JP2008233397A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the amount of liquid retained in contact parts where a photoreceptor and an intermediate transfer body come into contact with members to be brought into contact with them, to prevent a large amount of carrier liquid from sticking to a recording medium, and to prevent dropping of developer, then, to provide an image of high image quality, irrespective of the passing timing of the recording medium. <P>SOLUTION: The image forming apparatus includes an image carrier 1 on which an electrostatic latent image is formed; a developing device 11 for developing the electrostatic latent image on the image carrier 1 by using the liquid developer 9 and forming a visible image; and a transfer device 20 for transferring the toner image formed on the image carrier 1 to a transfer material 21, wherein a liquid amount regulating member is disposed at the prestage of a transfer position where the toner image is transferred to the transfer material 21, and the developer, stuck on the image carrier 1, is removed timely by the liquid amount regulating means, such as, a pre-transfer liquid amount regulating blade 30, before the developer comes in contact with the transfer member 20, so that the amount of the liquid retained in the contact part is reduced, as much as possible. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method using a liquid developer. In particular, excessive developer adheres to the recording medium in order to reduce the amount of developer that tends to stay at the contact portion between the photosensitive member or intermediate transfer member and the member that contacts them. It is possible to prevent this, reduce consumption of the liquid developer as much as possible, and form a high-quality image.

  In a conventional image forming apparatus using a liquid developer, when a toner image is transferred to a recording medium using a transfer member pressed against the photosensitive member or the intermediate transfer member, a direct transfer method from the photosensitive member to the recording medium is performed. In some cases, the developer may accumulate at the contact portion. Further, even when the intermediate transfer member is used, there may be a problem that the developer accumulates at the contact portion between the photosensitive member and the intermediate transfer member and the contact portion between the intermediate transfer member and the transfer member.

  These problems are caused by an image forming apparatus using a two-component type liquid developer, between the sheets in the case of a sheet, or until the first recording medium reaches the photosensitive member or the intermediate transfer member after starting image formation. Even in the non-image areas such as the gaps, although the toner hardly adheres, the carrier liquid keeps adhering.

  As a means for the above-mentioned problems in the prior art, since the developer is a liquid, it is difficult to stop or supply instantly, and the developer is supplied in advance at the time of image formation. In some cases, the liquid supply was not stopped.

  In addition, when a toner image is transferred to a recording medium typified by fine uneven paper, a gap may be generated between the recording medium and the photosensitive member or intermediate transfer member. When such voids are generated, it is difficult to perform good transfer, resulting in a problem that a high-quality image cannot be obtained.

  As a means for the above-mentioned problems in the prior art, the carrier liquid is filled between the recording medium and the photoconductor or intermediate transfer body in order to transfer well and obtain a high-quality image. In order to avoid the formation of the gap as described above, the pressure between the photosensitive member and the intermediate transfer member may be increased, but the higher the pressure here, the higher the pressure. Since the amount of liquid increased, the liquid retention tended to increase.

  In addition, when the developer accumulates in the contact portion in this way, when the first recording medium reaches the contact portion, a large amount of carrier liquid or the like adheres to the leading end portion of the recording medium, causing a conveyance failure. In many cases, it is difficult to damage the image, absorption of the carrier liquid into the recording medium or drying of the carrier liquid from the recording medium, and the overflowing liquid may drip and wet the recording medium or device. The problem was not solved.

As an example of the above prior art, it relates to toner cleaning at the end (Japanese Patent No. 313834) and pre-transfer cleaning, and is removed from the photoconductor on the pressing side of the photoconductor at the time of transfer and at the non-transfer time. Side bias application (Japanese Patent Laid-Open No. 08-036339), a rotational speed control method and an image forming apparatus (Japanese Patent Laid-Open No. 2003-125591), and a double-sided image forming apparatus related to recovery of excess carrier liquid ( Japanese Laid-Open Patent Publication No. 2002-116627), an image forming apparatus and an image forming method relating to excess carrier liquid absorption (Japanese Laid-Open Patent Publication No. 2006-106096) are disclosed.
Japanese Patent No. 3138034 Japanese Patent Laid-Open No. 08-036339 JP 2003-125591 A JP 2002-116627 A JP 2006-106096 A

  In order to avoid the above-described problems in the prior art, when the recording medium does not pass, the intermediate transfer member and the like are separated from the photosensitive member, and the transfer member and the like are separated from the intermediate transfer member and contacted when the recording medium passes. However, this method often involves vibration when the members are in contact with each other, affects writing, and often disturbs the image.

  The present invention has been made in consideration of the above-described circumstances, and suppresses the amount of liquid accumulated in a contact portion between a photosensitive member or an intermediate transfer member and a member that contacts them, and the recording medium has not existed for a while. Even when the toner passes, a large amount of carrier liquid or the like does not adhere to the recording medium, the developer is not unnecessarily taken out of the image forming apparatus, the developer does not sag, and the toner with a large amount of carrier liquid. An object of the present invention is to provide a high-quality image regardless of the timing at which the recording medium passes without being pushed away.

  The means for solving the above problems is to measure the timing, and before or after the developer adhering on the photosensitive member or intermediate transfer member comes into contact with the intermediate transfer member or the transfer member, the liquid amount regulating mechanism is activated or deactivated. By removing by the switching mechanism, the amount of liquid accumulated in the contact portion is suppressed.

  According to this invention (the inventions of claims 1 to 9), the developer adhering to the photosensitive member or the intermediate transfer member is applied to the contact portion between the photosensitive member or the intermediate transfer member and a member that contacts them. Since the accumulated amount can be reduced, it is possible to prevent a large amount of developer from adhering to the recording medium, and therefore, it is unnecessary from the image forming apparatus without causing the conveyance failure of the abnormally wet recording medium. The developer is not taken out, the developer does not sag, the toner image is not swept away by a large amount of carrier liquid, and an excellent image quality can be obtained regardless of the timing. .

