JPH09244437A - Wet image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent transfer image quality over a wide range from a highlight part where toner sticking amount is small to a dark part where the toner sticking amount is large by providing a control means changing the setting of transfer charge amount imparted to an opposed member for transfer based on the charge amount of a toner image. SOLUTION: Transfer voltage outputted from a small-sized transfer power source 10 which is called a power pack constituted to perform constant-voltage control or constantcurrent control is impressed on a transfer roller 6. The transfer voltage impressing timing and the magnitude of the transfer voltage by the power source 10 are respectively controlled in accordance with an ON/OFF control signal and the pulse width of a voltage control pulse signal transmitted from a controller 11 functioning as a control means constituted of the CPU of a device main body, etc. The setting of the transfer charge amount per unit time imparted to the roller 6 is changed based on the charge amout of the toner image expected to pass a transfer position on a photoreceptor drum 1 per unit time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet image forming apparatus such as a copying machine, a facsimile, a printer, and the like. More specifically, the image carrier is uniformly charged and then an image is applied to the image carrier. A latent image forming means for forming a latent image by irradiating the formed light; a developing means for developing the latent image on the image bearing member with a developing solution in which toner is dispersed in a liquid carrier to form a toner image; The present invention relates to a wet image forming apparatus including a transfer unit that transfers a toner image to a transfer material by applying a transfer charge to the toner image on the image carrier so as to face the transfer material.

[0002]

2. Description of the Related Art Conventionally, a latent image formed on an image carrier is
Development is performed using a developing solution in which toner is dispersed in a liquid carrier, a toner image is formed on the image carrier, and a transfer charge is applied to a transfer opposing member facing the toner image via a transfer material. There is known a wet image forming apparatus which transfers the toner image to the transfer material to form an image.
The optimum amount of transfer charges applied to the transfer opposing member in this type of wet image forming apparatus depends on the charge amount of the toner image formed on the image carrier. For example, when the transfer charge amount applied to the transfer opposing member is smaller than the charge amount of the toner image on the image carrier, transfer failure or image deletion may occur. On the contrary, when the transfer charge amount applied to the transfer opposing member is larger than the charge amount of the toner image on the image carrier, image blurring or the like may occur.
Moreover, in the actual image formation, the toner adhesion amount in the toner image on the image carrier is not constant and changes depending on the type of the image, so the charge amount of the transferred toner image also changes. As described above, the optimum amount of the transfer charges applied to the transfer opposing member changes every moment depending on the type of the image.

Further, a power source for performing constant voltage control or constant current control is used as a power source for applying a charge to the transfer opposing member of the transfer means, and a highlight portion having a small toner adhesion amount to a dark toner having a large toner adhesion amount is used. It covered a wide range up to the department.

[0004]

However, in the conventional configuration in which electric charges are applied to the transfer opposing member of the transfer means by using a power source for performing constant voltage control or constant current control, as shown in FIG. Since the proper transfer current range is different between the highlight part and the dark part, it is difficult to obtain good transfer image quality in both the highlight part and the dark part.

The present invention has been made in view of the above problems, and an object thereof is to obtain a good transfer image quality over a wide range from a highlight portion having a small toner adhesion amount to a dark portion having a large toner adhesion amount. It is to provide a wet image forming apparatus capable of

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 is such that after uniformly charging the image carrier,
A latent image forming unit that irradiates the image carrier with light corresponding to the image to form a latent image, and the latent image on the image carrier is developed with a developer in which toner is dispersed in a liquid carrier. And a developing unit that forms a toner image, and a transfer unit that transfers the toner image to the transfer material by applying a transfer charge to a transfer opposing member that faces the toner image on the image carrier via the transfer material. In the wet image forming apparatus including the above, a control unit for changing the setting of the transfer charge amount applied to the transfer facing member based on the charge amount of the toner image is provided.

According to a second aspect of the present invention, in the wet image forming apparatus according to the first aspect, the charge amount of the toner image is calculated based on the optical writing signal used in the latent image forming means. is there.

According to a third aspect of the present invention, in the wet image forming apparatus according to the first aspect, surface potential detecting means for detecting the surface potential of the image carrier before the transfer is provided, and based on the detection result of the surface potential detecting means. It is characterized in that the charge amount of the toner image is calculated.

