and Electrophoresis is performed between the developing roller 106 and the electrostatic latent image toward the electrostatic latent image to adhere. By this adhesion, the electrostatic latent image is developed into a toner image.

FIGS. 3A and 3B are diagrams schematically showing the state of the developer 60 in the developing nip. The developing roller 106 has a photosensitive member surface potential (600 V).
A lower developing bias voltage (400 V) is applied, and in the image part, between the part exposed to light of 50 V or less by the exposure device and in the non-image part, between the charged photoconductor surface potential. A developing electric field is generated. In the image portion of the photoconductor drum 1, as shown in FIG. 3A, the toner 60a in the developer moves to the photoconductor drum 1 side by the electric field to visualize the latent image. On the other hand, in the non-image part, FIG.
As shown in FIG. 3, the toner 60a in the developer is attracted to the surface side of the developing roller 106 by the electric field formed by the developing bias potential and the photosensitive member surface potential (hereinafter referred to as the non-image area electric field), and is transferred to the non-image area. Try to avoid leaving the toner 60a.

The cleaning blade 107 is made of a material such as metal or rubber, and abuts on the surface of the developing roller 106 after passing through the developing nip to scrape off the residual developer from the surface. Here, the cleaning member for cleaning the developing roller 106 is not limited to the cleaning blade described above, but may be a roller. By this removal, the surface of the developing roller 106 is initialized. The removed residual developer returns to the tank unit 101 via the return unit 108. Also, a plurality of developing rollers may be provided.

The developing section 109 is configured to develop the electrostatic latent image on the photosensitive drum 1 in this way.

In the developing nip, it is necessary to secure a developing time (a nip passage time of the thin developer layer) that allows the toner to be sufficiently electrophoresed. This developing time depends on the width of the developing nip and the process linear velocity which is the peripheral velocity of the photosensitive drum 1 and the developing roller 106.
In the printer according to this embodiment, the developing time is secured by setting the width of the developing nip to a value equal to or larger than the product of the process linear velocity and the developing time constant. This development time constant is the time required for the development amount to saturate,
It is a value obtained by dividing the process linear velocity by the width of the minimum development nip required for saturation of the development amount. For example, the process linear velocity is 300
[Mm / sec] and development time constant is 10 [msec]
Then, the width of the developing nip is 3 [mm]. In addition,
The width of the removal nip, which will be described later, is set in the same manner.

As described above, the developing roller 1 in the developing nip.
Between 06 and the background portion, the toner in the developer thin layer electrophoresically collects toward the surface of the developing roller 106, and therefore theoretically does not adhere to the background portion. However, there is a case in which a toner having a smaller charge amount than usual is electrophoresed later than other toners and adheres to the background portion to cause a phenomenon called so-called fog (background stain).

The sweep section 112 has a function of removing the fog toner causing such fog from the photosensitive drum 1. Specifically, the sweep unit 11
The sweep roller 110 of No. 2 is provided with a conductive elastic layer made of conductive urethane rubber or the like on its peripheral surface,
The removal nip is formed by contacting the photosensitive drum 1 while rotating at substantially the same speed as the photosensitive drum 1. A sweep electric field is formed in the removal nip by a potential difference between the sweep roller 110 to which a removal bias having the same polarity as the charging polarity of the toner is applied from a power source (not shown) and the photosensitive drum 1. Figure 4
(A) and (b) are photoconductor drum 1 and sweep roller 1
FIG. 6 is a diagram schematically showing a state of the developer at the removal nip formed by 10 and.

To the sweep roller 110, the toner layer surface potential (10) on the photosensitive drum 1 is set so that the toner 60a from the toner layer after development is not returned to the sweep roller 110.
A bias voltage (250V) close to 0 to 200V is applied. In the non-image part, as shown in FIG.
The floating fog toner 60c is moved to the sweep roller 110 by the electric field generated by the difference between the potential of the non-image portion of the photosensitive drum 1 and the potential of the bias voltage. As a result, the fog on the non-image area can be completely prevented. As a result, the fog toner that could not be collected on the surface of the developing roller 106 at the developing nip is electrophoresed toward the sweep roller 110 between the background portion and the sweep roller 110, and is removed from the photosensitive drum 1. . Further, by installing the sweep roller 110, it is possible to remove about 70% of the excess carrier liquid adhered to the non-image portion on the photosensitive drum 1 during development. Since the sweep roller 110 moves in the same direction as the surface of the photosensitive drum 1 in the same direction, it does not disturb the toner image on the photosensitive drum 1.

The cleaning blade 111 is made of a member such as metal or rubber, and comes into contact with the surface of the sweep roller 110 after passing through the removal nip,
Residual developer is scraped off from this surface. By this removal, the surface of the sweep roller 110 is initialized.