[Embodiment 1]
The best mode for carrying out the invention will be described with reference to the first embodiment with reference to the drawings.
Here, the first embodiment is an embodiment when applied to an image forming apparatus using a liquid developer, and the material of each component to be used is an example, and the present invention is not limited thereto. It can be used without any problems.

  FIG. 1 shows an outline of the image forming unit around the photosensitive drum 1. In FIG. 1, a charging device 2 is provided above the photosensitive drum 1, and the surface of the photosensitive drum 1 is charged by the charging device 2. Further, the charges in the portion other than the image portion are erased by partial lighting of the erase lamp 3. Then, the exposure device 4 exposes the image data on the surface of the photosensitive drum 1, whereby an electrostatic latent image (not shown) is formed on the photosensitive drum 1. Here, the exposure device 4 includes two developing rollers, a first developing roller 5 and a second developing roller 6, and a reverse roller 7, which are provided at a distance from the photosensitive drum 1.

  The first developing roller 5 and the second developing roller 6 are preferably made of SUS, and the reverse roller 7 is preferably made of aluminum and has a hard anodized surface. The first developing roller 5 and the second developing roller 6 are arranged with a small gap (interval) with respect to the photosensitive drum 1, and the minute gap (interval) of the reverse roller 7 with respect to the photosensitive drum 1 is It is designed to be narrower than the gap between the first developing roller 5 and the second developing roller 6.

  A liquid developer 9 is prepared in the developer tank 8, and the liquid developer 9 is transported to a developing device 11 and a cleaning device 12 by a pump 10. The liquid developer 9 conveyed to the developing device 11 is poured into two developing rollers, a first developing roller 5 and a second developing roller 6. The two developing rollers of the first developing roller 5 and the second developing roller 6 rotate to supply a liquid developer to an electrostatic latent image (not shown) on the photosensitive drum 1. The toner component in the liquid developer 9 supplied on the rotating drum 1 adheres to the electrostatic latent image on the surface of the photosensitive drum 1 by electrophotographic electrophoresis, and forms a developer image (not shown). It is a form to form.

  Next, in the reverse row 7, the minute gap (interval) between the reverse roller 7 and the photosensitive drum 1 is the minute gap between the first developing roller 5 and the second developing roller 6 and the photosensitive drum 1 described above. Designed to be narrower than (interval). Therefore, the reverse roller 7 can remove excess carrier liquid and undeveloped toner in the liquid developer 9 from the liquid developer 9 attached to the surface of the photosensitive drum 1.

Thereafter, a developer image (not shown) formed on the photosensitive drum 1 is transferred by a transfer roller 20 to a transfer material 21 which is a recording medium such as paper or cloth.
Here, the liquid developer 9 remaining without being transferred to the transfer material 21 is sucked by the foam roller 22 in the cleaning device 12, and the liquid developer 9 sucked by the foam roller 22 is further sucked by the squeezing roller 23. The mechanism is squeezed from the form roller 22 and returned to the developer tank 8.
Further, the liquid developer 9 remaining on the photosensitive drum 1 is scraped off by a cleaning blade 24 for cleanly cleaning the surface of the photosensitive drum 1, and the scraped liquid developer 9 is also absorbed by the foam roller 22. Thus, it is finally recovered in the developer tank 8 via the cleaning device 12.

  Here, in the image forming apparatus of the present invention shown in FIG. 1, the circulation and recovery routes of the liquid developer 9 are collected from the cleaning device 12 to the developer tank 8, and from the developing device 11. Although the case where the systems recovered to the developer tank 8 are combined and used is shown, the design on the apparatus is not particularly limited. For example, the liquid circulation between the cleaning device 12 and the developing device 11 May be designed as separate device arrangements.

  Next, an example of the liquid developer 9 used in the present invention will be described. Here, the liquid developer 9 is a developer composed of a mixture of a toner component and a carrier liquid.

  The colorant used in the present invention is not particularly limited, but when the transfer material 21 as a recording medium is paper, a pigment of disazo yellow, quinacridone, copper phthalocyanine or carbon black is used. It is desirable to do.

On the other hand, when the transfer material 21 as a recording medium is a cloth, a direct dye, an acid dye, a basic dye (cationic dye), or a reactive dye is preferably used.
Examples of direct dyes used include direct fast yellow R, direct fast yellow GC, direct fast orange, direct sky blue 5B, direct splat red 3B, coplantin green G, and direct fast black D.
Examples of acid dyes include Acid Brilliant Scarlet 3R, Acid Violet 5B, Alizarin Direct Blue A2G, Acid Syanine 6B, Acid Syanine Green G, Acid First Black VLG, and the like.
Examples of the cationic dye used include cationic yellow 3G, cationic golden yellow GL, cationic orange R, cationic brilliant red 4G, and cationic blue 5G.
Examples of the reactive dye used include reactive orange 2R, reactive red 3B, reactive blue 3G, reactive brilliant blue R, and reactive black B.
These dyes are desirably those in which 80% by weight or more of them are present in the carrier liquid in a dispersed state.

  When the dye is used, it is excellent in the image transfer property on the back surface of a recording medium such as cloth and fastness to washing. Depending on the material of the cloth, etc., it is better to choose the dye, and the dyeing and washing fastness are better. For example, in the case of cloth made of synthetic fibers such as polyester, acetate, polyethylene, polyurethane, polyvinyl chloride, vinylon, disperse dye is used. Basic dyes in the case of acrylic, reactive dyes in the case of cellulosic fabrics such as cotton and hemp, direct dyes, direct dyes in fabrics such as nylon and rayon, acidic dyes in fabrics such as silk and wool Are desirable.

