JP3676071B2 - Wet image forming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wet image forming apparatus that visualizes an electrostatic latent image formed by an electrophotographic system using a liquid developer having a high viscosity and a high concentration.
[0002]
[Prior art]
An image forming apparatus that visualizes an electrostatic latent image using a liquid developer having a high viscosity and a high concentration is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 7-295339, 7-295372, and 7-325488. It is disclosed. In this image forming apparatus, the surface of the photosensitive member is uniformly charged by a charging unit, and then the surface of the photosensitive member is exposed according to image data by a writing unit to form an electrostatic latent image, which is visualized by a liquid developing device. The liquid developing device is a high-viscosity liquid developer having a viscosity of 100 to 10,000 mPa · s in which a toner as a visualized particle is dispersed at a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. The electrostatic latent image is visualized, and the liquid developer stored in the storage tank is applied to the developing belt with a uniform thickness, and the liquid developer thin layer on the developing belt with the developing bias potential applied to the surface is exposed to light. When passing through the development area close to the body, the electrostatic latent image on the photoreceptor is developed with toner of a thin liquid developer layer to form a toner image. The liquid developer remaining on the developing belt that has passed through the developing region is removed by a scraping blade and collected in a storage tank. The toner image formed on the photoconductor is transferred to transfer paper, and the toner image transferred to the transfer paper is fixed to form an image. The toner remaining on the photoconductor after the transfer process is completed is removed by a cleaning unit, and the image forming process is completed.
[0003]
When developing the electrostatic latent image on the photosensitive member with this thin liquid developer layer, the developing belt and the photosensitive member are pressed at a relatively low pressure through the thin liquid developer layer in the developing region in order to suppress the collapse of the toner image. It is necessary to be in contact (hereinafter referred to as soft touch). In order to realize this soft touch, a developing belt which is an endless belt is used, and the deflection of the developing belt is used. That is, the developing belt is wound around a driving roller whose surface layer portion is made of a material having a large friction coefficient, such as a rubber material, and one or a plurality of driven rollers, and the driving roller is rotated by the driving motor, and the developing belt is developed. The developing belt is rotated while applying a driving force to the belt.
[0004]
[Problems to be solved by the invention]
As described above, in order to realize a soft touch between the developing belt and the photosensitive member in the developing area, the circumferential tension of the developing belt cannot be increased so much that the driving roller and the developing belt slip. The phenomenon occurs. Increasing the tension of the developing belt to eliminate this slipping will not only realize soft touch, but also cause wrinkles in the circumferential direction of the developing belt and problems with the durability of the developing belt, thus realizing an ideal soft touch. It becomes difficult. In addition, when a pre-wetting liquid is used for the liquid developer or the photosensitive member due to an unexpected cause, if this pre-wetting liquid adheres to the inner peripheral surface of the developing belt, the friction between the driving roller and the developing belt Since the force is reduced, slipping is likely to occur, which causes deterioration of the image quality of the toner image formed on the photoreceptor.
[0005]
The present invention improves such disadvantages, and even when the circumferential tension of the developing belt is weak and the liquid has entered the inner peripheral surface of the developing belt, the development belt can be driven stably and the liquid developing device can leap forward. An object of the present invention is to obtain a wet-type image forming apparatus that can be reduced in size.
[0006]
[Means for Solving the Problems]
In the wet image forming apparatus according to the present invention, the driving force for moving the developing belt, which is an endless belt , is transmitted from the image carrier through the contact portion between the image carrier and the developing belt, and is applied to the developing belt from 100 to 10,000. A wet image forming apparatus that applies a liquid developer having a high viscosity of mPa · s and develops an electrostatic latent image formed on an image carrier with a thin layer of liquid developer applied to the developing belt. An electric field larger than the electric field formed between the image carrier and the developing belt is formed in the image region between the developing belt and the image carrier outside the image area at the contact portion between the image carrier and the image carrier. It is characterized by doing.
[0008]
Further, between the developing belt and the image carrier outside the image area at the contact portion between the developing belt and the image carrier, the electric field formed between the image carrier and the developing belt in the image area is larger than the magnitude of the electric field. It is good to form a large electric field. Furthermore, it is desirable that the absolute value of the surface potential of the image carrier outside the image area at the contact portion between the developing belt and the image carrier is larger than the maximum absolute value of the surface potential in the image area.
