JPH1063103A - Wet type image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the overflowing of liquid without complicating the mechanism by controlling a liquid carrier in a developer to stick to the surface of a latent image carrier and further, to be transferred to a transfer material, at a prescribed timing. SOLUTION: When entering a blank paper printing mode, a photoreceptor drum 1 is driven to rotate in the direction of the arrow at a fixed speed and uniformly electrified by a main charger 2 and then, becomes a potential state where toner can not be stuck on a developing bias condition when an image is normally formed, by an exposure device 3. After that, an electrostatic latent image passes through a developing roller 41 to be developed, but the toner in the developer is biased to the side of the developing roller 41 due to the potential difference between the electrostatic latent image and the roller 41. Then, as the developer stuck to the surface of the drum 1, only the liquid carriers exist. Further, a voltage applied to a transfer roller 51 is made lower than that when the image is normally formed, so that the carrier liquid easily passes through a transferring part. Thus, a larger number of carriers are stuck to a transfer paper 7 and pass through the transferring part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, and more particularly, to a latent image carrier and a latent image forming means for forming a latent image on the surface of the latent image carrier. And a developer storage unit for storing a developer in which a toner is dispersed in a liquid carrier, and developing the latent images formed on each of the latent image carriers using the developer to form a toner image. The present invention relates to a wet image forming apparatus including a wet developing device and a transfer unit that transfers a toner image formed on the latent image carrier to a transfer material.

[0002]

2. Description of the Related Art Conventionally, as a wet image forming apparatus, an electrostatic latent image is formed on a latent image carrier by a known image forming process, and a developer comprising a toner and a carrier liquid or a developer comprising only a toner is used. There has been proposed an image forming apparatus that develops the electrostatic latent image into a toner image by supplying a liquid agent or the like (hereinafter referred to as a developer) and transfers the electrostatic latent image to a transfer material conveyed by a transfer belt to form an image. I have.

When an image is formed in a wet image forming apparatus having the above-described structure, the solid toner in the developing solution has a presence or absence of a portion where the toner adheres to a transfer material (hereinafter referred to as a printing portion), or an image. In accordance with the ratio of the printing portion, it is consumed by attaching to, for example, paper as a transfer material. Further, the amount of carrier liquid adhering to paper does not depend much on the presence or absence of an image, and is substantially constant. When the solid toner in the developing solution in the developing tank serving as a developing solution storage unit for storing the developing solution is consumed by the image formation, the decrease in the toner concentration of the developing solution is detected by the transmission density detector of the developing solution. And the like, and the concentrated toner, which is a developer, is supplied from a concentrated toner bottle or the like. Thus, the toner concentration of the developing solution in the developing tank is controlled so as to be always constant. However, when replenishing the toner in the case of repeatedly forming an image having a large ratio of the printing portion, that is, an image in which the amount of toner adhered to the paper is significantly large compared to the amount of carrier adhered to the paper, Since the carrier liquid is supplied together with the toner solid content by the replenishment of the toner, the amount of the developing solution in the developing tank which is the developing solution storing section for storing the developing solution increases. Eventually, the liquid overflows beyond the capacity of the developing tank. The overflow causes the floor and the like to be soiled, and in the case of a color image forming apparatus, the liquid enters the developing units of other colors, causing color mixing.

In order to prevent the above-mentioned liquid overflow, a measure to increase the ratio of the toner solid content of the conc. Toner is conceivable. However, a problem arises that handling becomes inconvenient due to thickening at the time of manufacturing. Therefore, the above ratio is about 30%
It can only be increased to the extent.

In order to prevent such a problem, there has been proposed a technique of collecting overflowed liquid into a collection tank by using a pipe (see Japanese Patent Application Laid-Open No. 62-14180). According to this, the developer overflowing from the developing tank can be collected.

[0006]

However, according to the above construction, in an image forming apparatus having a plurality of developing devices such as a color copying machine, it is necessary to connect each developing tank to the collecting tank by a pipe. There was a problem that the configuration became complicated.

Further, according to the above configuration, a liquid overflowing from the developing tank, that is, a liquid prepared under optimum conditions for development by replenishing a suitable amount of the conc toner and carrier liquid in the developing tank is collected as waste liquid. , Will also discard toner solids that can be used for image formation,
There was also a problem that resources were wasted.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a wet image forming apparatus which prevents liquid overflow without complicating the mechanism. It is. It is a second object of the present invention to provide a wet image forming apparatus capable of effectively using toner in addition to the first object.