  Commercially available powder dyes have a dye purity of about 50% and often contain a large amount of salt and sodium sulfate, which adversely affects the resistance and chargeability of the liquid. It is better to use In the present invention, the purity is desirably 80% or more.

  The carrier liquid used in the liquid developer of the present invention is preferably a high resistance and low dielectric constant material, such as isoparaffin hydrocarbons and silicone oils. Isoparaffin hydrocarbons include Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M, and Isopar V (Exxon Chemical). Company), SH200, SH344 (Toray Dow Corning Co., Ltd.), TSF451 (GE Toshiba Silicone), and the like. Of these, saturated hydrocarbons having a boiling point of 130 ° C. or higher are good in terms of odor and safety. These solvents can be evaporated in the subsequent heating and steaming steps.

  The dispersing resin preferably used in combination with the present invention includes a vinyl monomer represented by the following general formula (1), a vinyl monomer represented by the general formula (2), and vinyl as the remaining third component. There are copolymers and graft copolymers made of at least one monomer selected from the group consisting of pyridine, vinyl pyrrolidone, ethylene glycol dimethacrylate, styrene, divinylbenzene, and vinyltoluene.

（Ｒ１は、ＨまたはＣＨ３を、Ｒ２はＣ１〜Ｃ４のアルキル基を、ｎは６〜２０の整数を表わす。）
成分（Ａ）と成分（Ｂ）の共重合割合は６０〜９５：４０〜５、望ましくは７０〜９０：３０〜１０であり、また、前記第３成分は、成分（Ａ）の０〜５％であることが好ましい。

(R1 represents H or CH3, R2 represents a C1-C4 alkyl group, and n represents an integer of 6-20.)
The copolymerization ratio of the component (A) and the component (B) is 60 to 95:40 to 5, preferably 70 to 90:30 to 10, and the third component is 0 to 5 of the component (A). % Is preferred.

  These colorants, resins, and carrier liquids are put into a dispersing machine such as a ball mill, a kitty mill, a disk mill, and a pin mill, and dispersed and kneaded to prepare a high solid content liquid developer, which is diluted with the carrier liquid. By doing so, a liquid developer used for development can be obtained.

As the cloth or the like, any cloth structure can be used regardless of a woven fabric, a knitted fabric, a nonwoven fabric, a braided string, or the like, and a woven fabric is particularly preferable.
As materials constituting the fabric, various polyesters such as polyethylene terephthalate and polybutylene terephthalate, synthetic fibers such as polyethylene, polyurethane, polyvinyl chloride, vinylon, acrylic, nylon and acetate, recycled fibers such as rayon, cotton, There are cellulosic fibers such as hemp and animal fibers such as silk and wool, and these may be blended or woven.

Next, with reference to FIG. 2, a description of a problem state where the liquid developer 9 stays and a characteristic part of the present invention that solves the problem will be described.
First, at the time of image formation using the liquid developer 9, a preparatory operation for image formation is performed in a portion before the latent image equivalent portion of the photosensitive drum 1 in the image formation sequence. That is, the photosensitive drum 1 and the developing rollers 5 and 6 are rotated, the developer is supplied to the developing roller, a developing bias is applied to the developing rollers 5 and 6, and the reverse roller 7 is rotated.
By this preparation operation, a uniform liquid developer 9 having a thickness of several μm to several tens of μm is formed in a film shape on the surface of the photosensitive drum 1. At this time, since the photosensitive drum 1 is charged and a developing bias is also applied, the liquid developer 9 adhering to the surface of the photosensitive drum 1 is the same liquid developer 9 as the non-image portion, and toner particles These components are very small or do not adhere at all, and most are due to adhesion of the carrier liquid.

On the other hand, as shown in FIG. 2, a transfer roller 20 is provided on the surface of the photosensitive drum 1 on the downstream side of the reverse roller 7.
The transfer roller 20 has a structure that can be brought into and out of contact with the presence or absence of a transfer material 21 that is a recording medium such as paper or cloth.
Here, when the transfer is performed, a pressure of a certain level or more is often required. When the transfer roller 20 is brought into pressure contact with the photosensitive member at a high pressure, the photosensitive drum 1 is vibrated at the time of the contact and separation. If the photosensitive drum 1 vibrates when writing fine image data, the position of the image data is shifted, and the image quality is impaired. Therefore, as an embodiment of the present invention, the transfer roller It is desirable that 20 does not contact or separate.
Further, when a preparatory operation for image formation is performed with the transfer roller 20 kept in pressure contact with the photosensitive drum 1, it is formed on the surface of the photosensitive drum 1 on the downstream side of the reverse roller 7. Since the film of the liquid developer 9 cannot pass through the contact portion between the photosensitive drum 1 and the transfer roller 20, the upstream side of the photosensitive drum 1 and the transfer roller 20 (the liquid pool Q shown in FIG. 2). ) Causes the liquid developer 9 to accumulate.

Next, an example of a technical problem that arises from the state in which the liquid developer 9 accumulates at the location of the liquid reservoir Q shown in FIG. 2 will be described.
When the image forming operation is started and the transfer paper is conveyed to the contact portion between the photosensitive drum 1 and the transfer roller 20 for transfer, the transfer paper 21a enters the liquid reservoir Q as shown in FIG. Then, a large amount of the liquid developer 9 adheres to the leading end portion of the transfer paper 21a.
As described above, the liquid developer 9 in this case has no toner particle component attached thereto, but the transfer paper 21a is abnormally wetted mainly by the carrier liquid. As a result, the liquid developer 9 is taken out of the apparatus in a normal operation. Since the amount of the carrier liquid that does not occur adheres to the transfer paper 21a and is taken out of the apparatus, the carrier liquid is excessively consumed.

  Further, when the carrier liquid adhering to the transfer paper 21a is volatilized in a process such as heat fixing, a large amount of heat energy is required, which is not preferable. In addition, when a carrier liquid that does not volatilize is used, it cannot be absorbed by the transfer paper 21a and remains on the surface, which may impair the shape quality of the output transfer paper 21a.