[0009]
Further, the developing belt is preferably held by an application means for applying the liquid developer to the developing belt , a developer removing means for removing the liquid developer remaining on the developing belt after the completion of the developing process, and a portion where the image carrier contacts. . Further, it is desirable to move both the coating unit and the developer removing unit or the coating unit in a direction away from the image carrier when not developing.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the image forming apparatus according to the present invention, light corresponding to an image to be formed on the photosensitive member uniformly charged by the charging means is irradiated from the writing means to form an electrostatic latent image. The electrostatic latent image formed on the photoreceptor is developed with a liquid developer by a developing unit and visualized. The liquid developer has a high viscosity of 100 to 10,000 mPa · s in which toner as developer particles is dispersed at a high concentration in a carrier liquid using an insulating liquid such as dimethylpolysiloxane oil. The visible image formed on the photosensitive member by the liquid developer is transferred onto a transfer sheet by a transfer unit, and then sent to a fixing unit and fixed by heat and pressure. The potential remaining on the photoreceptor is erased by the quenching clamp, and the liquid developer remaining on the photoreceptor is removed by the cleaning means, and the above processing is repeated.
[0011]
The developing means includes a developing belt wound around a plurality of rotating rollers with a constant tension, a developer liquid reservoir configured to store a liquid developer, and a developer recovery blade, which includes a coating roller and a metering blade. The developing belt is an endless belt having convex stepped portions on the outer peripheral surfaces at both ends in the width direction and a developer holding portion for forming a liquid developer thin layer between the stepped portions at both ends. The developer holding portion has conductivity, and a transfer bias potential is applied via a rotating roller. As the transfer bias potential, a potential between the minimum value and the maximum value of the latent image potential on the photosensitive member is applied. The stepped portion is made of a material having a high friction coefficient such as a rubber material, and the height from the developer holding portion is the same as the thickness of the liquid developer thin layer formed on the developer holding portion, for example, about 2 to 10 μm. Has been. The application roller consists of a gravure roller with a pattern on the surface, etc., and a liquid developer stored in the developer liquid reservoir is applied to the developer holding part of the development belt by the application roller and metering blade, and the developer belt has a uniform thickness. A thin layer of liquid developer is formed. The developer collecting blade collects the residual liquid developer on the developing belt that has passed through the developing area.
[0012]
The step portion of the developing belt in the developing region of the developing device contacts the surface of the photosensitive member with a constant tension, and the developing belt is rotated by transmitting the rotational force of the photosensitive member to the step portion of the developing belt. In this state, the liquid developer adhering to the application roller is regulated to a uniform thickness by the metering blade and applied as a liquid developer thin layer on the surface of the developer holding portion of the development belt. The liquid developer thin layer applied to the developer holding portion of the developing belt contacts the surface of the photoreceptor in the developing area. When this liquid developer thin layer comes into contact with the surface of the photoreceptor, the distance between the surface of the photoreceptor and the surface of the developer holding portion is regulated by the height of the step portion, and is the same as the thickness of the liquid developer thin layer. Therefore, the liquid developer thin layer can be soft-touched on the surface of the photoreceptor 1. Further, since the developing belt is rotated by a driving force applied from the photosensitive member to a step portion made of a material having a high coefficient of friction, the developing belt can be rotated without sliding with respect to the photosensitive member. The surface speed can be the same as the surface speed of the photoreceptor. Therefore, the electrostatic latent image formed on the photosensitive member can be developed by the thin liquid developer layer moving at the same speed as the moving speed of the photosensitive member, and a good quality toner image is stably formed on the photosensitive member. can do.
[0013]
【Example】
FIG. 1 is a block diagram of an embodiment of the present invention. As shown in the figure, the image forming apparatus includes a charging unit 2, a writing unit 3, a developing unit 4, a transfer unit 5, a quenching clamp 6, and a cleaning unit 7 disposed around the photoreceptor 1. The toner used in this image forming apparatus handles those having a positive charge. The photoreceptor 1 is uniformly positively charged by the charging unit 2 and then light corresponding to the image to be formed is irradiated from the writing unit 3 to form an electrostatic latent image. The electrostatic latent image formed on the photoreceptor 1 is developed with a liquid developer by the developing means 4 and visualized. The liquid developer has a high viscosity of 100 to 10,000 mPa · s in which toner as developer particles is dispersed at a high concentration in a carrier liquid using an insulating liquid such as dimethylpolysiloxane oil. The visible image formed on the photoreceptor 1 by this liquid developer is transferred to the transfer paper 8 by the transfer means 5 and then sent to a fixing means (not shown) and fixed by heat and pressure. After the potential remaining on the photoreceptor 1 is erased by the quenching clamp 6, the liquid developer remaining on the photoreceptor 1 is removed by the cleaning means 7 and the above processing is repeated.
