JPH10312115A - Wet type image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To individually recover toner and a pre-wetted liquid which remain on a photoreceptor after a transfer process is completed and to simply reuse the toner and pre-wetted liquid by arranging a toner recovering roller to which a voltage having a polarity opposite to that of the toner remaining on an image carrier is applied, on the downstream side of the transferring region of the image carrier. SOLUTION: At the time of forming an image, the surface of the photoreceptor 2 is coated with the pre-wetted liquid, with a uniform thickness, by a pre-wetted liquid coating means 3 and then, the photoreceptor 2 is uniformly electrified by an electrifier 4. After that, the photoreceptor 2 is exposed to form the electrostatic latent image. This latent image is made visualizable with a high-viscosity liquid developer in which the toner is dispersed at a high concentration by a developing means 6 and a toner image formed on the photoreceptor 2 is transferred to a transfer paper 11 by a transfer means 7. For recovering toner grains remaining on the photoreceptor 2 after passing through the transfer means 7, a toner recovering means 8 is provided along the photoreceptor 2 on the downstream side of the transfer means 7.

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 for visualizing an electrostatic latent image formed by electrophotography, electrostatic recording, ion flow, or the like by using a liquid developer, and more particularly, to a toner image forming apparatus.
It relates to improvement of collection efficiency.

[0002]

2. Description of the Related Art An image forming apparatus for visualizing an electrostatic latent image using a high-viscosity, high-concentration liquid developer is disclosed in, for example, Japanese Patent Application Laid-Open No.
No. 209922 and Japanese Patent Application Laid-Open No. 7-209998. This image forming apparatus, for example, as shown in FIG.
A pre-wet liquid applying unit 3 uniformly applies a pre-wet liquid such as dimethylpolysiloxane oil on the photoreceptor 2 to the photosensitive member 2 with a release property and a chemically inert dielectric property. The charged photoreceptor 2 is charged by a charger 4 and then exposed by a writing light 5 to form an electrostatic latent image on the surface of the photoreceptor 2. When this electrostatic latent image is formed, the portion of the surface of the photoreceptor 2 which is exposed to light loses the charge, and the portion which is not exposed to light retains the charge and becomes an electrostatic latent image. This electrostatic latent image is visualized by the developing means 6. The developing means 6 visualizes the electrostatic latent image with a high-viscosity liquid developer in which toner, which is visualized particles, is dispersed at a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. To do
The liquid developer in the developer tank 61 is applied to the developing roller 63 via the layer forming roller 62 to form a thin layer of the liquid developer. When the thin layer of the liquid developer on the developing roller 63 passes through the developing area in the vicinity of the photoconductor 2, the charged toner contained in the liquid developer layer is applied to the image portion of the photoconductor 2 by electrostatic force. Move and attach to visualize. In addition, no electrostatic force acts on the toner contained in the liquid developer layer that comes into contact with the non-image portion where the charge on the surface of the photoconductor 2 has disappeared, and the surface of the photoconductor 2 and the liquid developer layer are pre-wet liquid layers. , The toner does not adhere to the non-image portion, thereby preventing the image from deteriorating. The visualized image is transferred to the transfer paper 11 by the transfer unit 7 and then fixed by the fixing unit. The toner and the pre-wet liquid remaining on the photoreceptor 2 are removed by the cleaning means 9, and the charge remaining on the photoreceptor 2 from which the residual toner and the pre-wet liquid have been removed is erased by the static eliminator 10 and then again. The above process is repeated.

[0003]

As described above, the toner and the pre-wet liquid remaining on the photoreceptor after the completion of the transfer can be reused, but the remaining toner and the pre-wet liquid are cleaned by the cleaning means. And the pre-wet liquid is mixed in the liquid collected by the cleaning means, and it is difficult to reuse the liquid as it is.

Further, even if an attempt is made to separate the toner and the pre-wet liquid of the liquid collected by the cleaning means in order to reuse the collected toner and the pre-wet liquid, the recovered liquid is compared with the pre-wet liquid. Since a large amount of toner was mixed, the separation was not easy.

SUMMARY OF THE INVENTION The present invention has been made to solve such a disadvantage. Toner and pre-wet liquid remaining on the photoreceptor after the transfer step are individually collected to easily remove the toner and pre-wet liquid. An object of the present invention is to provide a wet image forming apparatus that can be reused.