  Further, since the transfer paper 21a having the wet front end is in a state of no stiffness, it may cause a conveyance failure and may not be discharged out of the apparatus. In addition, the toner image transferred thereafter may be pushed on the transfer paper 21a by the carrier liquid adhering to the tip in a large amount, and the image quality may be impaired. In addition, when the image forming preparation operation before the image forming is started is a long time or when the amount of the liquid developer 9 attached on the photosensitive drum 1 after the reverse roller 7 is large, the transfer roller 20 This is not preferable because the liquid overflows or drops from the liquid reservoir Q in the front and causes a problem of wetting the transfer roller 20 and the apparatus.

  In another example of the transfer material 21, in the case of a web-like transfer paper or cloth, there is a problem that only a problem occurs at the beginning of a print job and a wet tip is not used. There is a concern that the carrier liquid will be excessively consumed as much as it gets wet, and that the cost will increase.

  The problem that the carrier liquid accumulates in the contact portion between the photosensitive drum 1 and the transfer roller 20 to form the liquid reservoir Q is not limited to the above-described preparation for image formation before the image forming operation described above. Even when printing on the paper, it occurs between the papers. That is, in the case of a sheet of paper, it is not realistic to use the leading edge, and since the above-mentioned image preparation is often performed for several seconds to several minutes between papers, the photosensitive drum 1 is compared with that. The amount of the liquid pool Q at the contact portion with the transfer roller 20 is relatively small. However, depending on the image forming conditions such as the amount of the liquid developer 9 after the reverse roller 7 and the properties such as the liquid absorbability of the transfer paper, the above-described image flow and other problems may be problematic. .

Therefore, it is necessary to remove the liquid developer 9 adhering to the photosensitive drum 1 during preparation for image formation or between sheets.
For example, as shown in FIG. 1, the image forming apparatus of the present invention includes a pre-transfer liquid amount regulating blade 30 on the downstream side of the reverse roller 7 and the upstream side of the transfer roller 20 in the surface movement direction of the photosensitive drum 1. Is arranged.

As shown in FIG. 4, the pre-transfer liquid amount regulating blade 30 includes an elastic blade b, a holder-shaped support member h that supports the blade, a case, a drain, and the like.
The elastic blade b is formed of an elastic member such as rubber, for example, and can be elastically deformed. The elastic blade b is disposed so that an edge portion thereof is in contact with the photosensitive drum 1 (elasticity is provided). The blade b is hereinafter referred to as “elastic blade b” in order to clarify the difference in designation with the pre-transfer liquid amount regulating blade 30).

The elastic blade b is configured to be able to contact and separate by a driving mechanism (not shown) so that the elastic blade b can approach and separate from the photosensitive drum 1. The role of the elastic blade b is to scrape off the liquid developer 9 adhering to the surface of the photosensitive drum 1 after passing through the developing roller portion.
The pre-transfer liquid amount regulating blade 30 is housed in each case so that the liquid developer 9 scraped by the elastic blade b is collected. In addition, the scraped liquid developer 9 falls into the case due to its own weight, and is collected in the developer tank 8 through the drain hole and pipe of the case, like the photosensitive drum cleaning liquid and developer. The toner density and the like are readjusted and used repeatedly for development and cleaning.

The form of the case in which the pre-transfer liquid amount regulating blade 30 is accommodated may be the same as the case of the developing unit, and the pre-transfer liquid quantity regulating blade 30 is, for example, the developing shown in FIG. It may be installed in a part or unit of the device 11. This is because the recovered liquid developer 9 can be recovered together with the recovered liquid from the developing device by being housed and installed in the same case as the developing rollers 5 and 6 and the reverse roller 7. This is because it can be an advantageous place above.
Further, the embodiment of the present invention is not limited to the form of the case in which the pre-transfer liquid amount regulating blade 30 is accommodated, and the pre-transfer photoconductor to the developing device and the cleaning device (or cleaning unit). The attached developer may be circulated separately. This is because the ease of reuse by separation and the degree of design freedom are improved.

  As an example of the configuration of the pre-transfer liquid amount regulating blade 30 in this embodiment, as shown in FIG. 4, the elastic blade b is plate-shaped, and an example of the material is manufactured by Bando Chemical Co., Ltd. Using urethane material (Vancolan), thickness is 2mm, hardness is 70 degrees, the protruding amount is 10mm, the contact angle θ with respect to the outer peripheral surface of the photosensitive drum 1 is 80 ° to 85 ° ± 3 °, line The pressure is preferably adjusted to 14.7 to 24.5 mN / mm.

The timing at which the pre-transfer liquid amount regulating blade 30 contacts the photosensitive drum 1 is performed in the non-image forming area. Here, when describing the details of the “non-image-forming region”, a portion to which a toner component such as a character image adheres may be referred to as an image portion, and a background portion to which no toner adheres may be referred to as a non-image portion. The portion printed on one sheet of paper is called an “image forming area” including the image portion and the non-image portion. For example, the portion before and after the transfer between the paper and the transfer paper is “ This is called a “non-imaging region”.
The non-image forming area is an area before the image forming sequence starts to operate and before the image forming area reaches the position of the pre-transfer liquid amount regulating blade 30, and an area after passing. In the case of a sheet, it is an area where a large amount of developer has conventionally adhered between the transfer paper.

The pre-transfer liquid amount regulating blade 30 is driven by a driving mechanism (not shown) before the portion where the developer adheres in the non-image forming area reaches the contact position of the elastic blade b, and is a photosensitive drum. It moves so that the edge of the elastic blade b contacts the surface of 1. As a result, the liquid developer 9 on the photosensitive drum 1 is scraped and collected by the elastic blade b.
The pre-transfer liquid amount regulating blade 30 is driven before the image forming area reaches the contact position of the elastic blade b, and moves in a direction away from the photosensitive drum 1.