[0014]
The developing means 4 is composed of a developing belt 44 wound around a rotating roller 41, 42, 43 with a constant tension, a coating roller 45 and a metering blade 46, a developer liquid reservoir 48 for storing a liquid developer 47, and a developer. And a recovery blade 49. The rotation rollers 42 and 43 are provided at positions facing the photoconductor 1, and the developing belt 44 is brought into contact with the photoconductor 1 to form a developing region. As shown in the perspective view of FIG. 2, the developing belt 44 is an endless belt, has convex step portions 441 on the outer peripheral surfaces at both ends in the width direction, and a liquid developer thin layer between the step portions 441 at both ends. Has a developer holding portion 442 for forming the. The developer holding unit 442 has conductivity, and a transfer bias potential is applied from the bias applying unit 9 via the rotating rollers 42 and 43. As this transfer bias potential, a potential between the minimum value and the maximum value of the latent image potential on the photoreceptor 1 is applied. The step portion 441 is made of a material having a high friction coefficient such as a rubber material, and the height from the developer holding portion 442 is approximately the same as the thickness of the liquid developer thin layer formed on the developer holding portion 442, for example, 2 to 10 μm. It is formed to the extent. The application roller 45 is composed of a gravure roller having a pattern on the surface, and a liquid developer 47 stored in the developer liquid reservoir 48 is applied to the developer holding portion 442 of the development belt 44 by the application roller 45 and the metering blade 46. Then, a thin liquid developer layer having a uniform thickness is formed on the developing belt 44. The developer collecting blade 49 collects the liquid developer remaining on the developing belt 44 that has passed through the developing area.
[0015]
When the electrostatic latent image formed on the photoreceptor 1 is developed by the developing device 4 configured as described above, the step portion 441 of the developing belt 44 in the developing area between the rotating rollers 42 and 43 has a constant tension. The developing belt 44 is rotated by contacting the surface of the photosensitive member 1 and transmitting the rotational force of the photosensitive member 1 to the step portion 441 of the developing belt 44. In this state, the liquid developer 47 adhering to the application roller 45 is regulated to a uniform thickness by the metering blade 46, and as shown in the cross-sectional view of FIG. Is applied as a liquid developer thin layer 50. The liquid developer thin layer 50 applied to the developer holding portion 442 of the developing belt 44 is in contact with the surface of the photoreceptor 1 in the developing region as shown in the sectional view of FIG. When the liquid developer thin layer 50 contacts the surface of the photoreceptor 1, the distance between the surface of the photoreceptor 1 and the surface of the developer holding portion 442 is regulated by the height of the step portion 441, and the liquid developer thin film 50 Since the thickness is about the same as the thickness of the layer 50, the liquid developer thin layer 50 can be soft touched on the surface of the photoreceptor 1. Further, since the developing belt 44 is rotated by a driving force applied from the photosensitive member 1 to the stepped portion 441 made of a material having a high friction coefficient, the developing belt 44 can be rotated without sliding with respect to the photosensitive member 1. The surface speed of the developing belt 44 can be made the same as the surface speed of the photoreceptor 1. Therefore, the electrostatic latent image formed on the photosensitive member 1 can be developed by the liquid developer thin layer 50 moving at the same speed as the moving speed of the photosensitive member 1, and a good quality toner image can be formed on the photosensitive member 1. It can be formed stably.