According to a fourth aspect of the present invention, in the wet image forming apparatus according to the first aspect, the toner image and the liquid carrier on the image carrier before the transfer are opposed to each other through a gap, and the gap and the toner image are formed. It is characterized in that an electric field forming means for forming an electric field of such an intensity that a current flows therethrough with the image carrier is provided.

According to a fifth aspect of the present invention, in the wet image forming apparatus according to the first aspect, a light irradiating unit for irradiating the image carrier before transfer with light for reducing the electric resistance of the image carrier is provided. It is characterized by that.

According to a sixth aspect of the present invention, the transfer material is interposed between the image carrier and the transfer opposing member, or the transfer material and the transfer transfer member for holding and transferring the transfer material are interposed. 2. The wet image forming apparatus according to claim 1, wherein the transfer is performed in a state where the transfer charge is applied to the transfer opposing member based on the charge amount of the toner image and the charge amount of the transfer material or the transfer conveying member before transfer. It is characterized by changing the amount setting.

According to a seventh aspect of the present invention, a plurality of sets of the image bearing member, the latent image forming unit, the developing unit and the transfer unit are provided, and the toner images formed on each image bearing member are sequentially transferred to a transfer material. The wet image forming apparatus according to claim 6 is characterized in that the charge amount of the transfer material or the transfer / transport member is calculated based on the transfer control signal used by the transfer unit in the preceding stage.

According to an eighth aspect of the present invention, in the wet image forming apparatus according to the sixth aspect, surface potential detecting means for detecting the surface potential of the transfer material or transfer conveying member before the transfer is provided, and the surface potential detecting means detects the surface potential. Based on the result, the charge amount of the transfer material or the transfer / transport member before the transfer is calculated.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a wet image forming apparatus according to the present invention will be described below. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. The photosensitive drum 1 serving as an image carrier is rotationally driven in the direction of the arrow at a constant speed by a driving unit such as a motor (not shown). The outer peripheral surface of the photosensitive drum 1 is uniformly charged by the main charger 2 as a constituent element of the latent image forming means, and then converted into an optical writing signal by the optical writing device 3 as a constituent element of the latent image forming means. The light beam modulated accordingly is mainly scanned and irradiated, and an electrostatic latent image is formed on the photosensitive drum 1. The electrostatic latent image is developed by a developing solution in which toner is dispersed in a liquid carrier supplied from the developing roller 4 while passing through a region facing the developing roller 4 in a wet developing device as a developing unit. And becomes a toner image. Excess carrier liquid on the surface of the photosensitive drum 1 on which this toner image is formed is removed by a squeeze roller 5 as a surplus liquid removing means. Then, by the transfer roller 6 as a transfer opposing member of the transfer means, the transfer paper 8 as a transfer material is fed and held by a transfer / transport belt 7 as a transfer / transport member from a sheet feeding device (not shown). The toner image on the photosensitive drum 1 is transferred. At the time of this transfer, the toner image on the photosensitive drum 1 is transferred onto the photosensitive drum 1 and the transfer paper 8
Electrophoresis is performed in the liquid carrier filled in the space between the photosensitive drum 1 and the transfer paper 8. Photoconductor drum 1
After the transfer paper 8 is separated from the surface, the cleaning blade 9 removes the residual toner and prepares for the next image formation.

The transfer roller 6 used for transferring the toner image is a roller made of a conductive material. When a conductive transfer roller is used as described above, the amount of (ionic) charges that do not contribute to transfer is smaller than that of a corona charger,
High transfer efficiency and little ozone generation.

Further, at the time of transferring the toner image in the wet image forming apparatus, in order to prevent a ghost image due to a minute transfer omission, as described above, between the photosensitive drum 1 and the transfer paper 8. Although the liquid carrier needs to be filled, the filling of the liquid carrier can be promoted by pressing the transfer roller 6 against the photosensitive drum 1 side via the transfer / transport belt 7.

Discharge due to the transfer charge applied to the transfer roller 6 occurs in the gap upstream of the contact position of the transfer roller 6 in the transfer paper conveyance direction, and goes from the transfer roller 6 to the transfer conveyance belt 7 side. The size of the gap where the discharge starts follows the Paschen curve. When this transfer roller 6 is used, the transfer roller 6 is pressed against the photosensitive drum 1 via the transfer conveyor belt 6 and the transfer paper 7. Therefore, between the transfer conveyor belt and the transfer roller 6 on the upstream side of the contact position. It is easy to manage the gap, that is, the gap at which the discharge starts.