The timing at which the blade 30 is driven and the elastic blade b is brought into contact with the photosensitive drum 1 is mainly after the portion where the liquid developer 9 is attached reaches the contact position of the elastic blade b.
This is normal when the elastic blade b of the pre-transfer liquid amount regulating blade 30 is brought into contact with the dried photoconductor drum 1 so that the edge thereof is not easily slipped with respect to the drum surface and is pulled in a small amount or causes vibration. This is because it may not work.

As shown in FIG. 2, even if the pre-transfer liquid amount regulating blade 30 is provided and operated to prepare the image forming sequence at the start of the image forming sequence so that the liquid developer 9 adheres to the photosensitive drum 1. Such a liquid pool Q is not formed at the contact portion between the photosensitive drum 1 and the transfer roller 20. Therefore, even when the first transfer paper or cloth in one job passes, a large amount of developer does not adhere to the leading end and does not get wet abnormally.
Further, when the image forming preparation operation is performed for a long time or when the developer adhesion amount on the photosensitive drum 1 after the reverse roller 7 is large, the liquid overflows or drops from the liquid reservoir Q, and the transfer material 21 or It is possible to prevent the transfer roller 20 from getting wet.

[Example 1]
FIG. 5 shows an example in which the means for regulating the liquid developer 9 on the pre-transfer photosensitive drum 1 is a non-contact type roller with respect to the photosensitive drum 1.
The reverse roller 7 is provided to the photosensitive drum 1 at such an interval as to come into contact with the liquid film of the liquid developer 9 adhering to the photosensitive drum 1. Is installed with respect to the photosensitive drum 1 through a gap c (see FIG. 5) narrower than the reverse roller 7 in the developing device 11. As for the material of the non-transfer liquid regulating non-contact roller 50, it is possible to use hard alumite, SUS, or the like, similar to the reverse roller 7 in the developing device 11.

  In the example of FIG. 5, the rotation direction of the pre-transfer liquid amount regulating non-contact roller 50 is the same as that of the photosensitive drum 1, that is, the surface moving direction is the reverse direction (reverse). In order to increase the developer recovery efficiency from the photosensitive drum 1 by the non-transfer liquid volume regulation non-contact roller 50, the developer collected from the photosensitive drum 1 is further collected from the pre-transfer liquid quantity regulation non-contact roller 50. A blade is provided.

  Similar to the pre-transfer liquid amount regulating blade 30 in the embodiment of FIG. 1, the pre-transfer liquid amount regulating non-contact roller 50 is operated by a driving device in the non-image forming region. The operation / non-operation of the non-transfer liquid amount regulating non-contact roller 50 may be performed by switching between rotation and stop, or the movement mechanism may cause the pre-transfer liquid amount regulating non-contact roller 50 and the photosensitive drum 1 to be in a non-operating state. The distance may be increased. Even if the rotation direction of the pre-transfer liquid amount regulating non-contact roller 50 is opposite to the above, the efficiency is reduced, but the function of regulating the liquid amount is exerted. The direction may be opposite to the drum, and is not limited to the same direction.

  The pre-transfer liquid volume regulation non-contact roller 50 can regulate the liquid quantity of the liquid developer 9, but cannot remove almost 100% of the liquid as in the above-mentioned pre-transfer liquid quantity regulation blade 30. For this reason, the liquid amount of the liquid pool Q at the contact portion between the photosensitive drum 1 and the transfer roller 20 is slightly larger than that in the case of the blade 30, but the regulation effect by itself is particularly remarkable.

[Example 2]
FIG. 6 shows an example in which a pre-transfer liquid amount regulating contact roller 60 is used as means for regulating the developer on the pre-transfer photosensitive drum.
In this example, the pre-transfer liquid amount restriction contact roller 60 is disposed so as to come into contact with the photosensitive drum 1, and the rotation direction of the pre-transfer liquid quantity restriction contact roller 60 is the same as that of the photosensitive drum 1. Thus, the surface movement direction is the reverse direction (reverse).
Therefore, if the pre-transfer liquid amount regulating contact roller 60 is made of the same hard alumite as the pre-transfer liquid quantity regulating non-contact roller 50, the photoreceptor drum 1 is damaged by this. Further, a blade or the like that removes the liquid collected from the photosensitive drum from the pre-transfer liquid amount regulating contact roller 60, which has a surface moving direction opposite to that of the photosensitive drum and becomes resistance to the rotation of the photosensitive drum. It is necessary to provide it. For this reason, the pre-transfer liquid amount regulating contact roller 60 is preferably made of a surface material that is elastic, has low surface energy, and is slippery. Therefore, in this example, a urethane roller having a hardness of 50 ° and having a fluorine coating on the surface is used. As in the case of the pre-transfer liquid quantity regulating blade 30 in FIG. 1, the pre-transfer liquid quantity regulating contact roller 60 is operated in the non-image forming area. Further, in this case, contact / separation and rotation are included. The pre-transfer liquid volume regulating contact roller 60 has a higher liquid regulating effect than the non-contact roller 50 in FIG. 5, and almost 100% of the liquid is removed like the regulating blade 30.

  Further, the rotation direction of the pre-transfer liquid amount regulating contact roller 60 does not have to be reverse with respect to the photosensitive drum 1, and the surface moving direction thereof may be the same as the surface moving direction of the photosensitive drum 1. In the case of the same direction, the liquid volume regulation efficiency is lower than that of the reverse type, but the effect of the liquid volume regulation is particularly remarkable.