[0016]
In the above embodiment, the case where the developing belt 44 having the stepped portion 441 and the developer holding portion 442 for forming the liquid developer thin layer is used has been described. However, the developing belt 44 has the stepped portion 441 and the developer holding portion 442. By using the developing belt 44 having only the developing belt 44 or the developer holding portion 442 and increasing the electric field strength formed between the photosensitive member 1 and the developing belt 44, the rotational driving force is applied from the photosensitive member 1 to the developing belt 44. It can be transmitted efficiently. For example, as shown in the schematic diagram of FIG. 5, the potential of the image portion 11 of the electrostatic latent image formed on the photoreceptor 1 is +20 V, the potential of the background portion 12 is +560 V, and the developing bias potential applied to the developing belt 44 is +200 V. The electric fields E1 and E2 are formed in both the image portion 11 and the background portion 12, and the driving force can be transmitted to the developing belt 44 in both the image portion 11 and the background portion 12. Rotation can be performed efficiently.
[0017]
As described above, when the potential of the image portion 11 of the electrostatic latent image formed on the photosensitive member 1 is +20 V, the potential of the background portion 12 is +560 V, and the developing bias potential applied to the developing belt 44 is +200 V, The electric field E2 is about twice as large as the electric field E1 of the image part 11. When an electrostatic latent image having a very large background area is formed on the photosensitive member 1 at such a time, a sufficiently large driving force can be transmitted to the developing belt 44, but the photosensitive member 1 is formed on the photosensitive member 1. When the image area of the electrostatic latent image is very large, the driving force transmitted to the developing belt 44 becomes small, and there is a possibility that the developing belt 44 cannot be rotated with a sufficient driving force. Therefore, when the developing bias potential of the developing belt 10 is set to the average value of the potential of the image portion 11 and the background portion 12 of the photosensitive member 1, it is not affected by the image pattern of the electrostatic latent image formed on the photosensitive member 1. A constant driving force can be transmitted from the photoreceptor 1 to the developing belt 44. For example, when the potential of the image portion 11 of the electrostatic latent image formed on the photosensitive member 1 is +20 V and the potential of the background portion 12 is +740 V, the developing bias potential applied to the developing belt 44 is +380 V. E1 and the electric field E2 of the background portion 12 can be made the same, a uniform driving force can always be given from the photosensitive member 1 to the developing belt 44, and the developing belt 44 can be rotated stably.
[0018]
Further, for example, an electric field is formed between the developing belt 44 and the photosensitive member 1 even in a region where the electrostatic latent image is not formed on the photosensitive member 1 corresponding to the transfer sheet at the time of start-up before initial printing or continuous printing. It is possible to prevent wear between the photosensitive member 1 and the developing belt 44 by always rotating the developing belt 44 following the rotation of the photosensitive member 1 when the photosensitive member 1 is rotating. For example, when the potential of the image portion 11 of the electrostatic latent image formed on the photoconductor 1 is +20 V and the potential of the background portion 12 is +740 V, if a transfer bias potential of +380 V is always applied to the developing belt 44, the development is performed. The belt 44 can be rotated stably.
[0019]
Further, as shown in the cross-sectional view of FIG. 6, the developing belt 44 has a hybrid structure in which a conductive layer 61 provided at the center is sandwiched between both ends and an insulating layer 62 is interposed between the conductive layer 61 and the conductive layer 61. Independent bias potentials may be applied to the layers 63. In this case, a normal developing bias potential, for example, +380 V is applied to the conductive layer 61 provided in the center, and a bias potential sufficiently higher than the normal developing bias is applied to the conductive layer 63 at both ends, thereby exposing the photosensitive layer 61 to the photosensitive layer 61. The driving force transmitted from the body 1 to the developing belt 44 can be sufficiently increased. Therefore, the developing belt 44 can be stably rotated even if the driving load of the developing belt 44 increases.
[0020]
In the above embodiment, the development belt 44 is described as having a hybrid structure of the central conductive layer 61 and the conductive layer 63 provided on both ends with the insulating layer 62 interposed therebetween. However, as shown in FIG. Even if the absolute value of the charging potential of the region 13 in contact with the end portion of the developing belt 44 of the photosensitive member 1 is sufficiently increased without using the hybrid structure, the developing belt 44 can be removed from the photosensitive member 1 as in the case of the hybrid structure. The driving force transmitted to the developing belt 44 can be sufficiently increased. In this case, as shown in FIG. 8, the bias application region to the charging unit 2 is divided into a central bias application region 22 and bias application regions 23 at both ends by an insulating layer 21, and the bias application region 23 is A potential sufficiently higher than the bias potential of the bias application region 22 corresponding to the image portion may be applied.