Further, when a corona charger or the like is used as the transfer opposing member, the discharge area thereof is widened, so that it is installed so as not to give too much electric charge on the upstream side of the contact portion between the photosensitive drum 1 and the transfer paper 8. It is difficult to adjust the position, and in some cases it is necessary to provide a member that regulates the electric field region (discharge region) formed by the transfer charges. However, when the transfer roller 6 is used, the transfer roller 6 also has a function of bringing the photosensitive drum 1 and the transfer paper 8 into close contact with each other, and it is easy to apply an electric charge to the close contact portion, so that the image quality is deteriorated. There is no.

A transfer voltage output from a small transfer power source 10 called a power pack configured to perform constant voltage control or constant current control is applied to the transfer roller 6. The timing of applying the transfer voltage by the transfer power supply 10 and the magnitude of the transfer voltage are respectively the control device 1 as the control means including the CPU of the main body of the device.
It is controlled according to the pulse width of the ON / OFF control signal and the voltage control pulse signal sent from No. 1.

Here, the amount of transfer charge applied to the transfer roller 6 per unit time is set by the photosensitive drum 1.
The change is made based on the charge amount of the toner image before transfer, that is, the charge amount of the toner image expected to pass through the transfer position per unit time. For example, the optimum transfer voltage corresponding to the charge amount of the toner image is predicted and calculated from the image information, and the setting of the pulse width of the voltage control pulse signal is changed based on the optimum transfer voltage. It is sent to the transfer power source 10. The setting change of the pulse width of the voltage control pulse signal, that is, the setting change of the transfer charge amount applied to the transfer roller 6 is executed at a predetermined repetition timing.

As described above, according to the present embodiment, the transfer charges can be applied to the transfer roller 6 without excess or deficiency according to the charge amount of the toner image on the photosensitive drum 1, so that the toner adhesion amount is high. Good transfer image quality can be obtained over a wide range from the light area to the dark area where a large amount of toner adheres.

The charge amount of the toner image on the photosensitive drum 1 passing through the transfer position of the transfer roller 6 is shown in FIG.
As shown in, it can be calculated based on the optical writing signal input to the optical writing device 3. At the time of this calculation, information on the developing bias voltage applied to the developing roller 4 and the concentration of the developing solution is also referred to as necessary. Then, in the control device 11, Δt is set from the time of optical writing according to the calculated charge amount of the toner image on the photosensitive drum 1.
The transfer potential after a second is determined and is sent to the transfer power source 10 as a voltage control pulse signal. The setting change of the pulse width of the voltage control pulse signal is executed at a predetermined repetition timing. Further, the above time difference Δt is
t = (distance from the optical writing position on the surface of the photosensitive drum 1 to the transfer position) / process speed. In this way, the charge amount of the toner image is adjusted to the optical writing device 3
In the case of the configuration in which the calculation is performed based on the optical writing signal input to, it is not necessary to provide a sensor for detecting the charge amount of the toner image.

Further, as shown in FIG. 3, a surface potential sensor 12 as a surface potential detecting means for detecting the surface potential of the photosensitive drum 1 before transfer is provided, and based on the detection result of the surface potential sensor 12, The charge amount of the toner image on the photosensitive drum 1 that passes through the transfer position of the transfer roller 6 may be calculated. The surface potential sensor 12 is the photosensitive drum 1.
Plural in the axial direction, ideally one in the photosensitive drum axis
It is desirable to install them continuously in a line, and the average or sum of the outputs from the plurality of surface potential sensors 12 is used for control.

The output from the potential sensor 12 is converted into a digital signal by the sensor drive controller 13 and then sent to the controller 11. Then, the control device 11 determines the transfer voltage Δt seconds after the surface potential is detected according to the calculated charge amount of the toner image on the photosensitive drum 1, and sends it to the transfer power source 10 as a voltage control pulse signal. To do.

In this way, when the charge amount of the toner image on the photosensitive drum 1 is calculated from the detection result of the surface potential of the photosensitive drum 1 before transfer, the developing bias voltage applied to the developing roller 4 and the setting Even if there is an unexpected fluctuation in the voltage (current) applied to the roller 14, the optimum transfer voltage can be reliably applied to the transfer roller 6, and a good transferred image can be obtained.