[0006]

SUMMARY OF THE INVENTION A wet image forming apparatus according to the present invention provides a transparent and pre-wet liquid having a dielectric property on an image carrier before visualizing an electrostatic latent image formed on the image carrier. Image forming apparatus that develops an electrostatic latent image on an image carrier with a charged toner contained in a high-concentration liquid developer applied in a thin layer to a developer carrier and transfers the latent image to a recording medium Wherein the toner collecting roller to which a voltage having a polarity opposite to that of the toner remaining on the image carrier is applied is disposed downstream of the transfer area of the image carrier.

A pre-wet liquid collecting means for collecting the pre-wet liquid remaining on the image carrier may be provided downstream of the toner collecting roller.

Further, it is desirable to have a toner separating means for separating residual toner contained in the pre-wet liquid collected by the pre-wet liquid collecting means.

It is desirable to provide a plurality of the above-mentioned toner collecting rollers along the image carrier, and to apply an independent voltage to each toner collecting roller.

Further, it is preferable to provide a pre-wet liquid layer thickness uniforming means for making the thickness of the pre-wet liquid layer remaining on the image carrier downstream of the toner collecting roller.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an image forming apparatus according to the present invention, when an image is formed, a pre-wet liquid is applied to the surface of a photoreceptor with a uniform thickness by a pre-wet liquid application unit, and then the photoreceptor is charged. , And then expose the photoreceptor to form an electrostatic latent image. The electrostatic latent image is visualized by a developing means with a high-viscosity liquid developer in which toner is dispersed at a high density, and the toner image formed on the photoreceptor is transferred to transfer paper by a transfer means. To collect toner particles remaining on the photoreceptor that has passed through the transfer means, a toner collecting means is provided along the photoreceptor downstream of the transfer means.

The toner collecting means has a toner collecting roller, a toner collecting blade, and a toner collecting tank. Toner
A collection bias having a polarity opposite to that of the toner particles remaining on the photoconductor is applied to the collection roller, and the toner particles remaining on the photoconductor passing through the transfer position are attracted to the toner collection roller by the collection bias, and the toner particles adsorbed are collected. Is physically peeled off by the toner collecting blade and collected in the toner collecting tank. In this way, only the toner remaining on the photoreceptor after the transfer step is collected by the toner collecting means, so that the toner remaining on the photoreceptor can be effectively used.

The pre-wet liquid layer remaining on the photoreceptor after the toner particles have been removed is removed by a cleaning means. The photoreceptor from which the toner particles and the pre-wet liquid layer have been removed removes the remaining charge by the charge eliminator, and enters the next image forming step.

After the toner particles are recovered by the toner recovery means as described above, the toner particles contained in the pre-wet liquid layer existing on the photoreceptor are extremely small. The separation process can be relatively easily performed. Therefore, a very small amount of toner collected by the cleaning means
The mixed pre-wet liquid is separated into toner and pre-wet liquid by separation means, and the separated toner and pre-wet liquid are reused.

Further, a plurality of toner collecting rollers are provided in the toner collecting means, an independent voltage collecting bias is applied to each toner collecting roller, and the toner goes from the upstream toner collecting roller to the downstream toner collecting roller. By increasing the bias voltage to be applied, the toner particles that could not be collected by the preceding toner collecting roller are collected by applying a stronger electric field to the subsequent toner collecting roller to improve the toner particle collection rate. By efficiently collecting the toner particles remaining on the photoreceptor by the plurality of toner collecting rollers, almost no toner particles are present in the pre-wet liquid layer on the photoreceptor passing through the final-stage toner collecting roller. The pre-wet liquid collected by the cleaning means can be reused as it is.

Further, a toner may be used instead of the cleaning means.
A pre-wet liquid layer thickness uniforming means is provided along the photoreceptor downstream of the collecting means, and almost all toner particles remaining on the photoreceptor are recovered on the photoreceptor by the toner collecting means. The thickness of the pre-wet liquid layer is made uniform by the pre-wet liquid layer thickness uniforming means, and the pre-wet liquid remaining on the photoreceptor is used in the next image forming step, and the pre-wet liquid remaining on the photoreceptor is effectively used. Take advantage of