[0021]
In each of the above embodiments, the case where the developing belt 44 is wound around the rotating rollers 41, 42, and 43 has been described. However, as shown in FIG. 9, a developing belt 44a having an elastic and very small diameter sleeve is used. May be. In this case, the developing belt 44a is held at each contact position of the photosensitive member 1, the coating roller 45, and the developer collecting blade 49 without providing a rotating roller for supporting the developing belt 44a inside the developing belt 44a. Then, the developing belt 44 a is rotated by the rotational force of the photosensitive member 1. When the developing belt 44a is rotated, the rotational load of the developing belt 44a is only the contact portion with the coating roller 45 and the contact portion with the developer recovery blade 49, and the contact with the developing belt 44a is the development belt. Since the distortion of the belt 44a is caused by the restoring force to restore, the rotational load is not so large. The transfer bias potential applied to the developing belt 44a is applied via a developer collecting blade 49 or a coating roller 45 made of a conductor.
[0022]
In the transfer region where the sleeve-shaped developing belt 44a contacts the photoreceptor 1, as shown in a cross-sectional view perpendicular to the moving direction of the developing belt 44a in FIG. Thus, the developing belt 44a and the photosensitive member 1 are in contact with each other. The rotational force of the photosensitive member 1 is transmitted to the developing belt 44 a by shear stress in the liquid developer thin layer 50. In this case, the moving speed v2 of the liquid developer thin layer 50 in the vicinity of the surface of the photoconductor 1 is equal to the moving speed v1 of the photoconductor 1 as shown in the sectional view of the developing belt 44 in FIG. The moving speed v3 of the liquid developer thin layer 50 near the surface 44a is slightly smaller than the moving speed v1 of the photoreceptor 1. As a result, the moving speed v4 of the developing belt 44a is also slightly smaller than the moving speed v1 of the photoreceptor 1. However, since the liquid developer thin layer 50 has a very small thickness of 2 to 10 μm and the liquid developer used has a high viscosity of 100 to 10,000 mPa · s, the moving speed v4 of the developing belt 44a is photosensitive. The difference in the moving speed v1 of the body 1 is very small, and it is negligible even for a fine image and can be ignored.
[0023]
In this case, if the application roller 45 and the developer recovery blade 49 can be moved away from the photosensitive member 1, it is possible to easily correct even if the developing belt 44a is misaligned. For example, as shown in FIG. 12A, wedge-shaped members 71 are provided on both sides of the developing belt 44 a, and as a result of continuing driving with the developing belt 44 a in contact with the photoreceptor 1, the developing belt 44 a When it is shifted in the axial direction, as shown in FIG. 12B, the coating roller 45 holding the developing belt 44a and the developer collecting blade 49 are moved away from the photoreceptor 1. When the coating roller 45 and the developer recovery blade 49 are moved away from the photoreceptor 1, the developing belt 44a is separated from the photoreceptor 1, and the end of the developing belt 44a is engaged with the wedge-shaped member 71 and moved. Correct. After that, the developing belt 44a can be brought into contact with the photosensitive member 1 by returning the coating roller 45 and the developer recovery blade 49 to their original positions. The correction of the deviation of the developing belt 44a is performed when the deviation of the developing belt 44 exceeds a certain allowable range, or when a full-color image is formed using, for example, four independent developing devices. It is sufficient to carry out each time the developing device for each color is separated from the photosensitive member 1.
[0024]
【The invention's effect】
In the present invention, as described above, since the driving force for moving the developing belt is transmitted from the image carrier via the contact portion between the image carrier and the developing belt , means for directly driving the developing belt is provided. This is unnecessary, and the mechanism of the image forming apparatus can be simplified to reduce the size. Further, the surface movement speed of the developing belt can be made the same as the surface movement speed of the image carrier without requiring a particularly complicated mechanism, and a high-quality image can be stably formed.
[0026]
Further, when applying a driving force to the developing belt, by exerting an attractive force between the developing belt and the image bearing member to form an electric field at the contact portion of the image bearing member and the developing belt, a developing belt and the image bearing member the adhesion can be increased, it is possible to efficiently transmit the driving force to the developing belt from the image bearing member, it is possible to always rotate the developing belt in a stable driving force. Furthermore, since the adhesion between the developing belt and the image carrier is increased and the developing belt is prevented from slipping with respect to the image carrier, it is possible to prevent the development belt and the image carrier from being worn and stably for a long time. Can be driven.