The surface of each of the developing roller 106 and the sweep roller 110 is coated with a conductive material or a conductive tube to have a smoothness of Rz of 3 [μm] or less. It is desirable to configure so that it can exert its effect. This is because in order to make the developing roller 106 and the sweep roller 110 carry a thin developer layer having a uniform thickness of about 3 to 10 [μm], it is necessary to exhibit such smoothness.

The material of the conductive elastic layer of the developing roller 106 and the sweep roller 110 is JIS-A.
It is desirable to use one having a hardness of 50 degrees or less.
While the surface of the photosensitive drum 1 is formed of a-Si having a high hardness, in order to secure the developing nip and the removing nip having a desired width, the conductive elastic layer is formed with a hardness of 50 [degrees] or less. This is because it is necessary to freely transform it. The softer the toner, the wider the adjustment range of the developing nip becomes. However, if it is too soft, defects such as plastic deformation may occur, which is not preferable. Further, the material of the conductive elastic layer is not limited to the above-mentioned conductive urethane rubber (made conductive by mixing carbon etc.), but it exhibits conductivity and swells with a liquid carrier. Any substance that does not dissolve may be used. Also, the developing roller 1
06 and the surface of the sweep roller 110 are electrically conductive, and are materials that do not swell or dissolve in the carrier liquid / developer, and the inner layer does not come into contact with the carrier liquid / developer. The material of each elastic layer, which is the inner layer, may be elastic as long as there is no restriction on the conductivity and the swelling and dissolution.

Next, the characteristic structure of this printer will be described. In this printer, the amount of carrier liquid removed from the thin developer layer formed on the photosensitive drum 1 after development is variable so that the amount of carrier liquid contained in the thin developer layer can be changed to The amount is controlled to be the optimum amount according to the property.

[Embodiment 1] In FIG. 1A, the sweep portion 112 is movable by a eccentric cam 113 in the right and left directions in the drawing within a predetermined range. In the illustrated example, the sweep unit 109 is moved to the right to the maximum, and the sweep roller 110 is in contact with the photosensitive drum 1. Since the sweep portion 112 is always urged by the tension spring 114 so as to be pulled to the left side in the figure,
By rotating the eccentric cam 113, the sweep portion 112
Moves left and right. The eccentric cam 113 is the worm gear 11
It is adapted to be driven by the stepping motor 116 via the No. 5. The stepping motor 116 is provided with a resolver 116a as a rotational position detecting device, and the rotation is controlled by the control unit 118 based on the operation of the operation panel 117. It should be noted that FIG. 1B is an enlarged view of part A in FIG.

The example of FIG. 1A shows a state in which the sweep roller 110 is in contact with the photosensitive drum 1 with the sweep portion 109 moved rightward as much as possible, as described above. More specifically, as shown in FIG. 2C, the elastic conductive layer 110a is largely elastically deformed to form a large removal nip width N1 (for example, 3 mm). With this removal nip width N1, most carrier liquid can be removed from the thin developer layer formed on the photosensitive drum 1. For example, it is suitable when a coated paper is used as the transfer paper. At this time, the sweep roller ON display LED 121b having a large nip width in FIG. 1B is turned on.

In the printer having the above structure, in the printer of the present embodiment, the operator operates the operation panel 117 according to the kind of the paper set as the transfer material by setting the paper cassette or the manual paper feed tray (not shown) of the printer. , Switching of the removal nip width or separation of the sweep roller 110 from the photosensitive drum 1 is selected. When setting a transfer paper with a rough surface roughness, a transfer paper with good liquid absorption, a non-coated paper or a transfer paper with a low degree of coating, for example rough paper, it is necessary to attach a relatively large amount of developer, so The separation of the sweep roller 110 from the photosensitive drum 1 is selected. Specifically, the operator operates the operation panel 1 shown in FIG.
The sweep roller ON / OFF button 119 of 17 is pressed once. Then, in FIG. 1A, the control unit 118 rotationally drives the stepping motor 116 so that the eccentric cam 113 rotates in the CCW direction by a predetermined angle, and
The sweep roller OFF display LED 120 in (b) is turned on. Then, the sweep portion 112 is moved to the left by the tensile force of the tension spring 114, and the sweep roller 110 is separated from the photosensitive drum 1 as shown in FIG. In this state, the sweep roller 110 does not remove the excess carrier liquid from the thin developer layer formed on the photoconductor drum 1, but a high-quality image can be formed when rough transfer paper having good hygroscopicity is used as the transfer paper. .

On the other hand, when setting the transfer paper having the hygroscopicity of the carrier liquid between the rough paper and the coated paper, for example, plain paper, the operator presses the sweep roller ON / OFF button 119 once again. Then, in FIG. 1A, the control unit 118 rotationally drives the stepping motor 116 so that the eccentric cam 113 rotates in the CW direction by a predetermined angle, and at the same time, the sweep roller ON display with the small nip width in FIG. 1B is displayed. The LED 121a is turned on. Then, as shown in FIG. 2B, the sweep roller 110 comes into contact with the photosensitive drum 1 and the elastic conductive layer 110a is slightly elastically deformed to form a small removal nip width N2 (for example,
1.5 mm). The removal nip width N2 has a smaller amount of carrier liquid removed than the removal nip width N1, but is suitable for the case where plain paper or the like is used as the transfer paper. In addition,
In this state, the operator turns the sweep roller ON / OFF
When the button 119 is pressed once again, the eccentric cam 113 further rotates in the CW direction by a predetermined angle to move the sweep portion 112 to the maximum rightward, and again the large removal nip width N1 is formed.