[0009]

In order to achieve the first object, the present invention provides a latent image carrier and a latent image forming means for forming a latent image on the surface of the latent image carrier. And a developing solution storage section for storing a developing solution in which a toner is dispersed in a liquid carrier, and developing the latent image formed on the latent image carrier using the developing solution to form a toner image. In a wet image forming apparatus having a developing device and a transfer unit for transferring a toner image formed on the latent image carrier to a transfer material, at a predetermined timing, at least a liquid in the developing solution in the developing solution storage unit. Control means is provided for controlling the carrier to adhere to the surface of the latent image carrier and further transferring the liquid carrier to the transfer material.

In this wet image forming apparatus, the control means causes at least a liquid carrier in the developing solution in the developing solution container to adhere to the surface of the latent image carrier at a predetermined timing, and further causes the liquid carrier to further adhere. Control is performed so that the image is transferred onto the transfer material. Thus, at least the liquid carrier in the developer in the developer storage unit can be consumed by attaching it to the transfer material.

In order to achieve the second object,
According to a second aspect of the present invention, in the wet image forming apparatus of the first aspect, the control means is configured so that only the liquid carrier is transferred to the transfer material.

In the wet image forming apparatus, the control means controls the transfer so that only the liquid carrier is transferred to the transfer material. Thus, only the liquid carrier in the developer in the developer storage section can be consumed by attaching it to the transfer material.

According to a third aspect of the present invention, in the wet image forming apparatus according to the first or second aspect, the wet developing device has an excess liquid removing means for removing excess developing solution from the surface of the latent image carrier. In a state in which the amount of the developing solution removed by the excess solution removing unit is reduced as compared with the time of normal image formation, at least a liquid carrier in the developing solution in the developing solution storage unit is attached to the surface of the latent image carrier, The control means is configured to further transfer the liquid carrier to a transfer material.

In this wet image forming apparatus, the control means controls the amount of the developer removed by the surplus liquid removing means to be smaller than that in normal image formation, and the developer contained in the developer accommodating portion is reduced. At least the liquid carrier therein is attached to the surface of the latent image carrier, and the liquid carrier is further transferred to a transfer material. Thereby, the transfer to the transfer material can be performed in a state where more liquid carriers adhere to the surface of the latent image carrier.

According to a fourth aspect of the present invention, in the wet image forming apparatus according to the first or second aspect, the wet developing device is arranged so as to face the toner image on the latent image carrier at a predetermined interval. A developer for applying a predetermined voltage to bind the toner image, wherein the developing solution is used in a state where the absolute value of the voltage applied to the binder is reduced as compared with a normal image formation. The control means is configured so that at least a liquid carrier in a developer in a storage portion is attached to the surface of the latent image carrier, and the liquid carrier is further transferred to a transfer material.

When the predetermined voltage is applied to the binding means to bind the toner image, the charge is caused to fall from the binding means onto the liquid carrier on the latent image carrier, thereby providing the charged liquid. A repulsive force acts between the carrier and the binding means, which is an electrode, and as a result, the liquid carrier is blocked on the upstream side of the binding means, which has the effect of apparently squeezing the liquid carrier. This effect increases as the absolute value of the voltage applied to the binding means increases, and decreases as the absolute value of the voltage decreases. In this wet image forming apparatus, the control unit reduces the absolute value of the voltage applied to the binding unit as compared with a normal image forming operation, and reduces the absolute value of the squeeze in the developer storage unit. At least the liquid carrier in the developing solution is adhered to the surface of the latent image carrier, and the liquid carrier is further controlled to be transferred to the transfer material, so that more liquid carrier is adhered to the latent image carrier. The transfer to the transfer material can be performed in the state.

According to a fifth aspect of the present invention, in the wet image forming apparatus of the first or second aspect, the transfer means supports a transfer material and contacts the surface of the transfer material to the surface of the latent image carrier. A member and a transfer charge applying means for applying a charge to the front surface or the back surface of the transfer material support member, and the amount of charge applied to the transfer material support member by the transfer charge application means is reduced as compared with normal image formation. In this state, the control unit is configured to attach at least a liquid carrier in the developer in the developer storage unit to the surface of the latent image carrier, and further transfer the liquid carrier to a transfer material. It is assumed that.