Further, as shown in FIG. 4, the toner image and the liquid carrier on the photosensitive drum 1 before transfer are opposed to each other via a gap, and the strength is such that current flows through the gap and the toner image. You may provide the set roller 14 as an electric field formation means which forms an electric field between the photosensitive drum 1. A positive or negative DC voltage is applied to the set roller 14 from a DC power supply 15. For example, a set roller 14 whose surface layer is made of H-Al (hard alumite) is opposed to the photoconductor drum 1 with a gap of 80 to 100 μm, and the set roller 14 is −1.2 to 2.0 kV (toner polarity is negative. (In the case of characteristics), apply a DC voltage to set roller 1
A current of 30 to 70 μA is passed between the photosensitive drum 1 and the photosensitive drum 1.

By using such a set roller 14, the binding force (cohesion force) of the toner particles and the adhesion force to the surface of the photosensitive drum are increased, and an image quality with less image disturbance can be obtained. The phenomenon in which the binding force of the toner particles becomes large is that a strong electric field is applied to the toner particle layer in the toner image on the photosensitive drum 1, and the toner particles contact each other or the toner particles contact the surface of the photosensitive drum. An electric current flows, and at that time, a Maxwell stress is generated and the toner particles or the toner particles and the surface of the photosensitive drum attract each other (Johnsen-Rahbec).
It is believed that this is because the k effect) occurs.

When a discharge current flows through the set roller 14, q / m of the toner rises and charges are applied to the toner surface layer, so that the toner on the photosensitive drum 1 that has passed through the portion facing the set roller 14 is removed. The surface potential of the attached portion rises according to the voltage applied to the set roller 14 or the supplied current. On the other hand, no increase in the surface potential is observed in the part where the toner is not attached. When the set roller 14 is provided in this way, the transfer voltage applied to the transfer roller 6 is controlled in consideration of the change in the charge amount of the toner image due to the charge applied to the toner. For example, as shown in FIG. 4, the data of the voltage (current) applied to the set roller 14 at the time of image formation is sent to the control device 11, and the data of the voltage (current) is applied to the toner and the charge of the toner image. The amount of the voltage control pulse signal is predicted and the setting of the pulse width of the voltage control pulse signal to be sent to the transfer power supply 10 is changed in consideration of the surface potential increase in consideration of the prediction result.

Further, as shown in FIG. 5, an LED as a light irradiating means for irradiating the photoconductor drum 1 before transfer with light for reducing the electric resistance of the photoconductor layer of the photoconductor drum 1.
(QL) 16 may be provided. For example, in the case of a photosensitive layer made of α-Si, an LED having a peak of emission intensity near a wavelength of 660 nm is used. Such an LED (Q
L) 16 reduces the electric resistance of the photoconductor layer, and the residual charges on the photoconductor layer or unnecessary charges attached to the toner layer and unnecessary charges given to the toner layer are removed from the base of the photoconductor drum 1 ( It is allowed to escape through the raw material tube), whereby the transfer charge amount can be reduced.

Further, as shown in FIGS. 6 to 8, a transfer facing member different from the transfer roller 6 may be used. For example, as shown in FIG. 6, a conductive brush 17 may be used as the transfer facing member. In this case, as compared with the corona charger, the amount of (ionic) charges that do not contribute to the transfer is small, so that the transfer efficiency is high, the generation of ozone and the like is small, and the cost is low. Further, since the applied transfer voltage can be set lower than that of the corona charger, the load on the transfer power supply 10 is small. (Hereinafter, margin)

Further, as shown in FIG. 7, for example, a discharge plate 18 made of a conductive material such as metal having a knife-edge shaped tip may be used as the transfer facing member. The knife-edge-shaped tip of the discharge plate 18 extends in the axial direction of the photosensitive drum 1 (the direction orthogonal to the transfer paper conveyance direction), and the edge tip is processed to have a radius of curvature of about 100 μmR. ing. When transferring the toner image,
Transfer transfer belt 7 or transfer paper 8 from the tip of discharge plate 18
Discharge toward the back side of. Even when this discharge plate 18 is used, the transfer efficiency is high, the generation of ozone and the like is small, and the cost is low as compared with the corona charger because the (ionic) charges that do not contribute to the transfer are smaller. Further, it has excellent durability as compared with the conductive brush.