The pressure at the time of contact of the sweep roller 110 with respect to the photosensitive drum 1 may be changed without changing the pressure. In this case, the conductive elastic layer 110 is formed on the surface of the sweep roller 110.
a is not formed, the photosensitive drum 1 and the sweep roller 110
Both surface portions of and may be rigid bodies.

Here, the thickness of the liquid developer thin layer formed on the photosensitive drum 1 after development is preferably 20 μm or less, more preferably 10 μm or less. Sweep roller 110
When the removing nip is formed by bringing the liquid developer into contact with the photosensitive drum 1, it depends on the relationship between the pressure of contacting the sweep roller 110 with the photosensitive drum 1 and the viscosity of the liquid developer. If it is thicker than 20 μm, it becomes difficult for the liquid developer film to penetrate into the removal nip of both, and the photosensitive drum 1
This is because the film thickness of the upper liquid developer may be reduced and thinned. On the other hand, the thinner the film, the higher the electric field due to the lower potential difference, and the less the toner in the image area is removed,
Excess liquid can be removed. As a result, it is possible to form a good image without transfer defects, thick characters, trailing edge of the image, etc. without lowering the image density.

The weight ratio of the carrier liquid in the liquid developer on the surface of the photosensitive drum 1 after development can be said to be the same as the above film thickness. That is, the weight ratio of the carrier liquid in the liquid developer on the surface of the photosensitive drum 1 after development is preferably 85% or less. This depends on the relationship between the pressure at which the sweep roller 110 contacts the photosensitive drum 1 and the viscosity of the liquid developer, but the viscosity of the carrier liquid is lower than the solid toner content, and the carrier liquid ratio in the liquid developer is 85%. If it is too high, the viscosity of the developer as a whole becomes low, it becomes difficult for the liquid developer film to penetrate into the removal nip of both, and the liquid developer film on the photoconductor drum 1 is scraped off, and the liquid developer film on the photoconductor drum 1 is developed. This is because the developed developer film may be reduced.

[Embodiment 2] Compared to Embodiment 1, the carrier liquid can be removed more accurately, and more optimal transfer can be performed on various types of transfer paper. Figure 5
(A) is a schematic configuration diagram when two sweep parts are provided,
(B) is an enlarged view of a B part in (a). In addition to the sweep unit 112 (hereinafter, referred to as “first sweep unit” in the present embodiment) 112 of the first embodiment, the second sweep unit 12 having the same configuration.
2 was provided. Further, the operation panel 117 is provided with an operation unit of the second sweep unit 122 in addition to the operation unit of the first sweep unit 112. The second sweep unit 122 operates in conjunction with the first sweep unit 112, and the first sweep unit 112
The sweep roller 110 of the second sweep section 122 is provided only when the sweep roller 110 of FIG.
23 is controlled so as to contact the photosensitive drum 1. That is, when the sweep roller 110 of the first sweep unit 112 is separated from the photosensitive drum 1, the sweep roller 123 of the second sweep unit 122 does not contact the photosensitive drum 1 by itself. ing. Other than this operation, since it is the same as the first sweep unit 112, a detailed description of the second sweep unit 122 will be omitted. For example,
A removal nip width formed between the sweep roller 110 of the first sweep unit 112 and the photosensitive drum 1, and a second
The removal nip width formed between the sweep roller 123 of the sweep portion 122 and the photosensitive drum 1 is 1.0 mm when the removal nip width is small and 2.5 mm when the removal nip width is large. Then, these sweep parts 1
12 and 122 are combined and the removal nip width is 1.0m
m, 2.5 mm, 3.5 mm, 5.0 mm can be set to four different sizes, and the removal nip width is set to two different settings. The amount of liquid removed can be controlled.

In this embodiment, both of the two sweep rollers 110 and 123 are arranged so that they can be brought into contact with and separated from the photosensitive drum 1, but if at least one sweep roller can come into contact with and separate from the photosensitive drum 1, the transfer can be performed. It is possible to obtain the effect of switching the amount of liquid removed from the photosensitive drum 1 according to the property of the material.