When an electric charge is applied to the transfer material supporting member by the transfer electric charge applying means, a transfer electric field is generated between the latent image carrier and the transfer material supporting member by the electric charge. Then, in a region where an electric field is present, Maxwell stress acts in proportion to the square of the electric field, and the transfer material supporting member comes into close contact with the latent image carrier. When the adhesion between the transfer material support member and the latent image carrier is strong, it becomes difficult for the liquid carrier to pass between the transfer material support member and the latent image carrier, and the transfer material support member and the latent image carrier are difficult to pass. It stays in the vicinity of the close contact portion with the image carrier. Therefore, if the transfer electric field is weakened so that the adhesion is weaker than in normal image formation, the liquid carrier can easily pass between the transfer material support member and the latent image carrier. In this wet image forming apparatus, the control means controls the development of the developer in the developer storage section in a state where the amount of charge applied to the transfer material supporting member by the transfer charge applying means is reduced as compared with the normal image formation. At least the liquid carrier in the liquid is adhered to the surface of the latent image carrier, and the liquid carrier is controlled so as to be further transferred to the transfer material. Therefore, the transfer electric field is weakened as compared with the normal image formation. This weakens the adhesion between the transfer material support member and the latent image carrier, and facilitates the passage of the liquid carrier adhered to the transfer material between the transfer material support member and the latent image carrier. Therefore, it is less likely that the liquid carrier attached to the transfer material does not pass between the transfer material support member and the latent image carrier and stays in the vicinity of the close contact portion.

According to a sixth aspect of the present invention, there is provided the wet image forming apparatus according to the first or second aspect, wherein the excess liquid removing means for removing excess developer on the surface of the latent image carrier, and A binding unit that is arranged to face the toner image at a predetermined distance and that applies a predetermined voltage to bind the toner image, and a transfer material that supports the transfer material and holds the surface of the transfer material on the latent image carrier. A transfer material supporting member that is in contact with the body surface; and a transfer charge applying device that applies a charge to a front surface or a back surface of the transfer material support member. A state in which the amount of the developer removed by the developer is reduced as compared with the normal image formation, a state in which the absolute value of the voltage applied to the binding unit is reduced as compared with the normal image formation,
And a developer in the developer storage unit in a state where at least two of the states in which the amount of charge applied to the transfer material supporting member by the transfer charge applying unit is reduced as compared with the time of normal image formation are satisfied. At least the liquid carrier therein is attached to the surface of the latent image carrier, and the control means is configured to further transfer the liquid carrier to a transfer material.

In this wet image forming apparatus, the control means reduces the amount of the developing solution removed by the excess liquid removing means as compared with the normal image formation, and the voltage applied to the binding means is reduced. At least one of a state in which the absolute value is reduced as compared with normal image formation, and a state in which the amount of charge applied to the transfer material supporting member by the transfer charge applying unit is reduced as compared with normal image formation. At least two liquid carriers in the developer in the developer storage section are adhered to the surface of the latent image carrier in a state where the two are filled, and the liquid carrier is further transferred to the transfer material. Thereby, more liquid carriers can be transferred to the transfer material and consumed.

[0021] The invention of claim 7 is based on claims 1, 2, 3,
In the fourth, fifth, or sixth wet image forming apparatus, a detecting unit for detecting a liquid amount of the developer stored in the developer storing unit is provided, and based on a detection result by the detecting unit, the inside of the developer storing unit is detected. Wherein the control means is configured to cause at least a liquid carrier in the developer to adhere to the surface of the latent image carrier and further transfer the liquid carrier to a transfer material.

In this wet image forming apparatus, the control means controls the developer in the developer storage section based on the detection result of the detection means for detecting the amount of the developer stored in the developer storage section. At least the liquid carrier therein is attached to the surface of the latent image carrier, and the liquid carrier is automatically controlled so as to be further transferred to the transfer material.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is a wet image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to the present embodiment. The photoconductor drum 1 as a latent image carrier is driven to rotate at a constant speed in the direction of the arrow at the time of copying by a driving means such as a motor (not shown). After being charged in the dark by a main charger 2 serving as a charging unit, a light image of a document is irradiated and formed by an exposure device 3, and an electrostatic latent image is carried on the outer peripheral surface of the photosensitive drum 1. . Thereafter, the electrostatic latent image is developed while passing through the portion of the wet developing device 4. The toner image developed into the electrostatic latent image is transferred to a transfer belt 6 in a transfer unit 5.
Is transferred onto the transfer paper 7 conveyed. After the transfer paper 7 is separated from the photosensitive drum 1, the residual toner is removed by the foam roller 8a and the cleaning blade 8b. The cleaning liquid tank 80 is provided on the foam roller 8a.
The cleaning liquid is supplied to the surface of the photosensitive drum 1 and rotated while supplying the cleaning liquid to the surface of the photosensitive drum 1 to wipe off the toner on the surface of the photosensitive drum 1 and collect the cleaning liquid containing the toner. Then, the surface of the photosensitive drum 1 wiped by the foam roller 8a is further wiped by the cleaning blade 8b. The cleaning blade 8b
May be in the trailing direction or the counter direction. Thereafter, the residual potential is removed from the surface of the photosensitive drum 1 by the charge removing lamp 9 to prepare for the next copy. Also,
The transfer paper 7 to which the toner image has been transferred passes through a fixing device (not shown) and is discharged outside the apparatus.