Example 3
FIG. 7 shows an example in which a circulating belt 70 is used as means for regulating the developer on the pre-transfer photosensitive drum.
In this example, a pair of rotating wheels (pulleys) 70 a and 70 b are arranged vertically, a belt 70 c is wound around both rotating wheels 70 a and 70 b, and the belt 70 c is brought into contact with the photosensitive drum 1. The belt 70c is made of urethane, and has the same properties as the pre-transfer liquid amount regulating contact roller 60.
The belt 70c circulates in contact with the photosensitive drum, thereby regulating the amount of developer on the surface of the photosensitive drum.
According to the example using the belt 70c, the range in which the regulating member circulates is long in the vertical direction as compared with the case using the roller. Therefore, the installation place of the blade for collecting the developer collected from the photosensitive drum 1 from the belt. Therefore, there is an advantage that the selection range is wide and therefore the degree of freedom of these layouts is high.

Example 4
The example shown in FIG. 8 is an example in which the means for regulating the developer on the pre-transfer photosensitive drum is a liquid suction device.
In this example, in order to suck the liquid on the photosensitive drum 1, a slit-like suction port 80a that is long in the axial direction is provided close to the lower surface of the photosensitive drum 1, and the other end opposite to the suction port 80a is vacuumed. Connected to the pump 80b, the negative pressure at the suction port 80a is controlled by a valve or the like while being detected by a negative pressure sensor, and the suction force at the suction port 80a is maintained at an appropriate constant level. In the example of FIG. 8, the suction port 80a is not in contact with the photosensitive drum so as not to apply a load. However, one side of the slit of the suction port 80a is formed of an elastic member, and this is contacted with the photosensitive drum 1. Alternatively, the developer may be scraped off, and an operation mechanism may be provided in which the elastic member is brought into contact with or separated from the photosensitive drum 1. In this case, the other one side is disposed with a gap from the photosensitive drum so that the developer on the photosensitive drum is efficiently sucked toward the slit.

  As the vacuum pump 80b, there are a rotary pump, a diaphragm pump, a tube pump, and the like, and these pumps may be used. Further, since the amount of the developer adhering to the non-image forming area of the photosensitive drum is very small, the developer is sucked together with the air. Therefore, a pump most suitable for such conditions is desirable.

Example 5
The example shown in FIG. 9 is an example in which the means for regulating the developer on the pre-transfer photosensitive drum is a liquid absorbing roller.
The pre-transfer liquid absorbing roller 90 in this example is composed of a liquid absorbing roller 90a and a liquid squeezing roller 90b, and the surface layer of the liquid absorbing roller 90a is composed of a porous elastic material. This is pressed against the photosensitive drum 1 to absorb and collect the developer. Examples of the porous elastic body include polyester resin, acrylic resin, melamine resin, epoxy resin, urethane resin, silicone resin, urea resin, polyamide resin and other synthetic resins, ethylene-propylene rubber, epichlorohydrin rubber, silicone rubber, Examples thereof include foams of synthetic rubber such as fluoro rubber. In order not to disturb the electrostatic latent image on the photosensitive drum, an electrically insulating one is preferable.
Further, in order to be able to squeeze the absorbed developer, a liquid squeezing roller 90b made of metal or rubber is pressed against the surface of the pre-transfer liquid absorbing roller 90a. In this case, it is preferable that the liquid absorbing roller 90a and the liquid squeezing roller 90b are rotated in opposite directions and have a peripheral speed difference, and a blade for removing the developer is provided on the surface of the developer squeezing roller.

The liquid absorbing roller 90a can be rotated in either direction, but in this embodiment, the direction opposite to that of the photosensitive drum and the surface moving direction are the same. Similarly to the pre-transfer liquid amount regulating member, the pre-transfer liquid absorbing roller is operated in the non-image forming area. In this case as well, if the liquid absorbing roller 90a is always in contact with the photosensitive drum 1, the image may be disturbed. Therefore, it is desirable that the liquid absorbing roller 90a be separated when not in operation. It is preferable that the roller 90 be configured so as to be able to contact and separate from the photosensitive drum 1.
In this example, since the liquid absorbing roller 90a is used, it can be made compact compared to the shape of a belt, a web or the like, and the liquid absorbing roller 90a is formed of a porous elastic material. Can be efficiently removed. The liquid absorbing rollers 90a may be provided in multiple stages. In this way, the amount of developer that can be absorbed is larger than when only one is provided.

Example 6
The example shown in FIG. 10 is an example in which the means for regulating the developer on the pre-transfer photosensitive drum is the liquid absorbing web 100.
This web 100w is made of a material having good oil absorption such as multifilament polyester microfiber or nonwoven fabric. The web 100w is wound around a supply shaft 100a in a roll shape, wound around a rotating body (backup roller) 100b, and the other end is fixed to a winding shaft 100c. The web 100w is wound around the winding shaft 100c by the rotation of the winding shaft 100c and moves. The web 100w is pressed against the photosensitive drum at the position of the rotating body (backup roller) 100b, and absorbs the developer on the photosensitive drum. Since the portion that has absorbed the developer moves slowly toward the take-up shaft, the developer absorption capacity is stably maintained. When the web of the supply shaft 100a is used up, it is discarded and replaced with a new web.

The moving direction of the web 100w can be either the same direction as the moving direction of the surface of the photosensitive drum 1 or the opposite direction. In this example, the moving direction of the web 100w is opposite to the moving direction of the photosensitive drum surface. When the developer is absorbed using the web, the developer can always be absorbed by a new web portion.
According to this example, until the web of the supply shaft 100a is completely used up, the developer absorbing ability is stably maintained without removing the developer transferred to the web from the web. There is no need to provide a device (cleaning device) for squeezing the developer. Further, by moving the web 100w in the opposite direction with respect to the surface of the photosensitive drum, the absorption efficiency of the developer on the photosensitive drum is higher than when the web 100w is moved in the same direction.