[Embodiment 3] A sweep belt may be used in place of the sweep roller described in Embodiment 1. FIG. 6 is a schematic configuration diagram in which a sweep belt is used as the excess liquid removing means. The sweep portion 124 according to the present embodiment is a sweep belt 1 whose surface moves endlessly.
25, a drive roller 126 that stretches and rotates the sweep belt, a pair of driven rollers 127 and 128, and a cleaning blade 129 that cleans the developer adhering to the sweep belt 125. By using the sweep belt 125, the removal nip width can be made wider than in the case of the sweep roller. In addition, the space of the sweep portion can be made smaller than that of the configuration in which the two sweep portions are provided as described in the second embodiment, so that the layout of each constituent element is free. As described above, when the removal nip width is widened, the removal bias is applied for a long time, and the excess carrier liquid can be removed without removing the toner in the image area.

The removal nip width is adjusted by changing the distance between the pair of driven rollers 127 and 128. For example, the driven roller 127 on the rear end side of the removal nip is movably supported along the surface of the photosensitive drum, and the distance between the driven roller 128 and the driven roller 128 on the front end side of the removal nip can be changed. When the transfer paper is coated paper having poor absorbency, the driven roller 1 on the rear end side of the removal nip is used.
27 is separated from the driven roller 128 on the front end side to widen the distance between the pair of driven rollers. On the other hand, when the transfer paper is plain paper having better hygroscopicity than coated paper, the driven roller 127 on the rear end side of the removal nip is replaced with the driven roller 128 on the front end side.
To reduce the distance between the pair of driven rollers. The slack of the sweep belt 125 is adjusted by a tension roller (not shown). Further, the removal nip width may be adjusted by moving the entire sweep portion 124 left and right in the figure. If the transfer paper is a rough paper having good hygroscopicity, the entire sweep portion 124 may be moved to the left side in the drawing to separate the sweep belt 125 from the photosensitive drum 1.

[Embodiment 4] When the voltage applied to the sweep roller as a surplus liquid removing member is changed, the liquid removal amount is changed, and as shown in FIGS. 7 and 8, the liquid on the photosensitive member after the sweep is changed. The adhesion amount changes. FIG. 7 shows the relationship between the amount of liquid adhered to the image area and the non-image area on the photoconductor and the sweep bias value when the number of sweep rollers is one (Example 1). FIG. 8 shows a case where there are two sweep rollers (Example 2).
3 shows the relationship between the amount of liquid adhered to the image area and the non-image area on the photoconductor and the sweep bias value. The sweep pias represents the voltage applied to the sweep roller. In this case, the developing potential of the photoconductor as a latent image carrier is about +650 V, the image part potential is about +50 V, and the toner is positively charged toner. There is.

The developed image that adheres to the photosensitive member after development contains toner and carrier in the image portion and mainly contains the carrier in the non-image portion but also toner. In FIG. 8, the toner adhesion amount is also reduced in a portion where the image amount is particularly small. That is, the toner is also removed by the sweep roller, so that the image density becomes low, which is not preferable. In this case, for example, the sweep bias is about 300V to 600V.
It is better to set it to V.

Therefore, in the printer according to the present embodiment, the sweep bias voltage applied to the sweep roller is switched based on the property of the transfer material. FIG. 9 is a schematic configuration diagram of the printer according to the present embodiment. In FIG. 9, an operation panel 132 connected to a control unit 131 including control of the DC transformer 130 for the sweep roller 110.
Further, an up / down switch 133 for instructing switching of the setting of the voltage to be supplied to the sweep roller 110 and a display 134 for the selection level by the switch are provided. Then, the control unit 131 switches the setting of the voltage supplied to the sweep roller 110 in accordance with the instruction from the up / down switch 133.

In the printer having the above structure, in the printer of the present embodiment, the operator operates the up / down switch 133 according to the kind of the paper set as a transfer material by setting it in a paper feed cassette or a manual paper feed tray (not shown) of the printer. Then, an appropriate voltage to be supplied to the sweep roller 110 is selected. For example, when setting a transfer paper with a rough surface, a transfer paper with a good liquid absorption property, a non-coated paper or a transfer paper with a low degree of coating, it is necessary to attach a relatively large amount of developer. A large sweep bias voltage (for example, 600V) is selected. On the other hand, when setting a transfer paper with a good surface roughness, a transfer paper with a poor liquid absorption property, or a transfer paper with a high degree of coating, it is better to use a relatively small amount of developer on the transfer paper. Since the image can be obtained, a small sweep bias voltage (for example, 300V) is selected. In order to facilitate selection of the voltage supplied to the sweep roller 110, the type of paper corresponding to each voltage may be simultaneously displayed on the level indicator 134.

In addition to the configuration described in the fourth embodiment in which the sweep bias voltage applied to the sweep roller is switched based on the property of the transfer material, the removal nip width described in the first, second or third embodiment is used. A configuration for switching may be added. FIG. 10 is a schematic configuration diagram of a printer that switches the sweep bias voltage applied to the sweep roller and switches the removal nip width based on the properties of the transfer material. With this configuration, it is possible to remove the carrier liquid amount more finely based on the properties of the transfer material.