The wet developing device 4 includes a casing 40 having an open upper surface to which a developing solution is supplied,
0, a developing roller 41 provided in close proximity to the photosensitive drum 1, a squeeze roller 42 as surplus liquid collecting means, a set roller 43 as binding means, and a developing device used in the casing 40. A developer tank 44 serving as a developer storage unit for storing the liquid. (Hereinafter, margin)

A developing bias voltage is applied to the developing roller 41 from a power source (not shown) to prevent the image on the photosensitive drum 1 from becoming dirty. The developing roller 41 is rotationally driven by a drive motor (not shown) in a direction indicated by an arrow which is a reverse rotation direction to the photosensitive drum 1. This developing roller 41
On the right side of the drawing, a scraper 45 is disposed with its end portion in contact with the outer peripheral surface of the developing roller 41. Then, a developing solution is supplied from the developing solution tank 44 to a wedge-shaped portion formed by the developing roller 41 and the scraper 41a by the developing solution supply means 41b.
Is supplied to the developing section where the photosensitive drum 1 and the developing roller 41 are opposed to each other.

The squeeze roller 42 is rotated by a drive motor (not shown) in the same direction as the photosensitive drum 1 in the direction of the arrow, thereby squeezing excess carrier liquid on the photosensitive drum 1 after development. At this stage,
After passing through the developing roller 41, 90% or more of the carrier liquid adhering to the photosensitive drum 1 is removed.

A high voltage is applied to the set roller 43 from a power source (not shown) in order to generate a discharge electric field necessary for binding toner particles of a developed image developed on the photosensitive drum 1 to each other. ing. The set roller 43 is rotationally driven by a drive motor (not shown) in the direction of the arrow that is the reverse rotation of the photosensitive drum 1.

In the developer tank 44, a developer concentration sensor 45 for detecting the concentration of the developer in the developer tank 44, a toner bottle 46 for replenishing the developer tank 44 with the toner, a developer tank A lower float sensor 47 for detecting whether or not the height of the developer in 44 has reached a predetermined lower limit height, and a carrier bottle 48 for replenishing the developer tank 44 with carrier liquid are provided. When the developer concentration sensor 45 detects that the toner has been consumed and the developer concentration in the developer tank 44 has decreased, the conc. Toner is supplied from the conc. Toner bottle 46 to the developer tank 44. . The concentrated toner has a ratio of toner to carrier of about 10 to 15%, and is a developer having a concentration about 100 times that of a normal developer. Further, the lower float sensor 47 detects that the height of the developer in the developer tank 44 is lower than a predetermined lower limit height.
Is detected, the carrier liquid is replenished from the carrier bottle 48 to the developer tank 44.

An overflow port formed on a side surface of the cleaning liquid tank 80 and having a filter 81 attached thereto is connected to the developing liquid tank 44 via a tube. Then, the cleaning liquid tank 8
When the liquid level 0 rises above the overflow port, the cleaning liquid in the cleaning liquid tank 80 flows into the developing liquid tank 44.

In the transfer section 5, a transfer roller 51 as a transfer charge applying means is provided to face the photosensitive drum 1 via a transfer belt 6 as a transfer material supporting member.
A high voltage is applied to the transfer roller 51 from a power source (not shown) to form a transfer electric field.

In this copying machine, the above-described image forming operation is continuously performed on a large number of sheets in a state where the image area is large. When a large amount of condensed toner is supplied to the developer tank 44 from the above, the developer in the developer tank 44 may increase. Therefore,
In the present embodiment, a blank paper print mode for forming an image on the transfer paper 7 in which only the carrier liquid is consumed without consuming the toner is provided. Hereinafter, the blank page print mode will be described in detail. First, in the copying machine of FIG.
In order to determine when to execute the blank paper print mode, an upper float sensor 49 for detecting whether or not the developer level in the developer tank 44 has reached an upper limit is provided in the developer tank 44. Is provided. When the float sensor 49 detects that the developer level in the developer tank 44 has reached the upper limit, the detection signal is transmitted to a main control unit (not shown), and the blank print mode is set. Is determined. Here, in the illustrated apparatus, if the developing solution level reaches the upper limit during continuous printing, the continuous printing is completed and then the blank paper print mode is entered. For this reason, the height of the upper limit is set so that there is some margin before the overflow of the developer occurs even if the developer level exceeds the upper limit. It should be noted that control may be performed such that if the developing solution level reaches the upper limit during continuous printing, continuous printing is interrupted and the printer enters the blank paper print mode.