[Others]
The various pre-transfer liquid amount regulating members as described above may be provided in combination, and by providing them in combination, the developer attached to the front transfer portion on the photosensitive drum can be collected more effectively. There is a method of providing a blade after the pre-transfer liquid amount regulating reverse roller and the pre-transfer liquid absorbing roller.

[Embodiment 2]
The second embodiment is an embodiment of the invention using an intermediate transfer member, and is shown in FIG.
As in Embodiment 1, the developer image formed on the photosensitive drum 1 reaches a position facing the intermediate transfer roller 20 </ b> A as the photosensitive drum 1 rotates. On the other hand, the intermediate transfer roller 20A is pressed toward the photosensitive drum to form a primary transfer nip. The intermediate transfer roller 20A is provided with a power source (not shown) that applies a transfer bias having a polarity opposite to the charging polarity of the toner, and the intermediate transfer roller 20A is rotated in the direction of the arrow during printing.
A transfer bias is applied to the primary transfer nip, and a transfer electric field is formed by a potential difference between the intermediate transfer roller 20 </ b> A and the surface potential of the photosensitive drum 1. The developer image that has entered the primary transfer nip with the rotation of the photosensitive drum 1 is primarily transferred onto the intermediate transfer roller under the action of the transfer electric field and nip pressure.

  The developer image primarily transferred in this way is transferred by a recording material conveying member (not shown) by a secondary transfer nip or a transfer electric field formed by the intermediate transfer roller 20A and the secondary transfer roller 20. Secondary transfer is performed on the paper 21a. The transfer paper 21a onto which the toner image has been transferred is fixed by a fixing device (not shown). The transfer paper 21a on which the developer image is fixed is discharged from the fixing device to the outside through a paper discharge path. The surface of the photosensitive drum that has passed through the primary transfer nip is scraped off and removed by the cleaning roller 22 and the cleaning blade 24 of the drum cleaning device 12. Thereafter, the residual charge is removed by the charge removal lamp 25. As a result, the surface of the photosensitive drum 1 is initialized and prepared for the next latent image formation.

  In the case of transferring via the intermediate transfer roller 20A, the non-image forming area is attached between the intermediate transfer roller 20A and the transfer roller 20 as in the case of transferring directly from the photosensitive drum to the recording medium using the transfer roller. The developed developer accumulates. Further, a similar liquid pool occurs at the contact portion between the photosensitive drum 1 and the intermediate transfer roller 20A. Therefore, as shown in FIG. 11, in the non-image forming portion, the developer does not enter the contact portion between the intermediate transfer roller 20 </ b> A and the transfer roller 20. A pre-transfer liquid amount regulating blade 30 is provided upstream of the transfer unit.

  FIG. 12 shows another example of the second embodiment. In this embodiment, in the same manner as described above, on the surface of the intermediate transfer roller 20A on the downstream side of the primary transfer portion and on the upstream side of the secondary transfer portion, on the downstream side of the developing portion on the surface of the photosensitive drum 1 and on the upstream side of the primary transfer portion. Since the primary pre-transfer liquid amount regulating blade 30 is provided and the developer is recovered at two locations, the recovery of the developer is more efficient.

  Similar to the pre-transfer liquid amount regulating member provided for the intermediate transfer roller 20A (in the above example, the pre-transfer liquid quantity regulating blade 30 corresponds to this) and the pre-transfer liquid quantity regulating member provided for the photosensitive drum. A non-contact reverse roller, a contact reverse roller, an absorption roller, etc. (see FIGS. 5, 6, 9 etc.) can be used, and may be provided only on the photosensitive drum 1 or only on the intermediate transfer roller 20A. Two or more photosensitive drums may be provided in combination.

  When a toner image is transferred to a recording medium having unevenness such as cloth, a gap may be formed between the recording medium and the photosensitive member or the intermediate transfer member. If such a gap exists, good transfer is performed. And high-quality images cannot be obtained. In order to obtain a high-quality image with good transfer, it is desirable that the carrier liquid is filled between the recording medium and the photosensitive member or intermediate transfer member. In order not to create such voids, the pressure between the photosensitive member and the member that is in pressure contact with the intermediate transfer member may be increased. In particular, the higher the pressure, the more liquid is damped and the liquid pools. Becomes larger. For this reason, when cloth is used as the recording medium, the function of the pre-transfer liquid amount regulating member becomes more useful.

[Summary of Description of Embodiment]
The first embodiment and the second embodiment have been described above.
According to the first embodiment, by providing the pre-transfer liquid amount regulating member on the image carrier surface, the amount of developer accumulated between the image carrier and the transfer device can be reduced, and the recording medium can be reduced. It can be prevented from getting abnormally wet. Further, it is possible to prevent the carrier liquid from being normally taken out from the apparatus from adhering to the recording medium and being taken out from the apparatus. When the carrier liquid adhering to the recording medium is volatilized by heat fixing or the like, the amount of carrier liquid adhering to the recording medium is reduced, so that the amount of energy for that purpose can be kept low.

  When a carrier liquid that does not volatilize is used, the amount to be absorbed by the recording medium can be suppressed, so that the carrier liquid can be prevented from adhering to a place touched by a hand, a desk, or a recording medium. Further, it is possible to prevent a conveyance failure due to the front end of the recording medium being particularly wet, and to prevent subsequent toner images from being washed away on the recording medium by the carrier liquid adhering to the front end of the recording medium. And high image quality can be obtained. Also, when the image preparation operation before image formation is started for a long time or when the amount of developer adhering to the image carrier after the developing device is large, the liquid may overflow or fall from the liquid reservoir. It is possible to prevent the transfer member and the apparatus from getting wet.

  In addition, according to the second embodiment, by providing the pre-transfer liquid amount regulating member on the surface of the image carrier or the intermediate transfer member, the contact portion between the photosensitive member and the intermediate transfer member and the contact portion between the intermediate transfer member and the transfer member. In addition, the amount of developer accumulated can be kept low, and the same effect as in the first embodiment can be obtained.