[Embodiment 5] According to the experiment, it is found that there is a relationship as shown in FIG. 11 between the amount of liquid deposited on the sweep roller and the amount of liquid deposited on the photoconductor after liquid removal by the sweep roller. It was That is, when the amount of liquid adhered on the sweep roller is small, the amount of liquid removed from the photoconductor is large, and therefore the amount of liquid adhered on the photoconductor after removal is small. On the other hand, when the amount of liquid adhered on the sweep roller is large, the amount of liquid removed from the photoconductor is small, and the amount of liquid adhered on the photoconductor after removal is large. That is, the developer removed from the photoconductor adheres to the sweep roller, but if the developer remains adhered to the sweep roller,
When the sweep roller rotates and comes into contact with the photoconductor again, the amount of excess developer removed from the photoconductor is reduced. The present inventors have paid attention to this point, for example, by changing the liquid removing force of the excess liquid adhered on the sweep roller by the cleaning blade, the liquid removing force of the excess liquid on the photoconductor by the sweep roller is changed. I found that I can do it.

Therefore, a cleaning blade for adjusting the amount of excess liquid deposited on the sweep roller is provided, and the pressing force of the cleaning blade on the sweep roller is switched. FIG. 12 is a schematic configuration diagram of the printer according to the present embodiment. In FIG. 12, the cleaning blade 111 is attached to the swing support shaft 1 by a bracket 135.
It is swingably supported about 35 and can be moved left and right in the figure within a predetermined range by an eccentric cam 137. In the illustrated example, the cleaning blade 111 is swung to the right to the maximum,
1 shows that the sweep roller 110 is pressed by a large force. Since the bracket 135 is always biased by the tension spring 138 so as to be pulled to the left side in the drawing, the cleaning blade 111 swings together with the bracket 135 by rotating the eccentric cam 137, and the pressing force on the sweep roller 110 changes. To do.
The eccentric cam 137 is driven by a stepping motor 140 via a worm gear 139. The stepping motor 140 is controlled by the control unit 143 based on an instruction from the pressure changeover switch 142 on the operation panel 141. Then, the control unit 143 switches the setting of the pressing force of the cleaning blade 111 on the sweep roller 110 according to the instruction of the pressure switch 142.

In the printer having the above structure, in the printer of this embodiment, the operator operates the pressure changeover switch 142 according to the kind of the paper set as a transfer material by setting it in a paper feed cassette or a manual paper feed tray (not shown) of the printer. The sweep roller 11 of the cleaning blade 111
Select the pressing force for 0. For example, when setting a transfer paper with a rough surface, a transfer paper with a good liquid absorption property, a non-coated paper or a transfer paper with a low degree of coating, it is necessary to attach a relatively large amount of developer. It is selected so that the pressing force of the cleaning blade 111 on the sweep roller 110 is small. On the other hand, when setting a transfer paper with a good surface roughness, a transfer paper with a poor liquid absorption property, or a transfer paper with a high degree of coating, it is better to use a relatively small amount of developer on the transfer paper. Since the image can be obtained, the pressing force of the cleaning blade 111 against the sweep roller 110 is selected to be large. In order to facilitate the selection of the pressing force of the cleaning blade 111 on the sweep roller 110, the level indicator 144 may simultaneously display the type of paper corresponding to the pressing force.

FIG. 12B shows the cleaning blade 1.
11 shows another example of support. The bracket 145 is constantly urged to the right side in the figure by a pressure spring 146. The eccentric cam 137 is in contact with the end of the bracket on the opposite side of the cleaning blade 111 with respect to the swing support shaft 136. Then, by rotating the eccentric cam 137, the cleaning blade 111 swings together with the bracket 135, and the pressing force on the sweep roller 110 changes.

At least one of the structure for switching the removal nip width described in the first, second, or third embodiment and the structure for switching the sweep bias voltage described in the fourth embodiment, or the structure of the fifth embodiment. It is good also as a structure which combined.