In the blank paper print mode, the photosensitive drum 1 is driven to rotate at a constant speed in the direction of the arrow, and is charged in the dark by the main charger 2 in the dark. Under the developing bias condition, the potential is set so that the toner does not adhere. Specifically, the charge is removed by the exposure device so that the surface of the photosensitive drum 1 is uniformly charged to the surface potential of the background during normal image formation. Thereafter, the electrostatic latent image is developed by passing through a portion of the developing roller 41, but due to a potential difference between the electrostatic latent image and the developing roller 41,
The toner in the developing solution is shifted toward the developing roller 41, and the developing solution attached to the surface of the photosensitive drum 1 is only a liquid carrier. The surface of the photosensitive drum 1 may be uniformly charged to the surface potential of the background portion during normal image formation by the main charger 2 without performing the above exposure, but the characteristics of the photosensitive member may fluctuate. Therefore, it is desirable to adopt a method of performing the above exposure. Further, the developing bias may be set to a value different from that during normal image formation so that toner does not adhere to the surface of the photosensitive drum.

Next, the surface of the photosensitive drum 1 faces the squeeze roller 42. FIG. 2 shows the relationship between the rotation speed of the squeeze roller and the amount of carrier remaining on the surface of the photosensitive drum after passing through the squeeze roller. From this figure, it can be seen that the amount of carrier remaining on the surface of the photosensitive drum 1 increases as the rotation speed of the squeeze roller 42 decreases. Therefore, in the present embodiment, the rotation speed of the squeeze roller 42 in the blank paper print mode is reduced as compared with the normal image formation. As a result, in the blank paper print mode, more carrier is transferred to the transfer material while adhering to the surface of the photosensitive drum 1, so that the carrier liquid in the developer tank 44 can be consumed more.

After passing through the squeeze roller 42,
The surface of the photosensitive drum 1 faces the set roller 43. The set roller 43 is for binding the toner particles of the developed image as described above, and when a predetermined voltage is applied to the set roller 43 to bind the toner image, the set roller 43 By causing the charges to fall from the carrier liquid onto the photosensitive drum 1, a repulsive force acts between the charged carrier liquid and the set roller 43 as an electrode. Then, as a result, the carrier liquid is blocked on the upstream side of the set roller 43, so that there is an effect of apparently squeezing the carrier liquid, that is, performing so-called corona squeeze.
FIG. 3 shows the relationship between the set roller applied voltage and the amount of carrier remaining on the surface of the photosensitive drum 1 after passing through the set roller. As can be seen from the figure, the above effect is smaller as the absolute value of the voltage applied to the binding means is lower, and the amount of carrier remaining on the surface of the photosensitive drum 1 is increased. Therefore, in the present embodiment, the absolute value of the voltage applied to the set roller 43 in the blank paper print mode is reduced as compared with the normal image formation. As a result, in the blank paper print mode, more carrier is transferred to the transfer material while adhering to the surface of the photosensitive drum 1, so that the carrier liquid in the developer tank 44 can be consumed more.

Next, the image on the surface of the photosensitive drum 1 is transferred to the transfer paper 7 conveyed by the transfer belt 6 in the transfer section 5. When a high voltage is applied to the transfer roller 51 to form a transfer electric field, a Maxwell stress acts on the transfer unit 5 in proportion to the square of the electric field, and the transfer belt 6 comes into close contact with the photosensitive drum 1. During normal image formation, the adhesion between the transfer belt 6 and the photosensitive drum 1 is strong, and it is difficult for the carrier liquid to pass between the transfer belt 6 and the photosensitive drum 1, as shown in FIG. Further, a liquid reservoir 5a is formed near the contact portion between the transfer belt 6 and the photosensitive drum 1. FIG. 5 shows the relationship between the voltage applied to the transfer roller 51 and the amount of liquid pool in the liquid pool 5a. From this figure, it can be seen that the lower the transfer voltage, the smaller the amount of liquid pool. That is, it can be said that the lower the transfer voltage, the easier the carrier liquid passes between the transfer belt 6 and the photosensitive drum 1. Thus, in the present embodiment, the voltage applied to the transfer roller 51 in the blank paper print mode is reduced as compared with the normal image formation. This makes it easier for the carrier liquid to pass through the transfer section, so that more carriers can be made to adhere to the transfer paper 7 and pass through the transfer section 5 in the blank paper print mode. Therefore,
The carrier liquid in the developer tank 44 can be consumed more.