Further, for example, as shown in FIG. 8, as a transfer opposing member, a discharge needle 19 having a large number of needle-shaped tip portions 19a aligned in the axial direction of the photosensitive drum 1 (direction orthogonal to the transfer paper transport direction). May be used. The pitch of the needle-shaped tip portions 19a of the discharge needles 19 is, for example, several mm to several tens mm.
Set to about. At the time of transferring the toner image, electric discharge is made from the tip of the discharge needle 19 toward the back side of the transfer conveyance belt 7 or the transfer paper 8. Even when this discharge needle 19 is used, the transfer efficiency is high and the generation of ozone and the like is small as compared with the corona charger, because the (ionic) charges that do not contribute to the transfer are small.
Costs are also lower. Further, it has excellent durability as compared with the conductive brush.

In addition to the charge amount of the toner image on the photosensitive drum 1 before the transfer, the charge amount of the transfer conveyance belt 7 before the transfer is taken into consideration, and the transfer roller 6 or the like is provided with a transfer opposing member. The transfer charge amount setting may be controlled to be changed. By thus considering the charge amount of the transfer conveyance belt 7 before transfer, a plurality of image forming units including the photoconductor drum 1 and the optical writing device 3 are provided, and the transfer paper 8 held on the transfer conveyance belt 7 is provided. When the images formed by the respective image forming units are transferred so as to be superposed on each other, even if the charge amount of the transfer / conveying belt, that is, the surface potential of the belt is changed, the toner is attached from the highlight portion where the toner attachment amount is small. It is possible to obtain a good transfer image quality over a wide range up to a dark area where the amount is large.

Here, the charge amount of the transfer paper before the transfer is transferred from the control device 11 so as to set the transfer voltage applied to the transfer roller 6a of the image forming unit in the preceding stage, as shown in FIG. 9, for example. It can be calculated using the transfer control signal sent to the power supply 10a. 10 and 11 show an example of the relationship between the transfer current I (n) and the potential increase V '(n) -V' (n-1) of the transfer / transport belt 7 due to transfer, and between the belt and the roller. Potential difference V (n) -V '(n-1)
3 is a graph showing an example of the relationship between the transfer current I (n) and the transfer current I (n).
The data as shown in FIGS. 10 and 11 are prepared for various types of transfer paper, and the control device 1 is provided as a conversion table or conversion formula.
It is stored in the storage unit in 1. Then, the transfer charge amount required for transfer is calculated as the transfer current I (n) from the data on the charge amount of the toner image on the photosensitive drum 1 calculated or detected by the various means. The value of this desired transfer current I (n) and the potential V ′ (1) of the transfer conveyor belt 7 before the second transfer
11 is used to determine the transfer voltage V (2) applied to the transfer roller 6b using the data of FIG. 11, and the transfer control signal is sent to the transfer power supply 10b.

Here, the potential V '(1) of the transfer conveyor belt 7 before the transfer of the second step is the transfer voltage V (1) applied to the transfer roller 6 of the first step, and the transfer current I at that time. It is calculated using (1) and the above conversion table (conversion formula). Thus 2
When the potential V ′ (1) of the transfer conveyor belt 7 of the stage is calculated using the transfer potential V (1) of the preceding stage, it is not necessary to provide a new surface potential sensor or the like.

Further, as shown in FIG. 12, a surface potential sensor 20 is provided as a surface potential detecting means for detecting the surface potential of the transfer / transport belt 7 before transfer, and based on the detection result of the surface potential sensor 20, The charge amount of the transfer / conveyance belt 7, that is, the surface potential of the belt 7 may be calculated.
It is desirable to install a plurality of surface potential sensors 20 in the axial direction of the photosensitive drum, and ideally, to continuously install them in one line in the axial direction of the photosensitive drum. The output average or sum is used for control. The surface potential sensor 20 mainly requires an opposing electrode. In this case, the opposing electrode is installed on the transfer / conveying belt 7 side and the non-contact probe is installed on the transfer paper 8 side.

The output from the surface potential sensor 20 is converted into a digital signal by the sensor drive controller 21 and then sent to the controller 11. Then, the control device 11 determines the transfer voltage Δt seconds after the surface potential is detected according to the calculated charge amount of the toner image on the photosensitive drum 1, and outputs the transfer voltage to the transfer power source 10 as a transfer voltage control pulse signal. Send out.