[0017]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the figure, in an image forming / transferring section 1 of the image forming apparatus, a pre-wet liquid applying unit 3, a charger 4, a developing unit 6, a transferring unit 7, and a toner collecting unit disposed around a photoreceptor 2 are provided. It has means 8, cleaning means 9 and static eliminator 10.
When an image is formed by the image forming / transferring unit 1, first, a pre-wetting liquid having a dielectric property and a light transmitting property, such as dimethylpolysiloxane oil, is applied to the surface of the photoreceptor 2 by a pre-wetting liquid coating unit 3. Is applied uniformly. The photoreceptor 2 on which the pre-wet liquid layer is formed is uniformly charged by the charger 4. If the pre-wet liquid layer is not applied with a uniform thickness when charging the photoreceptor 2 with the charger 4, the capacitance differs depending on the location on the photoreceptor 2. Can no longer be charged. For this reason, the pre-wet liquid applying unit 3 applies a pre-wet liquid to the surface of the photoreceptor 2 with a uniform thickness by connecting a plurality of pre-wet rollers made of rubber or the like. After uniformly charging the entire surface of the photoconductor 2, the charge on the surface of the photoconductor 2 is removed by a writing light 5 corresponding to image data from an exposure unit (not shown) to form an electrostatic latent image. This electrostatic latent image is visualized by the developing means 6. The developing means 6 visualizes the electrostatic latent image with a high-viscosity liquid developer in which toner, which is visualized particles, is dispersed at a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. The liquid developer in the developer tank 61 is applied to the developing roller 63 via the layer forming roller 62 to form a thin layer of the liquid developer. The developing roller 63 is formed by applying an insulating process to a metal base, and is applied with a developing bias, and a thin layer of the liquid developer comes into contact with the electrostatic latent image on the photoconductor 2 and is included in the liquid developer. Visualize with toner. The toner image formed on the photoconductor 2 is transferred to the transfer paper 11 by the transfer unit 7. The transfer paper 11 to which the toner image has been transferred is discharged after the toner image is fixed by the fixing unit. Even after the transfer of the toner image to the transfer paper 11 at the transfer position, some toner particles remain on the photoconductor 2 without being completely transferred. To collect the toner particles, a toner collecting means 8 is provided along the photoreceptor 2 downstream of the transfer means 7.

The toner collecting means 8 includes a toner collecting roller 81.
And a toner collecting blade 82 and a toner collecting tank 83. As with the developing roller 63, the toner collecting roller 81 has a metal substrate subjected to an insulating process, and a collecting bias having a polarity opposite to that of the toner particles remaining on the photoreceptor 2 is applied. The toner collection roller 81 may have a large surface friction coefficient in order to efficiently adsorb the toner particles. Then, the toner particles remaining on the photoconductor 2 having passed the transfer position are attracted to the toner collecting roller 81 by a collecting bias applied to the toner collecting roller 81. The toner particles adsorbed on the toner collecting roller 81 are physically peeled off by the toner collecting blade 82 and collected in the toner collecting tank 83.

That is, as shown in the explanatory view of FIG. 2, the pre-wet liquid layer 21
Are formed, and the toner particles 22 remaining after the transfer to the transfer paper 11 are adsorbed thereon. In FIG.
The polarity of the toner particles 22 is positive. Since the positively charged toner particles 22 are thus adsorbed on the photoreceptor 2, the photoreceptor 2 is negatively charged. To remove the toner particles 22 from the photoreceptor 2, the apparent potential of the photoreceptor 2 is increased. Should be shifted to the positive electrode side. Since a bias charge is applied between the photoreceptor 2 and the developing roller 63 and the transfer roller of the transfer means 7 installed around the photoreceptor 2 as necessary, the relative potential can be changed. I have.
Since the bias voltages to be applied to the developing roller 63 and the like are different from each other, the photoconductor 2 side is normally set to the ground potential, and the potential of the developing roller 63 and the like can be changed.
The voltage to be applied to the toner collecting roller 81 can be similarly varied. When the toner particles 22 have a positive polarity and the photoconductor 2 has a ground potential, a negative voltage is applied to the toner collecting roller 81. By applying a negative voltage to the toner collection roller 81 in this manner, the toner particles 22 remaining on the photoconductor 2 are applied to the toner collection roller 81 by an electric field generated between the photoconductor 2 and the toner collection roller 81. Adsorbs electrically. Here, even when the photosensitive member 2 is not at the ground potential, it is sufficient that the potential of the toner collecting roller 81 can be set to a negative polarity relative to the photosensitive member 2. The toner particles 22 adsorbed on the toner collecting roller 81 are removed by the toner collecting blade 8.
2, the toner particles 22 collected in the toner collecting tank 83 and collected in the toner collecting tank 83 are conveyed to the developing solution tank 61 of the developing unit 6 and reused. The toner collecting roller 81 rotates at a constant speed in the same direction as the photoconductor 2 at a contact position with the photoconductor 2. This is to prevent physical friction with the pre-wet liquid layer 21. That is, the toner collecting roller 81
When friction occurs between the pre-wet liquid layer 21 and the pre-wet liquid layer 21, the pre-wet liquid adheres to the toner collecting roller 81 by physical force, and the pre-wet liquid mixes with the collected toner particles 22. This is to prevent it. In this manner, only the toner remaining on the photoreceptor 2 after the transfer step is collected by the toner collecting means 8, so that the toner remaining on the photoreceptor 2 can be effectively used, and the running cost can be reduced. be able to.