The transfer paper 7 to which the carrier liquid has adhered passes through the fixing device and is discharged outside the machine. In the blank paper print mode, the transfer paper 7 may be collected as it is without passing through the fixing device, or may be discharged outside the machine and discarded.

After executing the blank paper print mode and performing one blank paper print, the upper float sensor 49 determines whether the developer level in the developer tank 44 is higher than the upper limit.
Is detected again, and when the developer level in the developer tank 44 is higher than the upper limit, blank printing is performed again.
When the developer surface is lower than the upper limit, the image returns to the normal image forming state. The blank print mode is set so that the detection is performed by the upper float sensor 49 every time one blank sheet is printed, and the detection is performed again after performing a predetermined number of blank sheets of two or more sheets. May be.

As described above, according to the present embodiment, when an increase in the developer in the developer tank 44 is detected, the blank paper print mode is executed, and only the carrier liquid in the developer tank 44 is consumed. Can be reliably prevented from overflowing without complicating the method. Further, the developer tank 4
4 is not discarded, so that the toner solid content can be effectively used.

Further, according to the present embodiment, the rotation speed of the squeeze roller 42 in the blank paper print mode is reduced as compared with the normal image formation, so that more carrier liquid adheres to the surface of the photosensitive drum 1. Since the transfer to the transfer paper is performed in the state in which the transfer is performed, the carrier liquid in the developer tank 44 can be efficiently consumed, and the liquid overflow can be more effectively prevented.

According to the present embodiment, the absolute value of the voltage applied to the set roller 43 in the blank paper print mode is reduced as compared with the normal image formation, so that more carrier liquid can be supplied to the photosensitive drum. Since the transfer to the transfer paper is performed in a state of being adhered to one surface, the carrier liquid in the developer tank 44 can be efficiently consumed, and the overflow can be prevented more properly.

Further, according to the present embodiment, the voltage applied to the transfer roller 51 is reduced as compared with the normal image formation, so that the transfer is performed in a state where more carriers are adhered to the transfer paper 7. Since it can pass through part 5,
The carrier liquid in the developer tank 44 can be efficiently consumed, and the liquid overflow can be more effectively prevented.

In the above-described embodiment, blank paper printing is performed in which the toner is not consumed in the blank paper printing mode and only the carrier liquid is consumed. However, an image in which the toner is also consumed at a predetermined ratio is formed. However, it is possible to prevent liquid overflow from the developer tank 44 without making the apparatus complicated. If an image such as a thin line, a patch, or a gradation is used as this image, it can be used for checking the function of the system.

In the above-described embodiment, the blank paper print mode is executed based on the result of detection of the amount of liquid in the developer tank 44 by the upper float sensor 49. Without detecting the volume,
At a predetermined timing, for example, when the power of the copier is turned on, control may be performed to execute the blank paper print mode.

In the above embodiment, the rotation speed of the squeeze roller 42, the applied voltage of the set roller 43,
The voltage applied to the transfer roller 51 was decreased compared to the normal image formation to increase the consumption of the carrier liquid, but the rotation speed of the squeeze roller,
And only the transfer voltage to the transfer roller 51 may be decreased to increase the consumption of the carrier liquid. Alternatively, the blank paper print mode may be executed in the same state as during normal image formation.

In addition to the squeeze roller 42 used in the above embodiment, a corona discharger, an air knife or the like may be used as the surplus liquid removing means, and these may be employed.
Also in this case, the same effect as in the above embodiment can be obtained by reducing the excess liquid removing performance in the blank paper print mode.

As the above-mentioned binding means, in addition to the set roller 43 used in the above embodiment, there are those using a corona discharger and those using a plate-like electrode, and these may be adopted. . Also in this case, in the blank paper print mode, the same effect as in the above embodiment can be obtained by lowering the voltage applied to the corona discharger or the plate-like electrode compared to the normal image formation.

In the above embodiment, only the carrier liquid is applied to the surface of the photosensitive drum 1 in order to consume only the carrier liquid in the developing solution tank. By setting the voltage applied to the transfer roller 51 to a voltage at which the toner does not transfer to the transfer paper 7, only the carrier liquid is allowed to adhere to the transfer paper 7, and only the carrier liquid in the developer tank is consumed. May be configured.