In this way, when the charge amount of the transfer / transport belt 7, that is, the surface potential of the transfer / transport belt 7 is calculated from the detection result of the surface potential of the transfer / transport belt 7 before transfer, the transfer voltage of the preceding stage and the charge of the transfer / transport belt are calculated. Even if there is an unexpected change in the relationship with the amount, the optimum transfer voltage can be reliably applied to the transfer roller 6, and a good transferred image can be obtained.

In the above embodiment, the case of the wet image forming apparatus in which transfer is performed by interposing the transfer conveyance belt between the transfer facing member such as the transfer roller and the transfer paper has been described. The present invention can also be applied to a wet image forming apparatus that performs transfer by bringing a transfer facing member such as a transfer roller into contact with or in proximity to a transfer paper without interposing a transfer conveyance belt.

[0040]

According to the first to eighth aspects of the present invention, based on the charge amount of the toner image on the image carrier, a portion having a small charge amount of the toner image, such as a highlight portion having a small toner adhesion amount, is obtained. When a toner image is transferred to a transfer material, the transfer charge amount applied to the transfer opposing member that faces the toner image on the image bearing member via the transfer material is reduced, and the toner is attached to the toner image like a dark portion where a large amount of toner adheres. When the charge amount of the image is large, the setting of the transfer charge amount is changed so that the transfer charge amount applied to the transfer opposing member is increased. In this way, the setting of the transfer charge amount applied to the transfer opposite member can be changed to the optimum amount based on the charge amount of the toner image. There is an effect that a good transfer image quality can be obtained over a wide range up to a part.

In particular, according to the second aspect of the invention, the charge amount of the toner image is calculated based on the optical writing signal used in the latent image forming means, and the calculated charge amount is applied to the transfer opposing member. Since it can be used to change the setting of the transfer charge amount, the effect is that there is no need to provide a detection unit for detecting the charge amount of the toner image.

Further, according to the invention of claim 3, the surface potential detecting means detects the surface potential of the image carrier before transfer,
By calculating the charge amount of the toner image based on the detection result, the calculated charge amount can be used to change the setting of the transfer charge amount to be given to the transfer opposing member. Even if there is a fluctuation, the optimum transfer voltage can be reliably applied to the transfer opposing member, and a good transferred image can be obtained.

Further, according to the invention of claim 4, in the electric field forming means facing the toner image and the liquid carrier on the image carrier before transfer via a gap, a current is passed through the gap and the toner image. By forming an electric field of such a strength as to flow between the image carrier and the image carrier, the cohesive force (cohesion force) of the toner particles in the toner image and the adhesion force to the surface of the photoconductor drum are increased, resulting in less image distortion. There is an effect that can be obtained.

In particular, according to the invention of claim 5, the image irradiating means irradiates the image carrier before transfer with light to reduce the electric resistance of the image carrier, so that the image carrier remains on the image carrier. There is an effect that the amount of transferred charges can be reduced by escaping the unnecessary charges attached at the time of writing electric charges or light and the unnecessary charges given to the toner image through the substrate of the image carrier.

Further, according to the sixth to eighth aspects of the invention, the transfer charge amount used for transferring the toner image is set based on the charge amount of the toner image and the charge amount of the transfer material or the transfer conveying member before transfer. By changing the value, even if the charge amount of the transfer material or the transfer / conveying member fluctuates, good transfer image quality can be obtained over a wide range from the highlight part with a small toner adhesion amount to the dark part with a large toner adhesion amount. There is an effect that can be.

In particular, according to the invention of claim 7, a plurality of sets of the image carrier, the latent image forming means, the developing means and the transfer means are provided, and the toner image formed on each image carrier is formed. When sequentially transferring to the transfer material, by calculating the charge amount of the transfer material or the transfer conveying member based on the transfer control signal used in the transfer unit in the preceding stage, the calculated charge amount is transferred to the transfer opposing member. Since it can be used to change the setting of the transfer charge amount to be applied, there is an effect that it is not necessary to provide a surface potential detecting means or the like for detecting the charge amount of the transfer material or the transfer conveying member before transfer.