By using a blade as the pre-transfer liquid amount regulating member, the developer amount on the photosensitive drum can be regulated so that the developer hardly remains on the surface of the photosensitive drum.
By using a non-contact reverse roller that is non-contact and rotates in the reverse direction (the reverse direction to the surface of the photosensitive drum) as the pre-transfer liquid amount regulating member, the distance between the photosensitive drum and the reverse roller is reduced. Although it is necessary to make it narrow, other configurations can be made almost the same as those of the reverse roller, and the motor can be made the same, so that the cost can be suppressed. Further, since there is no contact with the photosensitive drum, it is possible to prevent a load from being applied to the rotation of the photosensitive drum and the non-contact reverse roller.

  Since the developer transferred from the photosensitive drum to the non-contact reverse roller is scraped every turn by the blade, the liquid remains when stopping the rotation of the non-contact reverse roller or separating the non-contact reverse roller from the photosensitive drum. Can be reduced. By using a contact reverse roller that is in contact with the photosensitive drum and whose surface rotates in the reverse direction as the pre-transfer liquid amount regulating member, the developer on the photosensitive drum is reduced compared to the case of using a non-contact reverse roller. It can be regulated more efficiently.

  Since a blade for scraping the collected liquid is provided on the non-contact reverse roller, there is little residual developer when the rotation of the non-contact reverse roller is stopped or the non-contact reverse roller is separated from the photoreceptor. can do. By using a liquid suction device as a pre-transfer liquid amount regulating member and making the suction port non-contact with the photosensitive drum, a friction load due to contact resistance is not applied to the photosensitive drum. When one end of the suction port is used as an elastic blade and brought into contact with the photosensitive drum, the developer can be collected more efficiently than in the non-contact case.

Further, by using the liquid absorbing member as the pre-transfer liquid amount regulating member, the liquid absorbing roller is made of a porous elastic material, so that the developer can be efficiently removed. In the case of the roller shape, the pre-transfer liquid amount regulating member becomes compact, and in the case of the web shape, the whole becomes large, but the degree of freedom of layout close to the photosensitive drum increases.
By combining or providing a plurality of the liquid amount regulating members, for example, the liquid reservoir is sucked and collected by another means when the regulating means by the blade is released, or, for example, It is possible to regulate and collect the developer more reliably and efficiently, for example, the developer remaining thinner downstream by the absorbing roller can be further regulated by the other blade.

  Also, when using cloth as the recording medium, the transfer roller may be pressed against the photosensitive drum or intermediate transfer roller at a higher pressure than when using other recording media. The amount of developer that accumulates at the contact portion between the transfer roller and the transfer roller also increases, but by providing a pre-transfer liquid amount regulating member, it is possible to prevent the liquid from dripping and improve the transportability of the transferred recording medium. And the amount of liquid taken out of the apparatus can be reduced.

FIG. 2 is a front view of the first embodiment. FIG. 2 is a diagram schematically illustrating a state in which a liquid pool Q is formed at a contact portion between the photosensitive drum 1 and the transfer roller 20 in the image forming apparatus according to the first embodiment. These are the figures which show typically the relationship between the liquid pool in FIG. 2, and a transfer paper. FIG. 2 is an enlarged view of a part of FIG. 1. These are the front views of Example 1 in Embodiment 1. FIG. These are the front views of Example 2 in Embodiment 1. FIG. These are the front views of Example 3 in Embodiment 1. FIG. These are the front views of Example 4 in Embodiment 1. FIG. These are the front views of Example 5 in Embodiment 1. FIG. These are Example 6 in Embodiment 1. FIG. These are front views of Embodiment 2. FIG. These are the front views of the other Example in Embodiment 2. FIG.

Explanation of symbols

1: Photosensitive drum 2: Charging device 3: Erase lamp 4: Exposure device 5: First developing roller 6: Second developing roller 7: Reverse roller 8: Developer tank 9: Liquid developer 10: Pump 11: Developing device 12: Cleaning device 20: Transfer roller 20A: Intermediate transfer roller 21: Transfer material 21a: Transfer paper 30: Pre-transfer liquid amount regulating blade Q: Liquid pool

Claims (9)

  An image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image on the image carrier using a liquid developer to form a visible image, and the image carrier. And a transfer device that transfers the toner image to a recording medium. The image forming apparatus includes a liquid amount regulating member before the transfer position for transferring the toner image to the recording medium. An image forming apparatus comprising an operation / non-operation switching mechanism. An image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image on the image carrier using a liquid developer to form a visible image, and the image carrier. An image forming apparatus comprising: an intermediate transfer body that transfers the toner image transferred; and a transfer device that transfers the toner image formed on the intermediate transfer body to a recording medium.
An image forming apparatus comprising a liquid amount regulating member before a transfer position for transferring a toner image to a recording medium, wherein the liquid amount regulating member comprises a liquid amount regulating mechanism operating / non-operating switching mechanism.   3. The image forming apparatus according to claim 1, wherein the liquid amount regulating member is a blade.   3. The image forming apparatus according to claim 1, wherein the liquid amount regulating member is a roller that does not contact and rotates with the image carrier or the intermediate transfer member.   3. The image forming apparatus according to claim 1, wherein the liquid amount regulating member is a roller that contacts and rotates with the image carrier or the intermediate transfer member.   3. The image forming apparatus according to claim 1, wherein the liquid amount regulating member is a liquid suction device.   3. The image forming apparatus according to claim 1, wherein the liquid amount regulating member is a liquid absorbing member.   The image forming apparatus according to claim 1, wherein the liquid amount regulating member according to claim 3 is provided in combination. 9. The image forming apparatus according to claim 1, wherein the recording medium is a cloth.

Images