Further, a toner image is formed on each of the photosensitive drums by a wet developing device provided corresponding to each of the photosensitive drums as a plurality of latent image carriers, and the plurality of photosensitive drums are transported using a transport belt. The transfer paper is conveyed so as to sequentially face the drum, and a toner image formed on the surface of each photosensitive drum is transferred to the transfer paper using a transfer unit to form a wet image forming apparatus that forms an image. The present invention may be applied to execute the blank paper print mode to consume the carrier liquid of each wet developing device. In this case, the amount of toner consumed by image formation is not always the same in each wet developing device.
Therefore, a means for detecting the amount of the developer in the developing tank is provided in each of the developing tanks in each of the wet developing devices. The configuration may be such that the voltage applied to the set roller or the voltage applied to the transfer roller is controlled. Specifically, how much the amount of the developer is larger than a predetermined upper limit is detected by each of the detection means, and the ratio of the surplus amount of the developer in each developing tank and the wet developing device having the developing tank are used. The blank paper print mode is executed in a state where the ratio of the amount of the consumed carrier liquid is substantially equal. As a result, the amount of the developer in the developer tank at the same time in each wet developing device becomes equal to or less than the upper limit, so that the blank paper print mode is not unnecessarily executed and the waiting time is not increased, and the operability is improved. I do.

[0049]

According to the first to seventh aspects of the present invention, at a predetermined timing, at least a liquid carrier in the developing solution in the developing solution container is attached to the surface of the latent image carrier, and the liquid carrier is further applied. By transferring the liquid carrier onto the transfer material and attaching the liquid carrier to the transfer material, the carrier liquid in the developer storage unit can be consumed. This allows
There is an excellent effect that the liquid can be prevented from overflowing without complicating the apparatus.

Further, according to the present invention, only the liquid carrier is transferred to the transfer material and the toner solid content in the developer storage section is not discarded, so that the toner can be effectively used. There is an excellent effect.

According to the third, sixth and seventh aspects of the present invention, the amount of the developing solution removed by the excess solution removing means is reduced in comparison with the normal image forming operation, and the amount of the developing solution contained in the developing solution storage section is reduced. At least the liquid carrier in the developer is adhered to the surface of the latent image carrier, and the liquid carrier is further transferred to the transfer material. Transfer can be performed. Therefore, there is an excellent effect that the liquid carrier in the developer storage section can be efficiently consumed, and the overflow of the liquid can be more effectively prevented.

Further, according to the present invention, the absolute value of the voltage applied to the binding means is reduced in the developer storage section in a state where the absolute value of the voltage is reduced as compared with the normal image formation. At least the liquid carrier in the developing solution is adhered to the surface of the latent image carrier, and the liquid carrier is further transferred to the transfer material. Can be transferred. Therefore, there is an excellent effect that the liquid carrier in the developer storage section can be efficiently consumed, and the overflow of the liquid can be more effectively prevented.

According to the present invention, the amount of charge applied to the transfer material supporting member by the transfer charge applying means is reduced in comparison with a normal image forming operation. Since at least the liquid carrier in the developer in the portion is attached to the surface of the latent image carrier, and the liquid carrier is further transferred to the transfer material, the transfer electric field is weaker than in the normal image formation. This makes it easier for the liquid carrier adhering to the transfer material to pass between the transfer material support member and the latent image carrier, so that more carrier can be efficiently consumed and the liquid overflow can be more favorably performed. Can be prevented.

According to the sixth and seventh aspects of the present invention, the amount of the developing solution removed by the excess solution removing means is reduced as compared with the normal image formation, and the voltage applied to the binding means is reduced. At least one of a state in which the absolute value is reduced as compared with normal image formation, and a state in which the amount of charge applied to the transfer material supporting member by the transfer charge applying unit is reduced as compared with normal image formation. At least two liquid carriers in the developing solution in the developing solution storage portion are attached to the surface of the latent image carrier in a state where the two are filled, and the liquid carriers are further transferred to a transfer material. It can be transferred to materials and consumed. Therefore, there is an excellent effect that the liquid carrier in the developer storage section can be more efficiently consumed, and the overflow of the liquid can be more effectively prevented.

In particular, according to the seventh aspect of the present invention, the control means detects the amount of the developing solution stored in the developing solution storage section based on the detection result by the detecting means for detecting the amount of the developing solution stored in the developing solution storage section. Since at least the liquid carrier in the developer is attached to the surface of the latent image carrier and the liquid carrier is automatically controlled to be further transferred to the transfer material, there is an excellent effect that the operability is improved.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a main part of an electrophotographic copying machine according to an embodiment.