After the toner particles 22 have been removed, the photosensitive member 2
The remaining pre-wet liquid layer 21 is removed by the cleaning means 9. The photoreceptor 2 from which the toner particles 22 and the pre-wet liquid layer 21 have been removed has the remaining charge removed by the static eliminator 10 and enters the next image forming step.

After the toner particles 22 are recovered by the toner recovery means 8 as described above, the toner particles 22 contained in the pre-wet liquid layer 21 existing on the photoreceptor 2 become extremely small. I have. Therefore, pre-wet liquid and toner
Can be relatively easily separated. Therefore, as shown in FIG. 3, the pre-wet liquid mixed with a small amount of toner collected by the cleaning means 9 is sent to the separation means 12 by using the weight of the liquid or the air pressure. The separating means 12 separates the sent mixture into toner and pre-wet liquid by using heat or specific gravity. This separated toner is referred to as toner.
It is sent to the recovery tank 83 and the pre-wet liquid is sent to the pre-wet liquid recovery tank 13 for reuse. Thus, the running cost can be reduced by reusing all the toner and pre-wet liquid present on the photoreceptor 2 after the transfer step.

In the above embodiment, the pre-wet liquid is applied before the photoreceptor 2 is charged by the charger 4, and the pre-wet roller group of the pre-wet liquid applying means 3 comes into contact with the pre-wet roller to charge the photoreceptor 2. Although the disturbance is prevented, if the pre-wet roller and the pre-wet liquid do not disturb the charge on the photoconductor 2, the pre-wet liquid may be applied after the photoconductor 2 is charged.

In the above embodiment, the toner collecting means 8 has one
Although the case where the toner collecting roller 81 is provided has been described, as shown in FIG.
For example, three toner collecting rollers 81a, 81b, 81c
May be provided. Thus, the plurality of toner collecting rollers 8
By repeating the collecting operation of the toner particles 22 a plurality of times in 1a to 81c, the toner particles 22 remaining on the photoreceptor 2 after the transfer can be more reliably collected. in this case,
An independent voltage collecting bias is applied to each of the toner collecting rollers 81a to 81c, and the toner collecting roller 8 on the upstream side is applied.
It is preferable to increase the bias voltage to be applied from 1a to the toner recovery roller 81c on the downstream side. In this way, the toner particles 22 that could not be collected by the former toner collecting roller 81a can be collected by applying a stronger electric field to the latter toner collecting roller 81b.
2 can be improved.

Further, a plurality of toner collecting rollers 81a to 81a.
Since the toner particles 22 remaining on the photoconductor 2 are efficiently collected by 81c, the toner particles 22 hardly exist in the pre-wet liquid layer 21 on the photoconductor 2 that has passed through the toner recovery roller 81c at the last stage. . Therefore, the pre-wet liquid collected by the cleaning means 9 can be sent to the pre-wet liquid application means 5 as it is and reused.

In the above embodiment, a plurality of toner collecting rollers 8
The case where the pre-wet liquid layer 21 remaining on the photoreceptor 2 is removed by the cleaning means 9 after the toner particles 22 are collected in 1a to 81c has been described. The thickness of the layer 21 may be made uniform and used in the next image forming step. In this case, as shown in FIG. 5, a pre-wet liquid layer thickness uniforming means 14 is provided along the photoreceptor 2 downstream of the toner collecting means 8 instead of the cleaning means 9. The pre-wet liquid layer thickness equalizing means 14 includes one or more layer thickness uniforming rollers 1 rotating in the same direction on the contact surface with the photoreceptor 2.
41.

After almost all the toner particles 22 remaining on the photosensitive member 2 are collected by the toner collecting means 8 as described above, the pre-wet liquid layer 21 is present on the photosensitive member 2. If the pre-wet liquid layer 21 remaining on the photoreceptor 2 has a non-uniform layer thickness due to a voltage applied in a developing step, a transferring step or a toner collecting step, or physical contact by various rollers. Conceivable. If the pre-wet liquid layer is used for the next image formation as it is, the electrostatic capacity varies depending on the location on the photoconductor 2 when the photoconductor 2 is charged by the charger 4, and uniform charging cannot be performed.
Therefore, after the toner particles 22 are collected, the thickness of the pre-wet liquid layer 21 existing on the photoreceptor 2 is made uniform by the layer thickness uniforming roller 141. This layer thickness uniforming roller 141
Any material such as metal or rubber may be used, but it is better to insulate the surface in order to prevent electric leakage. Further, it is preferable that the optimum value of the rotation speed of the layer thickness equalizing roller 141 is determined by a combination of the material of the layer thickness equalizing roller 141 and the material of the pre-wet liquid.