[0027]
Further, by applying a potential corresponding to the average of the maximum value and the minimum value of the surface potential of the image carrier to the developing belt, to form an electric field of constant magnitude in the contact portion between the developing belt and the image carrier Thus, a constant adhesion force can be obtained over the entire image area, and a stable driving force can always be transmitted from the image carrier to the developing belt without depending on the electrostatic latent image pattern.
[0028]
Further, between the developing belt and the image carrier outside the image area at the contact portion between the developing belt and the image carrier, the electric field formed between the image carrier and the developing belt in the image area is larger than the magnitude of the electric field formed between the image carrier and the developing belt. By forming a large electric field, the adhesion between the developing belt and the image carrier outside the image area can be sufficiently increased, and even when the driving force is not sufficiently transmitted only by the adhesion within the image area, A sufficient driving force can be transmitted to the developing belt and stably rotated.
[0029]
Further, by making the absolute value of the surface potential of the image carrier outside the image area at the contact portion between the developing belt and the image carrier larger than the maximum value of the absolute value of the surface potential in the image area, the configuration can be simplified. A sufficient driving force can be transmitted to the developing belt and stably rotated.
[0030]
Further, the developing belt is held by the contacting portion of the application means for applying the liquid developer, the developer removing means for removing the liquid developer remaining on the developing belt , and the image carrier, thereby contacting the developing belt. Can be minimized, the load when driving the developing belt can be reduced and stably rotated, and the supporting mechanism of the developing belt can be simplified to reduce the size of the apparatus.
[0031]
Furthermore, by moving both the coating unit and the developer removing unit or the coating unit in the direction away from the image carrier when not developing, the circumferential distortion of the developing belt composed of an endless belt is sufficiently weakened, so that the belt is offset. It can be easily corrected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a configuration of a developing belt.
FIG. 3 is a cross-sectional view showing a thin layer of liquid developer applied to a developing belt.
FIG. 4 is a cross-sectional view showing a photoconductor, a developing belt, and a liquid developer thin layer in a developing area.
FIG. 5 is a schematic diagram showing the operation of the second embodiment.
FIG. 6 is a cross-sectional view illustrating a configuration of a developing belt according to a third embodiment.
FIG. 7 is a configuration diagram illustrating a photoconductor and a developing belt according to a fourth embodiment.
FIG. 8 is an explanatory diagram illustrating a bias application region of a charging unit in a fourth embodiment.
FIG. 9 is a configuration diagram of a fifth embodiment.
FIG. 10 is a cross-sectional view in a direction orthogonal to a moving direction of a developing belt according to a fifth embodiment.
FIG. 11 is a sectional view of a developing belt according to a fifth embodiment in the moving direction.
FIG. 12 is an explanatory diagram showing a belt shift correction operation in the fifth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 4 Developing device 9 Bias application means 41, 42, 43 Rotating roller 44 Developing belt 45 Coating roller 46 Metering blade 47 Liquid developer 48 Developer liquid reservoir 49 Developer collecting blade 50 Liquid developer thin layer

Claims (4)

The driving force for moving the developing belt, which is an endless belt, is transmitted from the image carrier through the contact portion between the image carrier and the developing belt, and then applied to the developing belt. 100 ~ 10000 A wet image forming apparatus that applies a liquid developer having a high viscosity of mPa · s and develops an electrostatic latent image formed on an image carrier by a thin liquid developer layer applied to a developing belt,
Between the developing belt and the image carrier outside the image area at the contact portion between the developing belt and the image carrier, the magnitude of the electric field formed between the image carrier and the developing belt in the image area is larger. A wet image forming apparatus for forming an electric field. 2. The absolute value of the surface potential of the image carrier outside the image area at the contact portion between the developing belt and the image carrier is larger than the maximum absolute value of the surface potential in the image area. Wet image forming apparatus. The developing belt is held by a contact portion of an application means for applying a liquid developer to the developing belt, a developer removing means for removing the liquid developer remaining on the developing belt after the completion of the developing process, and an image carrier. Item 3. The wet image forming apparatus according to Item 1 or 2. 4. The wet image forming apparatus according to claim 3, wherein both the coating unit and the developer removing unit or the coating unit are moved away from the image carrier when not developed.

Images