FIG. 2 is a diagram showing the relationship between the rotation speed of a squeeze roller of the copying machine and the amount of residual carrier on the surface of a photosensitive drum after passing through the squeeze roller.

FIG. 3 is a diagram showing a relationship between an applied voltage of a set roller of the copying machine and a residual carrier amount on the surface of the photosensitive drum after passing through the set roller.

FIG. 4 is an enlarged view of the vicinity of a contact portion between a transfer belt and a photosensitive drum of the copying machine.

FIG. 5 is a diagram showing a relationship between an applied voltage of a transfer roller of the copying machine and a liquid pool amount in a liquid pool section.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 main charger 3 exposure device 4 wet developing device 41 developing roller 42 squeeze roller 43 set roller 44 developer tank 5 transfer unit 6 transfer belt 7 transfer paper

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yuichi Aoyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Masaki Hiroi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd.

Claims (7)

[Claims] A latent image carrier, a latent image forming means for forming a latent image on a surface of the latent image carrier, and a developer accommodating portion for accommodating a developer in which toner is dispersed in a liquid carrier. A wet developing device that develops a latent image formed on the latent image carrier using the developer to form a toner image, and a transfer that transfers the toner image formed on the latent image carrier to a transfer material Means for attaching at least a liquid carrier in the developing solution in the developing solution container to the surface of the latent image carrier at a predetermined timing, and further transferring the liquid carrier to the transfer material. A wet-type image forming apparatus, comprising a control unit for controlling the image formation to be performed. 2. The wet image forming apparatus according to claim 1, wherein said control means is configured to transfer only the liquid carrier to said transfer material. 3. A wet image forming apparatus according to claim 1, wherein said wet developing device has an excess liquid removing means for removing excess developing solution on the surface of said latent image carrier, and said excess liquid removing means. In a state in which the amount of the developer removed by the developer is reduced as compared with the normal image formation, at least a liquid carrier in the developer in the developer container is attached to the surface of the latent image carrier, and the liquid carrier is further removed. A wet image forming apparatus, wherein the control unit is configured to transfer the image to a transfer material. 4. A wet-type image forming apparatus according to claim 1, wherein said wet-type developing device is disposed so as to face a toner image on said latent image carrier at a predetermined interval, and applies a predetermined voltage. A developing means for binding the toner image to the developer in a state where the absolute value of the voltage applied to the binding means is reduced as compared with the normal image formation. A wet image forming apparatus, wherein the control unit is configured to attach at least a liquid carrier therein to the surface of the latent image carrier and further transfer the liquid carrier to a transfer material. 5. A wet image forming apparatus according to claim 1, wherein said transfer means supports a transfer material and contacts a surface of said transfer material with a surface of said latent image carrier, and said transfer means comprises: Using a transfer charge applying means for applying a charge to the front surface or the back surface of the material support member, in a state where the amount of charge applied to the transfer material support member by the transfer charge application means is reduced as compared with normal image formation, Wet image forming wherein the control means is configured to attach at least a liquid carrier in a developing solution in the developing solution storage portion to the surface of the latent image carrier and further transfer the liquid carrier to a transfer material. apparatus. 6. A wet image forming apparatus according to claim 1, wherein said means for removing excess developer on the surface of said latent image carrier has a predetermined distance from a toner image on said latent image carrier. Binding means for applying a predetermined voltage to bind the toner image, and supporting the transfer material to bring the transfer material surface into contact with the latent image carrier surface Removing at least two of transfer means using a transfer material supporting member and transfer charge applying means for applying a charge to the front or back surface of the transfer material supporting member, and removing the developer by the excess liquid removing means A state in which the amount is reduced as compared with normal image formation, a state in which the absolute value of the voltage applied to the binding unit is reduced as compared with normal image formation, and the transfer by the transfer charge applying unit. The amount of charge applied to the material support member is At least two of the states with reduced
The control means is configured to cause at least a liquid carrier in the developing solution in the developing solution storage portion to adhere to the surface of the latent image carrier and to further transfer the liquid carrier to a transfer material in a state where the two are satisfied. A wet image forming apparatus. 7. A wet-type image forming apparatus according to claim 1, further comprising a detecting means for detecting a liquid amount of the developer stored in said developer storing section. The control means is configured to cause at least a liquid carrier in the developer in the developer storage portion to adhere to the surface of the latent image carrier based on a detection result by the means, and to further transfer the liquid carrier to a transfer material. A wet image forming apparatus, comprising: