JP7300103B2 - LIQUID APPLICATION DEVICE AND IMAGE FORMING APPARATUS - Google Patents

Description

The present invention relates to a liquid applying device and an image forming apparatus.

2. Description of the Related Art Conventionally, there has been known a liquid applying device that has a liquid carrier member that carries liquid on its surface and a facing member, and that applies a liquid to a sheet sandwiched between the liquid carrier member and the facing member.
For example, Patent Document 1 describes a liquid application device applied to an image forming apparatus that applies a treatment liquid that promotes fixation of a toner image by heating by a fixing device to a recording medium before the toner image is transferred. It is

However, there remains the problem that the amount of liquid applied is not stable at the leading edge of the recording medium.

In order to solve the above-described problems, the present invention provides a liquid applying device that has a liquid carrier member that carries liquid on its surface and a facing member, and that applies a liquid to a sheet sandwiched between the liquid carrier member and the facing member. wherein the liquid carrier member and the opposing member are longitudinally aligned so that entry of the leading edge of the sheet into the nip portion between the liquid carrier member and the opposing member is partially initiated in the direction of the leading edge. It is characterized in that the sheet is inclined in different directions with respect to the leading edge of the sheet so as to have an angle other than 0 degree .

According to the present invention, it is possible to stabilize the amount of liquid to be applied at the leading edge of the recording medium as compared with the prior art.

1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment; FIG. FIG. 2 is a schematic configuration diagram of a coating liquid application unit 201; FIG. 2 is an explanatory diagram of configuration example 1; FIG. 10 is an explanatory diagram of Configuration Example 2; FIG. 11 is an explanatory diagram of configuration example 3;

An embodiment in which a liquid applying device according to the present invention is applied to an electrophotographic image forming apparatus will be described below.
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to this embodiment.
Symbols "Y", "C", "M", and "K" in the drawing indicate members for yellow, cyan, magenta, and black, respectively. Also, the conveying path of the printing medium P such as paper, which is the recording material, is indicated by a dashed line.

The print medium P fed from the paper feeder 300 is conveyed to the coating liquid applying device 200 as a liquid applying device, and the coating liquid that is liquid is applied to the surface of the printing medium P by the coating liquid applying unit 201. be. Note that the method of applying the liquid is not limited to coating, and other methods may be used. The applied coating liquid is dried by heat in the drying section 202 and then conveyed to the image forming apparatus main body 100 .

The image forming apparatus main body 100 includes four toner image forming units 101Y, 101M, 101C, and 101K for forming toner images of yellow, magenta, cyan, and black, respectively. These toner image forming units 101Y, 101M, 101C, and 101K use Y, C, M, and K toners of different colors as image forming substances, but otherwise have the same configuration. The symbols Y, C, M, and K indicating the colors of the toners to be used will be omitted as appropriate.

The image forming apparatus main body 100 includes an intermediate transfer belt 102 as an intermediate transfer member below four toner image forming units 101 . An intermediate transfer unit 103, which is a transfer means, endlessly moves the intermediate transfer belt 102 while being stretched by a plurality of tension rollers. Below the intermediate transfer unit 103, a fixing device 104 as fixing means is provided. The print medium P on which the toner image has been fixed by the fixing device 104 is finally conveyed to the discharge tray 105 .

FIG. 2 is a schematic configuration diagram of the coating liquid application unit 201. As shown in FIG.
Depending on the type of print media, image formation may not be possible because the required fixing strength cannot be obtained. In some cases, a predetermined fixing strength can be obtained by performing this. In this embodiment, in order to cope with such a print medium, the image is printed on the print medium before the fixing process (in this embodiment, the print medium before the image is formed (before the image is transferred)). A predetermined fixing strength is obtained by applying a coating liquid for increasing the fixing strength of (toner).

The coating liquid application unit 201 of this embodiment draws up the coating liquid 1 in the tank by the squeeze roller 2 that is rotationally driven, and supplies it onto the application roller 3 . The printing medium P conveyed along the conveying path 5 passes through the nip portion (pressure nip portion) between the application roller 3 and the pressure roller 4, and at that time, the coating liquid 1 on the application roller 3 is printed. It is applied (applied) to the medium P.

The coating liquid applying unit 201 shown in FIG. and a temperature control unit 7 for controlling the heater 8 based on the detection result. An optical sensor 10 for detecting surface roughness is arranged on the upstream side of the transport path 5 from the coating liquid applying unit 201 . A cooling fan 11 controlled by the temperature controller 7 is also provided. This cooling fan 11 blows air to the heat sink 9 provided in the tank of the coating liquid 1 .

In the conventional main coating liquid application unit, there is a problem that the amount of coating liquid applied to the leading edge of the print medium P is not stable. As a result of intensive research, we found the following. That is, as shown in FIG. 2, a liquid pool 1a is formed at the surface facing portion of the squeeze roller 2 and the application roller 3 on the liquid supply side of the squeeze roller 2. is controlled to be a constant amount. When the target print medium enters the nip portion composed of the application roller 3 and the pressure roller 4 and an impact is generated, the liquid pool 1a vibrates to temporarily transfer the coating liquid 1 to the application roller 3. supply may vary. This supply amount changed, and the application amount of the coating liquid 1, especially to the leading edge of the printing medium, changed. If the coating amount changes, the fixing performance becomes unstable, resulting in deterioration of image quality such as change in color tone.

Therefore, in this embodiment, in order to make the coating amount uniform at the leading edge of the printing medium, the leading edge of the printing medium enters the nip portion between the coating roller 3 and the pressure roller 4 only partially in the leading edge direction. to be started automatically. As a result, the leading edge of the print medium gradually enters the nip portion for applying the coating liquid at an angle, thereby reducing the impact when the print medium enters the nip portion. It is possible to avoid a phenomenon in which the coating amount varies at the tip, and to make the coating amount of the coating liquid uniform.

The impact caused by the print medium entering the nip portion can be mitigated by reducing the nip pressure when the print medium enters or by separating the rollers. It becomes necessary to perform control, and it is necessary to secure operation time for that purpose. This imposes restrictions on speeding up, and the addition of the mechanism causes an increase in the size of the apparatus. On the other hand, in the present embodiment, at least one of the application roller 3 and the pressure roller 4 is arranged at an angle with respect to the leading edge of the print medium in the longitudinal direction, which is a relatively inexpensive and simple mechanism. can mitigate the impact. Of course, if an increase in size is permitted, it is possible to concurrently use control such as reducing the nip pressure when the print medium enters.

[Configuration example 1]
FIG. 3 is an explanatory diagram of a configuration example (referred to as configuration example 1). In this configuration example 1, the center line Na of the pressure nip portion N indicated by hatching in the figure of the applying roller 3 and the pressure roller 4 which are parallel to each other is set at an angle other than 90° with respect to the conveying direction A of the print medium P. It is arranged so that it can be held. A specific method for achieving such an arrangement is to use a coating liquid coating device 200 (see FIG. 1) that accommodates a coating liquid coating unit 201 in which the coating roller 3 and the pressure roller 4 are arranged parallel to each other. 1), it may be arranged so as to have an angle other than 90° with respect to the conveying direction A of the print medium P in a plan view. Alternatively, in the coating liquid coating unit 201, the coating roller 3 and the pressure roller 4, which are parallel to each other, may be tilted at an angle other than 90° with respect to the conveying direction A of the print medium P in plan view. may be placed.

The specific method of the above arrangement is that the transport direction A of the print medium P in plan view is the transport path of the print medium P indicated by the dashed line in FIG. It is assumed that the apparatus body 100 is conveyed straight within the same width area when viewed from above. Contrary to this premise, if the transport direction A of the printing medium P in plan view in the coating liquid applying device 200 is set at an angle with respect to the above-mentioned straight, the coating liquid applying unit 201 side will be arranged in the same manner as the conventional one. However, the arrangement of configuration example 1 can be realized. In addition, the straight transport is performed as premised above, and the coating liquid application unit 201 side is arranged in the same manner as in the conventional art, and the leading edge Pa of the print medium P when passing through the coating liquid application unit 201 is positioned with respect to the transport direction A. A skew means may be provided so as to have an angle other than 90° so that the sheet may be conveyed while being inclined. Then, these arrangements may be realized by combining specific methods.

[Configuration example 2]
FIG. 4 is an explanatory diagram of another configuration example (referred to as configuration example 2). In configuration example 2, the central axis of rotation of the application roller 3 or the pressure roller 4 is arranged to have an angle other than 90° with respect to the conveying direction A of the print medium P in a plan view. The central line Na of the pressure nip portion N of the pressure roller 4 is arranged to have an angle other than 90° with respect to the conveying direction A of the print medium P in plan view. In the example shown in FIG. 4, the pressure roller 4 is arranged at an angle other than 90° with respect to the conveying direction A. In the example shown in FIG. The pressure roller 4 may have an angle of 90° (perpendicular) to the conveying direction A, and the application roller 3 may have an angle other than 90° with respect to the conveying direction A.

[Configuration example 3]
FIG. 5 is an explanatory diagram of still another configuration example (referred to as configuration example 3). In configuration example 3, both the rotation center shafts 3a and 4a of the application roller 3 and the pressure roller 4 are arranged to have different angles other than 90° with respect to the conveying direction A of the print medium P in plan view. It is the one that was made. In the illustrated example, the angles are different from each other. Unlike the illustrated example, by inclining in the same direction at different angles, the center line Na of the pressure nip portion N is inclined at an angle other than 90° with respect to the transport direction A in plan view of the print medium P. It can be placed in a holding position.

At least one of the coating roller 3 and the pressure roller 4 has an elastic surface, or the roller shafts are flexible, so that the roller shafts are at an angle and either one of the rollers can be rotated. Even if the center line Na of the pressure nip portion N has an angle with respect to the central axis of rotation, the center line Na is at an angle of 90° (perpendicular) to the conveying direction A in plan view of the print medium P. is possible. Even in the case of such an arrangement, the edge shape of the pressure nip portion N on the print medium P entrance side becomes a curved shape. Therefore, the leading edge Pa of the print medium P can be gradually entered into the pressure nip portion N. As shown in FIG.

[Configuration example 4]
Each of the configuration examples described above employs an inclined arrangement so that the entry of the leading edge of the print medium into the nip portion between the coating roller 3 and the pressure roller 4 is partially started in the direction of the leading edge. It is what I did. Instead of or in addition to the inclined arrangement, at least one of the application roller 3 and the pressure roller 4 may have the following shape. That is, a medium-thick drum shape (including a roller shape that is flat at the center in the width direction of the seat and tapered with a small outer diameter only at both ends) and a thin drum shape (flat at the center in the width direction of the seat and a large outer diameter at both ends only). (including tapered roller shapes). This also allows the leading edge of the print medium to partially start entering the nip portion between the application roller 3 and the pressure roller 4 in the leading edge direction.

In the present embodiment, the leading edge of the sheet starts to enter the nip portion between the liquid carrier member and the opposing member partially in the leading edge direction in order to make the coating amount uniform at the leading edge of the print medium. However, when the print medium is stiff and the amount of application is changed by the impact when the leading edge of the print medium comes into contact with whichever of the liquid carrier member and the opposing member comes into contact first, the liquid Contact of the leading edge of the sheet with at least one of the carrier member and the counter member may be partially initiated in the direction of the leading edge. Also for this purpose, the configurations of configuration examples 1 to 4 can be adopted.

In the present embodiment, an electrophotographic image forming apparatus will be described as an example, but other image forming apparatuses such as an inkjet method may be used. 2. Description of the Related Art Inkjet image forming apparatuses use a liquid application device that applies a treatment liquid to a recording medium to suppress bleeding of an ink image and improve image quality, as described in Japanese Unexamined Patent Application Publication No. 2002-200320, for example.

Although the above embodiments relate to the liquid applying device of the image forming apparatus, the present invention can also be applied to liquid applying devices for other devices.

Reference Signs List 1 : Coating liquid 1a : Liquid pool 2 : Squeeze roller 3 : Application roller 3a : Rotation center shaft 4 : Pressure roller 4a : Rotation center shaft 5 : Conveyance path 100 : Image forming apparatus main body 200 : Coating liquid coating device 201 : Coating Liquid application unit 202 : Drying unit 300 : Paper feeding device A : Conveying direction N : Pressure nip Na : Center line P : Print medium Pa : Leading edge

JP 2012-189639 A JP 2016-52740 A

Claims (5)

A liquid applying device that has a liquid carrier member that carries a liquid on its surface and a facing member, and that applies a liquid to a sheet sandwiched between the liquid carrier member and the facing member,
so that entry of the leading edge of the sheet into the nip between the liquid carrier member and the opposing member is partially initiated in the direction of the leading edge ;
A liquid applying device, wherein the liquid carrying member and the opposing member are arranged so that their longitudinal directions are inclined in directions different from each other with respect to the leading edge of the sheet at an angle other than 0 degrees. A liquid applying device that has a liquid carrier member that carries a liquid on its surface and a facing member, and that applies a liquid to a sheet sandwiched between the liquid carrier member and the facing member,
so that contact of the leading edge of the sheet with at least one of the liquid carrying member and the opposing member is partially initiated in the direction of the leading edge ;
A liquid applying device, wherein the liquid carrying member and the opposing member are arranged so that their longitudinal directions are inclined in directions different from each other with respect to the leading edge of the sheet at an angle other than 0 degree . An image forming apparatus comprising the liquid applying device according to claim 1 or 2 . An image forming apparatus comprising a liquid carrying member for carrying liquid on a surface thereof and a facing member, and comprising a liquid applying device for applying a liquid to a sheet sandwiched between the liquid carrying member and the facing member,
so that entry of the leading edge of the sheet into the nip between the liquid carrier member and the opposing member is partially initiated in the direction of the leading edge ;
An image forming apparatus according to claim 1, wherein the liquid carrier member and the opposing member are arranged such that their longitudinal directions are inclined in different directions with respect to the leading edge of the sheet at an angle other than 0 degree. An image forming apparatus comprising a liquid carrying member for carrying liquid on a surface thereof and a facing member, and comprising a liquid applying device for applying a liquid to a sheet sandwiched between the liquid carrying member and the facing member,
so that contact of the leading edge of the sheet with at least one of the liquid carrying member and the opposing member is partially initiated in the direction of the leading edge ;
An image forming apparatus according to claim 1, wherein the liquid carrier member and the opposing member are arranged such that their longitudinal directions are inclined in different directions with respect to the leading edge of the sheet at an angle other than 0 degree.

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