As described above, according to this embodiment, the photosensitive drum 1 as a latent image carrier, the exposure device as a latent image forming means for forming a latent image on the photosensitive drum 1, and the toner in the carrier liquid. A developing unit 109 as a developing unit that develops the latent image formed on the photosensitive drum 1 into a visible image by using a dispersed high-viscosity and high-concentration liquid developer; A sweep section 112 as excess liquid removing means for removing the excess liquid developer on the body drum 1 to regulate the liquid film,
In a liquid image forming apparatus having a transfer device as a transfer unit that transfers the visible image on the photosensitive drum 1 to a transfer paper P as a transfer material, the sweep section 112 contacts the photosensitive drum 1 and Sweep roller 110 as a surplus liquid removing member that moves in the same direction as the surface of photosensitive drum 1 in the same direction, and eccentricity as liquid removing force varying means for varying the liquid removing force of sweep roller 110. Cam 1
13 and the like, and the eccentric cam 1 based on the properties of the transfer paper P.
And a control unit 118 as a control unit for controlling 13 and the like. The liquid removing force of the sweep roller 110 of the sweep unit 112 is switched based on the property of the transfer paper P, and the excess liquid developer is removed according to the property of the transfer paper P to regulate the liquid film. Since the sweep roller 110 is in contact with the photoconductor drum 1, it is possible to easily remove, for example, a high-viscosity and high-concentration liquid developer that is difficult to remove by ejecting compressed air from a slit nozzle. Further, since the sweep roller 110 is brought into contact with the photosensitive drum 1, the mechanical accuracy is maintained at a high precision as compared with the conventional configuration in which the squeeze roller is opposed to the photosensitive drum 1 with a predetermined interval. You don't have to. Since the sweep roller 110 moves in the same direction as the surface of the photosensitive drum 1 in the same direction, it does not disturb the toner image on the photosensitive drum 1. The liquid removing power is switched based on the properties of the transfer paper P, for example, transfer paper that does not easily absorb carrier liquid, transfer paper with a smooth surface, transfer paper with a high degree of surface coating, that is, a large amount of surface coating, etc. When forming an image on, the removal power is switched to a larger value. On the contrary, when the image is formed on a transfer paper that easily absorbs carrier liquid, a transfer paper with a rough surface, or a transfer paper with a low surface coating amount, that is, a surface coating amount is small, the removal power becomes smaller. To switch. As a result, the liquid removing force of the sweep roller 110 is switched based on the properties of the transfer material, and the excess liquid developer is removed by the amount to be removed according to the transfer material to regulate the liquid film. It is possible to form a good image without thickening or trailing edge of the image. Further, in the liquid image forming apparatus, a plurality of sweep rollers as the excess liquid removing member are provided, and the liquid removing force varying means is provided with at least one of the plurality of sweep rollers 110 and 123 as the latent image carrier. The eccentric cam 113 as a contacting / separating means for contacting / separating with respect to the photosensitive drum 1 is used. Since the liquid removing force is larger when two sweep rollers are in contact with the photosensitive drum 1 than when one is in contact with the photosensitive drum 1, for example, when an image is formed on a transfer paper or the like that hardly absorbs carrier liquid, The two sweep rollers 110 and 123 are brought into contact with each other so as to increase the removal force. On the other hand, when forming an image on transfer paper or the like that easily absorbs the carrier liquid, the sweep roller 123 of the two sweep rollers 110 and 123 is separated from the photosensitive drum 1 so that the removing force becomes small. In the liquid image forming apparatus, the sweep roller 1 as the excess liquid removing member
At least one of 10 and the photosensitive drum 1 as the latent image carrier has an elastic layer on the surface thereof, and the liquid removing force varying means switches the pressure at which the sweep roller 110 contacts the photosensitive drum 1. Eccentric cam 1 as switching means
13 and the like. Specifically, when the elastic layer 110a is provided on the surface of the sweep roller 110, the amount of elastic deformation of the elastic layer 110a changes depending on the pressure with which the sweep roller 110 contacts the photosensitive drum 1.
The size of the removal nip width, which is the contact width between the sweep roller 110 and the photosensitive drum 1, changes. The larger the removal nip width is, the larger the liquid removal force is. Therefore, for example, when forming an image on transfer paper that does not easily absorb carrier liquid,
The pressure of the sweep roller 110 contacting the photosensitive drum 1 is increased to increase the removal force, and the removal nip width is increased. On the other hand, when forming an image on a transfer paper or the like that easily absorbs the carrier liquid, the pressure of the sweep roller 110 contacting the photosensitive drum 1 is reduced so that the removal force is reduced, and the removal nip width is reduced. . Further, in the liquid image forming apparatus, the sweep belt 12 as an endless belt whose surface moves the surplus liquid removing member endlessly.
5, the liquid removing force varying means is configured by using a removing nip width switching means for switching the size of a removing nip width which is a contact width between the sweep belt 125 and the photosensitive drum 1 as the latent image carrier. Configured. Specifically, the sweep belt 125 is connected to the drive roller 126 and the pair of driven rollers 12
7,128, and a pair of driven rollers 12
7, 128 are arranged so as to face the photoconductor drum 1, and the sweep belt 125 is brought into contact with the photoconductor drum 1 to form a removal nip. As described above, by using the sweep belt 125, it becomes easier to make the removal nip width wider than in the case of using the sweep roller,
For example, space can be saved as compared with a configuration in which a plurality of sweep rollers are provided to widen the removal nip width. In addition,
The removal nip width is adjusted by the pair of driven rollers 127, 12
8 is changed, or the distance between the entire sweep portion 124 and the photosensitive drum 1 is changed. In the liquid image forming apparatus, the liquid removing force varying means is provided to the sweep roller 110 as the excess liquid removing member to remove the excess toner floating between the background portion of the latent image and the sweep roller 110. A transformer as a bias voltage applying unit that applies an electric field in the direction of pulling to the sweep roller 110 and that does not peel off the toner adhering to the image portion, and that can change the magnitude of the electric field. Etc. According to the experiment, when the voltage applied to the sweep roller as the excess liquid removing member is changed, the liquid removal amount is changed as shown in FIGS. 7 and 8, and the liquid adheres on the photosensitive drum 1 after the sweep. The amount changes. As a result, a high-quality image can be obtained by switching the bias voltage so that the liquid removal from the photosensitive drum 1 is optimized based on the properties of the transfer paper. For example, transfer paper with rough surface, transfer paper with good liquid absorption,
When setting uncoated paper or transfer paper with a low degree of coating, it is necessary to attach a relatively large amount of developer, so a large sweep bias voltage (for example, 600 V)
Select. On the other hand, when setting a transfer paper with a good surface roughness, a transfer paper with a poor liquid absorption property, or a transfer paper with a high degree of coating, it is better to use a relatively small amount of developer on the transfer paper. Since the image can be obtained, a small sweep bias voltage (for example, 300V) is selected. Therefore,
By using it in combination with the contact / separation unit, the pressure switching unit, or the removal nip width switching unit, it is possible to more accurately control the liquid removal amount based on the properties of the transfer material.
In addition, since the liquid removal amount can be switched based on the property of the transfer material only by the bias voltage applying means, the switching mechanism can be controlled by an electric signal without the need for a driving mechanism as compared with the configuration in which the contacting / separating means is provided. Can be made compact. In particular, in the configuration using the endless belt,
Since the removal nip width can be widened, the time for applying the electric field becomes longer, and the excess liquid can be removed without removing the toner in the image area. Further, in the liquid image forming apparatus, a cleaning blade 111 is provided as a cleaning member for removing the excess liquid adhering to the sweep roller 110 as the excess liquid removing member, and the liquid removing force varying means is provided as the cleaning blade. The sweep roller 11
An eccentric cam 137 or the like as a cleaning member pressure switching means for switching the pressure abutting on 0 is used. According to the experiment, as shown in FIG.
When the amount of the liquid adhered is small, the amount of the liquid removed from the photoconductor drum 1 is large, and the amount of the liquid adhered on the photoconductor after the removal is small. On the other hand, when the amount of liquid adhered on the sweep roller 110 is large, the amount of liquid removed from the photoconductor drum 1 is small, and therefore the amount of adhered liquid on the photoconductor after removal is large. Since the amount of liquid adhered on the sweep roller 110 can be controlled by the pressing force of the cleaning blade 111, for example, when a transfer paper or the like having a rough surface is set, it is necessary to adhere a relatively large amount of developer. It is selected so that the pressing force of the cleaning blade 111 on the sweep roller 110 is small. On the other hand, when setting the transfer paper or the like having a good surface roughness, it is better to make the amount of the developer attached to the transfer paper relatively small, so that an image can be obtained, so that the cleaning blade 1
11 is selected so that the pressing force to be brought into contact with the sweep roller 110 is increased.