After the toner particles 22 are collected as described above, even if the thickness of the pre-wet liquid layer 21 existing on the photoreceptor 2 is made uniform by the layer thickness uniforming roller 141, If the pre-wet liquid is reduced from the initial level, the layer thickness may not be uniformed. In such a case, the shortage may be replenished by the pre-wet liquid application unit 3. Thus, the pre-wet liquid remaining on the photoreceptor 2 can be effectively used.

[0028]

As described above, according to the present invention, the toner particles remaining on the photoreceptor that has passed the transfer position are attracted to the toner collecting roller by the collecting bias and collected, so that after the transfer process is completed, the photosensitive Only the toner remaining on the body can be collected and reused, and the toner remaining on the photoreceptor can be effectively used to reduce the running cost.

Further, the pre-wet liquid containing a small amount of toner collected by the pre-wet liquid collecting means provided on the downstream side of the toner collecting roller is separated and separated into toner and pre-wet liquid. The running cost can be reduced by reusing all the pre-wet liquid. Further, when the mixed liquid of the toner and the pre-wet liquid is subjected to the separation processing, the separation processing can be easily performed because only a small amount of the toner is contained in the pre-wet liquid.

Further, a plurality of toner collecting rollers are provided in the toner collecting means, a collecting bias of an independent voltage is applied to each toner collecting roller, and the toner goes from the upstream toner collecting roller to the downstream toner collecting roller. By increasing the applied bias voltage, the toner particles that could not be collected by the previous toner collection roller can be collected by applying a stronger electric field to the subsequent toner collection roller, improving the toner particle collection rate. Can be done.

Further, by efficiently collecting toner particles remaining on the photoreceptor with a plurality of toner collecting rollers,
Since toner particles hardly exist in the pre-wet liquid layer on the photoreceptor that has passed through the toner recovery roller, the recovered pre-wet liquid can be reused as it is, and running costs can be reduced.

Further, after almost all the toner particles remaining on the photoreceptor are recovered, the thickness of the pre-wet liquid layer present on the photoreceptor is made uniform to remove the pre-wet liquid remaining on the photoreceptor. By utilizing the pre-wet liquid remaining on the photoreceptor by using it in the next image forming step, the configuration of the entire apparatus can be simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of collecting toner particles.

FIG. 3 is a partial configuration diagram of a second embodiment.

FIG. 4 is a partial configuration diagram of a third embodiment.

FIG. 5 is a partial configuration diagram of a fourth embodiment.

FIG. 6 is a configuration diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 2 photoreceptor 3 pre-wet liquid applying means 4 charger 6 developing means 7 transfer means 8 toner collecting means 9 cleaning means 12 separating means 14 pre-wet liquid layer thickness uniforming means 81 toner collecting roller 82 toner collecting blur -D 83 Toner-Recovery tank

Claims (5)

[Claims] 1. A method for applying a transparent pre-wet liquid having a dielectric property on an image carrier before visualizing the electrostatic latent image formed on the image carrier, and then forming a thin layer on the developer carrier. In a wet image forming apparatus in which an electrostatic latent image on an image carrier is developed with a charged toner contained in a high-concentration liquid developer applied and transferred to a recording medium, the polarity is opposite to that of toner remaining on the image carrier. Wherein the toner collecting roller to which the voltage is applied is disposed downstream of the transfer area of the image carrier. 2. A wet image forming apparatus according to claim 1, further comprising a pre-wet liquid collecting means for collecting the pre-wet liquid remaining on the image carrier downstream of said toner collecting roller. 3. A toner for separating residual toner contained in the pre-wet liquid recovered by the pre-wet liquid recovery means.
3. The wet image forming apparatus according to claim 2, further comprising a separating unit. 4. The wet image forming apparatus according to claim 1, wherein a plurality of the toner collecting rollers are provided along the image carrier, and an independent voltage is applied to each toner collecting roller. 5. The wet method according to claim 4, further comprising: a pre-wet liquid layer thickness uniforming means for uniformizing the thickness of the pre-wet liquid layer remaining on the image carrier downstream of the toner collecting roller. Image forming device.