In particular, according to the invention of claim 8, the surface potential detecting means detects the surface potential of the transfer material or the transfer conveying member before the transfer, and based on the detection result, the transfer material or the transfer material before the transfer. By calculating the charge amount of the transport member, the calculated charge amount can be used to change the setting of the transfer charge amount to be applied to the transfer opposing member, and even if the transfer condition in the preceding stage is changed, the transfer is performed. There is an effect that the optimum transfer voltage can be surely applied to the member facing member and a good transferred image can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of a wet image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 3 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 4 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 5 is a front view showing a schematic configuration of a wet image forming apparatus according to still another embodiment.

FIG. 6 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 7 is a front view showing a schematic configuration of a wet image forming apparatus according to still another embodiment.

FIG. 8 is a front view showing a schematic configuration of a wet image forming apparatus according to still another embodiment.

FIG. 9 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 10 is a graph showing a relationship between a transfer current and a potential increase of a transfer / conveyance belt.

FIG. 11 is a graph showing the relationship between the potential difference between the transfer conveyance belt and the transfer roller and the transfer current.

FIG. 12 is a front view showing a schematic configuration of a wet image forming apparatus according to another embodiment.

FIG. 13 is a graph showing the relationship between transfer current and transferred image.

[Explanation of symbols]

 1 Photosensitive Drum 2 Main Charger 3 Optical Writing Device 4 Developing Roller 5 Squeeze Roller 6 Transfer Roller 7 Transfer Conveyor Belt 8 Transfer Paper 9 Cleaning Blade 10 Transfer Power Supply 11 Controller 12 Surface Potential Sensor 13 Sensor Control Driver 14 Set Roller 15 DC Power supply 16 LED (QL) 17 Conductive brush 18 Discharge plate 19 Discharge needle 20 Surface potential sensor 21 Sensor control drive unit

Claims (8)

[Claims] 1. A latent image forming means for forming a latent image by irradiating the image bearing body with light corresponding to an image after the image bearing body is uniformly charged, and a latent image on the image bearing body. A developing unit that develops an image with a developer in which toner is dispersed in a liquid carrier to form a toner image, and a transfer charge is applied to a transfer opposing member that faces the toner image on the image carrier via a transfer material. In a wet image forming apparatus including a transfer unit that transfers the toner image to the transfer material by applying the transfer charge amount, the transfer charge amount applied to the transfer opposing member is set based on the charge amount of the toner image. A wet image forming apparatus comprising a control unit for changing. 2. The wet image forming apparatus according to claim 1, wherein the charge amount of the toner image is calculated based on an optical writing signal used in the latent image forming means. 3. The wet image forming apparatus according to claim 1, further comprising surface potential detecting means for detecting the surface potential of the image carrier before the transfer, wherein the toner image of the toner image is detected based on the detection result of the surface potential detecting means. A wet-type image forming apparatus characterized by calculating a charge amount. 4. The wet image forming apparatus according to claim 1, wherein the toner image and the liquid carrier on the image carrier before the transfer are opposed to each other through a gap, and a current flows through the gap and the toner image. A wet image forming apparatus comprising an electric field forming means for forming an electric field of such strength between the image carrier. 5. The wet image forming apparatus according to claim 1, further comprising a light irradiating unit for irradiating the image carrier before the transfer with light for reducing the electric resistance of the image carrier. Wet image forming apparatus. 6. A transfer is performed with a transfer material interposed between the image bearing member and a transfer opposing member, or with a transfer material and a transfer conveyance member that holds and conveys the transfer material interposed. The wet image forming apparatus according to claim 1, wherein the setting of the transfer charge amount applied to the transfer opposing member is changed based on the charge amount of the toner image and the charge amount of the transfer material or the transfer conveying member before transfer. A wet-type image forming apparatus characterized in that. 7. The toner image formed on each image carrier is sequentially transferred onto a transfer material by providing a plurality of sets of the image carrier, the latent image forming means, the developing means and the transfer means.
In the wet image forming apparatus, the amount of electric charge of the transfer material or the transfer conveying member is calculated based on the transfer control signal used in the transfer unit in the previous stage. 8. The wet image forming apparatus according to claim 6, further comprising surface potential detecting means for detecting the surface potential of the transfer material or the transfer conveying member before the transfer, and based on the detection result of the surface potential detecting means. A wet image forming apparatus, characterized in that the amount of charges of the transfer material or transfer conveying member before transfer is calculated.