[0065]

According to the invention of claims 1 and 7, since the excess liquid removing member is in contact with the latent image carrier, for example,
It is possible to easily remove a highly viscous and high-concentration liquid developer that is difficult to remove by jetting compressed air with a slit nozzle. Further, since the excess liquid removing member is brought into contact with the latent image carrier, the mechanical precision is maintained at a higher precision than the conventional structure in which the squeeze roller is opposed to the latent image carrier at a predetermined interval. You don't have to. Then, the liquid removing power of the excess liquid removing means is switched based on the property of the transfer material, and the liquid film is regulated by removing the excess liquid developer by the amount to be removed according to the transfer material. It is possible to form a good image without thickening or trailing edge of the image.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a main part of a liquid image forming apparatus. (B) is an enlarged view of part A of the operation panel.

FIG. 2A is an explanatory diagram showing a state in which a sweep roller and a photosensitive drum are separated from each other. (B) is an explanatory view of a state where the sweep roller and the photosensitive drum are in contact with each other with a small nip width. (C)
FIG. 4 is an explanatory diagram showing a state where the sweep roller and the photosensitive drum are in contact with each other with a large nip width.

3A and 3B are diagrams schematically showing a state of a developer in a developing nip.

4A and 4B are diagrams schematically showing a state of a developer in a removal nip formed by a photosensitive drum and a sweep roller.

FIG. 5A is a schematic configuration diagram of a main part of a liquid image forming apparatus according to a second embodiment. (B) is an enlarged view of part B of the operation panel.

FIG. 6 is a schematic configuration diagram of a main part of a liquid image forming apparatus according to a third embodiment.

FIG. 7 is a graph showing the relationship between the amount of liquid adhered to the image area and the non-image area on the photoconductor and the sweep bias value when the number of sweep rollers is one.

FIG. 8 is a graph showing the relationship between the amount of liquid adhered to the image area and the non-image area on the photoconductor and the sweep bias value when the number of sweep rollers is two.

FIG. 9 is a schematic configuration diagram of a main part of a liquid image forming apparatus according to a fourth embodiment.

FIG. 10 is a schematic configuration diagram of a main part of a liquid image forming apparatus having a configuration in which contact and separation of a sweep roller and application of a sweep bias are combined.

FIG. 11 is a graph showing the relationship between the amount of liquid deposited on the sweep roller and the amount of liquid deposited on the photoconductor after liquid removal by the sweep roller.

FIG. 12A is an explanatory view of a main part near a cleaning blade of a liquid image forming apparatus according to a fifth embodiment. (B) is
The figure which shows the other supporting example of a cleaning blade.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum (latent image carrier) 20 Charging device 31 Intermediate transfer belt 32 Transfer roller 33 Tension roller 40 Electrification lamp 50 Drum cleaning device 51 Cleaning blade 60 Liquid developer 100 Developing device (liquid developing device) 101 Tank section 102 , 103 stirring screw 104 anilox roller (developer coating body) 105 doctor blade (regulating member) 106 developing roller (developer carrying body) 107 cleaning blade 108 return section 109 developing section 110, 123 sweep roller 111 sweep roller cleaning blade 112 sweep parts 113, 137 eccentric cam 114 tension springs 116, 140 stepping motors 117, 132, 141 operation panels 118, 131, 143 control part 122 second sweep part 124 sweep part 12 Sweep belt 130 transformer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H074 AA03 BB02 BB20 BB22 BB41                       BB43 BB58 BB60 BB61 CC21                       CC28 CC41

Claims (7)

[Claims] 1. A latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a high-viscosity high-concentration liquid developer in which toner is dispersed in a carrier liquid, Developing means for developing the latent image formed on the latent image carrier to make it visible, and excess liquid for removing the excess liquid developer on the latent image carrier after the development to regulate the liquid film. In a liquid image forming apparatus having a removing means and a transfer means for transferring a visible image on the latent image carrier to a transfer material, the excess liquid removing means is in contact with the latent image carrier to carry the latent image carrier. Based on the properties of the transfer material, an excess liquid removing member that moves in the same direction as the surface of the body in the same direction, a liquid removing force varying means for varying the liquid removing force of the excess liquid removing member, A liquid image forming apparatus comprising: a control unit that controls the liquid removal force varying unit. 2. The liquid image forming apparatus according to claim 1, further comprising a plurality of said excess liquid removing members, wherein said liquid removing force varying means comprises at least one of said plurality of excess liquid removing members as said latent image carrier. A liquid image forming apparatus comprising a contacting / separating unit for contacting / separating with respect to the liquid image forming apparatus. 3. The liquid image forming apparatus according to claim 1, wherein at least one of the surplus liquid removing member and the latent image carrier has an elastic layer on the surface thereof, and the liquid removing force varying means is provided with the surplus liquid removing means. A liquid image forming apparatus comprising a pressure switching means for switching the pressure with which the liquid removing member contacts the latent image carrier. 4. The liquid image forming apparatus according to claim 1 or 2, wherein the surplus liquid removing member is composed of an endless belt whose surface moves endlessly, and the liquid removing force varying means comprises the endless belt and the latent image carrying member. A liquid image forming apparatus comprising a removal nip width switching means for switching a size of a removal nip width which is a contact width with a body. 5. The liquid image forming apparatus according to claim 1, 2, 3 or 4, wherein the liquid removing force varying means includes a background portion of the latent image and the excess liquid removing member in the excess liquid removing member. An electric field in the direction of attracting the excess toner floating in between to the excess liquid removing member side, and an electric field that does not peel off the toner adhering to the image portion, and the magnitude of the electric field is applied. A liquid image forming apparatus comprising a bias voltage applying unit capable of switching between. 6. The liquid image forming apparatus according to claim 1, 2, 3, 4 or 5, wherein a cleaning member for removing the excess liquid adhering to the excess liquid removing member is provided, and the liquid removing force varying means is provided. A liquid image forming apparatus comprising a cleaning member pressure switching means for switching the pressure at which the cleaning member contacts the surplus liquid removing member. 7. A liquid developer having a high viscosity and a high concentration in which toner is dispersed in a carrier liquid is supplied to the surface of a latent image carrier on which a latent image is formed to develop the latent image, and then a surplus liquid is formed. In a liquid film regulating method for a developed image in a liquid image forming apparatus, which removes an excess liquid developer on the latent image carrier by a removing means to regulate a liquid film and transfer the liquid film onto a transfer material. The surplus liquid removing means is configured by using a surplus liquid removing member that comes into contact with the surface of the latent image carrier and moves in the same direction at substantially the same speed as the surface of the latent image carrier, and the surplus liquid removing means has a variable liquid removing force. A method for regulating a liquid film of a developed image in a liquid image forming apparatus, wherein the liquid removing force is switched based on the property of the transfer material to regulate the liquid film.